hiya folks.
i recently went from my minolta z10 to a nikon d70 and after 2000 + photos getting used to it i have started submitting pictures again to the various sites. FP and BSP are great, i am still getting very few rejections off them, but all of a sudden i am getting heap loads of rejections from fotolia, DT and istock all for noise or artifacts or DOF.
easy question first ... DOF
i know what it is but i can't get it right it seems, i have my camera set for 6mm in the options, pics get rejected, i have the camera set for 12mm in the options, my pics get rejected. yes i have read the manual but it makes no sense to me, what should it be set at? is there a standard setting or is it variable dependant on what distance i am shooting?
tougher question.... noise/artifacts
i use psp9 and use the denoise and jpeg artifact removal tools, i have used the noise reduction up to 50% and can't see any on my pics (sky i check etc) and then hit the artifact removal tool and have that set at maximum unless it takes out detail in the pic. most of the time i am shooting at f3.8 or 4.6 i think the two lowest numbers are, so i get quite a fast shutter speed with this, though i do tend to leave the polarised filter on, should i take this off, could this be part of my trouble.

ok i am ready for the people who will call me a nincompoop and i have my flame proof undies on, but i really need some advice here as i am getting seriously frustrated.

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Paula