Astro Anarchy

Friday, March 21, 2008

Focusing & imaging system for the camera lens

I promised to post images of the focusing system I build for the camera lens,

so here it goes.

Focusing system from top.

image about whole imaging system

The Business end of the lens

Accurate focusing is needed doe the very fast lens. At f2.8 the sharp focus zone is about 20/1000 mm! Focusing by hand is a pure Lottery. I have TCF-s focuser and its temperature compensated, so thereis no need to refocus every time when temperature drops.

The focusing system has been build from the scrap metal and some parts found from

the drawer.

Its very easy to move the focuser back and forth between main scope

and the lens.

There is a right size can lid bolted down to a L-shape body.

Focuser is then atattched to the lid.

In a focuser, there is a brass tube. This tube goes back and forth when focuser moves.

Its then rotate the focuser ring of the camera lens. There is peace of fine sandpaper glued

to the tube to prevent slipery, tube has allso a spring load for the same purpose.

I have used TCF-s focuser but it can be any focuser, even manual one!

It will make focusing easier and less random.

The whole project took about three hours of time and cost 50c (I had to buy

some bolts)

The whole assembly is then attached to the dowetail rail at top of the LX200 scope.

This is a second version.

The firs version was made by blywood, but I made it again with metal doe flexsure problems.

Shematic

Thursday, March 20, 2008

IC 1396 & Dark nebulas in Hydrogen Alpha light

After playing with 3D stuff I returned back to real astro imaging. Last night was allmost full Moon and doe that I selected the target from opposite side of the sky. IC 1396 was about 30-36 degrees above horizont during the capturing. IC 1396 is a large emission nebula. Image scale fits well with field of view of Canon FD 200mm f2.8 lens. There is lots of faint nebulosity around the field. Dark nebulas, visible in image, are dark hydrogen clouds and they are blocking light from background stars. One part of the large nebula is a famous "Elephant's Trunk Nebula", seen in lower part of the image.

IMAGING DETAILS Optics: Canon FD 200mm f2.8 lens with full aperature Camera: QHY8 Platform and guiding: LX200 GPS 12" with QHY5 guider and PHD-guiding Exposures: 6 x 1800s = 3 hours + Flats and Bias frames, no darks Filter: Baader 7nm H-alpha

Elephant's Trunk detail from 10.12.2007