Any effect to enlarging at smallest aperture

lauffray · Sep 11, 2017

I was trying out my new enlarger this weekend and even at f/8 the exposure times were still very short. I've never printed at a smaller aperture, mainly because of diffraction but I'm not sure how much of that is internet paranoia.

If I'm enlarging a 35mm negative on 8x10 paper, using the standard leitz focotar lens that comes with the focomat 1c, can I just close down to f/11 or f/16 without losing too much quality?

faberryman · Sep 11, 2017

for your exposure times, how short is "very short"? Are they divisible by two?

lauffray · Sep 11, 2017

Yes they are. I had one print at 7 seconds (grade 3 filter) and another at 10, in those two cases I didn't need to burn or dodge but if I had to I would find that window a bit tight.

I don't know how comparable this is, but with my previous enlarger, also at f/8 I typically had exposures of at least 20-30 seconds for a wide variety of negatives

faberryman · Sep 11, 2017

Are you using the correct bulb for your enlarger? The manual calls for a 75w opal bulb.

Focomat 1C manual

pentaxuser · Sep 11, 2017

My experience with a Durst 605 is that you can drop down to 75W from the recommended 100W. I see no reason why this wattage drop should not be OK with any enlarger. Going to f11 is a one stop idecrease in aperture so doubles exposure which by itself puts you up to 14 and 20 seconds and I doubt if any diffraction problem will show at f11. Add the extra time for a lower wattage bulb and you'll be in very comfortable exposure times for any D&B

pentaxuser

MattKing · Sep 11, 2017

If you are just enlarging to 8x10, diffraction effects won't be significantly visible at any f/stop, so feel free to stop that lens down.
It is when you are working with larger magnifications that diffraction limiting becomes really important.

JensH · Sep 11, 2017

Hi,

I newer use smaller stops than 8, because I sometimes get strange artefacts from the AN-Glas at 11 or 16.
(Format is 6x6 cm with 4/80mm Componon-S on a Durst 138s)
Better use a matte glas or ND filter behind the bulb, or as said, take a weeker bulb.

Best
Jens

carioca · Sep 11, 2017

Why not use ND filters to cut down light power, always better than closing down your lens all the way for the reason you mentioned, deffraction.

M Carter · Sep 11, 2017

ND is a really good answer - and you don't even need camera filters. Get a sheet of one-stop ND lighting gel and cut it to fit your filter drawer. Stack additional sheets to reduce by 1-stop increments. Just keep them clean and store them as you would an MC gel filter.

lauffray · Sep 11, 2017

Thanks everyone, faberryman had it. I just checked and the bulb that came with the enlarger was in fact a 150W bulb, I'll be changing this very soon. Feeling kind of dumb, but thanks for all the good suggestions

bdial · Sep 11, 2017

That would do it. An enlarger I had for while came to me with a 150W bulb, I was trying to work with exposures of 1 - 2 seconds, sometimes less, at a "preferred" f/stop.

Arklatexian · Sep 11, 2017

lauffray said:
Thanks everyone, faberryman had it. I just checked and the bulb that came with the enlarger was in fact a 150W bulb, I'll be changing this very soon. Feeling kind of dumb, but thanks for all the good suggestions

Why not do as the book said and use 75W enlarging bulbs? That is what my Valoy II uses and you can forget ND filters and the like. In other words, YOU have control of the situation not your enlarger bulb. Sounds like someone had a large number of prints to make and put the 150W bulb in the enlarger to speed the process along. Things like this seem to always happen when someone gets in a hurry rather than taking the time to do things correctly. I also don't think the 150W bulb was doing your enlarger any favors either......Regards!

lauffray · Sep 12, 2017

oldtimermetoo said:
Why not do as the book said and use 75W enlarging bulbs?

When I bought the enlarger it had a bulb in it already and I didn't think to check if it was the right wattage

Any effect to enlarging at smallest aperture

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