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Old 12-03-2012, 08:39 PM
Martin Pugh
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Martin Pugh is offline
Join Date: Nov 2006
Location: Canberra, Australia
Posts: 1,317
Hi everyone
I posted the full FITS because I assumed that if people wanted to assess the image, an uncompressed image is the way to go, rather than a JPG.

Anyway - I guess the point I am making here, is that I dont believe I would get dissimilar results with the $380 85mm lens I first bought, and that I did not expect to go these lengths with a $1600 L lens. My next trial will be just that - I will take an image with the 85mm lens, stopped down appropriately, and compare those results. Really, at this stage, I think the differences will be negligble. We shall see.

The other point I was making is that I seem to have got fairly good stars across the field at f4.5 with the ST8300, so I expected similar results by using the lens at f4.5 on the 550D. This was not the case.

Tilt? Even if it is in the ST8300 - Cant do anything about that. I tried to measure with a caliper the depth of the SBIG Canon lens adapter, and was fairly satisfied that the measurements were very close. I am not ruling the adapter out though.

One question I have though - if I gently rock the lens, I can hear the lens elements moving about slightly - is this normal?

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