Potrait issues

[munsterman28]

December 17, 2012 at 2:52 pm

Hi

I take mostly sport and wildlife shots. Wildlife is easier to deal with and doesnt talk back.

Yesterday I was roped into doing the work Santa party. I was using a very recently purchased 7d which im unfamilar with so set it on auto setting. Was using a Tamron 28 to 75mm F2.8 lense, 430EX speedlight, on a tripod. Generally it was shooting at 1600 iso, F2.8, 1/60 sec.
The room was very dark (it being santas grotto) and the bench Santa was on was at an angle…people on the right were closer to me than the people on the left.

Anyway a lot of the shots have the people closest to me on right of bench in fosu while the people on the left are soft. Wondering if this is the autofocus on the 7d or is it the F2.8 aperature and the angle of the bench combining to throw those further away out of focus.

Also would people generally set their cameras to Av (aperature priority) and pick an aperature like F4 for group shots like this?

Thanks

[johnnymc]

December 17, 2012 at 6:44 pm

There are a few factors causing your focus problems…..and I don’t think it’s necessarily a camera problem (although the cropped sensor does play a role).

Your depth of field is very narrow at F2.8. For example, if you were only 5 feet from your subject when taking the shot and were zoomed in using the 75mm range of your lens, your depth of field is only about 4 inches. Shooting at the same distance but using the wide angle of your zoom gives you a depth of field of about 30 inches….considerable difference. It would help matters if you used one focus point on your camera as opposed to chancing matters with all of the sensors switched on….it gives you hit and miss results.

With regards to your results, it’s highly unlikely that you would have had both parties in focus at F2.8.

Av mode should NEVER be used when using flash……your camera will calculate an exposure for ambient lighting and never takes your flash into consideration.

Hope this helps somewhat,

John

It’s also recommended when using on camera flash not to go above 400 ISO.

[Isabella]

December 17, 2012 at 9:24 pm

i would always use the camera on manual for everything. f2.8 would be to blame id say, you’d way to be f8 or higher id say for angled view and focus on the mid point. by the sounds of it you weren’t really getting much out of the flash if those were the settings you were using, you should’ve been able to use a higher aperture and lower ISO without sacrificing shutter speed…

i don’t really do much of that kind of photography though

[munsterman28]

December 18, 2012 at 1:38 pm

Thanks Guys

Ya John I wouldnt use AV with the flashgun. What would ye recommend so, go completely manual and set the aperture and shutter speed myself.

[johnnymc]

December 19, 2012 at 9:44 pm

Manual in my opinion is the only way to go as long as you have a flash meter.

Tripod, slower shutter speed and try manually setting the flash while using a large (number) aperture.

Good luck,

John

[Murchu]

December 29, 2012 at 3:41 pm

Would check the depth of field from online tables to see if you were simply expecting more in focus than was possible, as f2.8 is a wide enough aperture. If you are seeing softness at the point of focus, then I think it would be wise to run a few tests to see if the lens is simply a little less sharp at those apertures, of if it was a case of the autofocus simply not locking onto the right spot for you. I’ve used autofocus happily enough in such environments, and would see no need to resort to manual focus for such non-static photography, but then I would always be aware of focussing on something that has enough contrast for the autofocus to lock onto easily.

Generally by the way, the 28-75mm you mentioned is regarded as a pretty sharp lens, although probably a smidge less sharp at f2.8 than the rest of its range, so substantial softness in your images at the point of focus, may indicate the issue is with the focussing. Running a few boring tests will get to the bottom of it, and the web is awash in such tests if you are looking for any ideas on testing.

EDIT: re-reading your original post, I suspect it is most likely that f2.8 was simply not a small enough aperture to get everything in focus. For such group shots, you are probably best looking at some sort of additional lighting (two lights/ flashes I am thinking), to ensure you can stop down your aperture enough to get everyone in focus. Shooting at an angle, with such limited depth of field at f2.8, just made the whole issue worse.