D50 edge softness w/ 20mm AF Nikkor

[arond a.]

I recently bought a D50, my first foray into the realm of digital.

Since then, however, I've noticed some rather unpleasant edge softness

with the lens I'm using, an AF Nikkor 2.8 D. Softness seems to occur

when I'm within about a meter of a subject. It's most apparent at

wider apertures, but it still shows up, as the f/8 shot of the park

sign reveals (see folder). The effect becomes more pronounced the

closer I get, as the example below shows. Any suggestions? Thanks.

 

http://www.photo.net/photodb/folder?folder_id=580465<div></div>

[arond a.]

By the way, I'm using a fixed focal length lens, if that wasn't make that clear.

[melvin_bramley]

The original owner of this website Philips Greenspun! had a faulty Nikon 20mm F2.8 D lens. The results you posted would seem to be the same.

[frank_skomial]

I have the same brand 20 mm / 2.8 Nikkor AF, D, and pictures are sharp even when wide open, at any distance.

[titospna]

Arond: If you bought this lens brand new, you need to exchange it for a different sample. My lens is sharp all over, also used on a D50. I don't believe that with the 1.5 crop factor, you should be seeing any softness that's been reported in the past on this lens, when shot wide open. Your park sign at f8 should be tack sharp and that alone would make me run to exchange it. Don't give up on this lens because I've found it to be excellent. Good luck, sir.

[patricks]

faulty lens, do return it if you bought it new or contact the seller if you bought it from a private party. i have that very lens, one of my favs, and that performance is not kosher.

[frank uhlig]

Is it the 20mm f/3.5 (AIS, maybe)(as in the pic title) or the 20 f/2.8 AFD? Your pic shows huge amounts of barrel distortion also. Very uncharacteristic of a Nikkor lens. Toss/exchange it!

 

The AFD and the AIS lens are both quite nice even on 35mm film, so should have no discernable edge softness if cropped by 1.5 times; none whatsoever. Did you drop your lens recently? Does it clink when shook gently? Something is quite loose, broken. Sorry.

[erik_loza]

Yes, something is wrong, here. It almost looks like you've used some other lens than the

Nikkor 20mm AF to have the results be that poor. Not to doubt you, but is there any

chance you have shot those pics with something like a kit lens and gotten the jpeg's mixed

up ( I have done that before)? The field of view looks a bit wide for 30mm and the level of

distortion there I have never seen, even in FF format, with the 20mm.

 

We're on your side, here, but something is missing from this equation. The softness might

be explainable if there were some element misalignment but the distortion is a whole

different thing and it appears uniform. Why don't you you tripod your camera parallel to a

wall and shoot an image of some printed material at 1m and f2.8, then post? Good luck.

[luxus]

This is not normal for this lens at all. The corners are a little soft and there is some CA on D200 but only on 100% viewing.

[ilkka_nissila]

Mine behaves the same way. The plane of focus is not flat when you focus close. This explains why the corners are not sharp when you focus to a near subject Also, there is some barrel distortion up close. This is imo not a fault. Try a subject at longer distance e.g. 10m, if the images there are ok, then the lens works as intended.

[ilkka_nissila]

Looks like my left side of the lens is systematically softer than the right side. I shot the same box at a histance of about 2 m with the right and left side of the field (I panned the camera on a tripod to do the two shots).<div></div>

[ilkka_nissila]

... and right side. I did refocus and used the D200 sensor right corresponding to the point where the crop was taken.

 

I've got some real world prints where I've suspected something is wrong but haven't done anything about it. I should have remembered Philip's article.<div></div>

[ilkka_nissila]

I suppose the quality control and mechanical construction of AF Nikkors is typical of a consumer electronics company, not an optics company.

[ilkka_nissila]

I did notice some left-side softness when I bought the lens 2 years ago and used it with the D70. I didn't notice anything on 35 mm film and was happy with it as I mainly use digital for tele shots.

 

Basically what I think it boils down to is that the 1.5x crop factor forces Nikon to redesign lenses with tolerances 1/1.5 of what they were with film, if a similar level of performance is to be maintained on a similar sized lens. And this is what I see one of the fundamental problems of the DX format: eventually most of film-designed existing gear will be discarded because of inadeqate performance on the small sensor, and new lenses will replace old ones. So my conclusion is that Olympus was really right in making a new lens mount for digital, although they should have chosen a larger sensor size. I'm kinda angry about this because I've got a large investment in primes and Nikon basically haven't updated them to account for the properties of digital sensors that they use. Basically the performance advantage is lost and now the 12-24, 17-55 and 70-200 are the best lenses to use. (The 17-35 and 28-70 were also designed with digital in mind, which shows in their performance. Nikon made these the first ED normal and wide angle lenses because of the characteristics of digital sensors.)

 

I'm going to ask Nikon USA to look at my files and if they can fix the lens. I doubt it as this is probably a question of tolerances which are built into the structure of the lens (and it's in like new conditions).

[titospna]

Ilkka: If you bought your lens brand new, do you know if this applies as a warranty issue? Just curious since I've never had to turn a lens in for repair. I always felt the 5 year warranty was pretty generous. Also, you don't have this same issue with other wides using your D200 do you or have you noticed? Thanks.

[ilkka_nissila]

No, it's just this lens but I only have the 14 and the 20 which would quality as wides for the D200.

 

I don't have the 5-year warranty as at the time of purchase I was in Finland and to apply for it requires a US residential address as far as I can recall. So I have to pay for the repair if it can be done (although it is as it was when new, obviously).

 

The drop in sharpness on the left side is obvious (to anyone, not just me) in a 8x12 inch print at f/4 and still somewhat visible at f/5.6. I'm going to do some tests using 35 mm film to see if I can see it on it. If not, then I guess Nikon will say that it's within tolerances as the lens was designed for film (the actual design must be from the 70s or 80s, right?).

 

This is precisely the kind of thing which makes people want Zeiss wide angles which are presumably made with solid mechanics. Even the DX pro zooms are fragile and can go out of alignment with normal use. So what can one buy with confidence?

[ilkka_nissila]

An update on my lens: I sent the above crops to Nikon USA and they said that the lens requires service. I am glad.

 

Also, I mentioned the problem I had with stuck aperture on my 70-200 to them and they also asked that I send that in too. This one is still under warranty.

 

So there is hope ;-)

[walterh]

Ilkka - sorry to hear about your lens problem. I have seen alignment or similar problems too often to ever buy a wideangle lens wider than 35mm without testing it (- super deals excepted). Even though the problem is more prominent with wide zooms - primes also seem to suffer from quality control or the lack thereof. In my experience Nikon is better than some third party competititon but far away from the optimistic expectations of most consumers. The sad question is if the local Nikon repair facility is capable to do the adjustment.