Posts Made By: Cal Sandfort

Wow! It looks like you put a lot of work into this and it really paid off.

Great shot - Cal

Cool! It looks like you had good tracking and the 15nm lets more stars through. I think it looks better. Propus always buggers up this object but it looks better in your shot than it does in my image of this object.

Great shot - Cal

Another nice shot, Jim. I like your obscure objects.

Cal

The rule that the guider must be at least the focal length or more is a hold over from the days of manual guiding and does not apply to modern CCDs. You need to compare the pixel scale of the imager and the guider and aim for a ratio of 1:10 or better. However, some mounts will provide accurate guiding at greater ratios, even 1:20 but that is probably pushing it. Most guiding software has accurate centroiding algorithms that provide subpixels accuracy. Check out the mini-Borgs.

Cal

Nice first light shot!

Looks good - Cal

Nice job! The little tadpoles are well defined. I've had two clear nights but the wind was howling

Great shot - Cal

Nice shot, Greg. The DSLRs do a good job.

Cal

Chris, The ST-8 will work fine with many 35mm camera lenses if you have the correct adapter for the particular brand of lens. A problem occurs when you try to use the color filter wheel. Many lenses will not come to focus on the ST-x cameras with the SBIG color filter wheel. Nikon ED lenses will but Canon EOS lenses won't. I'm only aware of a color filter face plate for Nikon ED lenses. A Canon EOS prototype would not come to focus with the CFW-8 wheel but the new CFW-10 is thinner and may work. I can't comment on other makes.

Focusing the lens will also be tricky. The critical focus zone for wide field lenses is so small that is "difficult" to hand turn the focus ring and achieve fine focus. Robofocus is the way to go to solve this problem.

Two sites that really show what can be done with Nikon camera lenses on ST-x cameras are Steve Mandel's site at: http://www.galaxyimages.com/astrophotographybystevemandel.html and especially John Gleason's site at: http://www.celestialimage.com/index2.html Steve's site describes a Robofocuser setup and a faceplate for the ST-x cameras and Nikon lenses.

I hope this helps - Cal

This is great, Jeff! I can't think of a better person for the job. I'm too busy during the spring to participate but still like to browse and now feel that with people such as yourself helping these forums will continue.

I'll try to be good

Cal

That's COOL, Tom. The bubble on the lower left is nicely shown.

Cal