Where it goes wrong in the darkroom? Images printed not sharp enough with new enlarger lens

silvercloud2323 · Dec 8, 2023

Hello all,

I'm back with the images that I could scan.
Because of the smaller size of the print i printed at the friends place i misinterpreted as higher in sharpness. But now when i,look at 1/and 3/ i see there was not so much difference , it was only underexposed. I think i like underexposed print.

The difference between the old lens and the new is obvious clear. The newer lens has more contrast and better separation of the tone values.

1/ smaller print , (at friends place), with the other lens (17 cm on 11 cm)
2/ old lens print ; flat appearance low on inner contrast (29 cm on 20cm)
3/ new lens on enlarger print , but underexposed (24 cm on 16 cm)
4/ new lens on enlarger print , (24 cm on 16cm)

Hope that some people can learn from it.

koraks · Dec 8, 2023

Thanks for putting those examples up - and for putting up with all of us!

First of all, the image itself seems to have a little bit of motion blur to me, but I see it in all four prints, so it's not something specific to your home lab. I suspect the negative is just slightly blurry.

The difference in sharpness between print #2 and prints #3 and #4 is absolutely significant. Also, print #2 is much darker in the center than at the corners. What kind of enlarger lens did you use for these prints? And what aperture do you set them to when actually exposing the prints? Keep in mind that focusing is usually done with the lens at its largest aperture, because this makes the image easy to see. But for the actual print, you generally stop down by at least 2 stops (so a f/2.8 lens you would use at e.g. f/5.6 or f/8). This generally gives better sharpness, contrast and especially it reduces light falloff in the corners.

If you exposed print #2 with the enlarger lens at its widest aperture, I'd suggest trying again at a smaller aperture and see what you get. Even so, however, print #2 is low in contrast that either there must be something wrong with the lens (e.g. it was opened for cleaning and incorrectly re-assembled). Another possibility is that the lens was mounted incorrectly on the enlarger and/or there's something odd going on with the lens board. I have this sometimes on my Durst 138, where if I mount the lens slightly out of alignment, light spills past the lens board, severely degrading contrast very much like in your print #2.

Ian C · Dec 8, 2023

I’ve added the following to the example I gave in post #115 for completeness.

With the 0.012” (0.30 mm) thick sheet of paper under the focuser, the distance from the negative to the first nodal point of the lens is 55.3763mm.

If we omit the sheet of paper, the distance is 55.3728 mm, an error of 0.0035 mm.

This distance determines the focus of the projection. The difference is beyond trivial.

Lachlan Young · Dec 21, 2023

DREW WILEY said:
Lachlan - my Thomas Scoponet was so far off that I threw it in the trash can. The shims below the base and underneath the mirror were both susceptible to humidity swelling. The assumption that manufacturers know what they are doing is naive. Some mass produced items never are quality control tested prior to distribution. You get what you pay for. Precision accessories inherently cost more to make to begin with.

As far as paper thickness being a factor - again, generalizations do not apply. The shorter the focal length of enlarging lens, the more thickness and spacing differences factor, just like in a camera. Some papers are thicker than others. And, for gosh sakes, take most of the web video jockeys with a grain of salt. Their methodology is often sloppy as heck.

Drew, I know what it takes to get a 40x enlargement sharp - and your random extrapolation about focus magnifiers and paper thickness doesn't hold for the small Paterson or Peak MK. 1.

Though, once you are at those sizes, an electronic grain focuser (surprised no one has made in the last few years as the tech is not complex by today's standards) is massively easier to use than either.

DREW WILEY · Dec 21, 2023

Don't tell me "what doesn't hold up", when I've been doing it for decades now, higher than commercial standards.
On my biggest enlarger, I even have a special close-focusing telescope mounted way up there, so I can achieve critical focus when atop a steel rolling platform ladder. But I always double-check with the Peak.

No, I'm not doing 40X enlargements - that would amount to something over 30 feet across from a sheet of 8x10 film, and I'm not in the billboard business. Please keep that in mind. Nothing of that sort is EVER sharp. I'm talking about being able to see critical detail nose-up, not from a "normal viewing distance" of a third a mile away on the freeway.
That's why I don't like ever going over 8X enlargement at most.

Different strokes for different folks.

Electronic focus would be relatively easy to rig up nowadays if you know where to look for the components. I certainly had the right connections before I retired, especially at the laser end of things. Most of that development first transpired right here in the Bay Area. Things have come a long ways since the headache days of the early Durst auto-focus units. I know where there's a horizontal version of one of those right now, awaiting a buyer. I don't know why he's still holding out for $70,00 for it, when it was his least favorite Durst enlarger to begin with.

