Nikor 450M on 8x20

[Jorge Gasteazoro]

Ah, so it is a conversion back from Wisner.......not to start beating the dead horse again, but there are plenty of stories about the lack of quality control from Wisner's made to order cameras and conversions.

So I dont know what to tell you, I have the same lens and it covers 12x20 with 2 inches of rise and fall wide open. at f/32 it is sharp corner to corner. I dont care what Wisner says, the lens does cover 12x20 and it should cover 8x20 with plenty of rise and fall.

The only other thing I can think about, given that this is a Wisner conversion back is that the ground glass is seated incorrectly or the back where the GG rests was not build to specs, which would not surprise me about Wisner, or you have not installed the back correctly, either way I am leaning more towards a camera problem than a lens problem, if your lens has all the spacing rings inside the shutter then it should not be the problem unless someone took apart the cells and messed with the elements, which I highly doubt. As the sayign goes, when you hear hoves thinks horses not zebras.

Do this, just to test the lens. In a dark or semi dark room hang a piece 20x24 white mat board on the wall facing a window. Remove the back and the bellows from the camera and with the lens mounted on the front standard focus the image from the window on the white board. Examine the image, you should be able to tell without a loupe if the image is soft at the corners. If it is not, then the problems is with the camera back, if it is then the problem is with the lens. Other than mounting the lens on another camera of the same size, this is the only way I can think of testing your lens on your own.

Good luck ......

[Bruce E. Rathbun]

Jorge, My original thought was that there was something astray with the back. After suggesting there might be a problem with the camera Ron let me know that there would need to be a major problem that could be seen by the naked eye. Not a problem of millimeter type. For me it is a mute point. I can tell you if I pull the back as if I were inserting a film holder, the edge comes into focus. My big problem is that only ONE edge is out of focus. Do the math on that one. I will try your test in the morning. I will also try rotating the back 180 degrees. If the problem is with the back then I would expect to see the opposite corner out of focus after I rotate. Make sense? Is it possible that if the back is out of spec by a a few millimeters is it possible to have that much of an impact on the image? I fear that I am on the loosing end of the stick on this one.

[Jorge Gasteazoro]

Of course Wisner told you that, what is he going to tell you, "Yeah I made a crappy back"? You know he is not known for being the most straight forward person in this bussiness.

I disagree with him, but you dont have to take my word for it. Simply go into your darkroom, put a neg in the neg holder, focus the image on a piece of paper and once it is focused move one side of the paper up 2 mm. This will show to you how big a difference 2 mm can make in focusing.

I think he is misleading you if he tells you it would have to be a major misaligment for the plane of sharp focus to be bad. Specially now that you tell me that if you move the GG base the image comes into focus, this is definitly a tell tale of a misaligned GG. Why do you think many cameras need shims to align the GG? These shims are not thicker than 0.5 mm, yet they do the job.

I agree if you turn around the back the problem should surface in the opposite corner. If this is the case then you definitly have a misaligned back or GG and need to send it back to Wisner (good luck on that you poor soul). If this is not the case, this could still be a back problem. This might mean that the entire back frame is misaligned or skewed.

The more you tell me about this, the more I am convinced it is a back problem and not your lens.

[Michael Mutmansky]

Bruce,

Put the 450 on the 11x14, and dial in 1.5 inches of rise (or fall), and 3 inches of shift, and the corner of the 11x14 opposite the direction of the rise/fall and shift will be at the exact same place in the lens's image circle as the corner on the 8x20. Then, focus the same way you did on the 8x20 (off the center?) and see how the corner looks.

One thing, the field curvature may make it difficult to have both the center of the field and the corner in exact sharp focus at the same time. With some lenses, I will focus about 1/2 to 2/3 of the way out to the corner, and then stop down to bring in the corner and the center. Some lenses require a relatively small aperture to have sufficient DOF to maintain sharpness into the corners, partially due to sharpness falloff (this is especially true with the M lenses), and partly due to the field curvature.

This is the nature of ULF cameras, and with some lenses you really have no choice in the matter. Your only choice if you don't like that limitation is to use a different lens, probably with a longer focal length, or to not do ULF. A Fuji 600C would be a really great complement to the 450, and a third to consider is the 355 G Claron. A 305 G Claron may also cover. The longer lenses will have fewer issues with curvature and sharpness into the corners, and the shorter lenses will have more problems.

