Schneider-K. Componon-S 50mm enlarger lens - sharp??

[phelger]

a test I made today shows that this lens gets sharper for each stop down, from 2.8 to 16. At 2.8 it's not sharp at all, at 8 it's acceptable but there is still a substantial improvement by going down to 16. This seems to be contrary to what Schneider and most people say.
I think my method of testing was robust, enlarger head raised to ca. 10x enlarging, focused on the grain, used one single pin sharp neg (135), did'nt move the easel. My enlarger : Durst M670 VC.
I should be grateful if anybody can comment or help to explain what I'm getting wrong. It's a pain if I always have to use f16 to get my images sharp.Thanks in advance
Peter

 

[ath]

Did you focus with a red filter between lens and negative?

 

[mdarnton]

Try it again, but focus at the same lens opening you will be using for the exposure.

 

[Newt_on_Swings]

What type of grain finder are you using? and did you focus that correctly before you started to use it under the enlarger?

If you are not using the grain finder correctly, all your prints will not be sharp, and you would have to rely on stopping it way down. Once you get too small diffraction starts to kick in and from then on it will not be as sharp either.

And as well as including what the previous posts have said, I have read that in the past enlarger lenses had quite a bit of variation between each other in sharpness even from the same line and manufacturer. There is a old popphoto article on it somewhere and I think it was common at one time for a printer to buy a few copies of the same enlarger lens and choose the best, and return the rest.

 

[ic-racer]

This is what you should be seeing with a grain magnifiier if all is OK with your system:

At 2.8 at the center, grain is sharp but low in contrast. Edges my not be so sharp
As you stop down contrast increases but sharpness decreases with each stop.
At f8 you have a good compromise between diffraction and edge sharpness
Past f8 it gets mushy and the grain gets indistinct.

 

[Rol_Lei Nut]

My own experience with that lens: usable at f/2.8 (corner grain not perfect), but used it more often at 5.6 or 8.0 to offset any focusing or enlarger-paper geometric imperfections.
The older 4.0 Componon might have a touch more acutance at those stops, but the "S" is certainly no slouch!

As others suggested, check your technique.
Maybe shake the lens next to your ear to hear if there are any loose elements inside...

 

[Ian Grant]

Make 100% certain your Durst isn't creeping. Both the head on the column and the lens focussing wear over time and can slip, the head can actually creep up the column. There's pressure pads that prevent this and after a time they need a slight tightening.

Ian

 

[sandermarijn]

My M670 had focus creep. The seller fixed it.

 

[phelger]

thank you to everybody for your help!
to Andreas : no, there is nothing to disturb between neg and lens!
And yes, it's possible that my focusing on grain is the problem. Have three focus finders: Paterson major and minor and LPL . I prefer LPL because its bigger enlargement.
Tomorrow I'll return to darkroom and re-test. I also have a Nikon EL 50mm to compare with (not done so far).
Ian and Sandermarijn: pretty sure there is no creeping going on, that was first thing I checked. But the Durst is not that easy to adjust finely.
I'll report back after next tests.
Peter

 

[sandermarijn]

I think I still have a 50mm/2.8 Rodagon lying around unused. Will have to check tomorrow or the day after. If I can find it and if it looks decent enough you can have it if you like. Just for making things even more confusing ;-)

 

[darinwc]

Also check your corners with your grain magnifier to make sure the enlarger is aligned correctly.

 

[Jojje]

Someone probably has dropped the lens on the darkroom floor once too often...
I once encountered an el-Nikkor 50/2,8 which should be sharp as a tack but this one wasn't.

 

[RalphLambrecht]

a test I made today shows that this lens gets sharper for each stop down, from 2.8 to 16. At 2.8 it's not sharp at all, at 8 it's acceptable but there is still a substantial improvement by going down to 16. This seems to be contrary to what Schneider and most people say.
I think my method of testing was robust, enlarger head raised to ca. 10x enlarging, focused on the grain, used one single pin sharp neg (135), did'nt move the easel. My enlarger : Durst M670 VC.
I should be grateful if anybody can comment or help to explain what I'm getting wrong. It's a pain if I always have to use f16 to get my images sharp.Thanks in advance
Peter

very dtrange indeed. can you rule out enlarger vibration?

