Wednesday, October 15, 2014

Post-Calstar 2014 Wrapup: Thursday

My Thursday at Calstar was ... a bit challenging.

While it was great to learn to use the bow that Carl brought (no pictures of me doing this as far as I know) and having the clouds meant little heat from the late summer sun, there was not a lot going on.  The day was overcast in the morning and didn't break up until later in the afternoon.



The challenging bit was that I didn't power up the mounts until after dark.  Had I done a bit of testing beforehand, I would have been aware that the Dec motor on the G11 was experiencing an encoder failure.  The symptom was a jerky, incomplete slew that stalled prematurely.  Originally, I thought it might have been due to a tight gear, so I loosened the mesh a bit and that didn't solve things.  I recognized that this was an encoder issue and tried cleaning the optical discs with the puffer bulb and checking clearance.  Nothing worked.  By about 10 pm, I knew that the G11 was dead in the water.  Luckily, the GM8 was plugging away, going through a roll of E200, so there wasn't a total loss of progress.
Prior to failure!

I talked with Rich and Carl about the problem.  I knew that Casey's G11 was a push-to style, so he wouldn't have a spare motor.  Marek's G11 was sitting unused under its tarp.  I was tempted to "borrow" a motor.  We joked about how his gear could be stripped like a car at a chop shop, leaving it up on cinderblocks.  The only thing left would be some cut-rate parts, hanging forlornly at the end of a frayed cable.

It was getting late and the night was pressing on.  I finally made the decision to field strip the GM8, back convert it to the push-to motors, and cannibalize the spare Gemini motors and gear boxes for the G11.  In the dark, I spread out a sheet to catch small parts, and tore apart the mounts.  Surprisingly, the whole job only needed about 90 minutes to complete.  Everything was back to running a little before 1 am.

There seems to be a link between the failed gearboxes and the encoders going bad.  I think there's something about how the old gearboxes split open that allow the motor shaft to move and possibly collide with the encoders.  With all the cannibalism of stealing parts back and forth between mounts, the G11 currently has 2 good boxes and 2 good motors.  I dropped the slew rate on the G11 down to 500 as well, reducing the overall speed at the benefit of a lower noise and possibly a better chance to avoid stalls or gearbox breakage.

I did miss the luxury of using TheSky to point the GM8 to the part of the sky where I wanted the film shot to be.  I found that if I was patient, I could use the red dot finder well enough.

The rest of Thursday night into the wee hours of Friday morning was pretty much uneventful.  The camp got very quiet after 3 am.  At 5 am, the morning twilight was starting and thus I wrapped up the efforts.




Tuesday, October 14, 2014

Post-Calstar 2014 Wrapup: Tuesday and Wednesday

I attended Calstar 2014 from Tuesday to Sunday.

Packing for these trips is becoming more of an exercise.  I only use the Prius to travel and so everything has to fit into the car.  There are a lot of small hiding places all over the passenger compartment.  I try to use every bit of space that I can.  For example, I put 1 gallon water jugs under the front seats.  I can easily fit 5 gallons of water in this space.  All the tarps and sheets for the tent go into the foot space in the back seat and the tent fits across the gap.




In the future, I'd like to get a roof-top pod for the Prius to hold the tent and clothes, allowing better management of things inside the car.  As it is, there is no room for a passenger or their supplies.

I arrived just after Rich Crall and then Carl Larson showed up a few minutes later.  Tuesday was spent setting up, polar aligning, and chatting in the quiet evening.  The skies were the clearest on that night compared to the rest of the weekend.  Super dark, very clear and steady.  I worked on some Acros and a couple of digital targets until 5 am.  The Prius purred every 30 minutes or so, depending on how cold the temperature dropped.

Wednesday morning Carl needed to change a battery on his AstroWagon.  This required dropping the battery box and removing most of the wiring.  The weather was nice, no wind, just enough sun to warm things up so that it wasn't chilly.




Acorns were dropping like bombs -- and they hurt when they hit!  The deer were emboldened because of the acorns and we gathered and tossed the extras to the animals when they got close.

Later in the day, people started to filter into the site.  Marek showed up early to set up his tent and unload the scope.  He wasn't able to return until Friday.  Setting up the gear early saved him a lot of time.  Phil Manela and Peter McKone also arrived on Wednesday.  Dan Wright showed up late that evening with the UHaul van.





Wednesday night was a bit of a bust.  It was super clear earlier, but clouded up shortly after 1 am.  Dan showed up a little after midnight and was able to see a few stars before they went away.  Without the stars, there was little reason to stay awake and I got some extra sleep.

Monday, September 22, 2014

Calstar 2014: Forecast Looking Good


From WeatherUnderground.

Looking pretty good for the goal of taking pictures through the night.  There's a little bit of weather that may come to northern California on Thursday.  It shouldn't effect the night sky.

I'm as ready as I can be.  I was able to test the Gemini 1 system on the GM8.

