Correct lighting on the enlarger baseboard

[Joao]

Hello
I need to tune an old DURST 606 enlarger. I am currently trying to confirm an equal ilumination on the baseboard. The enlarger lens is wide open and I use a Sekonic Flashmate L-308X as a incident lightmeter, measuring the light at different points.
The prints will not have more than 30 cm (side) and they are not intended for professional use. Uneven lighting on the baseboard can be corrected by changing the lamp position – that is what the manual says and that is what I intend to do.

My questions:
1) How should I set the Sekonic parameters in what concerns ISO, time of exposure and aperture ?? Shoud I set fixed exposure time and ISO and use the aperture values ?? Or otherwise ??

2) Is there some “acceptable” tolerance for the difference between the light measured at the center and at the corners ? I know that “acceptable” is very subjective; I mean differences not obviously visible in the prints.

Thank you for your sugestions and advice

Joao

 

[kram]

Hi, My darkroom has been down for 4 years. After moving house I am trying to set up a new one. In the process of installing a darkroom blind. My few answers are from memory.
You will be able to visibly see the effect of illumination when moving the enlarger bulb up or down at different magnification. Illumination should be no more than 1/2 a stop at the corners, hopefully less. Paper ISO is low, try 6- 10. Change exposure time if you can and keep the aperture in the lens's sweet spot. Depends on the lens, anything from 1/2 to 3 stops down from max aperture.

 

[Ronald M]

Just make the 4 corners and center as even as possible for the largest size print the enlarger will make. Smaller sizes will be same or better.

When measuring in the corners, tilt the meter toward the lens.

Values are relative . Absolute is not important.

 

[Joao]

Thank you Kram and Ronald for your input. Your advice is useful,
Regards
Joao

 

[Bill Clark]

Hope this helps you:

http://www.jollinger.com/photo/cam-coll/manuals/enlargers/durst/Durst_606.pdf

Superman has a problem now because there aren’t phone booths around to change into costume!

 

[Joao]

Thak you Bill

I already have the Manual, and my questions arise after reading it. It does not mention any lightmeter values for a start - and that was the reason of my post.
It is not an easy task to move the lamp up and down while testing, as the lamp and the metal parts around it become very hot. But it is feasible.

Regards

Joao

 

[Hari]

The Durst 606 was my first
enlarger at 16. I had a Rollei T
and Minox B at the time.

 

[Erik van Straten]

The light fall-off in the corners will be compensated by the light fall-off on the negative if the taking lens has the same focal length as the lens of the enlarger and if the same f-stop is used.


Erik.

 

[Joao]

The light fall-off in the corners will be compensated by the light fall-off on the negative if the taking lens has the same focal length as the lens of the enlarger and if the same f-stop is used.


Erik.

Thank you Erik
You raised an interesting point !
Most of my negatives are shot with 50mm (135) or 80 mm (120) and the enlarger lenses are 50mm and 75 mm Rogonars.
But I wonder what will happen with the prints of 135 mm negatives shot through 28mm, 35mm or 90 mm lenses - I use those sometimes...
Regards
Joao