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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):

Pentax 500 mm f/4.5 on EQ6 mount

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)

Pentax 500 mm f/4.5 vignetting

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:

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 .

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To page VII, TS130 2.5" x0.7 field flattener 684 mm f/5.3

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