Enlarger lens f stops

[Huck]

What would be the best and optimum f stops for an enlarger lens, say of 50mm, 80mm and 150mm? Please tell all of us about your experiences.

 

[Dr Croubie]

The one that gets you the best picture?
I've read a lot of blurb from manufacturers that say "best 2 stops down from maxiumum", by 'best' I presume they mean sharpest (obviously after which they start getting diffractey). But if 2 stops down gives you a 1 second exposure, then suddenly 4 or even 6 stops down from max becomes the new 'best'

 

[geostog]

My opinion is to make some test prints for all the apertures your lens can provide.
As magnification has an effect on the image quality (manufacturers give an optimum magnification range) I would suggest making your tests at the paper size you usually print. It doesn't have to be a full print (if that is possible, go for it!) instead it can be a fraction of the whole print at the given magnification.

Just my experience as an amateur in the darkroom -the lens wide open gives you horrible prints. I found that when I got my Rodagon 80mm and made test prints. Stoping down give you the true quality of a great glass.

George

 

[snapguy]

buxk stop

My experience as a photojournalist in the film days is that worrying about the f stop is overrated. Granted, we were making 7x9 or 8x10 and an occasional 11x14 print -- nothing huge. And remember "X" lens may be rumored to be soft wide open but the particular version of that lens in your darkroom may be fine. You have to test the lens un your own working conditions and decide for yourself what works. The buck stops with you.

 

[jochen]

Even with a 6-lens type Rodagon, Componon, EL-Nikkor .... you should stop down to 8 or 11 to get more depth in field to compensate for the paper and the film not laying flat. My 2.8/50 mm Rodagon has a rather low contrast full open, for focussing on the film grain with my Peak I have to stop down to 4.

 

[gone]

It probably has more to do w/ the image you're printing and your particular enlarger bulb. You don't want to cook the neg w/ long, stopped down exposures.

 

[ic-racer]

You can calculate the optimum aperture based on the focus spread (based on view camera focus equation of Hansma).

N = 20/(1+M) * square root of 'dv'

N = Aperture number
20 = user dependent constant (circle of confusion 0.15mm for me)
M = magnification
'dv' = millimeters of focal depth on the enlarger column.

 

[ataim]

I have the big Durst Enlarger and according to them it wide open. www.durst-pro-usa.com/world_images/alignment.htm I sometimes make large prints (20x24 from 8x10 or 4x5). Because of the times involved open the lens up anyway and have not see any issues doing this.

 

[wildbill]

I tested my lenses and go with the sharpest results. There's not much of a difference but I wouldn't be shooting 4x5 and 8x10 for the hell of it, I like sharp prints.
It depends on the lens design. Apo lenses are said to perform best at only a stop or two down from wide open. My 135 rodagon is sharpest at f11 so I adjust the light source via output or nd gels and almost always print at f11.

 

[ic-racer]

I have the big Durst Enlarger and according to them it wide open. www.durst-pro-usa.com/world_images/alignment.htm I sometimes make large prints (20x24 from 8x10 or 4x5). Because of the times involved open the lens up anyway and have not see any issues doing this.

You have an Apo EL Nikkor, nice. For the rest of us, just check the MTF info on the Shcneider or Linos sites. You will want to stop down a few clicks (more if there is any focus spread, as above.)

 

[Jim Jones]

My 50mm f/2.8 EL-Nikkors have more even illumination at f/4 than wide open. By f/11 fine grain becomes somewhat mushy as viewed with a grain magnifier. Therefore, f/5.6 and f/8 are my preferred apertures. As Jochen notes, smaller apertures can compensate somewhat for enlarger misalignment, film buckling, etc.

 

[PKM-25]

I use almost all modern Rodagon APO lenses, 50N, 80N, 90 & 150N, the odd man out is the 135 Rodagon 5.6 which I use at F8-F16. I try to keep it around 1-3 stops from wide open in order to account for any film flatness or other sharpness bugaboos. I find as long as I am perfectly aligned and the film is flat as can be, I can go one stop down and be super sharp with the APO lenses.

Generally speaking, my target with most enlarging lenses is 2 stops down from wide open.

 

[Simon R Galley]

I was taught to stop down to between f8 and f11 and always did, and still always do !
at least it saves writing on the neg sheet, I always save ( and dry ) the last test before printing
and put it in the neg bag with the grade and exposure I used ( including didging and shading notes )written on the back of the print.

The exception to this was mural prints on the horizontal enlarger, the quicker the better, 1 stop down, still had some exposures over 20 mins on 16 foot wide prints !

Simon ILFORD Photo / HARMAN technology Limited

 

[Huck]

I have the big Durst Enlarger and according to them it wide open. www.durst-pro-usa.com/world_images/alignment.htm I sometimes make large prints (20x24 from 8x10 or 4x5). Because of the times involved open the lens up anyway and have not see any issues doing this.

Which model is your Durst? I have a Durst, and have lots of problems with the control box; the time I set changes, usually more, once I push the exposure button. Do you know how to correct this?

