Aperture Size For 5x4 Printing

[Stanley Kubrick]

Hello, I was wondering if anybody could tell me the optimum aperture for printing with a 5x4 enlarger & lens. I know thats not terribly specific, as I do not know the name of my college's enlarger's lens. When I use a medium format 6x6 enlarger I usually open up to about f8.

Thanks

[Cletus]

While there is such a thing as an 'optimum' aperture for each enlarger lens, you probably shouldn't get too caught up in that at this point. I'm kinda guessing by your question that you're a little new to darkroom printing and there are many many more things to concentrate on at this point.

Typically, the aperture in the enlarging lens is used more to control printing time, as opposed to the aperture in your camera lens, which is obviously important for depth of field. When making prints with an enlarger, regardless of format, I normally open the lens to within a stop or two of wide open for focussing the image on the paper, then adjust the aperture to obtain printing time of somewhere between 20 and 40 seconds on the baseboard.

As long as your negatives are more or less properly exposed and developed, for "normal" density (a whole 'nother topic), you could reasonably expect an aperture of somewhere between f11-f32, if you were aiming for about a 30 second print exposure. Half a minute, give or take, will typically allow enough time for a little dodging and burning as necessary and keep you well away from the paper reciprocity failure limits (yes, they have that for paper too) in your prints.

Ultimately, it will take some time and experience under the enlarger before you really start to understand and get a handle on all the variables. At some point in the future, after you start getting things down pat, then you can do things like find optimum apertures for your enlarger lenses. Right now I think you'll have many other things to test and to occupy your darkroom time! Good luck! :)

[Brian Ellis]

The rule of thumb I usually see is 1-to-2 stops from wide open.

[Larry Gebhardt]

If the enlarger is aligned and you have a high quality enlarger lens 1 stop from wide open is usually optimal in my experience. That assumes flat film too (glass carrier). I would go an extra stop down if there is any sag to the center of your film.

[Cletus]

So it's possible that even I, the self-proclaimed enlarger lens optimal aperture expert, might still have something to learn! (please disregard my snarky, facetious tone, joking :) ) it never occurred to me, since I've never actually tested for it, that my lenses might actually be sharper toward the small end of the scale. I'll need to give that a try, I always assumed I was better off with a smaller hole in the lens and longer printing times.....thanks!

[DanK]

I guess I'd be in the minority here....open 1-2 stops from closed down....believing optimum aperture around f-11 to 16....

Cheers,
Dan

[ROL]

Well, so far that realm of "optimum apertures" given by posters thus far is certainly welcome news to anyone with a Zone VI coldlight. Because of the degree of enlargement and manipulation (:eek:) under the enlarger that I normally employ, I am rarely able to use apertures on either my Schneider 180mm or Rodenstock 210mm more than 2 or 3 stops from wide open, and that only for smaller enlargements. One stop is pretty much de rigueur for murals. The mythical center of the range is normally obtainable only at the expense of fogged paper, sore wrists, and missed lunch (:eek:!). The print either looks sharp enough for any degree of enlargement, or it doesn't.

[Greg Lockrey]

If you have a keen eye and kind of know what you're looking for, you can see the ''optimum aperture'' when you stop down to it. It pops! Typically it's near two stops from open...

BTW: My first custom photolab was called "the OPTIMUM APERTURE"... the name was too Avant Guard for most to understand and I got more calls from companies that were building blast furnaces than from photographers... :)

[chassis]

This is a good thread. I have long printed using small apertures, sometimes including fully stopped down (f/45). This is due to the density of my negatives, which tends towards the thin side of "normal", and the intensity of the incandescent bulb in the enlarger. My target enlarging times are around 20 seconds, and given the combination of variables I mentioned, this results in small lens openings.

To use larger apertures, I would need to use a lower wattage bulb, or neutral density filters.

Does using the smallest aperture create problems, such as diffraction, as it can do with camera lenses?

[Vaughn]

I preferred about f16 (135mm/5.6 lens), but would use the f/stop that would give me about a 20 second base exposure...so I might use f11, rarely f8 or f22. This is on a D5-XL Condensor enlarger, 70W bulb and 16x20 prints on Ilford Gallery or Portriga Rapid (tried Pal print but man that stuff was slow!) No glass carrier, so I tried to keep the lens closed down for more DoF.


Does using the smallest aperture create problems, such as diffraction, as it can do with camera lenses?

I imagine so, the laws of optics hold for both taking and enlarging lenses. The difference would be if the lens design was tweaked (corrected) for use at a particular f/stop.

[John Koehrer]

Have ya noticed most seem go for a middlin' range? Two down or two up.

[Jac@stafford.net]

What Brian Ellis said. If your school darkroom has a grain focuser, use it. You can see the image sharpen as you stop one or two down, and mush up as you approach max (numeric) aperture.

[Stanley Kubrick]

What Brian Ellis said. If your school darkroom has a grain focuser, use it. You can see the image sharpen as you stop one or two down, and mush up as you approach max (numeric) aperture.

Thats a good idea, I didnt think of doing that

[Cletus]

Good point about using the grain focuser. To tell the truth, I always thought the "sharpening effect" as lens aperture was changed, clearly visible through the microscope, was more of an optical illusion than anything else. Who knew?

[Jac@stafford.net]

Another thing to consider is the fact that aperture diameter and diffraction have an absolute relationship rather than relative. F/22 with a 300mm lens on 8x10 is huge compared to the same with, for example 35mm format. We LF people do not fret diffraction as little format people do, or should.

One more thing - we enjoy much greater depth-of-focus with our long lenses. (Not to be confused with depth- of-field). Our degree of enlargement is also far lower than miniature photographers must suffer.

Life is good for LF.

[Drew Wiley]

Most actual enlarging lenses are optimal one or two stops down. The mfg specs will tell you, but it's
relative to format. You can check thru a good grain focus device - IF this is itself properly corrected.
With smaller amts of magnification, common with 8x10 film for example, you might tolerate small
f-stops without noticable degredation of the print, but small stops are ordinary going to cause an issue.
No reason to use them unless you're trying to compensate for things being out of level to begin with.
If the paper itself is curling, use a vac easel.

[Cor]

Just last night:

Incredibly slow paper: New Oriental seagull Portrait Grade 2
4*5 Negative enlarged to size 40*50 cm
Test strips done wide open f5.6, Schneider Kreuznach Componon S
Actual bigger test sheet at f11 for 215 seconds (!)
Definitive sharpness difference between the f5.6 and f11 teststrips, so I'lll be patient and print at F11 and listen to music during the 4 min exposures..

best,

Cor