Possible problems with 75 mm f/4.5 Grandagon N

[Leonard Evens]

I have a Toho FC-45X and four lenses. Three of the lenses work quite well, pretty much as I expect. That includes a f/6.8 90 mm Grandagon N. Because I was having some trouble using the 90 mm lens for photographing buildings where I couldn't get back far enough, I got a f/4.5 75 mm Grandagon N. I had checked and several people recommended it highly. But my lens seems to have serious loss of image quality as I depart from the center of the field, particularly if I use any movements. I expect illumination dropoff, but I'm seeing loss of fine detail and an out of focus look at all distances on the edge. I have to do some systematic tests to verify this since there are all sorts of ways to go wrong, which will probably be worse for a wide angle lens. Also, I suppose the illumination drop off could be a factor because of loss of contrast. I don't have these problems with my 90 mm lens.

The specifications say the image circle is 195 mm, which should allow me up to 20 mm shift either way in the long direction. In some cases, it is possible I shifted more than that, which is one reason why I have to do systematic tests. Just looking at the image on the gg under a loupe doesn't suffice because it is pretty hard to see just what is going on at the edges of the field with a wide angle lens, and in any event, after stopping down to taking apertures, it is hard to see much of anything.

The lens is a new lens, so mishandling should not be an issue.

Any input would be appreciated, either with respect to what I should expect from such a wide angle lens or how to go about doing the systematic tests. In particular, how much enlargement should be possible with such a lens before it is obvious that there is loss of image quality at the edges of the field?

[David Karp]

Leonard,

I have an older 75mm f/4.5 Grandagon-N that saw a lot of use before I bought it from a friend. It was originally in a Sinar DB shutter and I had it remounted on a Copal. I have used it for architecture and interiors, and have not seen the problems you describe. Sorry, I am not enough of an expert to suggest a test. All I ever do is photograph something that looks like a grid so I can test for distortion, and look at the negative or transparency with a loupe to see if it is sharp.

[Jean-Marie Solichon]

Are you talking on the basis of inspecting chromes on the light table, or on the basis of viewing the ground glass with the lens wide open? At full aperture this kind of lens can give a soft picture which will get much better at f:5,6.

[Henning Wulff]

This sounds like a mounting problem to me. I've had this on a lens a long time ago, in point a Grandagon 90/4.5 that displayed the same problems. It didn't resolve fine detail even at f/22 at the edges. Upon closer inspection I found that the lensboard didn't allow the two sections to seat together properly, so they had extra space between them. I fixed that, and the lens performed perfectly.

[Bob Salomon]

Is this a new lens or a used lens?

If it is a lens covered by our warranty you can send it to us with some images and we can see if their is a problem.

If it is a used lens have you reported this to the seller?

All Rodenstock lenses imported by us have a lifetime warranty against manufacturing defects which is extended to the original retail purchasor. If your lens qualifies we urge you to take advantage of it.

[Leonard Evens]

Jean-Marie,

I've taken several pictures with it, using negative films. The loss of detail is obvious under moderately high magnification in the negative and also in scans of the negative. You wouldn't see it in a contact print, though. But it might be the result of too extensive movements, or failure of the camera to be perfectly square, or something similar, which is why I need to do systematic testing.

I've also looked carefully at the image on the gg under 4 X and 7 X magnification today while doing some testing. It appears that field curvature may be part of the problem. Taking pictures of a wall of newspaper classified ads, it appears that the focus spread along the rail from center to corners may be as large as 1.5 mm. That was at 4.5. I stopped down to f/16, but even that may not be enough if there is a lot of field curvature.

Henning,

I wondered if mounting might be an issue. Jeff at Badger said not, but I do have it mounted in Toho's eccentric lens board. He also said that all Rodenstock lenses are bench tested before shipping, so it is highly unlikely there is anything wrong with the lens. Does anyone know how much tolerance there is for distances between the front and rear sections for a lens of this type?

Bob,

It is a new lens, purchased from Badger Graphics. I will check if I have a lifetime warranty. I want to be sure of my grounds before I try to invoke any warranty. Most likely the lens is performing normally and it is just a matter of learning its idiosynchrocies, but as noted above, it is possible mounting is an issue.

[Bob Salomon]

"purchased from Badger Graphics. I will check if I have a lifetime warrant"

You don't. It is a grey market lens and you are at least the third buyer of it. It was not shipped to Badger by Rodenstock. It was shipped by Rodenstock to a camera store who then shipped it on and it wound up at Badger. It is only covered by whatevr warranty Badger supplies or the Warranty which is valid at the factory in Germany.

There is no US Rodenstock Warranty on it.

