100mm and Tubes = Hazy photos

[alann]

Just wondering if it is something I am doing. I took some shots with the tubes and the 100mm macro canon lens and they seen to have a haze to them. Is this normal (I can eliminate it in PP) or am I not using proper settings?
Here is an example converted in LR2 with no PP. Settings: 1/200; f/16; iso 100; Canon XSI with Canon 100mm f2.8 USM and Pro Optix extension tubes (64mm); EX430 ETTL mode and Lumiquest soft box postitioned at end of lens:
http://northphotos.smugmug.com/photos/565851616_cEmhZ-XL.jpg
After PP in LR2:
http://northphotos.smugmug.com/photos/565858462_TCawM-XL.jpg

[noodle_snacks]

You are stopped down too much. Try f8 or so.

[alann]

Thanks. Will give it a try tonight. DOF will be super thin at f8; guess I need to learn to stack. :)

[LordV]

Not sure about this- looks more to me like slight underexposure - you need to set +ve FEC in ETTL when shooting light backgrounds. You will get a more even light at higher mags just because the apparent light source size to subject size has increased. As commented above- you do need to watch the aperture as diffraction softening gets worse at higher mags as the apparent aperture= set aperture * (1+M) where M= magnification. The apparent aperture has the nasty property of not giving more DOF but does give more diffraction.

Brian V.

[John_B]

alann,
I agree with LordV, it looks underexposed. Air really shouldn't create a haze unless the air is polluted ;)

[alann]

Thanks guys. Lord V, your info is very much appreaciated. I was going in the wrong direction with FEC :)