User talk:Wwcsig

Calculations

Dear Wwcsig, maybe that helps for your calculations. The lens was a Canon MP-E 65 which is a fast lens or bright. Maybe you can find some technical implementions about this lens which helps you for your calculations. There was a ring flash used and multi-field-meassurement. Maybe you can compare your calculations with this picture or this picture. Its closely the same scenario, but with no clouds. Do you think the cloud on the picture with the thistle could be the factor x in your calculation ? Best Regards, Richard --85.181.22.67 16:10, 12 September 2007 (UTC)

Dear Richard, I know the lens and envy you for it ;-) That being said, the first image picture (for which I also envy you) has ISO1250, F32 and was exposed for 1/400s. So it saw something like 1250/(32*32*400)=0.0030 light equivalents. Sunny16 (ISO100,F16,1/100s) sees 100/(16*16*100) = 0.0039 light equivalents, which would indicate that your image was underexposed (for the sky) by 1/3. Thus the sky appears in a beautiful dark saturated blue. For the second picture (btw, what's happened with that bar on the right?), things don't look as obviously right to me again. Here we have ISO100, F16 and 1/25s, thus we see 0.015 light equivalents, or an overexposure of 2 stops again. When you take this pictures, do you combine them from multiple shots to increase the DOF as is it frequently done with macro shots? Is it then possible that we don't have the correct exif data for the relevant image? Or - do you use polarizing filters on your lens to improve colors or the lower the brightness of the sky? This could explain me being off by 2 stops easily... Wwcsig 17:11, 12 September 2007 (UTC)

Also I just noticed that the whole EXIF data might be not too reliable after all. Your Thistle Image seems to have been exposed on 13:06, 21 September 2007, and this seems just a bit unlikely as of this writing. But given that your camera clock seems off the image could well have been taken not in bright daylight as the EXIF suggests but either early or late with less light available and then we wouldn't have any issue with a missing overexposed sky... Wwcsig 17:31, 12 September 2007 (UTC)

When i bought it the salesman spent me a security lens (no deduction on this 65mm lens!, puuh) for the MP-E 65 to avoid it from beeing scratched, he also said i would have more contrast with this. There is nothing written on it so i cant say if its a polarisation filter or not. How can i identify a polarisation filter  ? BTW. The picture was taken at 17:00 behind a woodpile Regards Richard --85.181.22.67 17:31, 12 September 2007 (UTC)

And what happen if its not a Polarisation filter ? Hopefully this other 2 pictures shows you that iam able to make macro pictures with a bright sky. --85.181.22.67 17:37, 12 September 2007 (UTC)

And i took this picture a few minutes before. --85.181.22.67 17:40, 12 September 2007 (UTC)

• Thank you for doublechecking and the amiable comment which made me laugh. Regards RIchard Makro Freak ^Website 20:31, 12 September 2007 (UTC)