Nikon Nikkor 65mm SW, f:4 - Sharpness

[Juergen Sattler]

I just shot my first 20 sheets with my 65mm Nikon Nikkor lens and the results are somewhat disappointing. I expected this lens to be tack sharp but my slides tell a different story. I used f22 and f32 apertures, took my time in focusing, but I can't get everything tack sharp. Even when I look on the GG, the outer rim is blurry - is this normal for these extreme wide angle lenses.
The widest lens I had used so far was a Rodenstock 6.8 90mm lens and I never had this problem before.

[Brian Ellis]

The 65mms with which I'm familiar from Rodenstock, Nikon, and Schneider all have an image circle of 170mm, which is just barely more than needed to cover 4x5 with almost no room for movements. So even without any movements the edges of the image are pretty much at the outer limits of the image circle where most lenses aren't at their best. Still, if you weren't using any movements I would have thought you could get a sharp image. Have you examined the lens for physical defects, e.g. separation of the elements, fungus, that kind of thing? Were you using any movements when you made the photographs? I don't know how valid comparisons are between lenses used with digital and film but FWIW I use a Nikon 17-35mm lens on my Nikon D100 and it's tack sharp.

[Juergen Sattler]

Brian, I think you hit the nail on the head. Looking at the GG it looks blurred at the edges - all around and I think it is a matter of the image circle. I used the lens on my Canham DLC45 with the regular bellows and there is no room for movements, but I can focus the lens on infinity. I guess what that means is cropping the image when priniting to eliminate the edge. I bought the lens at Midwest Photo Exchange and there is nothing wrong with it that I can see - the glass is perfect. Do other 65mm users (no matter what brand) have that same experience? Just curious.

[Andre Noble]

Retest at f11, f16

[Bill McMannis]

Juergen, I avoided the 65mm Nikkor for that very reason. On the other hand, I have a Nikkor SW 75mm f/4.5 that performs wonderfully. I use it extensively for shooting interiors of homes and it has always delivered great results. You may want to consider the extra 10mm in focal length as a reasonable trade for the performance.

[Matthew Cromer]

I have an older Schneider Super-Angulon 65/8 with an image circle rated even smaller than the Nikkor. The lens has a lot of light fall-off so I use it with print film and I adjust the gradient in photoshop, but it is quite sharp out to the edge of the frame. I'm happy with the lens.

[Ed Richards]

F32 and even F22 is way into difraction limits for a 65. Try one at F11 on something flat and see if it is sharp without difraction as an issue.

[Michael S. Briggs]

I have doubts about the hyothesis that unsharpness that Juergen is experiencing is due to diffraction. It sounds like he is content with the sharpness at the center but not at the edges. Softness from diffraction from stopping down too far would effect the entire image.





I haven't used a 65 mm lens, but I wouldn't be surprised if the ground glass image wide-open didn't hold up well to examination with a loupe. The coverage wide-open might not be 4x5. Nikon doesn't seem to publish MTF curves for their LF lenses -- for MTF curves for a comparable lens, look at http://www.schneideroptics.com/photography/large_format_lenses/super-angulon/pdf/super-angulon_56_65.pdf -- at f5.6, the MTF curves fall off pretty steeply off-axis. Schneider gives the image circle wide-open as only 135 mm diameter. Of course, this isn't the Nikon that was asked about, but the techology is similar and the Schneider data gives a feel for the expected performance.





When I had a Canham DLC, I found wide-angle lenses difficult to use. This was before a bag bellows was available. Applying any rise would cause the front standard to tilt. I suggest carefully checking the parallelism of the standards, whether or not rise is used.





Also, did you remove the small screw on the back of the shutter? If left, this screw will cause the shutter to be tilted on the lensboard.

[Nick_3536]

http://www.europe-nikon.com/specifications.aspx?countryid=20&languageid=22&prodId=516&catId=148

Wide open 110mm.

[Juergen Sattler]

Thank You all for your responses. I also doubt that this is a difraction issue, but I will do more tests with the lens. I will shoot another badge of film in various "staged" set-ups and see how the lens performs. The image circle for the lens is indeed 110 fully open and 170 at f22. That would explain the blurriness on the GG when viewing wide open. I will report back with my test results.
Juergen

[Madsen]

I have a example of this lens which is excelent, but beware of the

image circle at f 4.0.

I usualy uses the lens at F. 11.0 and 16.0, where it is a excelent

very sharp lens

[Steve Daniels]

I have the Nikon SW 65 f4 and find it to be extremely sharp. Even wide open, the ground glass image is very sharp in the center. I do not stop this lens down past f16 because of diffraction. I do some very long exposures and use ND filters to accomplish them rather than stopping down past f16. By f16 everything should be sharp with this lens.

You might check to see that the rear element is seated properly. I have seen a few lenses that were optimized for close up (not wide angle, though), and a spacer was inserted either behind the front element or in front of the rear element. It would look like a thin brass washer. If there is one there, remove it and it should improve sharpness.

In some cases, a thick lens board can cause the rear element to not screw in all the way.

If none of these are the case, you may have a defective lens.

Steve Daniels
St. Petersburg, FL

[Michael S. Briggs]

Nikkor-SW lenses come from the factory with a thin brass shim in between the front element and the shutter. This washer is supposed to be there for the intended use of the lens. It wasn't added by some photographer to improve the lens for closeups. I would be surprised if removing the brass shim from a Nikkor-SW improved the performance for distant subjects. Apparently the spacing of the lens cells on lenses of this design type is critical and the manufacturers compensate for manufacturing variations by tuning each lens with a shim.

[Steve Daniels]

Note that I mentioned that I had not seen it done on wide angle lenses. I have never taken the front elements off of my 2 Nikon SW lenses, so I have never seen them, and are probably there.

In the seventies and before that, shimming was done a lot to increase performance for close up photography. I once had a Rodenstock 180mm that had shims (4 of them) in the box and instructions on how to use them for this purpose. I haven't seen it done much since that, probably because of more modern techniques in optical performance.

Is it possible that the shims needed for Juergen's lens are missing? If the lens is a used one, it's very possible.