Beseler 45 MXT with 8x10 Conversion Alignment Problems

[jeroldharter]

I am finally trying to enlarge some 8x10 negatives. I converted my enlarger with the Beseler kit and went through the recommended alignment procedure for the 45MXT. First, I aligned left to right which required a slight shim of the upper assembly which includes the negative carrier and light source. Then I aligned front to back. Then I attached the lens and repeated the procedure for the lens plane. I used a Versalab laser which had previously aligned my 4x5 enlarger with no problem.

The result is that the very center of the projected image is sharp but the rest of the image is not. It looks like field curvature. I checked this with both the glass and glassless negative carriers without difference. Also, I could never get the edges sharp, even when tilting the easel or attempting to focus on the edges. The negative is tack sharp edge to edge with a loupe and is a photo of a wall which was flat to begin with.

I tried to focus on the easel and on just the baseboard with the same result so it is not an easel problem.

I have never used this lens before. It is a Beseler 240mm HD lens that I bought used but appears to be in excellent condition. The problem happens from wide open at f9 all the way to f64 so stopping down does not help.

Any ideas? Thanks.

 

[resummerfield]

…..the very center of the projected image is sharp but the rest of the image is not. It looks like field curvature.

…….I checked this with both the glass and glassless negative carriers without difference. Also, I could never get the edges sharp, even when tilting the easel or attempting to focus on the edges. The negative is tack sharp edge to edge with a loupe and is a photo of a wall which was flat to begin with……….

…….It is a Beseler 240mm HD lens ……… The problem happens from wide open at f9 all the way to f64 so stopping down does not help…….

If the enlarger is aligned and you are using a glass neg carrier, and yet the center of the neg is sharp with unsharp corners, then the problem must be with the lens.

I believe the Beseler 240mm f9 lens is a relabeled Rodenstock process lens. I don’t have the specs for this particular lens, but process lenses in general have smaller angles of coverage than enlarging lenses. Years ago I did a test of several process lenses and enlarging lenses in the 240mm to 360mm range, and ALL the enlarging lenses—Rodenstock and El Nikkor—out performed the Nikon and Schneider process lenses. In every case, the process lenses had significantly less resolution off axis than the enlarging lenses.

The best test would be to compare the prints made with your lens to those made with another enlarging lens. I have a Rodenstock Rodagon 240mm f5.6 enlarging lens that I’m not using, and I would be happy to loan it to you to test against your lens. This lens has a 72mm mounting thread, which may be a problem for mounting on your Beseler boards. Also, since I use threaded boards, I do not have a jam nut for this lens. But for testing purposes, you could make a cardboard lensboard and tape the lens in temporarily. Check the lens specs here. If you are interested, PM your address and I’ll send it along tomorrow.

 

[jeroldharter]

... then the problem must be with the lens...

The best test would be to compare the prints made with your lens to those made with another enlarging lens. I have a Rodenstock Rodagon 240mm f5.6 enlarging lens that I’m not using, and I would be happy to loan it to you to test against your lens. This lens has a 72mm mounting thread, which may be a problem for mounting on your Beseler boards. Also, since I use threaded boards, I do not have a jam nut for this lens. But for testing purposes, you could make a cardboard lensboard and tape the lens in temporarily. Check the lens specs here. If you are interested, PM your address and I’ll send it along tomorrow.

That is very kind of you. I might take you up on it soon. From what I have read, your Rodenstock lens is too large to fit on my enlarger.

I do have a 240mm G-Claron. I wonder if I could rig that up? It is Copal 1 (41.6mm). I wonder if that would fit in the standard 39mm Beseler lens board?

I agree that the problem points to the lens but I was hoping for something else that would be more immediately fixable. I could try putting on a 150mm Rodagon lens just to make sure that it is the lens and not the alignment.

 

[resummerfield]

The Copal 1 shutters that I have tried will fit a Beseler 39mm un-threadded lensboard. That would give a comparison to your Beseler 240 HD lens, but it will still be very dim to focus.

The 150mm Rodagon won't have the coverage for 8x10, or I should say it won't have the corner resolution.

Is there not some way to fabricate a lensboard for the Beseler that would accept a bigger lens? Maybe a "cone" system like the Omega enlargers, to space the lens farther from the neg? Then you could use a "proper" enlarging lens!

 

[jeroldharter]

The Copal 1 shutters that I have tried will fit a Beseler 39mm un-threadded lensboard. That would give a comparison to your Beseler 240 HD lens, but it will still be very dim to focus.

The 150mm Rodagon won't have the coverage for 8x10, or I should say it won't have the corner resolution.

Is there not some way to fabricate a lensboard for the Beseler that would accept a bigger lens? Maybe a "cone" system like the Omega enlargers, to space the lens farther from the neg? Then you could use a "proper" enlarging lens!

I just ran up and tried it with a 150mm Rodagon. I could get it about 11x4 and printed one edge on 8x10 paper. I did not re-align the enlarger. The print was quite sharp. So it is the lens. Damn. I hoped I had a deal when I spent $67 for it months ago.

I assume it was a bad apple as others have said it was a good lens. Although f9, it was adequately bright so I might try the 240 G-Claron. Having never done that: do I just use the enlarging lens board as a regular lens board so that I have aperture control?

For some reason, the Beseler enlargers have an arc shaped piece of metal that is inside and above the lens board. So if a lens has a large diameter or protruding rear element (e.g. even an Apo-Componon 150) it won't fit. I believe that S.K Grimes can make an extension cone that would permit the use of a Rodagon or regular 240mm enlarging lens. I might need to go that route.