As for suitability, I find it amazing that Ron made that statement regarding this lens. While your sample may be a lemon, there are many, many people out there using this lens with great success on 12x20, so using it with an 8x20 is clearly possible, once you know how to use it properly and you've confirmed that there isn't an optical problem with the lens or the camera.

---Michael

[sanking]

Yes, I am also pretty surprised that Ron Wisner would have said that about the 450 Nikor-M. He has done a lot of writing about lenses and one would certainly presume that he would know that this lens is one of the most popular lenses out there for the 12X20 format. Howeve, you do have to take into account the curvature of the field that Michael mentioned.

However, from what you have described so far I believe that for some reason your camera is not setting up with everything centered, in other words there is either some tilt in either the back or front standard, together with some slight swing in either the front or the back. This would explain why the image appears sharp on the top but not on the bottom.

[George Losse]

Bruce,

After you try rotating the back and focusing on the ground glass in the other direction. Try taking the back off the camera again, look at the back when its off the camera. Is the glass in the same place all the way around the spring back? Is there any material between the glass and the spring back the could have caused the glass to be off slightly.

Have you made any exposures with the camera yet? I would want to know if the same effect happens on the glass as happens on the negative. There is always a chance that there is something happening in the spring back that would not happen with a holder.

[rich silha]

i own two 450/f9 nikkor lenses and use both of them on 8x20, 12x20, 16x20, and yes can cover my 20x24 wisner camera. the tessar design has barrel distortion. the more you stop down the more the distortion is corrected and the image plane of focus flattens out to acceptable focus at the edges.

[Bruce E. Rathbun]

I found the problem. There were indeed two problems. The first was the camera. Not what you would think though. After a total disassemble of the 8x20 I was able to dial in the focus on the Artar. Here is what I found. The front standard had for a lack of a better description some twisting on the upper front standard. After the camera was disassembled I could see the problem with the front standard. There were also other points that needed an adjustment or two. Once the camera was back together I placed the Artar back on the camera for another test. My backyard faces a tree line in a field that makes for great subject matter with the 8x20. I placed the Artar on and I was amazed at the difference. The corners of the Artar were slightly out of focus. This is what I would expect from a lens on an 8x20. After placing my loupe on the glass I could see that at f22 to f32 the corners were indeed sharp.

Now....the 450M is a different story. I could now see that all four corners were out of focus. What I am seeing here is lack of coverage. There is definitely some curvature on the outer edges of the lens. Maybe this lens is on the lower edge of what is expected. I did attempt to work with the edges. I could see that at f45 they would be soft. At f90 they are sharper. A negative would tell the full story. So maybe the problem is my perceptions and expectations of the 450M. When I hear people telling me that they have full focus wide open is this what I would call sharp focus? I think maybe this particular 450M is not what others are experiencing. Believe me I would love to have a 450M that works side to side. This lens that I tested has some serious field curvature. Maybe I am looking at a lemon of a lens. I will ship it back on Monday. I would like to tray another Nikon 450M. Is it possible that maybe the lens that I am looking at is just at the bottom of the coverage? Now I need to decide to mount the Artar in a shutter or hold out and test another lens. Suggestions? I did try the 450M on my 11x14 with some wonderful results as well.

[John D Gerndt]

Bruce,

I too think you have a strange 450M. Maybe some research on the variances of those Nikkors is in order.

It would be wise not to drop the coin for a shutter conversion on any lens until you have negatives to prove the lens worthy. Patience.

You should also consider testing your camera’s alignment. With a little thought, one of those three beam laser levels and a mirror you should be able to test to see if front standard and GG are indeed parallel, first things first. Good luck.

[Bruce E. Rathbun]

At last we have proof! I was able to test another 450M Nikor lens. To my amazment the lens was much better! I feel better now. The camera is good, the current lens will be returned and I will try another. I want to thank all that chimed in to help. Another case where there is an enormous amount of talent on this forum. I will also archive this thread as there were many good suggestions for checking both the camera and the lens. Once again patience has prevailed. Having a new 8x20 with a lens that does not cover and should one month before a major vacation to Utah is stressful. Now I can move on. Thanks again to all.