Hi there, this is my first post, I'm a keen macro photographer and only recently read that distance to subject has a big impact also. I thought I'd check this out and did some tests on my Sigma 150mm lens, I plotted the results on excel (would attach if I knew how). It amazed me that going from 20cm to 40cm doubled the DOF for a given f stop, in fact more than doubled at higher f stops. Previously I have always tried to get as close as possible, this year I think I'll be keeping my distance from the bugs. That's my question really, I've just upgraded from a D80 to a D600 and wondered is there an optimum subject distance to work at? I'd really appreciate your comments as I want to up my game this year. Many thanks in advance.
Sun 12-May-13 05:49 PM | edited Sun 12-May-13 05:50 PM by AartPapaya
I am not an expert regarding this but I can assure you there is quite a bit of half-truths. I do not know if our lenses are better than earlier years, but with a few tests I did on a Sigma 50mm at different F-stops, I could not perceive any difference (at 1:1) in sharpness, except at F35 The Sigma lens also indicated F35 with red. In the "Critique, Artistic & ..."-forum I just posted a few pictures on the subject.
In my mind, it is not a bad idea to take the shots a bit further and crop. This is especially true if you are using live specimens .
Sun 12-May-13 05:54 PM | edited Sun 12-May-13 06:03 PM by aolander
"this year I think I'll be keeping my distance"
That's fine if you want less magnification (the bugs will be smaller in the frame), but if you plan on cropping to make the subject larger after shooting at a greater distance, you won't gain anything with DOF as DOF depends on enlargement, also.
So there is no optimum distance. The closer you get, the less DOF. Crop the image you get less DOF.
Hi Alan, thanks for your reply, I have to be honest I'm confused, I thought by being further away and cropping more of the subject would be captured in the DOF range. You've given me some more to think about which is great so thanks again.
In my macro work, I only consider long focal lenses: from 105 and up. In fact, I have a 85 PC lens that does cool macro work too and a 200 macro lens.
I prefer to stay away from my subject, • in studio, room should be left for the strobes and whatnot • in the wild, I prefer to contemplate through a 200mm somethings like rattlesnakes and alike… and it is sh…t when you've got a perfect shot on a bug but you are so close that you through your own shadow on it
Sun 12-May-13 07:18 PM | edited Sun 12-May-13 07:19 PM by aolander
DOF is calculated for a certain "Circle of Confusion" which could be described as "Circle of Blur". Except for the exact plane of focus, everything in front of and behind that plane is slightly blurry. Your eyes, however, will see sharpness up to a certain point (DOF). If you enlarge/crop an image, that blurriness will be enlarged, too. Perhaps a too simplified of an explanation and perhaps someone else can get more technical.
Hi there, I used a scale at 45 degrees and when I cropped to compare the 20cm and 40cm subject distance photo's I could definately see and increased DOF, however I take your point ref perceived vs real DOF. Time to get out and try it on real subjects, I'm a sucker for as much detail of the insects as I can hence the question, whether perceived or real, if I'm happy with the photo I guess thats all that matters. Thanks again folks.