Sea shells close-up & DoF
Dear colleagues,
I wanted to photograph the nice sea shells that my daughter collected. Aim was to make close-ups, with as much detail as possible, and a high Depth-of-Field, so the entire shell was sharp. That was way more difficult than I expected...
I first thought, I'll zoom-in as much as possible (135mm) and I'll use f-22 and I'm done. But that was not the case, the shells were not sharp everywhere :-(
On the web, I found a formula to calculate the DoF (see photo) based on the focal length of your lens, distance to your subject, f-stop and camera (circle of confusion). And it turns out that a shorter focal length increases your DoF. On top, Robert told me that a lens is at it's sharpest at f-8 or f-11. Based of this, I went with 100mm and f-11. I used (enough) natural light & a tripod, so I could set the ISO to 400 and keep noise very limited. I used 2 sec delay, to avoid all camera shake.
This set-up should give me a DoF of 4.6mm (in front, so above the table). Most shells are not that big, so that should work.
Nevertheless, I get mixed results. The photo with the 6 (not shiny) shells gives acceptable sharpness. The photo with only one (shiny) shell is NOT sharp everywhere, although exactly the same set-up and settings were used... WHY ?
Did the shiny shell make focussing impossible ? Although manual focus (via live-view) and auto-focus did not give different results.
Is one of my settings still wrong / not optimal ?
Please advise. Thanks !
EOS 80D, EF-S 18-135mm IS nano USM at 100mm, f-11, 1/10sec, ISO 400.
I wanted to photograph the nice sea shells that my daughter collected. Aim was to make close-ups, with as much detail as possible, and a high Depth-of-Field, so the entire shell was sharp. That was way more difficult than I expected...
I first thought, I'll zoom-in as much as possible (135mm) and I'll use f-22 and I'm done. But that was not the case, the shells were not sharp everywhere :-(
On the web, I found a formula to calculate the DoF (see photo) based on the focal length of your lens, distance to your subject, f-stop and camera (circle of confusion). And it turns out that a shorter focal length increases your DoF. On top, Robert told me that a lens is at it's sharpest at f-8 or f-11. Based of this, I went with 100mm and f-11. I used (enough) natural light & a tripod, so I could set the ISO to 400 and keep noise very limited. I used 2 sec delay, to avoid all camera shake.
This set-up should give me a DoF of 4.6mm (in front, so above the table). Most shells are not that big, so that should work.
Nevertheless, I get mixed results. The photo with the 6 (not shiny) shells gives acceptable sharpness. The photo with only one (shiny) shell is NOT sharp everywhere, although exactly the same set-up and settings were used... WHY ?
Did the shiny shell make focussing impossible ? Although manual focus (via live-view) and auto-focus did not give different results.
Is one of my settings still wrong / not optimal ?
Please advise. Thanks !
EOS 80D, EF-S 18-135mm IS nano USM at 100mm, f-11, 1/10sec, ISO 400.
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