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.