Camera Shake?

[JaimeGibb]

Hey all!!
I mainly use an 85mm 1.8 lens for portraits. However I am noticing that when I am far away from the subjects (trying to include more people or full-body) the images are not sharp when zoomed in. They seem either unfocused or slightly blurry. This happens with and without flash. When doing close-up shots, however, they are tack sharp.

I don't consider my 85 as that long of a lens, but could this be due to camera shake? It is very frustrating, and on this particular shoot I was not allowed a tripod (gardens rule).

My 50mm is currently broken and I plan on getting it fixed. Would shooting with this lens more often (or for further away shots) help with this issue? Grumble grumble...

Thanks in advance!!!

 

[Soocom1]

I would first test it on a tripod with a series of shots on a stationary object.
Check to see if there is a focus issue. if that is negative, I would then move to see if the lighting is causing it. check also the apature settings.

 

[KmH]

You're zooming in further and seeing how aliasing effects sharpness. This will happen with any lens to one degree or another.

Would they have permitted a monopod, in lieu of a tripod?

 

[musicaleCA]

I'm betting is a DoF issue. f/1.8 is really shallow. Check out the DoF calculator here. Assuming you're 3 meters from the subject you only have 9 centimetres of acceptable sharpness; 6 meters you have 25 centimetres to work with, but that's only barely enough to make someone's head look completely sharp.

Furthermore, according to this wonderful website (thanks kundalini for posting this elsewhere; damn has it ever been a boon for me), your 85mm is sharpest around f/4. At f/1.8 it gives only "very good" performance (but if you're pixel-peeping, then the difference between excellent and very good may be noticeable). My suggestion would be to try stopping down to f/2.8 to get the image markedly sharper. f/4 would be even better, and you can easily do that if the subject is on a close background.

 

[Garbz]

85mm isn't that long. No lens is long until the shutter speed is below 1/(85*crop factor). The question really is was it dark enough to assume that the shutter speed dropped below about 1/125th? Which is a rule of thumb for careful handholding sharpness.

 

[musicaleCA]

*facepalm* I didn't even think of lighting conditions. Darn Aussies, always thinking different. :greenpbl:

 

[JaimeGibb]

Wow, thanks for all the feedback guys!!

musicaleCA, I wasn't stopped at 1.8, more like 4-5.6 for them all. I am thinking now that maybe it was a lighting issue. I think my shutter was dropping too low for the distance I was, like Garbz said. That makes sense right? Ill post examples soon.