vignetting with 135 mm for 4x5

[fralexis]

I just purchsed a used 135mm Komuranon-E for 4X5 work. I use a Beseler Dichro 45S. I am getting pronounced vignetting. All four corners are cut off a few millimeters. I had understood that 135mm was sufficient for 4X5. Does anyone have experience with this? Do I need to buy a 150mm? Or, more than likely, am I just missing something? Thanks.

Alexis

[Michael E]

Maybe the wider angle shows the boundaries of your light source.

[fralexis]

Thanks. You are absolutely correct. The Beseler has an upper and lower bellows. The upper bellows has to be fully compacted to give the right coverage. Mine was not. This model allows for almost no mistake in that regard. Now I have full coverage, but just barely. Thanks again.

Alexis

[Gem Singer]

Alexis,

Make sure you are using the correct size light mixing chamber in the Dichro 45S head.

They are available in 35mm, medium format, and 4x5 sizes.

That 135 enlarging lens should be more than ample for 4x5, and you won't need to raise the enlarger head as high as with a 150.

[fralexis]

Gem,

Thanks for your answer. Is there a marking on the chamber that indicates which one I have? I think it must be for 4X5 since I am getting complete coverage even though it is right at the limits...no room to spare. Also on that enlarger, can the top bellows be removed and get even further coverage? I'm just thinking out loud, since I presently get enough coverage, but is there any advantage to extra coverage? I am new to LF so I have to work through all this. The variables seem more complicated than 35 or medium format.

[Gem Singer]

I'm not sure if there is a label or a stamp on the mixing chamber. I sold my Beseler 4x5 enlarger. Just going by memory.

No need to remove the upper bellows. Merely compress it to it's fullest extent.

Put an un-exposed, but developed, sheet of clear 4x5 film in the negative holder. Turn on the white light.

Project the image onto the easel (a sheet of plain white paper in the easel will make it easier to see).

You should be able to tell right away if the illumination is even across the entire 4x5 negative.

If not, you might not be using the correct size mixing chamber.

[Michael Graves]

If I were you, I'd snag one of those 150s that are in the For Sale section right now. You will be amazed at the improvement of either one of those lenses over a Komura.

[Gem Singer]

Alexis,

Using a 150 instead of a 135 enlarging lens will result in the need to raise the enlarger head higher on it's column.

That will make the exposure times longer when making a print.

If a 135 enlarging lens has enough of an image circle to cover 4x5, it's okay to use it as the lens of choice.

Don't underestimate the OP's lens. The manufacturer, Komamura (Horseman), is a top tier company.

[tgtaylor]

Is there a marking on the chamber that indicates which one I have? I think it must be for 4X5 since I am getting complete coverage even though it is right at the limits...no room to spare.t

Just open the door on the top of the 45S. The diffusion chambers usually have a label on top identifying it. If not, simply lift the chamber out. The diffusion glass of a 4x5 chamber is the same cirumference as the chamber and those of the smaller format are corespondingly smaller. While you have the chamber out dust it off.

Thomas

[fralexis]

Thanks Thomas. Indeed, it is marked 4X5. One more question. Since it is marked for a 4X5, can I still use it for medium and 35mm format?

Alexis

[jp]

You can use it for smaller films, you just won't get the quantity of light as something built for the smaller size (some light won't end up on the negative). I print 6x6cm negatives regularly on my 4x5 enlarger with 135mm lens. I don't even bother to crank up the upper bellows.

[fralexis]

Thanks. I realized this when I set up this enlarger. I have another smaller enlarger that I really love...Durst Accucolor. The exposure times on that enlarger are considerably shorter than on the 4X5. Years ago when I started film an enlarger was way beyond my budget...now I have two great enlargers that would have cost a fortune back then!