It's pretty finicky, or, it was.  I've replaced the clutch pads which fixed a lot of the problem of jamming DEC and RA.  The old pads must have been thin enough to lock up the ring gear or shift it too far, causing binding with the worm gear.  I replaced the motor reducing gearbox on the DEC axis.  This seemed to eliminate the whole problem with that axis completely.   The old gearbox was bad, broken either by high torque or by collision.

There are still nagging problems that will either be a non-issue or will make me replace the motors in the field and go back to a push-to configuration.   Also, two motors are bad.  One has a bad encoder and is non-usable.  The other is very weak and pulls a lot of current when in use.  It probably has a short in some coils.  It is too weak to use in RA and is only serviceable in DEC at very low slew speeds.  I've set it to 400 - which is half what the default is for the GM8.  I disassembled the motors to see if I could take the guts from one and put it on the encoder for another.  Unfortunately, I am unable to perform this task.  Once I'm back, I'll have to scrape together the cash to buy two more motors and swap from the G11 to the GM8.  Losmandy is only selling the high torque motors, so I'll put the new ones on the G11 and use the old ones on the GM8.  I'll probably leave the slew speed at 400 to keep things putting along.

I packed the car today excepting the last few clothes, the computers and books, some lenses, and one last Pentax 67 body.  If I keep loading this car so heavy, I'll really need to invest in a rooftop pod.  There's no room for a passenger at the moment.

I've managed to pack 5 gallons of fresh water with two gallons in the freezer to keep food.

Friday, September 19, 2014

The Countdown to Calstar 2014


I plan to make the most of my time at Calstar this year, shooting digital and film.
Evening Twilight is 20:30
Morning Twilight is 05:30

Digital:

SH2 129 - transits 22:06
Wizard Nebula NGC 7380 - transits 23:41
Continue the work on Sadr region (centered on SAO 49578) - transits at 21:18
SH2 171 - Transits 01:00

Later work might go after the California Nebula or Heart and Soul or Pleiades


Film:

Color (E200) at 200mm F5.6 for 1 hour
IC 1396 (transits 22:33)
Summer Triangle including Sadr, Deneb, Veil.  Need at least 3 - 1 hour exposures at F5.6 (transits 21:30)
Heart and Soul with Double Cluster (transits 3:30)
California to M45 Widefield (transits 4:40)

Black and White (Acros) at 300mm F5.6 at 40 minutes to 1 hour
Triple Cave (E nebula or Barnard 142) (Transits 20:35 - too low at 23:00)
Cetus widefield (Center on Zeta Cephus - transits 23:00)
Cygnus widefield (Center on GSC 3155:1976 - transits 21:00)
Perseus widefield (Center on Barnard 5 - transits 4:40 - start no earlier than 2 am)
Taurus widefield (Center on Barnard 213 - transits 5:14 - start no earlier than 2:30 am)

Given the need to center on specific targets, I may re-install the Gemini 1 on the GM8 so that it can be used to slew to a specific region.
If I have any extra time to do a trial run at home before Calstar, it will be to validate the installed work and refocus the ST80 with SSAG.  Once I do this, I may create a series of FITs with the SSAG to act as "bookmarks" for slews.

My plan is to arrive at Calstar 2014 on Tuesday, setup and polar align that first night and get some Acros started.  Wednesday and Thursday night will be all E200.  Friday will have a return to Acros, and Saturday will clean up whatever is left.

Stripping Down the Gear

Reducing the Load on the G11


I've been using a side-by-side imaging setup on the G11 for about a year.  In this time, I've found that while the extra mass helps stabilize the guide movements, the tradeoff with additional weight is a setup hassle.

When I put the water cooling system together, I wanted to put the Orion miniguider to work.  I'd tested it before and once the little telescope is properly focused with a fully calibrated SSAG, it shows a lot of stars, ideal for guiding.  Also, the resolved frame is nearly the same size as the APS-C sensor on the SV4.




Thursday, September 18, 2014

Sadr in Cygnus HaRGB


Taken in the back yard during September while I was testing before Calstar 2014.  Fairly happy with how this photo turned out.

Monday, September 15, 2014

Epoxy to the Rescue

Fixing the DSLR (again)

Smeared Sadr

I had some problems recently while testing in the backyard with the low-temperature hot melt glue inside the Pentax K10D camera.  The old glue decided that the heat of the September sun and the never-ending pictures every night was enough to let go.  Thus, the smearing stars came back.


Saturday, September 13, 2014

Losmandy G11 Gears and Stiction

I've been peeling onions in the backyard these past nights.  Based on some questions from Marek and Carl, they were experiencing strange DEC behavior when guiding near Sadr during August.  I felt that much of the problem was due to tracking through the Zenith where scope balance is most ineffective at keeping DEC meshed.

Since I'd moved onto the problem after handling some of the earlier questions about Gemini systems and getting the camera cooling nailed down, my current target is the same region as the problem area.  I quickly saw similar DEC jumping as bad as what Marek was experiencing.

