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Thursday, February 14, 2008

First light, Canon FD 200mm f2.8 lens

Last nigh was very windy, almoust a storm. Normaly I do not shoot under that kind of conditions. How ever, this time I wanted to test my 200mm f2.8 Canon lens under the stars. "HARTH & SOUL" IC 1805 & IC 1848 in H-alpha light. Only 6x1200s, this is a fast lens. Flats and Bias, guided with LX200 and PHD-guiding. Camera QHY8 + QHY5 guider.

I added some color, but there was problem with camera orientation, so image is clipped.

Color data: only 3x600s with UHC-s filter

I shoot California nebula as well. Elevation was very low at the end of the exposures,

only about 28 degrees.

H-alpha 4x900s, same setup.

Color version:

3x600s trough UHC-filter added.

Over all, I'm veryhappy with this lens. This is very first time to me use camera lens

for astro photography.

I was expecting severe distortion in the image edges, there is none!

I was expecting severe color aberration, there is none!!!

This lens was unexpencive, doe the old FD model, about 120€.

Here is the link for moreinformation: All the images are shooted with full f2.8 aperature.

The front lens aperature is 72mm.

FOCUSING Fast lenses are very difficult to focus manually, it's pure luck to reach sharp focus. 200mm f2.8 lens has about 20 microns sharp focus area! I build a simple autofocuser to my lens by using TCF-s temperature compensating focuser. I'll send real pictures about that later. Here is a picture about principle. This system solves allso problems with focus temperature shift! TCF-s focuser is easy to move back to the main telescope at anytime. I was able to use FocusMax with the lens and reach sharp focus in 30 seconds.

1 comment:

Muibien said...

Very impressive stuff! Carry on mate!