What lens for durst M800 enlarger?

tomfrh · Feb 14, 2016

I just picked up a durst m800 enlager. it has a unicon 50 and unicon 85 condensor, but no lens.

It has a lens board with 39mm screw thread.

I primarily wish to print from medium format black white negatives, up to say 20x16

Can someone suggest a good lens for it? I have zero knowledge of enlarger lenses!

Is the durst 85mm to go with the unicon 85 condensor a good choice?

should i consider different lens, with possibly a different lens board?

ic-racer · Feb 14, 2016

Look for a six-element 80mm lens that is clear and free from haze. The widest aperture does not matter. Set the lens to f11 or f8 when making prints.

BobMarvin11225 · Feb 14, 2016

I don't know how tall that Durst model is, but you MIGHT need a 60mm WA lens to make 16 X 20 prints on the baseboard. I also don't know if that will physically fit the Durst. My 60mm WA Companon has a sizable part of the lens barrel that fits inside the lens board. FWIW it works fine on my Omega B-8. In any case, with used enlarger lenses so cheap, you should also get a good 80 for smaller prints.

ic-racer · Feb 14, 2016

Specs show 10x enlargement of 6x6cm negative, so about 20". Some caution when using WA lens as there is no condenser combination for 60mm lens.

BobMarvin11225 · Feb 14, 2016

Re: "no condenser combination for 60mm lens" I use the aux.condenser designed for a 75mm lens with my Omega; perhaps a similar combination might work with a Durst.

tomfrh · Feb 14, 2016

Thanks guys.

Assuming same size prints, what is the difference between the 50mm lens/condensor and 85mm lens/condensor? Is it simply what image sizes you can have?

RobC · Feb 14, 2016

I'm surprised no one asked waht size medium format neg? An 80 may not be long enough for 6x9cm neg. You may want a 105.
So whats the largest neg size you want to be able to print from before getting recommendations.

I know the M805 can print upto 6x9. I don't know about the M800.

tomfrh · Feb 14, 2016

645 and 67

M800 goes up to 6x9.5

ic-racer · Feb 14, 2016

If you are going to do 16x20"s from 6x7cm you may find Rob's advice valuable. The combination of an 80mm lens and Unicon 85 may not fully cover nominal 6x7cm, depending on your exact negative size and if you crop. 6x7cm is not recommended for that combination in the spec sheet, but sometimes there is some leeway with manufacturer's recommendations. Plus, a 105 Unicon may be unobtainable.

tomfrh · Feb 14, 2016

Will 75mm and 90mm lenses work with the unicorn 85?

I don't necessarily need to go all the way to 20", and can crop if necessary...

RobC · Feb 14, 2016

I can only guess but if the unicon 85 is supposed to cover 6x7 then I would go for the 90 lens. The bigger the enlargement the closer the lens is to the negative and therefore the more critical the lens coverage becomes. A 90 should cover it. But as someone pointed out you need the available column height but I'm guessing that since the enlarger is good for 6x9 negs it will have sufficient column height and be able to handle a 90 lens.

My durst enlargers have magnification scales on the column for different focal length lenses. For example my L1200 will do over 10X enlargement with a 105mm lens. That means it will easily handle 10X with a 90mm lens. If yours enlarger has the scales on the coloumn then you should be able to work out the biggest enlargment you can get from any focal length lens. Use the longest focal length that will allow the magnification you need for your 6x7 negs.

ic-racer · Feb 14, 2016

Specs for the condenser head indicate 75 or 80mm lens for the Unicon 85 and 100 or 105 lens for the Unicon 105. When using combinations other than those, you can test the coverage by printing a gray print (no negative) with high contrast paper. Make sure you stop down to 11 or 16, otherwise the lens' hotspot will spoil the results. Make sure you focus where the negative would be, because the condenser system expects the lens to be in a certain range.

tomfrh · Feb 14, 2016

Regarding stopping down, what is the point of having say an F/4 to f22 Range on an enlarger lens?

why the need for bariable
Aperture?

When might you go wide open? When might you stop all the way down?

MattKing · Feb 14, 2016

tomfrh said:
Regarding stopping down, what is the point of having say an F/4 to f22 Range on an enlarger lens?

why the need for bariable
Aperture?

When might you go wide open? When might you stop all the way down?

The wider the maximum aperture, the easier it is to see well enough to focus and compose on the easel.

And sometimes - especially when printing colour negatives at high magnifications - you need the wider apertures in order to end up with a print time that isn't inconveniently long or even so long you start having problems with reciprocity.

In addition, some light sources are much less bright than others - cold light heads come to mind.

ritternathan · Feb 15, 2016

Hi, I have this enlarger and use it for 645 and 6x7 (also 35mm). I can easily get a 16x20 print from a 67 negative even with cropping with my 80mm lens F4 (schneider companion-s). The 50, 85, and 105 unicon condensers are for 50mm, 80mm-ish and 105mm lenses, corresponding to the 135, 645-67, and 6x9 formats. I have the manual (in French) let me know if you are interested and I can try to email it to you. I recommend using the flat lapla lens board for all three condensers/lenses/formats. Enjoy, its a great enlarger, Nathan

ic-racer · Feb 15, 2016

The enlarging lens only gives optimal results on a few aperture numbers. One needs the MTF curve to know for each lens, but usually 2 or 3 stops down from wide open. Wide open is for focusing. Stopping down past the optimum aperture can be used when making smaller prints where times are too short and the blur from the airy disks (diffraction effects) won't be noticeable.

tomfrh · Feb 15, 2016

thanks for all your comments. I am learning a lot.

ritternathan · Feb 16, 2016

Yes, go to Ctein's Post-Exposure second edition at this link:

http://ctein.com/PostExposure2ndIllustrated.pdf

There are several pages of the tests of modern lens, useful notes, and their optimum apertures.

eddie · Feb 16, 2016

ritternathan said:
Hi, I have this enlarger and use it for 645 and 6x7 (also 35mm).

Nathan- Isn't that the one you got from me? Picked up in Arlington? Glad to hear it's doing well for you.

ritternathan · Feb 16, 2016

Yes, it is!

What lens for durst M800 enlarger?

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