Friday, February 27, 2015

Rosette with the Pentax K10D DSLR


This image of the Rosette Nebula was taken in the backyard during January 2015.

Taken with the Pentax K10D DSLR with smc P-A* 1:4 300mm lens.  An IDAS LPS P2 filter was used on the lens to improve contrast.

This is not a great picture, just OK.  The upper right shows issues with framing and a green gradient due to DSS' mosaic process.  The focus is soft across the whole field, largely due to operator error.

Eventually I'd like to get the camera back into the field to try a wide target like this again.  Galaxy season is happening now and while it's fun to consider, I'm not sure if the DSLR would be sensitive enough to make much of the galactic light show.  Would be worth a shot to get the whole Markarian Chain.


Thursday, February 26, 2015

Sharpless 274 with the QSI 683

First real picture with the new camera.




As noted in the earlier post, this was a sum of RGB and Luminance data.

The RGB comes from 7 Blue, 9 Green, and 9 Red subs at 600 second durations.
The Luminance is from 15 subs also at 600 seconds.

Shot using the Stellarvue SV4 scope with flattener.

I'm happy enough with the image.  The sky isn't fully dark as there's still glow from streetlights.  I look forward to getting up to MBOSP to see how it looks different up there.

Wednesday, February 25, 2015

SH2 274 in Process


A view of the workspace in PI as I'm processing the data from SH2 274 AKA "Medusa Nebula."

I started gathering data before the new moon and up to first quarter.  Tried using 2x binning on color data but didn't like how it appeared afterwards.  Ended up using 1x binning for everything.

The windows seen here are still linear, post DBE, with just an unlinked STF for display purposes.

The RGB comes from 7 Blue, 9 Green, and 9 Red subs at 600 second durations.
The Luminance is from 15 subs also at 600 seconds.

I noticed gradients that needed to be flattened with DBE before this screenshot was taken.  The Luminance image needed to bring up the upper left corner.  This is either due to a bias from streetlights.  The RGB had a hot red spot in the middle, centered over the nebula.  I didn't think that this glow was from nebulosity as it was too evenly dispersed.  DBE removed both with minimal trouble.

At this point, I'm going to freeze the work progress to get some JIT learning regarding noise reduction in the linear state before the color and lum data are merged.

Monday, February 23, 2015

First Light


First image from the new camera a little while back.  Been putting it through the paces recently, getting familiar with how it works.  Major changes to the setup to accommodate this addition.

Friday, February 20, 2015

Focus and Tilt


The end of 2014 featured my processing the images from Calstar and with no more trips out to the field.  I did set up the scope a few more times in the back yard in October, with no other sessions due to weather and time.

One of the interesting thought experiments I followed during that time was concerned with sensor tilt.  It seemed that no matter what I did about shimming the adapter/flange interface, there was always a little bit of trailing stars in the corner.  Using the bahtinov mask and taking a picture of an open cluster quickly showed how the sensor was tilted to the image plane.  Open clusters M35, M44 (the Beehive), and M45 (the Pleiades) are always good targets for this kind of testing.

In the example seen here, the edges of the image show what the bahtinov mask spikes look like.  It's plainly visible that there's some tilt happening.

Finally, I used the depth gauge to measure each part.  I checked the distance from the glass of the flattener to the end of the T threads.  No difference at each edge.  The DSLR sensor showed a tilt of .06 mm.  I ruled out measurement error by checking multiple times.  Using the calculator for CFZ at Wilmsloastro.com, the SV4 has a CFZ of 105 microns.  This sensor tilt would most likely be lost in the allowable error.  Still, I shimmed underneath the Kmount flange by using thin layers of tape to reduce the measurable tilt to less than .02 mm.

Finally, I checked the T ring adapter.  I was surprised that it had a tilt of .11 mm.  This, coupled with the sensor tilt would be more than enough to show the skew in the bahtinov mask image.  The offending adapter was one of the two-part devices where grub screws hold the pieces together.  I checked another adapter that I've used and found it to have no tilt.  Thus, this is now the adapter that I plan to use!

I've not had the chance to test since these full changes.  Instead, I've shot the comet using a 300mm camera lens.  The tilt fix for the flange mount seems to be holding up and the star images are in focus across the whole field, given the limitations of an 80s vintage lens design.  There is slight curvature (surprising for a telephoto) but not too bad when stopped to F5.6.

In the effort to use the camera lens, I firmed up the configuration for using the DSLR to shoot widefield.  I needed to lengthen the hoses for the liquid cooling and add a dovetail bar to allow the camera to pivot.  I believe that this will be the final way I leave this DSLR.  It's firm yet movable.




To continue the testing on this method, I shot some of the Rosette from the backyard.  The data looked good, better than the struggles of trying to get comet Lovejoy.  More on this image later.

Wednesday, February 11, 2015

Good news from Lick

Check out @LickObservatory's Tweet: https://twitter.com/LickObservatory/status/565219385195765760

Tuesday, February 10, 2015

Final thoughts from Calstar 2014

On the final evenings of Calstar, I worked with a neighbor camper who was setting up gear for the first time. I'd met Wes at GSSP earlier in the year and so it was nice to reconnect. 
Carl and Wes before nightfall

He was using a new IOptron z-mount with a new QSI camera and Lodestar with a new laptop. Lots of learning to do in just a few nights! Note all the cardboard boxes in the picture above.  In this picture, everybody is all happy before the night(mare).

There were some serious challenges that night with getting the camera to talk to the laptop.  Lots of troubleshooting was done to figure out what could be done. We used the barely-there internet from Casey's phone to look online for drivers. 

The next night, the camera was able to talk just fine to the laptop and the evening's exercise of getting Maxim and PHD to talk to the mount was well underway.  Unfortunately, there were issues with getting the mount to talk to the computer as ASCOM wasn't setup.  Using the hand paddle, we slewed around to the basic stars, did alignments and got a few test images of M27 to ensure focus and framing.

During this time we learned that the Lodestar was no longer issuing guide commands.  Rather, it was issuing the commands, but the instructions weren't getting to the mount.  We checked LED activity when manually slewing within PHD to confirm that certain directions weren't working.  PHD calibration was failing, but it required so long to show the error (40+ steps) that we'd miss the error message.

As a final insult, the scope slid off the mount, damaging the adapter plate on the camera.  Things looked like they would have to go back to QSI for repairs. Frustration, gnashing of teeth, and cold temperature all combined to make it so we didn't get much time to just look at the stars on Friday and Saturday nights.

In thinking afterwards I believe that the lodestar st4 jack had been plugged into the firmware port on the mount at some time earlier. This has been known to fry the couplers on the camera. It makes sense because we saw that phd could manually issue slews only in certain directions.

I didn't get Wes' contact information, so I don't know what was the outcome after the event.

Digital Work from Calstar 2014

Here are some of the photos from Calstar 2014.

When I returned from the trip, I developed my roll of Acros but ran into a problem with sticky reels, I ended up damaging the film with light leaks and thus only one frame was salvageable. 

The e200 has a strong magenta color cast, something that I've been challenged with managing in post. 

On the other hand, the digital images worked well!







Calstar 2014 Rest of Week

When I last posted, the report of Calstar 2014 stopped with the field cannibalizing repair of the Gemini system on Thursday night.  The rest of the weekend was actually minor compared to the events of earlier days, which is why there's not much to say!

On Friday, there was a return to viewing the sun with Rich and putting the Herschel wedge on my SV70ED scope.