Friday, September 12, 2014

Upgraded Camera Cooling

Water Cooled DSLR


In the past, I've been cooling the DSLR for astrophotography by using a peltier device with CPU style fan heatsink.  It's been working OK, but I've not been getting the best performance out of the peltier devices because the waste heat simply hasn't been removed fast enough.

I knew that the real performance gain would come from better management of heat.  Also, using a single peltier device does not drop the temperature enough to cool the camera.  Thus, I've been playing with stacked cooling chip.  However, these stacked devices will generate a large amount of waste heat on their own, requiring even more heat management.

I use a water cooling system on my home computer, so I was already familiar with the requirements for fluid flow, pumps, heat sink sizes, tubing, etc.  After doing some more research on the yahoo group for DSLR Modifications, I settled on some hardware.

I started with a collection of parts from FrozenCPU:
Swiftech MC350 pump
120mm radiator and fan and mounting kit
 Swiftech Apogee CPU waterblock
1/2 inch tubing with anti-kink coils



Wednesday, September 10, 2014

Full moon backyard testing

Preparing for Calstar 2014 

I've set up the gear in the backyard to test a few problems.  I set the goal to identify the issue with flexure, to collaborate with Carl and Marek to find and fix the problem experienced with DEC guiding, and to push the camera cooling to the next level.

Monday, August 18, 2014

Fixing Collimation on the SV4

In the previous post, I wrote about how images taken at an earlier session showed collimation/centering errors.

I picked up a laser collimation tool to help with the exercise of centering the focuser on the SV4 refractor.  The focuser has been removed from the scope several times over the last year or for flocking.

At the time I tested, I noted that the reflected dot from the laser collimator was offset by a significant amount.  With some judicious tweaking, I was able to keep the dot centered as the grub screws were tightened.  To seal the final adjustment, I ran a tiny bead of blue locktite along the seam to act as a removable glue.

Also while the focuser was off the scope, I removed the flocking paper and painted the internals with the flat black paint.  This worked better for the other metal parts and doesn't leave fuzzy bits to cause problems later.

After the focuser was centered, I figured that I'd try to identify issues of tilt with the DSLR.

I've read the method that Starlight Xpress suggests to fix tilt on their cameras.  The idea is to put the camera into a rotatable system, point a laser at the sensor and then note the position of the reflected spot as the camera is rotated.  If the sensor is tilted, the spot will wobble and wander as the camera is rotated.  Minimal movement will show a sensor that is perpendicular to the axis of rotation.


So I made a jig from a collection of stuff including the flattener, t-ring, and 2 inch drawtube extender with a set of 3-point rings for a 50mm finder.



Once I had the camera in place, I lined up the laser pointer.




Reflections of the laser were shined on a far wall, about 12 feet distant.  The initial test showed wobble of at least 6 inches.  After shimming, the deflection was reduced to less than 1 inch.  Not too bad from just a little collection of parts!




Thursday, August 7, 2014

Centering/Collimation Error

While reviewing the frames from the M8/M20 project, I noticed that all had a region in the upper left that was blurred.  The stars were streaked outwards and didn't look good at all.

So I ran CCDI on an example and this is what it shows:


When I did some measuring, it appears that there could be two things happening here:
Tilt and Centering.

Tilt makes sense because I've noticed the way that focus gets better when the camera shifts position.  I'd shimmed the camera body to avoid this whole issue.

Also, Centering makes sense, too, since I've had the focuser off the telescope several times.

So I put a collimation tool on the scope.  When using the Feathertouch-supplied 2 inch to 1.25 inch adapter, there was a slight deflection of the reflected laser.  I loosened the focuser and shifted it to show a centered dot.  What's annoying is that this centering wasn't uniform for the adapter - when rotated, the reflected dot wanders.

Tilt is easy to remedy.  I'll have to shim the camera adapter by wedging small bits of metal in the flange.

The final challenge will be to test and get some results from stars.


Saturday, August 2, 2014

Trifid Nebula from MBOSP

This is crop of the M8/M20 project.

M20 at MBOSP July 2014

The total data set is 22 lights - a 90% stack gives 19 lights.  All were done at Montebello over three nights: July 23, 29, and 30th. The crop was made as a custom rectangle in DSS and a 2x drizzle stack.  In processing in PI, I was happy with how it looked, but on importing to LR, the blue and red were garish so they were toned down a bit.

There were some general issues along the way. 

After the first session, I went up again on the 26th, but the weather didn't cooperate.  This was fine, because I learned that the shutter and mirror had let go because of the heat in the car.  The low-temperature hot melt glue had lost the ability to hold the small parts in place.  Thus, I had to fix the problem.  I went with small drops of cyanoacrylate adhesive.  It's a permanent solution and that's fine with me.  If anything, it reminds me that the choice to make changes to the camera to ONLY run as an astro camera is OK.

