sharpest focus

[AgNO3]

Is there a way I can determine the aperature on my lens that will yield the sharpest results?

I'm not sure if it's "this number" x "this number" divided by "this number". I"m sure it varies depending on the different situations... like outdoor vs studio. But why do some people shoot f/5.6 and others shoot f/8 in the same situation?

I do understand the DOF between shooting at f/2.8 vs f8. And I shoot mostly in my studio with strobes, a tripod, a remote trigger. I just dont understand why f5.6 is better (or worse) than f8

Here's more info if it'll help.

I'm shooting on a Nikon D300, Tamron 17-50 f2.8, Nikon 50mm 1.8, Nikon 10.5 fisheye, and 12-24 Nikon.

[wulf]

Take a series of pictures of a static subject in good light. Vary the aperture and the shutter speed to balance the exposure (a tripod would be useful for consistence even if the light is good enough that hand-holding is feasible). Now compare the results side by side. Even once through will help you draw some conclusions about the lens in question; repeating the test with a range of subjects and locations will help you learn even more.

Wulf

[kencaleno]

In most cases,but not always,sharpest aperture is 2 stops down from wide open,so if your lens has a maximum aperture of F2.8,then F5.6 will be the sharpest-and if this aperture is combimed with 2/3 focal length of a zoom lens-you have the lense's "sweet spot".

regards, Ken

[AgNO3]

thanks everyone for your help.. I'll have to sit down this weekend and try these methods or a combination of these methods. At least i'm headed in the right direction.

[dcclark]

Many many kit lenses have a sweet spot around f/8 -- just as a general starting point for you.

[OsmosisStudios]

Anything about f/8 will beget diffraction: anything below f/2.8 will beget softness (generally). 4-5.6 is usually best.

[wulf]

It does depend on the lens. For example, I've heard that Zeiss lenses are sharp all the way open (although, to be fair, you do pay for that precision). That's why I advocate doing your own testing. It doesn't take long and it helps inculcate an observant methodology which will stand you in good stead in all apsects of photography.

Wulf

[dcclark]

Originally Posted by OsmosisStudios

Anything about f/8 will beget diffraction: anything below f/2.8 will beget softness (generally). 4-5.6 is usually best.

Diffraction is a problem at all apertures (since it always happens when light passes through an opening), but I wouldn't say it becomes noticeable until at least f/16 -- and then, you have to look at least fairly close. I shoot at f/8 all the time and don't notice any problems.

[sybren]

Originally Posted by wulf

It does depend on the lens. [...] That's why I advocate doing your own testing.

It doesn't just depend on the lens, it also depends on the sensor. The higher the resolution of the sensor, the sooner the softness due to the diffraction starts to become noticeable. Another reason to do your own testing.

Sybren

[OsmosisStudios]

Originally Posted by dcclark

Diffraction is a problem at all apertures (since it always happens when light passes through an opening), but I wouldn't say it becomes noticeable until at least f/16 -- and then, you have to look at least fairly close. I shoot at f/8 all the time and don't notice any problems.

I used to shoot my nifty at f/8, but was noticing diffraction. It became VERY evident at f/11, and this has been confirmed with other users and other lenses.

The 50mm in particular has a sweet spot between 5.6 and 7.1, leaning a bit more heavily towards the 5.6 range.

With my 18-70, the sweet spot is 6.3, and with my 18-200 it's fairly soft anywhere, but sharpens up around f/5.6-6.3.