mikeski30 Offline Upload & Sell: Off
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p.1 #1 · p.1 #1 · Same focal length and aperture... different DoF? | |
Hi everyone!
Apologies in advance for the long story!
I'm a big fan of extreme macro insect photography, and have had some luck getting some halfway decent shots using a 105mm with extension tubes on an APS-C sensor camera (Nikon d7100 mostly).
For the longest time, I was using an older Sigma 105mm EX DG lens. I found that f11 provided just enough DoF to allow say, all the front eyes of a jumping spider to be in focus if I got it just right before diffraction started in. I never had any real luck with focus stacking of shots taken out in the field... probably a combination of my twitchy, flailing technique and skittish subjects. So basically I had to get it right in one shot, which leaves very, very little room for error.
After a while I got pretty good at tweaking all my settings (all fully manual) depending on the bug's environment (darker leaves, lighter bricks etc.), but for the most part with my flash and diffuser setup, I could reliably set my ISO to 100, aperture to f11, and flash to 1/2 power and be good to go; only changing the flash power settings depending on the environment.
I traded the Sigma in and got the Nikon 105mm IF-ED because I wanted the VR, and was excited to see how the Nikon would blow the Sigma out of the water in every respect. I set the camera up with all the usual settings, but found that f11 gave me nowhere near the same DoF that the Sigma had provided. I found that I had to stop down to f16 to even come close, but that's as far as I wanted to go because the in focus parts were starting to lose sharpness and detail due to diffraction.
I've read everywhere that f11 is f11 is f11, no matter what lens you use if they're the same focal length, but I swear these two lenses performed in wildly different ways. Has anyone ever experienced anything like this? Could it have something to do with the fact that the Nikon had internal focusing and the Sigma would extend? Or could it be that even the slightest variations in a lens's build would just be more evident when focusing much more closely with extension tubes?
Anyway, it's just been bugging me (no pun intended) for the longest time, and I'm just curious if anyone else has any idea what the issue might be (I could just be going nuts!)
Thanks all!
Mike
Nikon 105mm at f13
Nikon 105mm at f13
Sigma 105mm at f11
Sigma 105mm at f11
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