On the evening of the 29th, I found that something was amiss with the USB cable.  The tethering software wouldn't see the DSLR and the SSAG wasn't connecting. Very strange!  So, I checked the USB repeater cable and found that it was dead!  Luckily, I brought the old USB hub I had sitting around.  That worked OK - although it didn't like being powered by 5V.  This might be the reason why the serial cable stopped working properly.  I've ordered replacement parts.

On the evening of the 30th, I wanted to secure this replacement hub as the cable joint is weak.  I used a bungee ball and unfortunately, that got jammed by the DEC motor.  Only after several attempts to unbind the DEC axis gear did I realize the true problem.  Major disaster averted, lost about 1 hour under the stars.

Also on this evening, I noticed after finishing the M8/M20 target - and near the end of the night - that the cooler wasn't running.  Had to wiggle the connection with the powerpole to get it running again.  Later in the morning, I inspected that connector and saw that the metal contact wasn't properly seated.  This was likely the source of the problem that I'd noticed for some time.  Now it's fixed and all is good again.


During these nights I was running the dual setup, just like at GSSP.  The GM8 was plugging away with the Pentax 67 camera on it.  I put the IDAS LPS filter on the 200mm lens and let it capture several parts of the sky, repeating some of the targets missed at GSSP.  Since the mosaic worked so well in PixInsight, I thought it would be a good thing to continue.

I'll be scanning and posting those images later.

Thursday, July 24, 2014

Lagoon and Trifid at MBOSP

Last night was another great evening at Montebello.

We were missing a few critical team members but soldiered on.  Casey brought a bunch of food and a table and there was a lot of chattering happening. 

I finished up the roll of E200 leftover from GSSP, so that's going off to the lab today.

The digital project was a tight crop of M8 and M20 in the same field of view.  Managed to get 9 good frames.  Quick calibration with 11 darks, 24 flats, and 64 bias in Maxim and Kappa Sigma Clipping stack of 90% in DSS gives this view "autostretched" in PI.


Yep, that's a good set of data.  I hope to add another 9 frames before the weekend is done.

Friday, July 18, 2014

Post GSSP Maintenance

When I came back from GSSP, I had a small list of things that needed to be addressed:

1. Flaring was an issue on some of the digital shots.  I believe that this returned because of the failure of one of the pieces of flocking material.  This same flocking paper had fallen onto the shutter mechanism of the DSLR and caused it to die. 
To solve the flaring problem, I wanted to try painting some of the shiny parts with flat black paint.  The spray paint I'd used on the plastic garage sale signs to make extra long hoods seemed to be flat enough and did a nice job of sticking to plastic.  I sprayed the inside surface of the Kmount/T ring adapter.  I also sprayed a bit of paint into a makeshift palette of aluminum foil and used a small brush to carefully paint the anodized metal of the SSF6 flattener. Lastly, I touched up the inside rim of the Kmount flange to hide any shiny metal.
2. Because of the dead shutter on the DSLR, I wanted to fix the mirror in a locked-up position as well.  The intent was to reduce the possibility of dust movement during flats and other images. 
While I had the camera off the scope, I hot glued the mirror up.  I also noticed the bumpers that the mirror rests upon may cause issues with either flats or possible diffraction.  If I see more evidence, I may melt off these bumps with a hot screwdriver.
3. Lastly, during GSSP, there were some strange issues with COM ports not triggering the end of a shot sequence.  Thus, I had to test whether it was a cable or port issue.
I tested a different camera and showed that there was no problem with a short cable.  Then I used the long cables and saw no problems.  Lastly, I added the imaging camera and saw that everything just worked.  Not sure what was the cause of the original problem.  It may come back at MBOSP. 

To do:
1. Paint the inside of the Feathertouch focuser.  Will require removing the focuser from the scope and reattaching, possibly collimation issues.
2. Replace a peltier device with one with more capacity.  Requires partial disassembly of the cooling system to put it into the stack, plus additional darks for comparison.
3. Get heavy, short extension cords for power management; 10 gauge is ideal.
4. Recharge dessicant and clean optics as needed.

New procedure to add to my normal work:
1. During setup, I noticed that the Garmin GPS puck for the Gemini 2 is highly magnetic.  The idea is that it would be able to be stuck to a metal plate for use - usually a car roof.  However, this is probably what is throwing off the compass readings, making it difficult to properly set up for north.  I want to find a way to affix this GPS device in such a way that it does not impede with finding magnetic north.
2. While at GSSP, I borrowed a neighbor's thermometer - the kind where you point a red laser dot at a subject and get a reading.  The question that I had at the time was how much heat was leaking into/from the DSLR during cooling.  I'd always considered that the dovetail connection was acting like a heatsink and was bringing heat into the system, robbing effective cooling.  During GSSP, I found that the camera body did show a consistent temperature and that the dovetail was cooler, but not any cooler than the rest of the telescope. 
The interesting thing to learn was that this device gives a specific reading on the telescope body.  Thus, I can start to figure out what the best setting and location for dew heater straps will be, plus understand when temperature shifts occur, letting me know when a need to refocus would be.

