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12-06-2013, 11:51 PM   #1
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All in focus problem

I am using th k7 with a sigma 150-500 lens. I seem to be doing something wrong and would love some help. I cannot get both birds in focus in any of the shots I took. Sadly there were some super shots of the mother bringing in bugs and dragon flies, but all spoilt by my ignorance. The photo 'one in focus' was an attempt to solve the problem. I was using f11 1/1250 at440mm. I went for the bigger f stop in the hopes of including more in focus, but to no avail. The 'dinner time' was at f6 1/1600 340mm and a super shot ruined by the baby being blurred. I would have thought at these settings mother and baby would be sharp. Soooo any help would be much appreciated.

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12-07-2013, 12:18 AM   #2
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It looks like the lens simply doesn't have any more depth of field at that focal length. The only solution would be to zoom out, either with the lens or with your feet.

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12-07-2013, 12:19 AM   #3
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Your best option here is to use a wider focal length and crop. If you stop down more you lose quality to diffraction. Alternatively, you can use the same focal length and just stand further back.

At 440mm and f11, I'll take a wild guess and say your subject was 9m away, your DOF is going to be about 16cm. However if you zoom out to say 300mm and keep everything else the same, your DOF grows to almost 39cm.

If your subjects are relatively still, you could potentially focus stack multiple shots, as long as your lens doesn't focus breathe too much.
12-07-2013, 01:14 AM   #4
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QuoteOriginally posted by elliott Quote
Your best option here is to use a wider focal length and crop. If you stop down more you lose quality to diffraction. Alternatively, you can use the same focal length and just stand further back.

At 440mm and f11, I'll take a wild guess and say your subject was 9m away, your DOF is going to be about 16cm. However if you zoom out to say 300mm and keep everything else the same, your DOF grows to almost 39cm.

If your subjects are relatively still, you could potentially focus stack multiple shots, as long as your lens doesn't focus breathe too much.
Thanks Adam, but elliott 'subjects still'? Have you never seen the speed of welcome swallows. I shall try the stepping back, but not in this case or I would have been in the river!

12-07-2013, 01:42 AM   #5
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I said relatively still, if you have maybe 2 seconds to get all of your needed shots. They don't have to be perfectly still, just remaining in the same area. As long as you are capturing a full in focus bird with each shot it wouldn't be that hard to stack them even if one bird turned around during the sequence of shots. Not the easiest process, but it is the only way to get otherwise impossibly deep DOF.

This guy does it with bugs, which are not known for being still either:
Thomas Shahan's photosets on Flickr
12-07-2013, 04:46 AM   #6
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Trishytee - take a look at this on-line depth of field calculator: dofmaster.com.

Pop in some of the focal lengths and apertures you have used in your own images and take a guess at the distances to your subjects. You will soon see that depth of field on long focal length lenses is next to nothing. Combine trying to avoid camera shake with moving subjects and you can some appreciate that those who post good bird images are highly skilled at their art. But they only got that way from practice and learning about their equipment. The beauty of digital is that learning is cheap (no rolls upon rolls of disappointing images to pay for).

In your second image (340mm at F6.3), if I were to guess you were 5 metres from the birds, the depth of field (the range of acceptable sharpness) is 2.4 cms in front and 2.4cms behind the point of focus. And the drop-off from there to semi-abstract bokeh is very fast. The good news is that you did a great job of nailing the focus on the mother bird. The narrow depth of field has made her stand out as the primary item of interest in this shot, which is well deserved in this case with such a good catch of dragonflies.

I have gone so far as to install a depth of field app on my mobile phone, so I can check what DOF I might be dealing with while out in the field (even if out of mobile reception).

Last edited by southlander; 12-07-2013 at 04:53 AM.
12-07-2013, 06:12 AM   #7
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If you look at the mother bird, it is possible that even her tail is oof, that's how narrow the dof is!

I think the image is perfect as it is, the mother is the star, baby merely supporting act.
12-07-2013, 06:18 AM   #8
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If you are quick and really steady or on a tripod you can focus at two different spots in two or more shots and stack them, it's extremely hard though.

12-07-2013, 07:31 PM   #9
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Hi Trishytee,

These are nicely executed shots, despite the fact that they don't meet your expectations.

Another answer might be to add a system with a smaller sensor. Personally, I favor the Q/Q7 system with adapted lenses, but a good superzoom bridge camera would work if you need AF. Small format BSI CMOS sensors are now surprisingly good, and in bright lighting conditions can give you outrageous reach for the FL, very good IQ, and deeper DOF for those times that you need it. Small sensors get panned quite a bit by DSLR shooters, but there are things that they can do that the bigger sensors cannot, and here is a case in point. I shoot the Q with adapted lenses because it is capable of getting shots that my DSLRs and a (very big) bagful of lenses are not able to manage -- and the Q adds little weight or bulk to my kit.

Scott
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