D90 DOF clarity

[aliceat41]

Just upgraded from a old D40 to a brand new D90 + 18-105mm kit lens. I'm having trouble with dof clarity and clear focus points in general. With the D40 I got lovely clear and detailed focus and got best dof clarity overall with F-11, but could go to F-18 and still get reasonably good clarity overall for zooming in if I wanted to crop and enlarge. Now I've had the D90 a couple of days, taken about 1000 shots and I cant get the bugger to give me decent dof clarity, neither most times can I get any decent focus point at any F-stop. I've tried everything I can think of but the fact is, when I compare images side by side, I'm wondering why I bothered upgrading at all! Now is there some new setting on the D90 I'm not familiar with, or does this sound like there's something wrong with the camera or lens?

I thought at first that it might be the filter I was using so I ditched that today but the shots are no better. The clarity at F-11 is 'ok' but at F-18 it is terrible, it even has little pixelated squares in it when you zoom in (it's been sunny today so iso 200) what is going on? Some people say to not go above F-11, but surely the D90 should be able to give good results at F-18 in the right light??

Help! Advice?

[ravncat]

I have to think more - But, if the pixelated squares are what I think they are, they're showing up in the lcd monitor at a high zoom? If so they are artifacts of the jpg preview and not part of the final image.

double check the quality settings, maybe. F18 will introduce softness from diffraction, that will be noticable if you're zooming in that much. Image samples would be helpful in determining what is going on.

[aliceat41]

I only shoot in Nef. I'll convert to jpg and post a few, thanks.

[zona5101]

I am not sure why this isn't a function of the lens and not the body..

Is this the same lens as on the old body?

[Gulf Coast Girl]

Originally Posted by aliceat41

Now is there some new setting on the D90 I'm not familiar with, or does this sound like there's something wrong with the camera or lens?

I'm a beginner so I don't know that anything I say will help, but I do have the same camera and kit lens so I thought I'd try.

I've seen a lot of experienced photographers here on the forum post about every lens having a "sweet spot" in terms of Aperture and clarity, DOF, ect. Now after reading your post and thinking about the shots I've taken with that lens, the ones I'm happiest with all seem to be around F/11, so maybe that is the sweet spot for that lens?

Anyhow, I went outside and snapped a few shots of my dog with that lens at F/18 so I could post them here and you could see if they are similar in quality to the ones you are unhappy with.

All three of these are SOOC, no editing or cropping done on them. I only re-sized them to comply with forum rules. All were taken at F/18, ISO 200 in Aperture Priority Mode. I've taken 3 at different focal lengths (18 mm, 40 mm & 105 mm). Hopefully these will give you enough to compare.


#1 - Shutter 1/80, Focal Length 105mm





#2 - Shutter 1/60, Focal Length 40mm




#3 - Shutter 1/60, Focal Length 18mm




The photos look better when viewing them on Flickr.

[OsmosisStudios]

Originally Posted by Gulf Coast Girl

All three of these are SOOC, no editing or cropping done on them. I only re-sized them to comply with forum rules. All were taken at F/18, ISO 200 in Aperture Priority Mode. I've taken 3 at different focal lengths (18 mm, 40 mm & 105 mm). Hopefully these will give you enough to compare.

Here's your problem: I never go below f/16, and almost never go below f/11. I don't know what you're doing at f/18, especially with a shutterspeed of only 1/80 at 105mm. You want at least 1/f for the shutter speed.

The reason for not going so far down on the aperture is simple: Diffraction. It robs sharpness, and it gets worse - and starts being visible earlier - on higher resolution sensors. So, you went from a D40 to a D90: 6.1mp to 12.3mp. That's twice the resolution, which has an impact, for sure.

Your RAW developing process may also need some work: the newer bodies tend to require a bit more effort on that front.

[ravncat]

Pst. Osmosis , gulf coast girl isn't the OP. She was taking them at 18 because the OP did.

Osmosis is probably right. Your resolution jump, and your slow shutterspeed are a big part of it. The squares you talked about are from the Jpg Preview that the NEF file uses to display - when you look at a fully rendered preview in ACR or in lightroom you should not see the "Squares" A faster shutterspeed and brighter aperture should help alot - try shooting around F8 for awhile...

Originally Posted by OsmosisStudios

So, you went from a D40 to a D90: 6.1mp to 12.3mp. That's twice the resolution, which has an impact, for sure.

Resolution is via area so you need 4x the pixel count to double the resolution. 24megapixels is double the resolution of 6.

[Gulf Coast Girl]

Originally Posted by OsmosisStudios

Here's your problem:

LOL... dude, it's not my thread. I only posted those images at F/18 because that's what the OP said she was not happy with on her same camera/lens and I was giving her something for comparison...... did you even read my post?

[OsmosisStudios]

Originally Posted by ravncat

Resolution is via area so you need 4x the pixel count to double the resolution. 24megapixels is double the resolution of 6.

No, 24mp is 4 times the resolution. 24mp is doubling both dimensions in pixel count, 12 is doubling only in one direction (which is double the resolution).

6mp: 3000x2000 (D40)
12mp: 4288x2848 (D90)
24mp: 6048x4032 (D3x)
(figures from DPReview)

So, a D90 isnt *exactly* double, but it's very close. Note how the numbers only really change in one direction (2000 -> 4288) where as they stay close to normal in the other (3000 -> 2848). The D3x, however, doubles both numbers (3000 -> 6048 and 2000 -> 4032). The D3x, therefore, has 4 times the resolution from doubling BOTH dimensions, the D90 has 2 times the resolution from doubling ONE dimension.

My math is correct.

Originally Posted by Gulf Coast Girl

LOL... dude, it's not my thread. I only posted those images at F/18 because that's what the OP said she was not happy with on her same camera/lens and I was giving her something for comparison...... did you even read my post?

It would seem my brain is still somewhere over the Atlantic: I've just returned from Europe, so I'm gonna blame Jetlag.