 

[jochen]

Hello,
are you shure that your negative is flat in the enlarger? By stopping down the dephth of field increases and the visual sharpness of your picture is improved from the center to the corners. Even for a simple 3-lenser (Rodenstock Trinar) it would be quite unusual that you have to stop down to f/16 to get a sharp picture. Since enlarger lenses are designed for their job, they do not show a curvature of field. They show their best performance stopped down by 2 - 3 steps. from f/11 to f/16 the performance gets worst due to diffraction. My 2,8/50 Rodagon has a low contrast at f/2,8, exact focussing on the grain (Peak II)needs f/4, for printing I use f/8 to f/11 since I have a negative frame without glasses for 35mm. The a double glass negative holder for 6x6 (with Meopta Meogon 80 mm) improves the sharpness in the corners dramatically versus a glassless holder but you have to be very careful because of the dust!!!

 

[phelger]

I spent a good moment reading everything about sharpness in 'Way Beyond Monochrome' 2.ed which I got recently - thank you, Ralph, I find this book as indispensable as A.Adams three vols. in any serious photographer's library.
Then I restarted testing and discovered that my first test neg. was not really sharp! Found a better one and made comparisons of the three objectives I have: Componon-S, EL-Nikkor 50mm, 2.8, Rodagon 80mm, 4.
The Nikkor was sharpest and slightly better in contrast, Rodagon came close but my Componon still seems to lack something. At full opening neither of them were sharp - no surprise. At one stop down Nikon is brilliant, Rod. not quite but acceptable, Comp. not acceptable. At two stops down Nikon and Rod. brilliant, Comp. not quite and just acceptable. Three stops down and couldn't see any difference. I did not test the two last stops.
So now the EL-Nikkor sits on my enlarger and the prints I made today were to my full satisfaction.
I still can't explain why in my first test the result improved with each stop down to f16, maybe it was due to my clumsiness and if so I apologise for having disturbed you with that - I hope it didn't give you any sleepless nights
Peter

 

[Rol_Lei Nut]

I spent a good moment reading everything about sharpness in 'Way Beyond Monochrome' 2.ed which I got recently - thank you, Ralph, I find this book as indispensable as A.Adams three vols. in any serious photographer's library.
Then I restarted testing and discovered that my first test neg. was not really sharp! Found a better one and made comparisons of the three objectives I have: Componon-S, EL-Nikkor 50mm, 2.8, Rodagon 80mm, 4.
The Nikkor was sharpest and slightly better in contrast, Rodagon came close but my Componon still seems to lack something. At full opening neither of them were sharp - no surprise. At one stop down Nikon is brilliant, Rod. not quite but acceptable, Comp. not acceptable. At two stops down Nikon and Rod. brilliant, Comp. not quite and just acceptable. Three stops down and couldn't see any difference. I did not test the two last stops.
So now the EL-Nikkor sits on my enlarger and the prints I made today were to my full satisfaction.
I still can't explain why in my first test the result improved with each stop down to f16, maybe it was due to my clumsiness and if so I apologise for having disturbed you with that - I hope it didn't give you any sleepless nights
Peter

Strange....

In my experience, the EL-Nikkor should have come in behind the other two (with a slight edge for the Rodagon).
Sample variation or some kind of mechanical interaction?

 

[phelger]

I think I still have a 50mm/2.8 Rodagon lying around unused. Will have to check tomorrow or the day after. If I can find it and if it looks decent enough you can have it if you like. Just for making things even more confusing ;-)

hi Sandermarijn,
this is indeed very kind of you, thank you so much. Hold it for the moment, I must confess I bought an APO-Rodagon 50mm the other day (havn't seen it yet) when I've tried it out I'll report back
Peter

 

[sandermarijn]

Indeed Peter, if none of the lenses you have now appear to be sharp all over the image, then something else must be badly wrong.

BTW, if it appears that your enlarger is all messed up you may consider getting another one instead of trying to fix it. I don't know how things are in Luxembourg, but in Holland M670's and the like go for less than their lenses. You could have a look at www.marktplaats.nl for offers in the SE of Netherlands- not a very long drive from your country. I don't know how things are in Belgium, France and Germany, but there should be similar options/sites there as well.

 

[clayne]

Enlarger is typically just a metal frame. Unless it's been thrown off a truck I'm sure the problem is workable. We just need to figure out what's out of alignment.