Long printing times - when they're really long? :)

[pentaxuser]

Dear Pentaxuser,

Your apology is more than accepted. I didn't mean to sound quite as pettish when I replied, so I apologize too. Frances is perfectly happy.

Cheers,

Roger

Thanks. You didn't.

pentaxuser

 

[Ed Sukach]

Of course there is a "best" - optimum aperture - in ALL lenses. That is NOT restricted to enlarging lenses alone. In the design specifications, every parameter is given as a center "target", with acceptable limits either way.

What continually amazes me is the brittleness of some who use those lenses. There is something of a "perfectionist cult" out there that does propagate the idea that "Only the OPTIMUM MUST be used!!" Unfortunately, this philosophy necessarily LIMITS the flexibility of use. Most photographers will not hesitate to use a camera lens over a wide range of apertures; yet some of the same photographers will use only ONE stop in enlarging.

One useful flexibility is the depth of focus (remember this is a projection lens). A wide (? "deep"? "extensive"? - a whole lot) is a definite disadvantage in focusing the enlarger. The use of the maximum aperture results in the most "snapping" into place when focusing, and stopping down from there adds a cushion, minimizing errors. Additionally, if one has ever employed "The Brick Trick" (note 1) - tilting the easel to correct perspective issues, the value of using the smallest available aperture for its great depth of focus becomes apparent.

Here I write about "acceptable" limits. There are those who will cry, "There are NO acceptable limits! Everything MUST be PERFECT!" Good luck to them! It is certainly noble to try to do the "best we can", but after the twentieth or thirtieth print (don't laugh, it has happened to me!) there is a time to stop - and consider the realities involved: No work, in photography, or art, or any other human endeavor, will ever be perfect. All we can hope for is producing an "acceptable" print (and I think my standards of acceptability are pretty damned high - certainly higher than I've seen in some exhibition printing) in the most efficient manner possible.

Personally, I have never found my "standards" compromised by the use of ANY aperture of any enlarger lens. Certainly there is a DIFFERENCE - but , paraphrasing Isaac Asimov, there are a whole lot of factors other than enlarging lens apertures that are far more significant in enlarging.

All that above must be protected: My Opinions - Your Mileage May Vary.


Note 1: From a Camera and Darkroom article of the same title. I miss that magazine!

 

[eumenius]

Ed,

your words seem to be very true - I really can't see much difference in my Fujinon EX 50/2.8 and 105/5.6, and Rodagon 80/5.6 lenses behaviour on their maximum aperture and, say, f/max+2 stops. I made the normal-sized prints (8x10'') and a maximum magnification possible prints, and the grain pattern is as crisp as it could be from this negative. Some stopping down doesn't alter the picture significantly, or that's just my eyes that lie There's indeed some very slight subtle change - but it doesn't change the picture, really Looks like the optical designers really know their stuff, don't they?

Cheers,
Zhenya

 

[Roger Hicks]

There is something of a "perfectionist cult" out there that does propagate the idea that "Only the OPTIMUM MUST be used!!" Unfortunately, this philosophy necessarily LIMITS the flexibility of use. Most photographers will not hesitate to use a camera lens over a wide range of apertures; yet some of the same photographers will use only ONE stop in enlarging.

Here I write about "acceptable" limits. There are those who will cry, "There are NO acceptable limits! Everything MUST be PERFECT!" Good luck to them! It is certainly noble to try to do the "best we can", but after the twentieth or thirtieth print (don't laugh, it has happened to me!) there is a time to stop - and consider the realities involved: No work, in photography, or art, or any other human endeavor, will ever be perfect. All we can hope for is producing an "acceptable" print (and I think my standards of acceptability are pretty damned high - certainly higher than I've seen in some exhibition printing) in the most efficient manner possible.
QUOTE]

I couldn't agree more. My only caveat would be, "Work as close to the optimum as makes sense. After that -- the picture is the thing, not theoretical perfection"

In other words, if you can work at the optimum aperture, do. If not -- well, as you say, that's why the other apertures are there!

Betcha, though, that there are tech-nuts who would criticize your prints on purely theoretical grounds, even if (a) they're superb pics and (b) the tech-nut couldn't begin to come close, even technically.

Cheers,

Roger (www.rogerandfrances.com)

 

[Jim Jones]

Observing a projected B&W image through a grain magnifier while varying the aperture is illuminationg (groan. It's the best pun I can manage in the mornings). With a good lens, fine grain can start to get slightly mushy below f/5.6. That's a problem? If a client persists in examining my prints with a 10X loupe, I'll not stop down below f/8. Nor will I use the maximum opening. There is some vignetting with my EL-Nikkor 50mm f/2.8 wide open. My biggest objection to limiting the small apertures on an enlarging lens is the small depth of field when used as a camera macro lens. Life is too short to waste time enlarging at f/32.

 

[srs5694]

One useful flexibility is the depth of focus (remember this is a projection lens). A wide (? "deep"? "extensive"? - a whole lot) is a definite disadvantage in focusing the enlarger. The use of the maximum aperture results in the most "snapping" into place when focusing, and stopping down from there adds a cushion, minimizing errors.

Unfortunately, some lenses (particularly cheaper ones) suffer from focus shift when the aperture is changed. Focus correctly at the maximum aperture, adjust the aperture, and the focus shifts. I've done some tests with my lenses to verify that this effect is real, and it is real with the 4-element lenses I tested. IIRC, the effect was undetectable with my 6-element Nikon el-Nikkor f/2.8, though.

Personally, I prefer focusing at the aperture I use for exposing the print simply because when I use the maximum aperture for focusing, I often forget to reset the aperture before exposing the print. That makes for a lot of wasted paper (and chemistry, since I usually don't discover my mistake until I've at least begun to process the print).

 

[Ed Sukach]

Unfortunately, some lenses (particularly cheaper ones) suffer from focus shift when the aperture is changed. Focus correctly at the maximum aperture, adjust the aperture, and the focus shifts. I've done some tests with my lenses to verify that this effect is real, and it is real with the 4-element lenses I tested. IIRC, the effect was undetectable with my 6-element Nikon el-Nikkor f/2.8, though.

I've read this before... but IMHO, there is nothing optically that can cause this to happen, other than having a severely curved field of focus. As one decreases the aperture, it is possible to exclude errant rays - possible, I guess, but I've never seen it happen, in Optical Bench testing of some hundreds of lenses (so - I'm dating myself ... all that is done with lasers and automated sensors now).

*NONE* of the enlarging lenses I've used over the years have exhibited this "shift", and if I were to find one, I'd sell it on eB... nah! I'm a victim of integrity. I'd take it to my local pond and see how many "skips" I could achieve with it.

One thing to be wary of... incorrect re/ assembly. Many enlarging lenses have been disassembled for one reason or another (usually over-zealous cleaning) and are re-assembled improperly. Most I've seen contain shims to obtain/ correct element spacing errors, and it is all too easy to forget them, or install the wrong ones. Very bad effect on optical quality - but in no way dependant on the chosen aperture.