 

[resummerfield]

......do I just use the enlarging lens board as a regular lens board so that I have aperture control?.....

I haven't done that either, but I would use the Beseler lensboard, and leave the shutter focus lever open.

..... I believe that S.K Grimes can make an extension cone that would permit the use of a Rodagon or regular 240mm enlarging lens. I might need to go that route.

I've found the optimum aperture on the 240mm and 300mm El Nikkor enlarging lenses to be about 2 stops down, or f 11. I suspect the process lenses, or the G-Clarons, would reach their optimum aperture at about the same 2 stops down, or around f 19. So using a regular enlarging lens would speed up your printing!

Good luck with the G-Claron!

 

[jeroldharter]

I have seen links for an SK Grimes extension cone for enlarging lenses but I can't find it on their website. Anybody have a link for it or other information such as cost?

 

[Curt]

I often wondered why Beseler made that arc shaped projection of metal in there. I never figured out if it was of any use except to restrict the size of lenses. I have a 240mm 5.6 Rodagon that I'm going to use on my Durst, it's a big lens.

Good luck Jerold, I was wondering how long you would take you to go from contact prints to enlarging, it's addictive isn't it?

Curt

 

[resummerfield]

I have seen links for an SK Grimes extension cone for enlarging lenses but I can't find it on their website. Anybody have a link for it or other information such as cost?

Beseler Enlarger Lens Board Adapters. SKG has slightly changed their website. Click on the "Home" button (not found on all pages) and then click "As seen on the What's New... Page!".

 

[ic-racer]

My Rodenstock Rodagon 300mm has curvature of field at 1:1 (this is outside the MFG specs for the lens). By stopping down to f16 it works Ok at that range.

So, have you tried stopping down to f16 after setting the focus the the geometric half-way point between the center focus and edge focus settings.

 

[jeroldharter]

My Rodenstock Rodagon 300mm has curvature of field at 1:1 (this is outside the MFG specs for the lens). By stopping down to f16 it works Ok at that range.

So, have you tried stopping down to f16 after setting the focus the the geometric half-way point between the center focus and edge focus settings.

I will check this out again today. The thing is, I could never get the edges sharp in all 4 corners, only the center. I will double check that the lens is mounted properly as this is the first I have used it since acquiring the lens months ago in anticipation of 8x10 enlarging.

I like the looks of the SK Grimes adapter. If I can't fix this lens problem, I will look for a 240 mm Rodagon. I don't seem many Componons or Nikkors in that focal length for some reason.

 

[ic-racer]

I will check this out again today. The thing is, I could never get the edges sharp in all 4 corners, only the center.

Ok, so it is looking like that lens does not really cover 8x10.
If you could actually get a sharp image at the corners you can 'adjust' the field curvature by experimenting with the lens element separation. That is, experimenting with various shims (or just partially unscrewing the lens elements from the barrel) and seeing what happens to the field curvature.

 

[Curt]

Dead Link Removed

Is height the reason to go with a 240mm lens? I'm aware of your lens board problem, I wonder what S.K. Grimes can do and in what range.

 

[jeroldharter]

Dead Link Removed

Is height the reason to go with a 240mm lens? I'm aware of your lens board problem, I wonder what S.K. Grimes can do and in what range.

Thanks for the link. I would buy that if it were a 240. Yes, height is the issue. SK Grimes can make an adapter board for regular 240mm lenses (Nikkor, Rodagon, Componon) to work with Beseler enlarger for $160-200 depending on who supplies the lens board.

 

[ic-racer]

Actually ceiling height is only an issue once your baseboard is on the floor and the image is still not big enough!
Personally, I'd use a longer lens and lower table or counter or baseboard.

 

[RJS]

Sounds to me as if your enlarging lens was no bargain. I have found, over many years, that bargains seldom are. I would suggest purchasing a first class lens made for enlarging 8X10 from a dealer who will allow you to try and return if you are for any reason unhappy. KEH from what I read here might be such. Fooling around with bargains, whether cameras, cars or you name it has cost me more money, grief and time than I can describe. Making a fine, sharp print is well worth whatever it costs - short of your best wife.

 

[jeroldharter]

Sounds to me as if your enlarging lens was no bargain. I have found, over many years, that bargains seldom are. I would suggest purchasing a first class lens made for enlarging 8X10 from a dealer who will allow you to try and return if you are for any reason unhappy. KEH from what I read here might be such. Fooling around with bargains, whether cameras, cars or you name it has cost me more money, grief and time than I can describe. Making a fine, sharp print is well worth whatever it costs - short of your best wife.

I generally agree about the "you get what you pay for" concept. However, I have also adopted the philosophy that some of the rock bottom pricing for more obscure items is simply market and people can't sell for more. Sometimes I get burned. I still don;t know how a lens that looks so good can be so off. Anyway, I ate that purchase but I have had so many wins that a few losses are justified.

Fortunately I have already found a Rodagon 240 mm enlarging lens through the kindness and generosity of a fellow APUGer and will have SK Grimes adapt it for me.

Of course, then I will have to grapple with how to use below the lens filters with a larger chunk of glass but one thing at a time.

 

[jfish]

You could also just cut that arc out on the lens stage to give the rear element more room to go in. I did it to mine with no problems.

 

[jeroldharter]

I finally received my lens today having been adapted by SK Grimes to fit my enlarger. They did a beautiful job, well worth the wait. Aligned easily and the image on the baseboard is laser sharp. Can't wait to make some prints with it.

The lens is a Rodenstock 240mm Rodagon with an adapter cone to fit on a Beseler lens board for the 45MXT enlarger with 8x10 conversion.