No pictures for all these steps, just text.


Monday, July 14, 2014

Some E200 Slides at GSSP 2014

The last two nights at GSSP 2014 I was using one of the Pentax 67 cameras to work on two rolls of Kodak E200 film I'd brought.  I was able to finish one roll with minimal issues, but the second is still in the camera, half complete.

One of the exercises I'd done to help use the film while under the stars with good transparency and darkness was to get multiple exposures of the same region of the sky.  Adin, CA does not have much airplane traffic, so being vigilant and watching for streak-causing planes was not as much of an issue. 

To fill the experiment/challenge, I snagged 3 frames of the Sadr area in Cygnus.  The field of view with the 200mm lens allows the whole complex of Ha nebulosity to shine from the North America Nebula through to the clouds around and past Sadr.  If I offset the frame a bit more, including the Veil would be possible, too.  Would be very easy with the 165mm lens.

After "scanning" by taking pictures of the negatives on a light source with the Pentax K10D camera with SMC PENTAX-DA 1:2.8 35mm Macro Limited lens and AF540FGZ flash in PTTL mode, I had pretty reasonable files to use.  Flatness of the film was an issue in one case and I had to flip it over.  Also, I kept the film in the protective contact sheet/sleeve as it seemed to not be an issue.  However, what was an issue was flare from the light spill around the dark areas of the slide.  I may need to rescan by masking off a piece of glass.

Brought the files into LR where I fixed keystoning from not having the film and camera parallel.  Then exported to TIFF files and ran PixInsight's Gradient Mosaic Merge tool.  Very slick tool and it gave really good results!  While in PI, the picture was increased in contrast and saturation slightly before working in LR again for vignette work and slight white balance tweaks.

Sadr region on E200 at GSSP 2014
Sadr region on E200 at GSSP 2014


In the end, I like the picture and am pleased with the results.  I can see now that future work will probably have 3 or so images of the same area to improve film grain results.

Digital work at GSSP 2014

Friday and Saturday night (June 27 & 28) were busy for my cameras at GSSP.

Friday night had some clouds obscuring most of the eastern sky while the south and west remained clear-ish.  Luckily, the clouds that did appear were black and wouldn't mar any exposures, so long as the autoguiders tracked through the murk.

The Pentax K10D banged away at the snake nebula through some gaps in the clouds.  Being in Adin, which is far north of my normal position, this target rides low in the sky.  I was concerned about the stars being soft.  However, so long as the tracking was good, the data gathered was perfect.  Stars were tight and small.  Once home and after I'd gone through the black and white film, I was able to process the digital data.  Notice how the flare from a bright star is entering the shot from the left.  I think it's time to paint the T to Kmount adapter.

Snake Nebula at GSSP 2014
Snake Nebula at GSSP 2014


Saturday was super-clear and great and thus I was busy from twilight to twilight.  I had to spend more time at the start of the evening because polar alignment had sagged on both the GM8 and G11 due to the soft ground.  Altitude had drooped by 4 arc minutes on the G11, somewhat less on the GM8.  To take advantage of the good skies, I shot the Veil Nebula.  However, I did not take the time to check focus again as the temperature had dropped, so all the subs were slightly blurry.

Veil Nebula at GSSP 2014
Veil Nebula at GSSP 2014

In both shots, I used the HEUIB-II filter, which is a UV-IR filter with a notch just above 650nm, helping to remove the red skies that my full-spectrum DSLR is prone to give.  The filter helps dust clouds show up nicely. 



Friday, July 11, 2014

GSSP 2014 Slideshow

Here's a quick link to the whole collection from the recent star party. Since it's linking directly to the flickr set, as I update the album this slideshow should automagically extend.

Tuesday, July 8, 2014

Kodak TriX 400 and Diafine at GSSP

I shot two rolls of TriX at ISO 1000 for processing in Diafine.

They turned out pretty good, even with "digitizing" with an aging Pentax K10D.  Click on the first picture to see a larger photo window.

Friday, July 4, 2014

Clouds and Rain at GSSP 2014


When I arrived at the site, I'd already driven through some rain so I was expecting things to get worse before any stars might have appeared.

Got the tent set up quickly and my supplies unloaded and left the scopes inside the car.  During the Disorientation session, rain came down hard.


Later that night, the rain came again in earnest with lots of wind.  There was 1/4 inch of rain, a lot for late June weather.  A little bit of the rain made its way under the tent and remained sandwiched there between the tent floor and the tarp.  There were wet spots for the rest of the week.

Thursday had some good chances to get around and take nice pictures during the swap meet and among the vendors.  The daytime sky started to suggest that scopes could be put up at least to try for polar alignment if the clouds cleared a bit, however, the clouds never really parted that evening.  I set my alarm for 1 hour intervals to check for gaps - nothing happened except a few bits of rain at 1am.

