Radio Shack 13.8v 3 amp DC Converter-Power Supply REPAIR - Radio Shack recently recalled these DC
power supplies because the power leads were incorrectly plugged into the PC board. Using the image below, remove the cover and make sure you plug the Black(Line) wire onto the spade labeled "L" and the White(Neutral) wire onto the spade labeled "N" and then you are good to go.
DISCLAIMER: Do this at your own risk.
Cracked Lens on Upgraded ST-402ME - I just received my ST-402ME back from SBIG Friday and had first light with it Sunday
night. Found major banding across the field of view. Opening the camera revealed that the CCD lens window to the sealed chamber is cracked. Don't know whether UPS mishandled during transport or error was made upon reassembly.
Below Left) First Light -- Post Cooler Upgrade on ST-402ME -
Noticed this when taking this first 20sec image at -20C. Raw, no dark frame subtraction.
(Below Right) ST-10XME First-Light after guider relay repair. Seeing was very poor and I had a
hard time keeping the guide star from fading, but the repair appears to be good on the ST-10XME.
Mount-Imaging Issues
Below are a portions of; first a 10min unguided ST-10XME image and, second a 20min guided image of IC1848 in the NNE quadrant of the sky. Both were taken at 384mm focal length on my MI-250. Guiding on second image conducted at 660mm 2x2 binning with an ST-402ME.
Below are:
-
Images of error/flex
-
PemPro periodic error charts of each axis.
-
Image of additional 3-point ring to address flexure issues. This should help significantly, but will it fix all? Time will tell.
Correction - Images below were previously rotated incorrectly. This vertical orientation is now correct. RA is left-right and DEC up-down. Error appears to be in DEC. Sorry about the mix-up, ... guess that happens when you get
thinking too much! <VBG>
(below) 10min tracked only
(below) 20min guided
PEC OFF - Periodic Error by PemPro -- RA on left, DEC on Right
PEC ON - Periodic Error by PemPro -- RA on left, DEC on Right
I added an additional 3-point ring to the TMB80/480 in order to steady/handle the extra weight of the CCD and reducer. This is a 160mm ring that I had sitting around and will be replaced by more appropriately sized 90mm ring whenever the
backorder gets here. I replaced the Delron tips with a 1/4" fiberglass rod to make this quick-fix work.
|
Not So Par-Focal Filters - When I first started monochrome filtered imaging, I purchased an entire LRGB, Ha, SII, OIII set of Astrodon's Tru-Balance "Par-Focal" filters in
order to make my transition from DSLR to chilled CCDs much easier and to shorten my learning curve with my new ST-10XME w/CFW10 imager. For the most part I have to admit, I was impressed with my newly acquired level of imaging and using what I was told were "par-focal" filters. After 2 years of experience
with CCD imaging, I continued to look for ways to improve each of my images. The more I paid attention, the more I began to realize that not all of my color filtered sub-frames were as par-focal as I first assumed. Understanding that not all refractors were equal in color correction, I replaced my Orion
80ED with high-end APOs (a 99.0 strehl TMB80/480 and a Televue NP-127). However, I continued to notice the focus disparity and finally decided to try and quantify it this past week.
Below is a comparison of TWO focus routines I used to record a set of RGB images of the Trifid Nebula M20:
-
Par-Focal Focusing Routine - Focused only using the Luminance filter and set CCDSoft to record a color series of 5min RGBs (Sequence = RGB, RGB, RGB, etc.). Refocusing after every one degree drop
in Celsius.
-
Filter Specific Focusing Routine - Focused using Blue filter, image all Blue sub-frames refocusing as temperature dropped, repeated focusing and imaging procedure with Green and then Red filters.
Conditions:
-
Seeing was roughly equal at 3/5 on both nights (8/6-7/2007 and 8/8-9/2007)
-
Transparency was slightly poorer during second imaging session of 8/8-9/2007
-
Target imaged at same time, location and with same equipment (ST-10XME w/CFW10 on NP-127 on MI250 mount) as well as same temperatures, both ambient air temperatures and equal CCD cooling set-points.
Results:
-
Blue sub-frames went from an average 4.82" FWHM with Luminance par-focal focusing to 3.0" FWHM with filter specific focusing
-
Green sub-frames went from an average 3.3" FWHM with Luminance par-focal focusing to 3.08" FWHM with filter specific focusing
-
Red sub-frames went from an average 3.57" FWHM with Luminance par-focal focusing to 3.0" FWHM with filter specific focusing
-
SEE TABLE BELOW FOR DETAILS
Conclusions:
-
There appears to be a filter induced focus shift across the visible spectrum moving from lower frequencies (Red) through higher (Blue) frequencies when using these purported "Par-Focal" filters when using the par-focal focusing routine
referenced above.
-
FWHM measurements of filter specific focusing routine are nearly identical at 103% greatest variation, however, the par-focal focusing routine shows 146% greatest variation when each imaging night is looked at separately.
-
BOTTOM LINE - The "par-focal" filters I purchased are NOT par-focal on my NP-127.
-
At some point in the future I want to repeat this using my 99.0 strehl TMB 80/480 to see if the same variation exists on that telescope as well. It is possible that this may be partially telescope induced (color correction levels
of a particular APO versus another). On the other hand, one would think that filter sets being marketed as "par-focal" would take into account the varied color correcting abilities between telescopes -- Either that or quit marketing them as "par-focal."
|
