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Old Jan 8, 2003, 12:09 PM   #1
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Default New shots added to my album

Hello all, I have added a few astro shots to my yahoo photo album. please review and provide comments. http://photos.yahoo.com/bc/netmole20...tos.yahoo.com/

Please keep in mind these were taken with my Oly 2500 and a homade adapter. Thanks for any comments
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Old Jan 12, 2003, 5:35 AM   #2
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Seem ok. I find it a little bit hard to comment on photos in that limited size you present them in. Why not shot us the real stuff!
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Old Jan 14, 2003, 6:32 PM   #3
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What setup are you using for these? You may want to try astrostack and bring out more detail in the planets. It looks like your scope may have more capability than your photos show.
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Old Jan 15, 2003, 11:32 AM   #4
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Default Equipment, and setup

I'm using an Olympus C2500-L, a vintage Criterion Dynascope RV-6. This is a 6" f/8 reflector, I believe it to be 1250mm in focal length. The camers is mounted using a homemade eyepiece projection adaptor, camera settings, infinity focus, speed 100, arpature priority mode, with arpature wide open. Exposure for the astro shots was .2 seconds. I believe you are correct about Astrostack, and additionally I most likely need to lenghten the exposure to maybe 1 or 2 seconds? Maybe longer, shoot 10 - 20 shots, and possiably stack them with Astrostack. Any idea's would be appreciated. Thanks for the comments.
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Old Jan 15, 2003, 2:05 PM   #5
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Default Re: Equipment, and setup

Quote:
Originally Posted by rualert
I most likely need to lenghten the exposure to maybe 1 or 2 seconds? Maybe longer, shoot 10 - 20 shots, and possiably stack them with Astrostack. Any idea's would be appreciated. Thanks for the comments.
But if your telescope is not motorized you will get blured pictures with shuters longer then 1/20 sec with the moon. Not to mention overexposure!.
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Old Jan 15, 2003, 2:50 PM   #6
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Default Longer exposures

The scope in question is on a GEM and has a clock motor for tracking. Any sugestions appreciated.
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Old Jan 15, 2003, 8:16 PM   #7
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The moon should photograph fine with a single photo. I use 1/500th sec at f/8.0. With the tracking motor, you can do longer exposures. Solar system objects should be fine with about 10 minutes total exposure. I have not found any gain with more than that on Saturn or Jupiter. DSOs can use hours of total exposure. You may want to make sure you have an eyepiece with 20mm or so eye relief. Orions Expanse (telescope.com) are the least expensicve eyepieces that work well. Try a 9mm for your scope. This will give you 140X size. A moderately WA eyepiese like the expanse will lessen the vignetting and give you larger photos. You also want the closest focusing you can get. The C2500 has a fairly large diameter lens.

Be sure for the long exposure to take 1 or 2 with the lens cap on and the same time as the other ones. This will give you dark screens to subtract to eliminate hot pixels. If you take the photos over different nigths, do the dark subtractions each night. Make one of them like the 3rd or 4th photo and the other one right after the last photo of the session. The CCD hot pixels change with temp and the display warms up the longer it is used. This is why you need the 2 subtractin photos. For every long sessions try a subtraction photo every 20 minutes or so. And be sure and check your dark frame photos. If you are getting too many hot pixels turn the camera off and let the CCD cool down.

If your budget supports it, try an Orions ED2 eyepice. I would not go any more magification than the 9.5mm. I am guessing your GEM is a midweight (less than 50 pounds) mount. This will limit the magnification you can photograph. At large meginfication, the motor drive will cause vibration of the scope and blurring of the image. Also any breeze, etc will do the same. 150mm will be the maz you would want to attempt to photograph and that may be too high.


http://www.pbase.com/demorcan/out_of_this_world
This is a 20 minute track'nstack with a 3.5" scope. Yours should do better. The moon photo is 1/500 f/8.0. These were December photos with the jetstream over head and limitiing vieiwng and sharpness.
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Old Jan 25, 2003, 9:47 AM   #8
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Demmy, what eyepiece, and adapter combo are you using? I am still having issues with my 2500 and finding the elusive eyepiece/adapter combo that produces the least vingetting. I am aware that I may not be ablo to fully eliminate vingetting, however I would like to also use a Celestron WideView 80 spotting scope for daytime shoots, as thr RV-6 is much too large to cart around. Thanks for the useful information about taking longer exposures, and stacking. I haven't had a good night here in a while. Cloudy, snow, or just plain cold(teens and lower). But hopefully I will have some better viewing weather soon. I may also be able to do a shoot in the early morning, I've noticed the moon still very visable until around 10:00am here. My only concern, is with that much ambient light, will the detail, and contrast be good enough to produce good photos?
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Old Jan 27, 2003, 8:40 PM   #9
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I use a number of eyepieces. I have a 40mm adapter from http://www.scopetronix.com/. It gives the least vignetting. I also use a 6mm or 9mm expanse from Orion (telescope.com). These are WA EPs with good eye relief. I also use premium 25mm & 32mm Plossls. The 40mm has an adapter that comes with it. The other adapters are tmouunts from Scope Tronix and a Tmount to 49mm adapter for the C2100. I still have some vignetting. But except for the moon, solar objects are usually smaller so the vignetting does not effect the subject. Andromeda, the Orion Nebula, etc do get cut off by the vignetting even with the 40mm EP. I have a 10" reflector that came last week. As soon as the panacorr gets here, I am going to try a 2" 50mm EP and see how that does. For now, I do the panoramic and put together 3 to 5 photos to make the pano. They need to be stacked to the same depth, etc. and it is really a pain. I do not have any I am ready to post yet. I am still working on them.
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