# Defusing light from enlarger bulb.



## Grandpa Ron (Oct 16, 2018)

I am resurrecting my uncles late 30's or 1940's vintage Kodak auto focus enlarger. (See Photo) I have everything working except the even distribution of light across the paper. 

The enlarger is a simple box with a light, film carrier, bellows and lens. When I turn it on I get a square of light with a bright spot in the middle.

I have tried,

Adding a sheet or two of frosted glass at the film carrier. Better.
Painting the center of the bulb white. Better.
Adjusting the bulb height to film carrier. Better.
Placing a sheet of white printer paper inside the enlarger below the bulb gives Uniform light but very dim.
The end result of my experiments is a fairly well illuminated 4x5 negative with a noticeably brighter 3 inch or so circle of light in the middle.

There does not seem to be any evidence of a condenser lens and if I were working with a 2x2 negative it would be sufficient.

It is hard to believe the old timers  would have put up with this. I feel I am missing something.


----------



## Derrel (Oct 16, 2018)

I am wondering about the bulb itself. Do you have the exact bulb that is supposed to be used?


----------



## 480sparky (Oct 16, 2018)

It doesn't appear to be a very sophisticated enlarger.  In fact, it looks home-made.  If so, there's not much optical engineering that went into it.


----------



## compur (Oct 16, 2018)

I think it's time for a newer enlarger.


----------



## Grandpa Ron (Oct 17, 2018)

Yes if I was going to do any significant amount of film enlarging I would be looking at a new enlarger. This is a sentimental thing. I rebuilt it after decades in the attic. I am going to use it with my 1910 era 4x5 camera. Bringing old things to life has its own rewards. 

It is not home made as it has the brass Kodak Autofocus name plate and the auto focusing mechanisms the head is raised. Judging from the assorted negative masks It may have been used with 620 or smaller format films. The 4x5 format may be too large.

The name plate says 200 watts but the original bulb is long gone. I know that some bulbs are silver colored on the ends I have tried both frosted and clear 200 watt bulbs. Given the heat generated by the 200 watt bulb a switch to an LED my be in order; not historically correct but expedient.


----------



## 480sparky (Oct 17, 2018)

Grandpa Ron said:


> ...........and the auto focusing mechanisms the head is raised. .........



Autofocus?


----------



## Grandpa Ron (Oct 17, 2018)

Yup, a Kodak auto focus enlarger. 

As you raise the head of the enlarger, the lens on the end of the bellows is mounted on a scissors type assembly track that increases and decreases the bellow length. So the bellows adjust to keep the image in focus as it get larger. 

Not bad for 70 plus year old technology.  Remember, we are talking about a completely different state of the art requirements.


----------



## 480sparky (Oct 17, 2018)

It must be based on one single lens then.


----------



## Grandpa Ron (Oct 17, 2018)

Yes the optics are a light source, glass plate, film holder, bellows and a small 3/4 " single projecting lens.

It is a bit like pinhole photography, the objective is to see how good of a photograph you can take or in this case print.


----------



## 480sparky (Oct 17, 2018)

Unless you're using the maximum-sized negative for the enlarger, I think it would be difficult to use film any smaller.  I mean, if this is a 4x5 enlarger, I can't imagine trying to make any prints with a 35mm negative.... unless you like wallet-size prints.


----------



## webestang64 (Oct 18, 2018)

In it's day that was a nifty piece of kit......

http://www.libraryweb.org/~digitized/tradecats/kodak/Kodak_professional_apparatus_1936.pdf


----------



## compur (Oct 18, 2018)

Kodak used to sell "flashed opal glass" for diffusion purposes. It's a milky white glass that is different than ground or frosted glass. That may have been used with this enlarger. They also used "Mazda lamps" with their enlargers though I don't think they're much different than modern tungsten bulbs as far as diffusion goes.


----------



## dxqcanada (Oct 18, 2018)

That sounds like it is missing a condenser ... I remember encountering the bright centre spot at the school darkroom when the last user did not put it back in.
My Google-Fu, does not find much info on this model to say if it is supposed to have one.


----------



## Dave442 (Oct 18, 2018)

Good to learn that the smaller Model B enlarger is for "miniature" negatives of 2-1/4". Anyway, that Kodak Autofocus enlarger sounds like an interesting unit - and it should work with 4x5 negatives. Might just need the diffusing disc.


----------



## compur (Oct 18, 2018)

Leica/Leitz had autofocus enlargers too.


----------



## Derrel (Oct 18, 2018)

compur said:


> Leica/Leitz had autofocus enlargers too.



Yes...I used several in a university fine art department darkroom. The Leitz Focomat IIc is what we had at WOSU. We had several of them, and YES, they were *automatically focusing enlargers*...worked perfectly on all sizes of prints, from tiny to extreme. They were set up with one,specific lens, and as I recall, a cam system that focused as the enlarger head was raised and lowered. I think the Leitz company developed these in the 1940's; possibly earlier, or later. I dunno...anybody interested could Google for info on the LEITZ Focomat autofocus enlarger models.


----------



## Grandpa Ron (Oct 18, 2018)

Well I could not find Flashed Opal Glass but two layer of a white plastic garbage bag over a piece of frosted glass worked just fine.

The auto focus magnification range is 1.3 to 2.3 time the negative size. This would give a 8" x 10" photo with a 4x5 negative or a 5"x 7" photo for a 6 x 9 ratio 120 format. Unfortunately, the 35 mm becoming popular at the time would only make about a 3  1/4" by 2  1/8" print. 

I will consider the project complete when I get a print from my vintage 4x5 camera negatives. There are of course a lot simpler ways to take pictures, but the fun is in the doing.

Thanks for all the info and interest.


----------



## compur (Oct 19, 2018)

It shows up on eBay occasionally:








That's where I sold the sheets I had. 

Recently I needed some and I pulled off the diffusion panel from an old broken light box which worked pretty well.


----------

