Beseler 45 MCRX Heavy Vignetting

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mercurye

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I am using a Beseler 45 MCRX (standard Condenser head) with a 100mm lens to try and print 6x7. As far as I can tell this is the recommended lens for this format, however there is very strong vignetting, only on the bottom (see photo). If I put a 150mm lens on, there is no vignetting, but the resulting image is too small for my space. There is even no vignetting with a 150mm and 4x5 negative holder, the rough equivalent of 100mm and 6x7.

I've searched around the internet and haven't really found anything that would work, so any ideas you all have would be helpful. My top "negative stage" bellows are all the way closed, which should be more than enough. If I can't figure it out, I may just have to buy a 135mm lens for 6x7 and not print as big as I had hoped.

vignette.jpg
 

bernard_L

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  1. Vignetting is affecting more two of the corners. So at least one of your problems is centering of the lamp with respect to the general optical axis, or some other element...
  2. "with a 100mm lens to try and print 6x7" (...) "If I put a 150mm lens on, there is no vignetting"
    Please specify how you adjust the condenser stage for each of these focal lengths
  3. Does your setup include a turret for lenses?
I may just have to buy a 135mm lens for 6x7
There must be a better way...
 

glbeas

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Have you tried checking the illumination with the top bellows set in the correct position for the format? What bulb do you have in the enlarger head? The wrong bulb, physical size not wattage, will throw a wrench into any effort to fix this. If all else fails you may just have to remove the baseboard from the frame and set the whole thing up on blocks to get the desired image size.
 

mshchem

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Check out the filter drawer right above the lens. These are on the older enlargers, it could be partially opened / closed.
 

mshchem

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I am using a Beseler 45 MCRX (standard Condenser head) with a 100mm lens to try and print 6x7. As far as I can tell this is the recommended lens for this format, however there is very strong vignetting, only on the bottom (see photo). If I put a 150mm lens on, there is no vignetting, but the resulting image is too small for my space. There is even no vignetting with a 150mm and 4x5 negative holder, the rough equivalent of 100mm and 6x7.

I've searched around the internet and haven't really found anything that would work, so any ideas you all have would be helpful. My top "negative stage" bellows are all the way closed, which should be more than enough. If I can't figure it out, I may just have to buy a 135mm lens for 6x7 and not print as big as I had hoped.

View attachment 209960
I always left my bellows fully closed, 4x5 position, double check that the above lens filter drawer isn't partially closed . Something simple is not right, these enlargers are very straightforward.
 

grahamp

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Is the filter drawer fully inserted? If the vignetting is nearest the operator on the baseboard, then the issue should be above the lens and to the rear - unless you have badly positioned swing in filter holder.

What do you see without a negative carrier? Should be a clear circle.
 
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mercurye

mercurye

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Hi everyone, I have gotten around to your suggestions, thanks for all the help. Unfortunately I have not yet found the solution.

  1. Vignetting is affecting more two of the corners. So at least one of your problems is centering of the lamp with respect to the general optical axis, or some other element...
  2. "with a 100mm lens to try and print 6x7" (...) "If I put a 150mm lens on, there is no vignetting"
    Please specify how you adjust the condenser stage for each of these focal lengths
  3. Does your setup include a turret for lenses?

1- I took apart the lamp-house and beneath the bulb was a loose screw. I tightened the screw and the bulb now looks more centered in the housing [pic 1]. However, there is still vignetting, only now more centered [pic 2]
2- I do not know how to adjust the condenser stages, and the manual hasn't mentioned anything about it. My condenser head is in [pic 3]
3- No, this is the earlier version with 'trapezoidal' negative-stage bellows, so it only takes the single lens board.

IMG_5850.jpg IMG_5855.jpg IMG_5847.jpg

Have you tried checking the illumination with the top bellows set in the correct position for the format? What bulb do you have in the enlarger head? The wrong bulb, physical size not wattage, will throw a wrench into any effort to fix this. If all else fails you may just have to remove the baseboard from the frame and set the whole thing up on blocks to get the desired image size.

Yes, I have set the top bellows to the setting for 6x7, it only increases vignetting.
The bulb is here in [pic 4] and the shape is [pic 5]. It is a GE #211 75 watt bulb, and apparently the recommended bulb is a PH212 150 watt which I have just purchased. Though if you say the problem is mainly the shape and not the wattage, it may not help.

IMG_5856.jpg IMG_5858.jpg
I always left my bellows fully closed, 4x5 position, double check that the above lens filter drawer isn't partially closed . Something simple is not right, these enlargers are very straightforward.

Check out the filter drawer right above the lens. These are on the older enlargers, it could be partially opened / closed.

The filter drawer right above the lens is fully open.

Is the filter drawer fully inserted? If the vignetting is nearest the operator on the baseboard, then the issue should be above the lens and to the rear - unless you have badly positioned swing in filter holder.

What do you see without a negative carrier? Should be a clear circle.

When I open the filter holder compartment in the condenser, it is empty (no filter drawer or filter). I am not sure if a holder would affect the distance, but that may be a culprit as well. [pic 6] is what the image circle looks like without a holder and with a 100mm lens.

IMG_5851.jpg


Thanks again for the help everyone!
 

Sirius Glass

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Email the http://www.darkroomdoctor.com/ Dave and his wife Norma specialize in darkroom equipment. I think that you have an alignment problem and the condenser may not be set up correctly. Once he sees your photographs, you could talk to one of them on the phone.
 

mshchem

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Will do, thanks!
Someone may have taken the condenser lenses and glass out and failed to re-assemble correctly. I'm sure you have checked but make sure there's not a filter or something partially obstructing the lower bellows.
There are copies of these old enlarger light source manuals on line, free just look and call either KHB or the darkroom doc.
 
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