sharpness under low contrast conditions?

[joe_austin1]

I have been photographing small birds over the last couple weeks and

have been quite disapointed with the sharpness that I have been

getting from my photos. I have been studying sharpness technique in

books, on the web, the archives, and Moose Petersons 'long lens

technique' and have been trying to follow those suggestions carefully.

I am using a N90/F4s with a Nikkor 300f4 on a Bogen 3221 with Kirk

ballhead.

 

But I still only get 3 or 4 sharp photos per roll. Most of my

subjects are perched and looking around when I shoot them. The sky

has been overcast almost all of the time and I have been using flash

for fill or key light and 1/250 shutter speeds on almost all the

shots.

Does sharpness appear softer under low contrast light? Even

stationary objects have appeared softer than I expected. With the

300mm the birds are often only small subjects in the frame, will the

feathers appears soft and fuzzy from 20ft? All of my really sharp

photos have been close shots from 8ft or so.

 

What could I be leaving out?

 

Thanks,

signed : Bewildered (Joe)

[bill_king1]

Joe -

 

Just a guess, but do you have a UV or Skylight filter on your 300/4? It's possible that this extra glass (especially for lower quality filters) is throwing off your autofocusing ability.

[bobatkins]

You may be confusing sharpness with detail. If the image of the bird is 5mm long, you're not going to see as much feather detail as you will if it's 20mm long (in fact you'll see 1/4 of the detail). They may be equally high resolution in the technical sense (lp/mm) , but the small bird won't look as sharp. Sharpness is subjective, and it does drop under low contrast conditions.

[paul_ashton]

Joe: I am not sure this is an answer, more like thinking aloud. Living, as I do, in a high humidity

environment it becomes immediately clear after a cold front comes through that everything looks sharper

because there is less moisture in the atmosphere. I wonder if this also applies to close up telephoto shots

which compress the air space between lens and subject. You mention that many of your photos appear

less sharp that were taken on overcast days. Low contrast light would create a subjective difference in

sharpness, as Bob suggests, but would moisture in the air create a real difference?

[joe_austin1]

I think the answer to my question is D) All of the above.

 

In looking over all my photos it is apparent that the best (subjective) sharpness comes in the high contrast light so I suspect that I expect too much from low contrast situations. I have read that sharpness is best judged by the edges of the subject and since re-evaluating some of the photos I see that the edges are sharp but the sharpness (or is it detail?) in the feathers on the breast/wings is not what I had expected.

 

Also I have been focusing manually and discovered yesterday, in the bright sun, how much easier is was to resolve focus in the higher contrast. I have been using the focus assist with my manual focusing but have noticed that it is more easily confused in the low contrast as well.

 

Thanks for the responses,

Joe

[stu_weiss]

Lack of "sharpness" is really lack of detail (I know I'm a genius). I'm convinced that the main reason for lack of detail has nothing to do with focus, camera shake etc. I'm convinced the main problem is improper exposure. Over/under exposure will leave you with sharp edges but little detail. How do you figure out your exposure? Are you autoexposing?

[joe_austin1]

I have been using a blend of sunny 16, spot metering middle tones or spot metering a solid area and then over or under exposing the value according to the tone I want it to be. For the most part I have been pleased with my exposure.

 

Joe

[patrick_chase]

Hi Joe;

 

Textured detail as seen in feathers, fabrics, and the like is most visible when illuminated by directional sidelighting. Low-contrast conditions typically imply nondirectional lighting (for example, uniform overcast or open skylight), which is about the WORST thing you can have if you want to reveal texture in your subject.

 

Regards,

 

Patrick