"Soft" Nikon 300mm

[Prospero]

Hi all,

First let me acknowledge that it's been substantially more than a couple of years since I was last on here. Work was busy, wife was ill, so photography - and APUG - took a back seat, and I let my subscription lapse.

Anyway, things are looking good again, we're planning a trip to Italy in a couple of months, I've dusted off the LF gear, and I'm back on APUG. I'm delighted to see it is still in business.

And now to the question that has brought me back.

I have a Nikon Nikkor-M 300mm 1:9 lens mounted in what seems to be the appropriate Copal shutter. My Horseman 45FA doesn't have enough extension by itself for this lens but I use it with a special lensboard with a built-in extension.

I've noticed that the focus is a little soft. No matter how hard I try with a loupe to get the image as sharp as possible, the results are not as sharp as they are with any other lens I have. At first I assumed that the focal length meant that it was more sensitive to vibration and I was getting tiny amounts of camera shake. But over time I have realised that it must be the lens itself. It's not terribly bad, but I'd be better off getting a similar effective focal length with a sharper lens and a 6x8cm back. Which is not what I want.

Everything seems to be assembled nice and tightly.

Is this softness likely to be a characteristic of the lens? If so does anyone have a suggested alternative?

If there is something wrong, is there any way of finding out what it is? I do not have access to any special equipment.

Grateful for any suggestions.

 

[Jesper]

I have the M300/9 for use on 8x10, and in my experience it is a very sharp lens.

Could it be that something is askew in the setup?
If you focus on a specific detail, will that detail come out sharp and the rest somewhat fuzzy?

 

[Prospero]

Thus far I've never had anything come out particularly sharp.

 

[ChuckP]

Are you saying that a negative stopped down to say f22 isn't sharp or just viewing the ground glass at f9? I've never found mine to be different compared to my other modern lenses. But I'm talking about negatives taken at f22-f45 range. I can focus Ok but have never made any sharpness judgements using the ground glass. I think you will find that this lens has a good reputation for being sharp.

 

[Doremus Scudder]

When my Nikkor M 300mm was new, I had a similar problem... I, too, thought everything was assembled correctly, but kept getting softer images than I liked.

Finally, after more careful scrutiny, I noticed that the retaining ring was not screwing down past the end of the lens mounting threads for the rear element because the lens board was a bit too thick. This kept the rear element from seating properly. A bit of work on the board and the problem was solved. You might check your set up.

Also, longer lenses are notoriously harder to focus, especially if they are a bit dark (f/9), so, you may just have to work harder at it. Get out the 10x loupe and really give it a test.

Also, your ground glass and film plane may not be well aligned. A quick test: focus on and shoot some silhouetted objects on the horizon at full aperture. If they come back in focus, your set. If not, you need to do some shimming...

Hope this helps,

Doremus Scudder
www.DoremusScudder.com

 

[Nicholas Lindan]

This is a very sharp lens.

I'll second Doremus' suggestion - check that nothing is altering the seating of the cells on the shutter housing.

Some retaining rings have a shoulder on them - the shoulder is meant to enter the lens mounting hole and center the lens in the hole - make sure the shoulder isn't hanging up on the edge of the hole.

 

[Ian Grant]

This is a Tessar type lens design so don't expect too much wide open their optimum aperture is f22 but with a 300mm f32 or f45 is better.

I have the same lens and find that on my Wista with the bellows fully extended the whole camera is far less rigid and very much more prone to camera shake, you do need to use faster shutter speed where possible to compensate.

However the same lens on my 10x8 Agfa Ansco behaves quite differently because the camera is so much larger & far more stable. So it's probably a combination of issues, Nikon's QC is good so it's unlikely to be a problem with the lens itself.

Ian

 

[pgomena]

My 305mm f/9 Schneider G-Claron gives an "almost sharp" image when I focus it wide-open. From f/16 onward, it is bitingly sharp. I know this is a different lens design from yours, but stopping down a bit solves my problems. Ditto what the others say about checking your system for proper mounting and alignment.

Peter Gomena

 

[Prospero]

Thanks all for the replies, in particular those who report it is not a soft lens by design.

ChuckP. I'm saying the negative is not sharp, not the image on the GG. When scanned on a Flextight II and viewed at 1:1, the 300mm produces results noticeably softer than any other lens I possess.

Doremus: I was hoping it would turn out to be something this simple, but alas, no. The retaining ring does screw down past the end of the lens mounting threads, so there is nothing stopping the rear element screwing in all the way. As for alignment of the GG and film plane, see above - the 300mm produces worse results than other lenses.

Nicholas: No, there is no shoulder, in fact it's a bit fiddly centering the lens while I tighten the retaining ring.