[Kirk Keyes]

Hi,

I have both of these Rodenstock lenses - I love them. I bought both of them new a little more than 10 years ago, and fairly quickly I noticed that the 75 was getting fuzzy. I took the front and rear cells off and there was something loose in the rear element. I noticed that the inner lens assembly (the cylindrical tube with a lens in it that is next to the shutter blades when the cells are screwed into the shutter) were unthreading. So I gently retightened it and reassumbled the lens. It would come undone, mostly after travelling long distances, and I put up with doing this for a few years. I finally got tired of it, so I got some clear fingernail polish and placed a small dab of it between the outer edge of the inner element housing and the main body of the rear cell. (I believe that it was Steve Grimes that recommended trying this to me.) I left the cell out of the shutter for a few days to let the polish completely dry so it would not collect any solvent vapors in the lens. This locked the cell in place and it has not loosened for many years now.

Try unscrewing the front and rear cells and (gently) shake them and see it there are loose elements as I described.

Bob Salomon's recommendation to send it in for a check-up might be the best thing to do though.

Kirk

www.keyesphoto.com

[Henning Wulff]

Re: -------------------------------------------------------------

I wondered if mounting might be an issue. Jeff at Badger said not, but I do have it mounted in Toho's eccentric lens board. He also said that all Rodenstock lenses are bench tested before shipping, so it is highly unlikely there is anything wrong with the lens. Does anyone know how much tolerance there is for distances between the front and rear sections for a lens of this type?

------------------------------------------------------------

Mounting tolerances/cell spacing is very critical. My 90 lens had about an extra 1/4 to 1/2 mm space, and it performed terribly. I had it on a very old Linhof board that was slightly too thick, and I didn't notice it at first. I've had or have the 90, 75 and 65/4.5 Rodenstock lenses, and they all perform very well at f/11, and superbly at smaller stops when mounted correctly. You should see almost even performance to the edges of the image circle at f/22, except for light falloff. I replaced the 90 and 75 for reasons other than their performance over their designed image circle. The three Grandagons were my primary lenses for my architectural photography for 15 years.

[Leonard Evens]

I've now done one test, and I'm pretty sure the problem is field curvature. At f/16, I took a picture of some newpaper text taped to a wall, with the lens centered on the field, and the results look pretty much okay. I then shifted by about 18 mm, and the part of the field now visible is blurred. This is consistent with my observation that there appears to be a 1.5 mm shift in focus from the center to the edge . Stopping down to f/16 would not be enough to bring the text into focus. I would probably have to stop down to at least f/32 and possibly f/45 to get it all in focus.

The most likely explanation is that the lens is not mounted properly in the eccentric lens board. I will try it with a conventional lens board to see if there is an improvement. If that doesn't do it, I will ask Badger to replace the lens.

[Gem Singer]

Hi Leonard,

After thinking about it over night, did you remove the little indexing screw from behind the shutter before you mounted the lens in the lensboard? That could cause the effect you are experiencing.

I'm certain that Jeff will be willing to make good on this lens if it is defective.

[Leonard Evens]

Eugene,

Badger mounted the lens for me in a Toho eccentric lens board. I am relatively new---two plus years---to 4 x 5, although I've used a Horseman Technical Camera, including movements for over 30 years. So far I haven't actually mounted a 4 x 5 lens myself, but I've read how to do it and it doesn't look too hard. If I understand correctly, you are talking about a screw that keeps the lens from rotating in the mount, and is often left out. But I believe it has to be there for the eccentric board to work. Badger must have done it right because the eccentric board does work properly, as described in Kerry Thalmann's review. After I do some more tests and clarify in my mind just what is going on, I plan to remount the lens in standard lens board and see if that makes a difference. If I still have trouble, I will ask for an exchange, but I think I do have to be able to document the problem.

I've generally avoided testing with my 4 x 5 equipment up to now because I find I get so involved with it I don't do anything else. The only testing I've done so far is checking that the film plane and gg are not far enough off to make any practical difference.

[Joe Photo]

You don't mention what type of shutter the lens is mounted in (if you did I missed it). Copal shutters come with two deco rings, one in the front and one in the packaging for lenses with smaller barrels. If the front element is screwed in and it doesn't clear the deco ring it will stop turning and not be in the right place. The deco ring can be removed by popping it out with a screwdriver or fingernail. If it doesn't cause any interference it can be popped back in.

[Glenn Kroeger]

Another issue with Grandagons is "focus-in". I bought a 55mm Apo-Grandagon from Badger and ran some initial tests and thought is was soft. But then I retested using a series of focus positions. I found that, particularly at 10-15 ft distances, there was a distinct shift of focus between f/4.5 and f/16. When focused properly at f/11-f/16, it was tack sharp edge-to-edge. This hasn't been a problem in the field, where the subjects are three dimensional and cover a wide range of distances. Only a problem shooting flat test targets.

[Leonard Evens]

Joe,

It is a Copal 0 shutter, and I presume it came with the lens as provided by Rodenstock.

Glenn,

I've done some more testing, and I think the lens does perform differently at different distances. Namely, there seems to be some curvature of field, which may curve differently at different distances. I will have to redo those tests, taking notes this time, since it is easy to get confused. What I need is a building with a brick facade that is high enough. That way I ought to be able to see the field curve on the gg, even after stopping down, provided there is some sunlight. Unfortunately, the weather has not been cooperating.