Nikor 450M on 8x20

[Bruce E. Rathbun]

The past few weeks have been very busy for me. I now have a wonderful Wisner 8x20 camera with a Nikor 450M lens. I went out today to see how the lens works. I was slightly bummed when I noticed that the corners are out of focus. Depending on the subject matter the focus can be out a tad bit or a major amount. I am guessing this is due to the actual coverage of the lens wide open at infinity. After working with the lens for an hour or so I started to get the hang of it. By stopping down to around f64 the corners seem to come into focus. I will find out this weekend after a test shot on Friday. So here is the question. The corners in the upper part of the image are out of focus more than the lower corners. One of the upper corners is out even more. Can I assume that if the image is in focus in the center that stopping down to f45 or f64 will bring the corners in to focus? I was hoping that I would get a good focus at infinity wide open but this is not the case. Is this normal for this lens on an 8x20? Thanks in advance for any help. I will say that the image looks fantastic in the glass. Can't wait to shoot an image.

[Jorge Gasteazoro]

Where did you get this lens? I use it with a 12x20 and I dont need to stop down anywhere near f/64 to get sharp corners. If you got the lens new, check to see if you did not drop the shims used for cell separation. Sometimes when putting the lens on a board and unscrwing the cells the thin circular shims fall out, I have done it before.

Other than that, I dont know what to tell you. I wish you luck.

[Bruce E. Rathbun]

Jorge, The lens was purchased from Columbus Camera Group. It is in mint condition. I get the same result with a 19" Red Dot Artar. Based on my research I was thinking that both of these lenses would cover. Yet I am confused as to how far out of focus the edges are. I am not sure what to do now. Should the 450M cover an 8x20 at infinity?

[George Losse]

Bruce,

I use a Nikon 450M with my 8x20. It covers the whole image without any of the problems with the corners like you are talking about.

I did have a problem with my back sticking after making an exposure. It would not always go all the way back to the flat focusing position after removing the holder. I do remember a couple of times wondering why something was out of focus just after making an in-focus exposure. I figured it out when the back snapped back into place. From then on I check to make sure it goes all the way back.

[sanking]

Something is wrong, either with your lens or with the adjustments on you camera. I have used the 450mm Nikor-M lens on 12X20" and the corners are sharp at f/32, even with several inches of horizontal or verical movement. And at f/64 it covers 20X24" with adequate corner sharpness.

[Bruce E. Rathbun]

George, After close examination I think I might have found a contributing factor. Does the plastic collar go between the lens and the front of the lens board? I called for CCG for help mounting the lens. I was told the plastic collar goes on the back of the board. When the collar is on the back the lens is offset. Maybe this is the problem?

[Steve Nieslony]

Bruce,

The 450M should cover 8x20 with ease. I have used it on my 12x20 and it has been sharp corner to corner.

Since you are new to the camera and to ULF you may find that even slight misalignments may move you out of focus. make sure your standards are level when you start. You will need to avoid extreme movements in some cases, though you should have enough coverage.

One other trick to consider, perhaps less so with the 450 but certainly with shorter focal lengths. The trick is to focus on the right and left (long side)edges, you will see them get sharp and the center may be a bit soft, then stop down and the image will pop into focus. I experienced this with my 210 Computar on the 7x17 format.

Enjoy shooting your 8x20!

Steve

[Michael Mutmansky]

Bruce,

What plastic collar? Sometimes there is a spacer provided with the #3 shutter with some lenses, but in my experience they have always been made of metal. I doubt you would need a spacer with a wooden lensboard.

Take the lens off the board and screw it together so the rear element is tight on the shutter. Measure the distance from the front to the back elements (total depth, if you will).

When you put the lens on the board, the distance should be exactly the same. If it is not, you have a problem with the rear element being interfered with by the lensboard.

Check to make sure there is no anti-rotation screw on the lens (located on the surface of the shutter that will be pressed against the outside face of the lensboard). The shutter should be perfectly interfaced with the lensboard with no apparent alignment eccentricity.

If the lens checks out fine, then you need to check the camera. If the camera is not built properly, it may appear that it is all squared up, but there may still be an alignment problem. Check to make sure that the back is properly seated in the rear frame. Check everything, and then figure out a way to confirm that the alignment is as the camera says it is (by confirming truely parallel planes for the GG and the lensboard). You can do this by taking a straight edge and placing it with one edge against the front standard. Measure from the straight edge to the left and right edges of the rear standard. If the dimension is the same, you are probably parallel. If it is different, you may have a problem.

Do you have another camera that you can check the lens on, and also check the camera out with another lens? You may have to go through a series of elimination steps to confirm what exactly is the problem.

---Michael

[Jorge Gasteazoro]

Ah, the plastic collar you are talking about is used to prevent the aperture lever from "binding" with the lens board. I use it on the front of the lens board as I dont see how they can tell you to place it on the back, it would be useless this way.

Michael is correct, I was talking about the spacers that go inside the copal shutter to provide spacing for the cells. In any case either you could be missing the spacers or you have placed the plastic ring on the wrong side. Try moving it to the front and see if this works.

Another thing I thought about, does the lens still have the securing screw? This is a little brass screw that supposedly you use to "secure" the lens by drilling a little hole on the board. This way the lens wont rotate, I never use them, but if you leave it in place without drilling the board your lens would be crooked. Check on that also.

Good luck and let us know how you get along.

[Bruce E. Rathbun]

Update: I worked again with the lens and have had no luck. The far bottom right corner of the Ground Glass is way out of focus. The left corner is a tad out of focus but nothing like what I am seeing in the bottom right corner. I talked to Ron Wisner for over 30 minutes to determine if the camera was at fault. The camera is fine. I went back and tried the 19" Artar. This time after working with the Artar I had better results. Even with the Artar the corner can be out of focus but not as much as the Nikon. From the discusion with Ron he is of the opinion that the Nikon WILL NOT COVER the 8x20. He is even surprised that the 19" Artar will cover. Now I have no clue what to do. Did I make a mistake moving to the 8x20 format? Should I have chosen 7x17? Maybe my luck is bad or I have different standards. I have been shooting large format for 18 years. I own an 11x14 and have had no problems. I enjoy the larger cameras. Am I expecting too much? Many times I hear the phrase "good enough for a contact print". At the risk of offending anyone...if I can see that the image is way off in the ground glass I fear the stopping down will not even be good enough for a contact print.

From what Ron Wisner is telling me I am seeing the limitations of the Nikon lens. Due to the field curvature of the lens what I am seeing is falloff. The Nikon is spec'd to 55 degrees. For proper 8x20 coverage a lens needs to be around 62 degrees. I hate to split hairs here but that lack of 7 extar degrees is why Ron feels that I am seeing what I am seeing. I am by far no expert in the field of lens design. I only know that many others have had great luck with the Nikon 450M. Even on 12x20. I only wish that I could compare my lens on my camera with another lens of the same design. Am I out of luck here? Again the lens is a mint condition from Columbus Camera Group. All of the elements are screwed in tight. The lens looks good on the board. I am miffed. I could really use some help here. For over six months I have waited for a conversin back only to have this problem bite me square in the pants. Any suggestions?