Enlarger Evenness

[L Gebhardt]

I am in the process of setting up a Durst 138S with condenser head.

With a large 500watt bulb I can get a a very even field of light (about .1 stop variation) over the whole 5x7 negative area. But I need to get and hook up a blower to cool this. Since my current goal for this enlarger is to handle 6x17 negatives I decided to see how even the light was with a 150watt bulb. This bulb is much smaller than the 500Watt. I was surprised to see that it has only a 1/3 of a stop fall off over the 6x17 area. At first I decided that this couldn't possibly work. Then I noticed my 4x5 enlarger with the Ilford 500 head and decided to use it as a reference, since I have been happy with the results. I found the corners of the 4x5 image area to have about .5 stops of falloff. I guess that explains why I sometimes need to burn in the corners a bit. So the Durst for 6x17 with the "wrong" bulb is actually more even than what I am used to in 4x5.

So who else has measured their enlargers? What were the results?

I am using one of the Darkroom Automation meters to take the measurements, but I imagine a handheld camera meter could work as well.

Time to see how a few prints come out. I'll try both bulbs.

 

[eclarke]

I do and you need to kmow what the enlarger is doing..It's also important to know if all the cormers are sharp..read this as laser alinger..EC

 

[ic-racer]

Make sure you do all the measurements at the same aperture and lens-to-film distance as these have big influences. Another way to test is to make a print on high-contast paper after focusing but removing the negative. Your setup seems pretty good if it is only 1/3 stop off at the corners.

 

[vedmak]

I've had 138S, which is really nice, the problem is that bulbs are no longer produced for it, but because the head is so big, you can also play with some super bright LEDs with some kind of milky white plastic for a diffuser, that will also solve your heat problem

 

[L Gebhardt]

Well, I just made the first test print with the setup. A 6x17 enlarged to 13.5" wide. The negative was taken with a 90mm lens and no center filter on Agfa APX 400.

First I aligned the enlarger with a laser and mirrors. I used the 150watt small bulb, a 180mm Componon S and 2 240mm condensers. After a few test prints to determine exposure and grade I made a print with no dodging or burning. I was quite surprised to see the exposure was even out to the corners. Looks like I lucked out and the falloff in the printing compensated for the falloff in the taking lens.

I haven't printed with a condenser in a while, but I do like the increased sharpness of the grain. It's apparent even in a small print like this, and quite obvious with the grain focuser. It will be interesting to make a few comparison prints between the diffusion and condenser enlargers.

I still haven't heard how even other enlargers are on the baseboard.

 

[fotch]

Visually, never had a problem with any format with my Beseler 45. When I checked with a light meter device, it seemed pretty even if I recall, not perfect, just nothing to indicate a problem. HTH