Is the 18-105 soft for distant subjects?

[georgehudetz]

Or is it operator error?

Background:

New D7000 shooter with the 18-105, both of which I bought (lightly) used. Brought it skiing on Mt Hood (Timerbline Lodge) over the weekend since the weather was supposed to be glorious (it was) and I was hoping to get some good shots.

Have not done AF calibration, however, I do not think AF is the issue here, since I am shooting at F8-F9 and have a generous depth of field. Also, I took over 100 shots that day, with only one obviously OOF shot (yay!). I’m using the Ray Soares setup, and it worked quite well for me capturing both stationary and moving subjects against the snow, even when fumbling around with gloves on.

I’ve attached one of those shots. The focus point (using 9 sensors) is right in the middle of the image, as per VNX, so I should be well beyond the hyper focal distance. Details in the center of the image (lift towers and tiny little people) look fairly good to me, but the mountain peak looks soft. Note that I’m not pixel-peeping – just looking at the image at 1:1.

Is this to be expected of the 18-105? Or does anybody suspect operator error? If this is typical, can you suggest any lenses that have good sharpness for distant subjects? If not, what am I doing wrong?

The image has been post-processed from raw in DXO8, with the default settings. I can get more sharpness out by using the unsharp mask and micro-contrast controls, but there always seems to be a trade-off when doing this and I am wondering if there is something I can do to alleviate the need for sharpening of distant subjects (not that I am against PP – still a lot to learn there).

Thanks in advance!

 

[Leonard Migliore]

I certainly can't see any unsharpness on the image you posted. It is, however, considerably down-rezzed from the original so there's nothing to see.

I would not expect any unsharpness on distant objects at f/8. Snow-capped mountains, however, have very little detail to resolve.

 

[georgehudetz]

Hmm. I uploaded the full resolution image, but I agree when you view it at 100% on dpreivew it looks very fuzzy. Clicking on View Original shows more detail.

And, there is some bare rock in the mountain peak that does not show as much detail as the center - I'm looking at the rock as opposed to the snow.

 

[RP McMurphy]

F8 wont give you sharpness from middle of the scene to the mountain peaks - those mountain peaks are very far away and at 105mm your hyperfocal distance is unlikely to cover to infinity

Equally at those altitudes UV will impair the sharpness on longer distances

The kit lens is not going to give you huge sharpness, seems to be a decent lens for a kit but I think you're expecting a bit much

Last and not least, the lens is not optimised for detail at infinity

What you have is consistent with what I would expect - try a higher aperture and push the focal point back a but if detail in the rocks is what you need

 

[mais51]

Sunset over Atlantis Ocean - Porto. Zoom in to see the fishing rods of the two fishermen on the riverbank



I have no problem with this lens - looking at the photo you wouldn't think that there are fishermen on the far side river bank with...fishing rods clearly visible at more than 300 m distance !

 

[mais51]

This is the enlarged portion of the above image - jpg direct from the camera - no enhancement or post processing

I notice that the loupe does not give sufficient enlargement on the original image - not bad for a cheap lens

 

[Leonard Shepherd]

georgehudetz wrote:

Or is it operator error?

(snipped) I took over 100 shots that day, with only one obviously OOF shot (yay!).

(snipped) I’ve attached one of those shots. The focus point (using 9 sensors) is right in the middle of the image, as per VNX, so I should be well beyond the hyper focal distance. Details in the center of the image (lift towers and tiny little people) look fairly good to me, but the mountain peak looks soft.

I think you are saying most of your pictures are sharp, but a few, including this one, and not.

If I have understood you correctly the likely cause of the problem is the detail on the individual sky supports used as a autofocus target is too small for auto focus to accurately detect.

As a guide with a D7000 the size of the autofocus detail should be at least half the size of the viewfinder autofocus mark. The nearest support, just below where the three legs join, would probably have been a better autofocus target, but it is not in the middle of the picture area.

Nikon give some guidance on difficult autofocus subjects on page 93 of the camera instruction book but the guidance does not deal well with this type of autofocus problem.

--
Leonard Shepherd
Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

 

[georgehudetz]

Thanks for replying.

RP McMurphy wrote:

F8 wont give you sharpness from middle of the scene to the mountain peaks - those mountain peaks are very far away and at 105mm your hyperfocal distance is unlikely to cover to infinity

That particular shot was at 58 mm, which gives a hyperfocal distance of about 70 feet, which I easily achieved, assuming the camera got the focus distance right.

Equally at those altitudes UV will impair the sharpness on longer distances

Interesting point about UV, I hadn't though about that.

The kit lens is not going to give you huge sharpness, seems to be a decent lens for a kit but I think you're expecting a bit much

I think my expectations for sharpness are reasonable, given that if you look at other areas of that shot - like the rock formation at the left edge - the sharpness is much better than the mountain peak.

Last and not least, the lens is not optimised for detail at infinity

This is what I am wondering.

What you have is consistent with what I would expect - try a higher aperture and push the focal point back a but if detail in the rocks is what you need

Yes, I will experiment with that on some other scenes. Thanks again.

 

[georgehudetz]

Leonard Shepherd wrote:

I think you are saying most of your pictures are sharp, but a few, including this one, and not.

If I have understood you correctly the likely cause of the problem is the detail on the individual sky supports used as a autofocus target is too small for auto focus to accurately detect.

As a guide with a D7000 the size of the autofocus detail should be at least half the size of the viewfinder autofocus mark. The nearest support, just below where the three legs join, would probably have been a better autofocus target, but it is not in the middle of the picture area.

Nikon give some guidance on difficult autofocus subjects on page 93 of the camera instruction book but the guidance does not deal well with this type of autofocus problem.

 

[Zampa the lion]

Sorry to rake up an old thread..but I picked this up on the net while researching my problem..

I used my 18-105 to take a standard family group shot, indoors, with the camera on auto in good daylight..I took the picture handheld..and then later using a tripod, and both shots came out very soft..this has been a constant issue when using the lens at 18mm...I have been told this is normal and not to expect sharp pictures at this focal distance..

Why?

 

[OpticsEngineer]

From what I read on test results for this lens, it is slightly sharper at f=18 mm than longer focal lengths. So all I can think is that someone was saying it was soft compared to prime lens? which of course it is. But it should be more than good enough for a family snapshot.