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Old 31-10-2010, 03:24 PM
Martin Pugh
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Martin Pugh is offline
Join Date: Nov 2006
Location: Canberra, Australia
Posts: 1,312
Hi all, and thanks again for the input. I shall certainly go after those step-down rings now that I have seen the result of the internal diaphragm and its effect.

Well, I managed to rent the 70-200mm f4L lens for this weekend, and got out with it tonight. This is only an assessment, so the image is short on exposure, high on noise etc. But I am pleased with the lens.

The image here is 11 x 3 minutes, shot at f6.3, FL was 100mm, ISO800.

The image is 50% of its original size, and the lens had an UV filter on the front of it.

Instead of dark subtracting, I used a high dither rate, and used the power of CCDSTACK to remove the dark noise (it did an okay job).

I accept its noisy, and needs more exposure, but I like the lens. There is almost no cropping on this image except for minor alignment areas, and the stars are pretty good.

I have some more questions for you DSLR experts later.

Comments on this image very welcome.

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