First Light...

There have been some nice images I have seen on this forum. It has been eons since I have posted anything though...

This is a totally new setup for me. A G-11 ordered almost a couple of years with the new Gemini-2, but that ended up on backorder for over a year... (long story). I have had it for a while, but then there were other "issues."

This fall I got an Orion ED80T CF. I am going to really like the carbon fiber, since 40 degree swings are the norm rather than the exception here. The first image, with only one mount motor working, was M31:

http://www.fortlewis.edu/observatory/image_detail.asp?ID=248

Then I got the motor fixed (actually the circuit board), and had other delays. Finally last week I got the Leo Trio. This I wanted to count as the first long autoguided image, but it was without a field flattener, which has since been ordered.

http://www.fortlewis.edu/observatory/image_detail.asp?ID=246

In the mean time I ordered a field flattener, which of course brought some clouds and now a full moon... Actually, I have it outside right now with an H-alpha filter, but that might be a few days before I get to see how IC1948 looks.

I will have to give an update on the FLC 16" scope in another post one of these days. The last image posted was about a year ago. I did reprocess M78 more recently though. That is here:

http://www.fortlewis.edu/observatory/image_detail.asp?ID=245

Thanks for looking.
Charlie

This fall I got an Orion ED80T CF. I am going to really like the carbon fiber, since 40 degree swings are the norm rather than the exception here.

It is a fallacy to believe that carbon fiber will work to keep the focus constant in a refractor. The only way that carbon fiber can work is if the optics also are zero expansion, and that only occurs in reflectors that use Zerodur, Sital or fused quartz.

Unfortunately refractors use optical crown and ED glass, both of which have significant expansion co-efficients. In other words, a refractor's focal length shortens when the temperature drops. An aluminum tube also shortens, but at a lower rate, so there is some tracking of the focal point, but not perfect compensation. Using carbon fiber makes the problem worse. It may not show up much with a short focus 80mm, but it is definitely a problem in a 5"F6 size scope.

Rolando