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02-27-2010, 06:28 AM   #1
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Focus issues

I took this photo at an indoor wedding using my K20D with an autofocus Pentax 1.4 50mm prime lens attached. ISO 800, f 8.0, 1/125, in manual mode, flash unit mounted, bounced off ceiling. My concern is focus...The people are very soft focused but the flowers behind the gentleman are quite clear. @ f.8 with this much light, my thought is that the entire photo should have been in focus. Any feedback as to why it is not?

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02-27-2010, 06:30 AM   #2
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additional note

This was taken with spot metering...not center weighted.
02-27-2010, 07:31 AM   #3
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My first guess is the obvious; the focus was on the flowers. If I suspected such a BF problem I would lay out the yardstick and target to do some controlled testing.
02-27-2010, 07:40 AM   #4
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Have you noticed that the flowers are sharper than the two guys?

02-27-2010, 07:43 AM   #5
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It was a wedding, I couldn't whip out a yardstick to measure & obviously I didn't expect such backfocus issue. I assume that your comment refers to the spot metering setting? If so, (and obviously I'm wrong) I'd assume that shooting at f/8 would increase the area of focus. Can you tell me why this is not true? Clearly I'm missing something because this is a consistent problem I have, & I do not have the ability, or time to physically measure my distances...I shoot weddings and events, I'm not in the studio. I can eye them, but thats clearly (pun intended) not working for me.

In addition, can you suggest what settings, and/or lens would be a better solution to helping me get greater areas of focus even in well lit situations?

Thank you.
02-27-2010, 07:47 AM   #6
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Rusty, yes I noticed that & that is the question.
02-27-2010, 07:51 AM   #7
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QuoteOriginally posted by bethtphotos Quote
It was a wedding, I couldn't whip out a yardstick to measure & obviously I didn't expect such backfocus issue. I assume that your comment refers to the spot metering setting? If so, (and obviously I'm wrong) I'd assume that shooting at f/8 would increase the area of focus. Can you tell me why this is not true? Clearly I'm missing something because this is a consistent problem I have, & I do not have the ability, or time to physically measure my distances...I shoot weddings and events, I'm not in the studio. I can eye them, but thats clearly (pun intended) not working for me.

In addition, can you suggest what settings, and/or lens would be a better solution to helping me get greater areas of focus even in well lit situations?

Thank you.
What? Those two guys wouldn't hold a yardstick to help out?? Ok, thats why I said controlled testing, which means not at a wedding. Yes, F8 gives a greater depth of focus than f2.8 but you said the magic word which is the problem is consistant. Thats why you do a search on this forum or the web for how to do controlled testing and correction. Or, as in a current thread, a smart person said just shoot your normal distance with a detailed subject, bracket the shot with corrections, and view them on your computer to select the correction that works best.

edit - no, I did not read "spot metering" as "spot focus on the flowers". most of us (by survey) use spot metering and recompose

Last edited by imtheguy; 02-27-2010 at 07:58 AM.
02-27-2010, 07:52 AM   #8
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well, with f/8 and a subject distance of 6 feet (estimating), your depth of field will cover all of 1.38 feet. That isn't enough to get both the people and the flowers in focus. You need to focus on the people if you want them in focus.

02-27-2010, 07:56 AM   #9
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Check out:
Hyperfocal Distance and Depth of Field Calculator - DOFMaster

DOF is going to depend a lot on how far you were form the subjects. I'm guessing by the photo, if not cropped, that you may have been about five feet away from your subjects.

Lets say you were five feet away for argument's sake. That gives less than 1 ft that would appear acceptably sharp. If the plants were a foot away behind the subjects, your subjects would start to appear a bit out of focus for a 50mm lens at f8.

Assuming my assumptions are accurate with regards to distances, your results would be "expected".


[edit]
Argh, just a few minutes too long finding the darned web page and typing my response. Well at least you now have a few good opinions on what happened. :-)
02-27-2010, 08:03 AM   #10
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Ok, enoeske, allow me to clarify... are you saying change the metering mode, or get closer? If I'm standing about 5 ft from my subjects, I need to do what to get the entire subject area in focus? Would the 16 point metering have been the more obvious choice? Is the 1.4 lens a poor choice? I'm not trying to be dim, but I need a clear direction.
02-27-2010, 08:08 AM   #11
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amoringello..thanks for the link....so what you're saying (as is enoeske, I think) is that my distance from the subjects is what dictates my f stop? So I should probably just default to Aperture priority as a setting, I'm thinking, then using the charts figure my need f stop. My fingers will be practically dancing around my setting buttons. I don't get it, I've been told that if I'm shooting at 5.6 I should get everything in focus...my God, I'd have to be sitting on my subjects for that to happen.
02-27-2010, 08:16 AM   #12
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Metering has no effect.

You're concern is DOF, not particularly on fstop.
DOF is affected by; lens focal length, aperture, and distance to subject.

Depending what you want, you may change any or all of these.
In this case, rather than figuring out all this math... simply aim at one of your subjects, hold the shutter half down to focus, and while holding half way, re-compose to contain both subjects.
This way the camera will not be focused on the flowers.
02-27-2010, 08:18 AM   #13
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QuoteQuote:
Or, as in a current thread, a smart person said just shoot your normal distance with a detailed subject, bracket the shot with corrections, and view them on your computer to select the correction that works best.

edit - no, I did not read "spot metering" as "spot focus on the flowers". most of us (by survey) use spot metering and recompose
The auto bracketing function would definitely have come in handy. I think I set the camera into spot metering mode to do some earlier prop shots & just shot this...when I saw that the indicator light telling me I had focus, I just didn't give it another thought...& I find the playback useless for focus detection, everything looks in focus in a 3 inch display.

So in summation, my problems were too low of an f stop for the distance I was shooting? Is that correct? My metering mode had nothing to do with it, and changing this would have little effect?

Last edited by bethtphotos; 02-27-2010 at 08:21 AM. Reason: corrected "two" to "too"... I'm all veklempt.
02-27-2010, 08:20 AM   #14
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QuoteOriginally posted by amoringello Quote
Metering has no effect.

You're concern is DOF, not particularly on fstop.
DOF is affected by; lens focal length, aperture, and distance to subject.

Depending what you want, you may change any or all of these.
In this case, rather than figuring out all this math... simply aim at one of your subjects, hold the shutter half down to focus, and while holding half way, re-compose to contain both subjects.
This way the camera will not be focused on the flowers.
THANK YOU! I was exactly hoping for a technique that'd help me. So doing this, I wouldn't have to move closer or change my aperture? I'm just isolating my focus point?
02-27-2010, 08:25 AM   #15
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Metering has no effect on focus. You should use center spot focus point. Then do a half press on the shutter button while aiming at the face. Keep the button at half press, recompose, and shoot. Then the faces will be in focus and the flowers will probably be unfocused.

And yes. You can stay the same distance, and aperture.
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