Friday offered more interesting puffy clouds with clear blue sky behind them.  I tried some shots on Acros with the Orange 21 filter.  On developing, I realized that a wratten 21 filter needs 4 stops of compensation to properly expose with this wavelength.  Everything was underexposed by at least 2 stops.  Live and learn.

Was able to polar align and get some shots done on Friday, including several images of the Snake Nebula, some polar star trails on Ektar, and some shots on E200.  The skies had lots of black clouds moving around, giving a challenge to getting good exposures.

Also had some issues with serial ports and triggering the DSLR.  Seems that running the shutter off the com port was starting exposures but not stopping them.  Had to fall back to USB control via the tether software. Did some trouble shooting with removing unused COM ports and was able to better control the shutter for short exposures, but longer exposures cause issues.

More pictures coming soon.  I've scanned most of the TriX I shot, have two more rolls that will be developed in Diafine which will need to be scanned the old-fashioned way as I'm finally giving up Dan's scanner to Casey.


Wednesday, June 25, 2014

GSSP 2014 Weather Forecast

Looking pretty soggy for the next 24 hours. I expect to run through some rain on the way up.  At least the car will be clean before I hit the muddy field.  Will be interesting to try to set up the tent for rain.  Still, the chance of rain is fairly low - it peaks at about 33%.


From Weather Underground.

M13 from the Backyard

M13 June 2014

This image was taken under a deadline to get ready for GSSP 2014.

Monday, June 23, 2014

Camera Repair

Problems never cease! 

In working to solve the issue with the trailing as noted on an earlier post, I set up the gear in the back yard and waited for some dark, clear skies.  In waiting, I set up the camera to record darks.

Unfortunately, during these 2 nights of waiting, a piece of the flocking material dislodged and wedged against the shutter, preventing it from opening.  Not an issue for darks, but it meant that the electronics to open the shutter are dead.

The mirror flaps up and down, but the shutter remains closed, no matter the setting. 

There's not enough time to get the camera repaired before GSSP.  Thus, I've done the drastic step of putting a dab of hot glue on the retracted shutter to fix it into the open position.

It works now.  Since the timing of the exposure is now set by the mirror position, short exposures are extremely limited in their ability to properly expose.  Taking flats requires reducing the light level vs changing the shutter speed.

First tests seem to work OK.  The dragging issue is not seen, so it appears that the problem was due to snagged cables.

Thursday, June 19, 2014

JIT Problems

Just in Time for GSSP, I'm beset with problems for fixing!

Last night at MBOSP, I set up the G11 and tried for a basic target M13.  Something was amiss.


It appears that maybe cables snagged?  Maybe something was unplugged, not sure at this point.  The Maxim logs show that guiding stopped after just 15 minutes.  No errors regarding star faded, it's almost as if Gemini stopped running.

The only other clue that I saw was that when I went to shut down Maxim at the end of the evening, Maxim showed that the mount was already disconnected.  However, I was able to issue commands to park via the PC-based control panel.

Will be testing tonight to see if I can replicate the error.  If the problem doesn't show again, I'll assume that it was a dragging cable.

Monday, June 9, 2014

Orion ST80 Collimation

I've been following some tips online regarding tuning up the Orion ST80 budget telescope.
Here are the links I've been following:

Major steps taken:
  • Blackened the edges of the lenses.  Pretty easy, just remove the retaining ring and drop out the lenses.  Darken the edges with a Sharpie.  
  • Cleaned the lenses with microfiber rag with Methanol.  This is my preferred method for lens cleaning.  Does a nice job of removing fingerprints and pollen.
  • When inserting the lenses, I made sure that they were seated squarely by rapping the scope body while holding it upright.  Gravity ensured that the lenses rested solidly against the cell.
  • Collimated using airy ring test with my 7mm Nagler.  Even with two extension tubes, it didn't have enough travel to bring it to focus, so I had to let the extensions out a bit more.  I found that the optics were pinched even though I had them loose earlier in the day.  Temperature is a big factor!


Next major step will be to remove/cut/grind off the screws that protrude into the light path.  When looking at the bahtinov mask image, I can see lots of diffraction "curls" appearing.  I don't have a method to grind the screws, I may try fitting a different screw/bolt or press a dremel into service.

Future work may be to get a GSO focuser to replace the stock unit.  This would allow using a reducer/flattener on the scope, further tightening star images.

Already seeing improvement in star images.

Note how close the FWHM value is to "perfect" for this scope as referenced at http://www.calctool.org/CALC/phys/optics/spot_size

Friday, June 6, 2014

Killing time with the ST80, 85mm lenses, and GM8

Doing some practice work in the back yard as I prepare for GSSP, I've been fiddling with trying to get the most from what will be the film setup.