Ian and Peter: I never use the lens wide open. I generally expose on f/90 or f/128. Will try some apertures in the middle of the range to see if they are better.

To those who suggest I must be getting camera shake, that's a hard charge to disprove, other than to say I am using a fairly chunky Manfrotto geared head with a fairly substantial Manfrotto tripod. I use an extra long shutter release cable and ensure there is plenty of play in it when I trip the shutter.

I will keep trying to minimise shake, and see if I can improves thing that way. If not, I will replace the lens.

 

[Yamaotoko]

G'day Stewart,

Whereabouts in Australia are you? I've got the same lens, so if you're anywhere near me, you're welcome to give it a try and compare it with yours and see whether the same issues present again. I know mine is a sharp lens, so if it were to produce soft images on your camera, then maybe camera shake could be your problem.

However, I use a fairly insubstantial Manfrotto, but still get sharp images, even with the 300mm hanging out there at full extension.

 

[Prospero]

Thanks Steve, that's a very kind offer.

I'm near Canberra but family in Melbourne so get down your way several times a year. If I can't resolve the issue I may PM you.

 

[ChuckP]

Using f90 and f128 may be the problem. Too much diffraction? Definitely try some exposures at f22-32 to see how they look.

 

[Yamaotoko]

No worries, we regularly travel between Geelong and the Eastern Suburbs of Melb, so if it comes to it, I'm sure we could work something out.

 

[TheFlyingCamera]

Just a thought - I assume you're using some kind of "top hat" lensboard extension to mount this lens and use it on your Wista. This is creating an extension above and beyond the limits of the camera platform, which would magnify any vibrations you would get through the tripod, or with wind. Also, given the depth of the "top hat", is it possible you've not fully tightened the retaining ring? One more thing to look into - often lenses like that came with a shim to go between the lens element set and the shutter body (usually on the rear element, but not always). Check and see if A: your lens has a shim, and B: if it does not, try to find out if that lens model shipped with a shim. Often the shims are significantly less than 1mm in thickness.

If you can't solve your problems, I'd consider getting a Fuji 300T f8. Not only is it faster (nominally) but it's also a true telephoto, so it requires less than 300mm of bellows to focus to infinity. Downside is limited movements. If you have to switch, you could probably get an even-up trade from your Nikon to a Fuji 300T.

 

[Ian Grant]

Manufactures sometimes use shims when matching up pairs of cells so it's not necessarily dependent on the model/batch rather just their QC getting the best from a particular paired combination of cells. This is also why some lenses have serial numbers on both front & rear cells,

But Scott's observation of the extension etc mirrors my experiences that it's a difficult lens to use on 5x4, that extension amplifies any shake,

Ian

 

[Nicholas Lindan]

I generally expose on f/90 or f/128. Will try some apertures in the middle of the range to see if they are better.

A rule of thumb is that the optimum aperture is equal to the focal length / 6 for a 'normal' lens.

Like most rules of thumb there are probably more exceptions than adherents.

As an example:

format - F.L. - optimum f-stop

35mm - 50mm - f8
6x6 - 80mm - f11
4x5 - 150mm - f22
8x10 - 300mm - f45

The better the lens, the wider the optimum aperture. A good APO lens will have an optimum that is 1 to 1 1/2 stops wider.

Using a 300mm on a 4x5 means you are only using the center of the lens' coverage, the Nikkor is close to an APO, and so f22/f32 will yield the best results.

Using the 300mm (4x5) at f128 is about like using a 50mm (35mm) at f22/f32 - soft results should be expected.

 

[Prospero]

TheFlyingCamera: Yes, it's a "top hat", but the "crown" (ie the part that the lens attaches to) screws off, making access easy. When using this lens (and a big Fuji 210 that also uses an extension) on my Horseman, I always use the forward mounting point for the tripod shoe, to balance the camera and minimise shake.

ChuckP and Nicholas: Thanks very much for that advice. My "rule of thumb" - obviously wrong - was to use an aperture one or two back from the smallest. I'll try using f22 and f32. It will be a while before I get the opportunity but when I have I will bump this thread and report results.

 

[Prospero]

Bumping the thread as promised to report results. Yes, images taken at f22 are much, much sharper. So thanks for all the advice, and I'm keeping the lens!

 

[Tom Stanworth]

phew, I was going to chime in there that f90 and f128 is going to cause serious diffraction induced softness!

Even my cheapo 300 f9 Geronar is tack sharp at f22-32. I love a bargain!

 

[ic-racer]

Ian and Peter: I never use the lens wide open. I generally expose on f/90 or f/128.

Woa, you just answered you question.