Lens Sharpness & Sensor Performance

[natek313]

I recently did some shots outdoors - all natural lighting. When I got the photos on the computer and looked at them, the majority of them seemed not as sharp as they could be and not as sharp as some other photos with the same lens.

See attached for 100% crops (otherwise, SOOC) on two photos taken with the same lens (Canon EF 85mm f/1.8 USM) and camera body (Canon Rebel XS). Here is the EXIF information:

First Photo: ISO 100; f/7.1; 1/200s

Second Photo: ISO 200; f/5; 1/250s

To me, there's a pretty big difference in image quality between these two photos. The only relevant differences would be the ISO and aperture settings. The shutter speeds are definitely fast enough to freeze any slight subject motion and any camera shake (I usually use good form in holding the camera).

Do you think those different settings (ISO and aperture) could be the reason for the degradation of image quality? It just seems that all my studio shots are sharper than my outdoor shots. I'd love to get so thoughts/input on this.

Thanks in advance!

EDIT: I just realized that the second photo isn't as tightly framed around the face (in the full, original photo) as the first one is. Could that be what I'm seeing as well?

[bono]

Usually lenses tend to be sharpest at about f/11 but the range betwenn f/8 and f/16 ist best in situations with a lot of light. You just have to look if you can reach about 1/60s or faster speeds. In good light I would also choose low ISO settings - ISO 100 should be enough.

If the image is not really sharp, perhaps you got to near. Every lens has an individual minimal focus distance, this could be more than 1 meter. You should also try to control the AF or head for manual focus.

[LeeR]

There is a world of difference between studio light and ambient light. I actually try to take advantage of the softer quality of ambient light as much as possible. Studio lighting tends to be extremely sharp and accurate which is why the PP pros spend so much time softening images for their clients. Why not skip a step and take photos in areas where the light does the softening for you?

[wannabephotographer]

The change in setting can make a difference but if you really want to know you have to do take two pictures of the same subject in a controlled environment. This way you can make sure it's not a lens or camera problem.

I test my lenses on a tripod, indoors and shoot whatever is around that day. Newspaper, magazine, aspirin bottles, etc.

[autofocus]

Nate, I know you are a good photographer, your work proves it, and I'm sure you will always focus off an eye for your portrait work. The first shot is pretty much straight on...both eyes nice and sharp. But on the second shot, a 3/4 view, only one eye will be sharp and the other will fall off a bit, especially with a wider F/stop. Sometimes shots like these have a perception of being soft...was your distance to the subject the same for both shots? As you know, that will also play a part in DOF.

[natek313]

Originally Posted by bono

Usually lenses tend to be sharpest at about f/11 but the range betwenn f/8 and f/16 ist best in situations with a lot of light. You just have to look if you can reach about 1/60s or faster speeds. In good light I would also choose low ISO settings - ISO 100 should be enough.

If the image is not really sharp, perhaps you got to near. Every lens has an individual minimal focus distance, this could be more than 1 meter. You should also try to control the AF or head for manual focus.

Yeah, I was wondering if I was just closer to the sweet spot of this lens in the first shot than in the second. I've never really tested this lens, but I plan on doing that today.

I definitely wasn't too close to my subject; that's for sure.

Originally Posted by LeeR

There is a world of difference between studio light and ambient light. I actually try to take advantage of the softer quality of ambient light as much as possible. Studio lighting tends to be extremely sharp and accurate which is why the PP pros spend so much time softening images for their clients. Why not skip a step and take photos in areas where the light does the softening for you?

I'll have to keep that in mind. Thank you.

Originally Posted by wannabephotographer

The change in setting can make a difference but if you really want to know you have to do take two pictures of the same subject in a controlled environment. This way you can make sure it's not a lens or camera problem.

I test my lenses on a tripod, indoors and shoot whatever is around that day. Newspaper, magazine, aspirin bottles, etc.

Yep. This is what I am going to do today. Thanks!

Originally Posted by auto-focus

Nate, I know you are a good photographer, your work proves it, and I'm sure you will always focus off an eye for your portrait work. The first shot is pretty much straight on...both eyes nice and sharp. But on the second shot, a 3/4 view, only one eye will be sharp and the other will fall off a bit, especially with a wider F/stop. Sometimes shots like these have a perception of being soft...was your distance to the subject the same for both shots? As you know, that will also play a part in DOF.

Thanks. I really appreciate the compliment.

No, my distance to subject was definitely not the same in both shots. In the first one, if I remember correctly, I was maybe 6ft away or so. In the second shot, I was much farther - probably around 15ft - 20ft.

[OsmosisStudios]

Originally Posted by LeeR

There is a world of difference between studio light and ambient light.

This is the issue: studio lighting will almost always give you "sharper" looking results.

[natek313]

Originally Posted by OsmosisStudios

This is the issue: studio lighting will almost always give you "sharper" looking results.

Thanks, Os.

I'm starting to think it's a combination of the difference between studio and natural light along with the difference in settings.

I did some testing this afternoon. The lighting was natural (skylight window). The subject distance was probably 15ft - 20ft or so. See attached photos (SOOC; 100% crop) and below for EXIF data (same settings as in the first post):

First photo: ISO 100; f/7.1; 1/20s

Second photo: ISO 200; f/5; 1/100s

There is a rather significant difference in image quality; look at the detail difference in the chicken.

I'll have to keep all this in mind. Plus, I have to remember I'm pixel peeping... Haha.

[CiiVii]

Call me crazy, but the very first pic you posted has catchlights in the eyes which clearly appear to be a strobe in an umbrella.

Or AM I crazy?

[natek313]

Originally Posted by CiiVii

Call me crazy, but the very first pic you posted has catchlights in the eyes which clearly appear to be a strobe in an umbrella.

Or AM I crazy?

Haha. No, you're not crazy at all. In that photo, I was using my AlienBees B800 and shooting it through a 45" umbrella. Well, that was the main light, anyway.