 

[PKM-25]

The exception to this was mural prints on the horizontal enlarger, the quicker the better, 1 stop down, still had some exposures over 20 mins on 16 foot wide prints

Alright Mr. Galley....20 minutes?

This is really good to know because I have heard all kinds of stuff regarding paper's ability to work after times longer than 3-4 minutes. The reason I ask is that I am trying to plan ahead for my mural work in terms of light sources, working apertures, etc, pretty much considering Ilford's largest paper size of 56" tall. I know that the new "Classic" paper is faster than just about any other you make, so it is a good candidate for this type of use.

But really, what are the practical exposure limits of your modern papers such as warm tone fiber and the new Classic?

I know this is a bit off topic, but 20 minutes from a man who knows paper is an eye catcher...

 

[DREW WILEY]

Not all enlarger lenses are the same. First of all, read the mfg tech sheets for your specific lens (or lenses). That will tell you the magnification ratio the lens is optimized for and recommended ideal f-stop - though it might work decently somewhat outside its ideal parameters, depending. How much depth of field do you need - is everything on your enlarger properly aligned, is your printing paper held flat, is the neg held flat in a glass carrier, or do you need to stop things way down just to compensate for otherwise sloppy technique? How much speed do you need for a given size of print relative to the speed of the paper? All these variables come into realistic place. And you simply cannot make one shoe fit every different foot out there. Just as we make choices about our camera lenses, we also need to make intelligent choices about enlarger lenses and how to best use them.

 

[DREW WILEY]

Wide open vs stopped way down?... more blah blah. I can use a 150 Apo-Rodagon N completely wide open at f4 on 35mm or 6x9 film because my system is precisely aligned and I'm using just the center of the lens. If I did the same thing for 4x5 film, for which this particular lens is
marketed, I would have excessive illumination falloff, though detail rendition would be OK (not fantastic like one stop down, but OK). Maybe
this weekend I will be printing some more of this new MG Cooltone paper in 16x20. My 8x10 cold light is pretty powerful, so until I get some
more ND filtration for the diffuser, I actually have to stop my 305 Apo Nikkor clear down to f/45 just to slow the exposure of this FAST new
paper down to around 10 sec. But that only a 2X magnification from 8x10 film, so the print still looks extremely sharp. If I did that same thing
for, say, 6x7 film, and stopped my 105 lens down to f/45, that would amount to around a 7X enlargment and look horrible due to diffraction
at such a relatively small stop. My garsh, these are LENSES just like those in your camera. The same laws of optics apply. Think!

 

[AndreasT]

Alright Mr. Galley....20 minutes?

This is really good to know because I have heard all kinds of stuff regarding paper's ability to work after times longer than 3-4 minutes. The reason I ask is that I am trying to plan ahead for my mural work in terms of light sources, working apertures, etc, pretty much considering Ilford's largest paper size of 56" tall. I know that the new "Classic" paper is faster than just about any other you make, so it is a good candidate for this type of use.

But really, what are the practical exposure limits of your modern papers such as warm tone fiber and the new Classic?

I know this is a bit off topic, but 20 minutes from a man who knows paper is an eye catcher...

I have exposed mural prints upto about 40 min. Dodging the whole time. That gives back pains.
I have always had the impression when doing big prints the grain is sharper only one stop closed. If the lens can handle the enlargement of course.
Especially with lenses at around 300mm.
Otherwise I never stop more than two stops down unless the times are too short. After that I am of the meaning the grain gets worse.

 

[bdial]

if you'd like a short-cut to doing your own testing, Google "Post Exposure" by Ctein, it's a book he published a while ago, and he has made it freely available on his web site in PDF form.
In it he has tests of a number of the "usual suspect" lenses, with the best apertures of each (according to his testing).
There is lots of other good information in the book, and it's hard to beat the price.

 

[PKM-25]

My garsh, these are LENSES just like those in your camera. The same laws of optics apply. Think!

The OP is thinking, that is how one often arrives at asking questions....

I have exposed mural prints upto about 40 min. Dodging the whole time. That gives back pains.

So it looks like I need to do a little research on paper reciprocity times and nuances, this is good to know....

 

[DREW WILEY]

When I had a Durst color mural head it would punch big Cibachromes with attached .90 masks in about 15 sec. That means if I was printing
black and white papers or C-prints I would need about twenty stops of extra density just to slow things down to that time. I would be like a
flashbulb otherwise - fractions of a second. Conversely, when I've enlarged straight onto azo paper (allegedly only a contact speed paper),
I'd use a fast enlarging lens. Again, nobody can realistically make blanket generalizations about all this. It all depends.

 

[ataim]

Which model is your Durst? I have a Durst, and have lots of problems with the control box; the time I set changes, usually more, once I push the exposure button. Do you know how to correct this?

I have the 184. I don't use the Durst control box sorry

 

[RalphLambrecht]

What would be the best and optimum f stops for an enlarger lens, say of 50mm, 80mm and 150mm? Please tell all of us about your experiences.

same as with any lens;stop down a couple of stops to reduce lens abberations but not as far as to gett into lens diffraction.I'ts a balancing act between the twof/8-11 is always a good start. for quality 6-element lenses.