Project:
Analyzes of vignetting from my
lenses and telescopes

Contents:

1. Introduction vignetting
2. Sigma 150 mm f/2.8 APO (f/4)
3. Pentax 67 165 mm f/2.8 (f/2.8)
4. Pentax 67 165 mm f/2.8 (f/4)
5. Canon 300 mm f/4 L (f/4)
6. Pentax 645 300 mm ED f/4 (f/4)
7. Pentax 500 mm f/4.5 (f/4.5)
8. TS130 2.5" x0.7 field flattener 684 mm f/5.3
9. TS130 3" x1.0 field flattener 910 mm f/7

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

7. Pentax 500 mm f/4.5 (f/4.5):

This Pentax 500 mm telephoto lens I had before I bought the TS130 APO refractor. With it's big opening of f/4.5 I thought it will be a perfect low cost lens to my astronomy hobby. Already at that time I used a full frame camera, the Canon 5D (mk I)

This lens is built for for full frame and some use them at medium format. But there are limitations in the optical construction, especially here when I use it at full aperture. In center the signal is about 73'000 and at the corners about 33'000. The signal drops 55 %.

Signal drop at corners relative center = 55 % or 1.15 EV (full frame sensor).

Pentax 500 mm f/4.5:

• https://www.pentaxforums.com/ lensreviews/ Takumar-Super-Multi-Coated-TAKUMAR-500mm-F4.5.html

The result from this lens was not too bad, it cost just a fraction of the cost of my APO refractor. See the photo of Panstarrs comet .