So far:

  • Tested polar alignment within PHD2 (2.2.2a) that it works well without an ASCOM mount.  Just point it at the proper parts of the sky, set the approximate values in the Drift Align tool within PHD2 and go.  The rest of the method seems to work.  What's nice is that the way PHD2 now has equipment settings that are savable and selectable, notes from the respective Drift Tool are persistent.
  • I have seen the return of a slow, consistent RA drift.  Considering that I've removed the three-point rings on the ST80 in favor of the clamping rings, I'm thinking that what's happening now is a refraction-based compression and expansion of the scene as the scope points higher into the sky.  Will need to run some math and see what the expected distortion should be and if it checks out.  Also, it would be worthwhile to check in other parts of the sky to see if the apparent movement tracks via RA or via refraction.  Testing near the pole, but low in altitude would be worthwhile.
  • Tightened up the DEC backlash that was causing issues with calibration.  Checked to ensure that the grub screws attaching the motor and worm gear were tight, then watched the spinning gear vs movement in the eyepiece.  Turned out that the backlash problem was irrespective of TVC or motor connection play.  What was the real problem was gear lash between the worm and the ring.  Tightened up this play via repositioning the worm blocks and offsetting the DEC balance.  Now the mount will move in DEC within 5 seconds of a change in direction.
  • Tested the performance of a couple of lenses.  Last year I picked up the smc PENTAX-A* 1:1.4 85mm lens for K mount.  I also had the S-M-C Takumar 6X7 LS 90mm f/2.8 lens.  The K mount lens performs well at F4 - sharp to the corners and minimal fringing once it's in focus.  I tried putting the B+W 486 filter on it to control the fringe, however this introduced star flare.  In reaction, I tried the medium format lens with an IDAS LPS P2 filter inside the adapter.  After a long time attempting to focus the 67 lens using the bahtinov mask, I was disappointed to see that the field flatness of the lens left a lot to be desired!  Also note the red doughnuts visible in the 67 lens image.  This was shot on a non-converted camera, so it seems the unfocused starlight is a problem even before the NIR range.
Upper left corner at 100%

Vega region, near center of FOV
Final testing to complete on the ST80:
  • Continue adjusting lens cell of the ST80 to improve star images for the SSAG.  I will loosen the holding screws on the lens cell and try tilting it to improve the out-of-round patterns of the stars.
  • Test different filters on the SSAG.  I have just a few available in the 1.25'' size.  Baader Moon and Skyglow, UHC, Baader Contrast Booster, Yellow, and Red 25.  The yellow showed some promise, but not as good as I'd like.  I think it was passing too much NIR.  The Moon and Skyglow filter has a built in IR block, so it should work well.

Wednesday, June 4, 2014

GM8 No Longer Goto

I removed the Gemini 1 electronics from the GM8 mount and now it's a simple push-to GEM.

I had to adjust the RA gear mesh and tighten the motor to worm attachment.  Everything is working smoothly now.  I've also removed the 3-point rings on the Orion ST80 in favor of solid rings.  They grip nicely and there's no slop.

There's a new SSAG in the mix (old style).  I did the same maintenance that I'd done to my earlier SSAG; removed the t-thread plate and hot glue the edge of the circuit board to the frame.  This removes any possible flex within the camera.

I'd done some work on the ST80 as well.  I removed the lens cell and blackened the edges of the lens with a sharpie.  I'd also over-tightened the lens cell and there seemed to be some pinched optics.  Also, instead of using a UV-IR filter, I'd opted for a yellow filter!  I've been very pleased with the star images and how well the focus can be made.

With all the work, I set up the mount to track Vega/Lyra.  Note the scatterplot.  The horizontal band is RA and shows the range of the periodic error.  I did turn on PEC training.  


Monday, June 2, 2014

Prep work for GSSP

GSSP is coming in just a few short weeks. 

I've been recently fixing up the gear to try to do a two-mount setup, learning from Calstar where the GM8 with Gemini 1 didn't work well at all.

Went to MBOSP last week and tried out the GM8 with Gemini 1.  It exhibited signs of a fatal error in the encoder chip on the main board.  When the mount powered up, it would slew uncontrollably.  Swapped the cables and motors with spares and replaced the CMOS battery twice.  No signs of improvement.  I've sent a message off to Losmandy about what repairs can be done to this old device.

I converted it back to the digital drive system - the non-goto setup that it had from the factory.  The DDS does not use ASCOM and it has no understanding of where it is in the sky.  Nicely, I've been able to keep using the PHD2 drift align tool so long as it is forced to calibrate each time.

I did see that the conversion didn't go as smoothly as it should - the RA worm slipped and needed to be tightened.

Last night, I went up to MBOSP again and was able to figure out a pretty good power system.  However, I managed to break the Gemini 2 Hand Controller.  One of the tactile buttons stopped working, so I followed the procedure to open up the device.  The LCD shattered in the process.  I've ordered a replacement controller and am asking Losmandy about repairs.

In the meantime, I can still use the G2 without the HC.  It will require a lot of running back and forth to click on buttons on the laptop.  Still, if I'm not able to get a replacement prior to GSSP, I can still use the system.

I'll be practicing again with the old GM8 DDS in the backyard a few days to see if the tracking is good.

