Troubleshooting enlarger won’t focus

[vssoutlet]

I have a customer who just got a mint condition Rodenstock Beseler APO HD 240mm f/9 enlarging lens from me. I received the following message:

I received the Beseler 240mm lens today.

It seems to be in excellent shape, but I cannot seem to get any kind of focus with it.
The lens is being used in a Beseler 45 MX enlarger.
My goal is to produce very, very small prints, and no matter how I configure the enlarger head, I cannot achieve focus.

Can anyone help me figure out what’s going on?

Thanks!

[Keith Pitman]

I think that lens is too long for 4x5.

[Vaughn]

Perhaps needs to be on a cone of some sort to extend the focus?

[vssoutlet]

I think that lens is too long for 4x5.

So you’re thinking that the head can’t get far enough away from the easel?

[Vaughn]

The lens may not be able to get far enough away from the negative.

[jonby]

To make a 5x4" print, the lens would need to be 500mm away from the film, and the baseboard 500mm from the lens (approximately). If they want to make even smaller prints than this, then the lens would need to be even further away from the film. So yes - sound like there's a good chance that bellows extension on the enlarger is the problem. If the user detaches the lens from the head and moves it gradually downwards, they may see the image come into focus (albeit with lots of light spill). This would confirm the problem.

[Duolab123]

Yeah, in the good old days there were big cones for making reductions from large format negatives, huge extension tubes. Here's a Saltzman lens cone offered by glennview . That lens is a darn nice lens, nice for copy work too.

202071

[Duolab123]

Should have mentioned the lens cone pictured is 12 inches in length. For making reductions from 8x10 negatives.

[Tin Can]

What size negs are they using, a 4X5 enlarger can use much smaller negs

What size print?

a 240mm lens needs about 19" bellows to make a 1 to 1 print

A 35mm neg will make a 35mm print

Reduction cones were common once

I have a 10" cone for an Elwood, never used it

If they want 1 to 1 prints, they can contact print...

[ic-racer]

Most of the enlargers with which I am familiar that are capable of making reductions usually show or describe how to do it in the user's manual. If it is not in the manual, then it may not be possible. But this is how to do it.

The enlarger needs a lot of bellows draw. Once in the correct orientation, moving the head up makes the image smaller. If this is not the case, then it is not setup correctly.

Focal length selection when making reductions is based on the diagonal of the print not the negative. So if making 4x5" reductions from 8x10" negative, don't use a 300mm lens, use a 150mm lens.

Since the lens will be very close to the paper, most enlargers will not be able to do this without propping the easel up on a box of some sort (not shown in the pictures below.)

In my darkroom reversing the lens is not needed when making prints due to the low resolution of printing paper and, of course, the small size of the prints.

If making copy negatives that will be enlarged, reversing the lens might improve results at the corners.

1:1 printing setup is similar. In that case for 8x10" negative a 210mm lens works best in my darkroom (specs on my 210mm lens show it covers 11"x11" at 1:1).



202081
202082

[Jim Noel]

The lens is too long to make a small print with a Beseler. a 75mm, or maybe 100mm should do the job. I Use a 50mm on my Beseler to make reduced size prints.

[jelsiek]

Negative popping is probably the answer to your current situation, since a condenser lamp house is probably the hottest running version that your enlarger could have. I have printed for 30 years with cold lights and glassless carriers, in part to avoid negatives popping and going out of focus. Diffusion is also helpful for minimizing dust spots and myloweslife (https://roadrunneremail.org/) I found that when I switched from a previous condenser enlarger (Omega D 2) to cold light that it was easier to get a long smooth tonal range in my prints.