Wednesday, May 14, 2014

GSSP 2014 is coming

Making my shot plan!


To continue the success of the film work last fall at Calstar, I'm planning to bring some film to the event.  Last time, I brought rolls of Acros and E200.  I worked through two rolls of each for star fields with just one camera.  The sessions were grueling and required dedicated attention to the camera the whole night, much longer than I'd originally planned.

For this coming session, I'd like to split the effort over two camera bodies so that I can shoot different focal lengths at the same target with different emulsions.  The idea is that I could shoot Acros at 165mm and E200 at 200mm.  Or some other variation. 

Ideally, the digital target would be the clouds of Ophiuchus since it would be well placed.  Getting a whole night on that target would be great.  Another option would be to revisit the areas around Sadr.

What's important to this goal is to ensure that I can break the digital and film into two platforms.  At Calstar, I had significant issues with running the second platform for film, mostly because the Gemini 1 system didn't like the low voltage and polar aligning with the Mak was painful at best.

To be tested in the coming weeks:

Run Gemini 1 (on the GM8) at 12 V to see if it can track and perform OK. 

Run SV4 with mini-guider for autoguiding to see if it can track and perform with no flexure.  Advantage is that this will allow the SV70ED to be used with the Nexguide device for automated guiding for film.

Will need to confirm side by side setup for film that it works and is stable. 

All of these "works" and "track" and "perform" conditions require a night or more of testing.  Luckily, I can do some of this in the back yard. 

Friday, May 9, 2014

Pentax Flashes

Learning about old kit


Today I learned something new about some flashes that I've had in my collection.


Wednesday, May 7, 2014

Drift Tool Android Development

Spreadsheet Development

For some time, I've been using a spreadsheet I made to figure out if my polar alignment is good enough to prevent field rotation.  This was done as a part of the effort to beat flexure.  At the time, I didn't fully realize how much of the seen drift was due to field rotation vs differential flexure.

Friday, May 2, 2014

Whale of a time at MBOSP

So I went up to MB and braved the elements two nights in a row to test the backyard exercises.

The weather was clear and cold once the clouds blew away.  First night was strongly windy, but consistent wind without being too gusty.  It was also a dry wind and it was cold - low 40s F.  Second night was wetter, more dew, less wind and not as cold (50F) but the wind was aloft - seeing was bad.

Both nights afforded a good chance to test a few things: newly calibrated SSAG showed clear, dark background with lots of stars and few hot pixels, dew shield/hood did a good job of keeping stray light from the camera and dew off the optics, and power system kept everything running with good volts.


Tuesday, April 22, 2014

Beating Flexure

Backyard Trials Show Promise


One more night under the backyard stars shows that the modifications made for the astrophoto system on the SV4 are proving to be more than a fluke.  The results from a second night give very good values on differential flexure.  Once I can replicate these results in the field, I will say that the challenge was beaten.  For now, I'm documenting the success so far.

Sunday, April 20, 2014

Best Results Ever

Flexure Possibly Fixed?


The image shows the results.  Pretty good and it blows away previous work.  There's still a tiny bit of wobble in DEC, but that's another task altogether and it's fully within the range for acceptance.

Finally got the scope set up last night after work done earlier in the week.  Spent extensive time getting good polar alignment with PHD2.  The readings on the drift tool had results under 1 arc minute for Alt and Az.  Drift was within the 1 arc seconds per minute range as needed for precise work.

Everything worked smoothly.  I was able to get the SV70ED with the Televue FR to a precise focus and then locked down.  Moving the star to the center of the field didn't require much effort and the star images remained nice and round - no oblong smears like I'd been struggling with in the past.

Used the mount at the default sidereal rate rather than the custom rate I'd tried before.  With autoguiding, I'm not certain that the custom rate was effective.

Focus on the DSLR did shift slightly over the course of the evening.  This is something that I expect to happen and it's not surprising.  In the field, I'd check focus a few times during a session and it's only because I'm at home where I want to go to sleep is this a missed step.

I tried using the Pinpoint Guider Calibration plugin on Maxim and was annoyed that the Imaginova control window for the SSAG was overlaying the plugin control panel.  This is unavoidable as the two panels probably come from the same resource, so the positions are locked together.  I also tried the Multistar guider and was unable to get it to work for me.  I think that the SSAG doesn't have clean enough star images to make it worthwhile to use.  Many times I am unable to see the stars that Maxim ends up using to guide.  The stretched field is just too noisy to pick out the proper stars.

I've also re-enabled pulse guiding over ASCOM.  I'm ditching the ST4 cable from the SSAG to the mount.  The way I read the information about pulse guide is that it gives specific guide information to the mount without having to wait for start/stop signals that could be interrupted.

Great results in the end!  With the guider chugging along and giving super results, everything just worked!  Looking at the graph above, the jump after the first few images is because of playing with the multistar guider plugin.  For a while the scope was unguided.  Everything afterwards seems to be as good as I've ever seen.