Pieter12 · Dec 21, 2023

Lachlan Young said:
Drew, I know what it takes to get a 40x enlargement sharp - and your random extrapolation about focus magnifiers and paper thickness doesn't hold for the small Paterson or Peak MK. 1.

Though, once you are at those sizes, an electronic grain focuser (surprised no one has made in the last few years as the tech is not complex by today's standards) is massively easier to use than either.

Someone makes or has made such a thing?

DREW WILEY · Dec 21, 2023

Been around for decades, greatly improved technology now. Plus precision stepper motors and rails are now common enough to show up on the used industrial market at reasonable pricing. Precisely measuring distances with lasers is quite common too. Military and astronomical or space applications are an important market, many manufacturing applications too. But closer to earth in budget are fairly affordable examples which could be adapted to enlarger usage if one felt they needed that. Decent machinist skills would be required.

Pieter12 · Dec 21, 2023

DREW WILEY said:
Been around for decades, greatly improved technology now. Plus precision stepper motors and rails are now common enough to show up on the used industrial market at reasonable pricing. Precisely measuring distances with lasers is quite common too. Military and astronomical or space applications are an important market, many manufacturing applications too. But closer to earth in budget are fairly affordable examples which could be adapted to enlarger usage if one felt they needed that. Decent machinist skills would be required.

Not the possibility or an adaptation. The actual thing: an electronic grain focuser for photographic enlarging applications.

DREW WILEY · Dec 21, 2023

It's how it does it. There's a whole big field of modern industrial applications already out there. The distance measurement is automatically linked to the focus calibration. That HAS been done in the past. Like I said, I know where you can buy what was once a state of the art enlarger doing exactly that right now. But state or the art when that thing was made in the 80's is a far cry from what could hypothetically be done now with an enlarger if one had the will to do it.

It's actually fairly simple, but unlikely to show up on an actual factory model enlarger ever again, due to such a limited market today. I could do it in my own humble shop. Factories do this kind of thing all the time, integrating things like machine optics to stepper motors and so forth. There are engineers who specialize in it. It's now routine technology.

But no, I doubt anyone is going to offer a retrofit version for popular extant enlarger models. It would cost significantly more than the units themselves, and still require precise installation which ordinary extruded aluminum enlargers aren't capable of holding precisely. The older largely machined commercial units like Durst L138's and L184's etc. would be amenable.

Pieter12 · Dec 21, 2023

In the end, the OPs negative is soft.

Lachlan Young · Dec 21, 2023

Pieter12 said:
Not the possibility or an adaptation. The actual thing: an electronic grain focuser for photographic enlarging applications.

Effectively it's a box with a mirror like a grain focuser, but with a CCD where the eyepiece would be on a regular grain focuser - and which is hardwired to a minature TV monitor (real early 1990s tech!). The box has a magnetic back to stick on a vertical easel. The optical package in a phone camera today is massively more sophisticated by way of comparison (and would seem like a good place to start from for making something equivalent today).

I'm not sure who all sold them, other than they seem to have been available under a few brands in the 90s & were not cheap. Most will have probably gone to mural operations of the sort that probably disposed of them after moving to Lambdas and the like.

skahde · Dec 22, 2023

Forget about pictures. Also your Paterson is probably fine, mine always was and if I was in doubt the proof is the pudding. You should be able to produce sharp GRAIN in your finished prints over the whole of the print. Then work on the contrast. Even too cold developer in winter can ruin perceived sharpness so there is many variables to get straight. Welcome to a path of frustration, confusion but maybe final success.

grain elevator · Dec 22, 2023

I don't think I see much difference in sharpness between the examples above. BTW the one you call underexposed seems exposed about right to me; the others have no white in the picture. Ultimately the grain has to look sharp; image content seems probably affected by camera shake.

GregY · Dec 22, 2023

grain elevator said:
I don't think I see much difference in sharpness between the examples above. BTW the one you call underexposed seems exposed about right to me; the others have no white in the picture. Ultimately the grain has to look sharp; image content seems probably affected by camera shake.

I agree, the one labelled "underexposed" looks reasonable with visible detail, while the others look muddy.

skahde · Dec 22, 2023

How sure can you be, that anything done "at a friends place" is comparable to prints done in your darkroom? Is he using the same developer? Was it fresh and unexhausted? Does his darkroom and enlarger have the same level of stray-light? Is his safelight safe? Are all relevant variables under sufficient control to draw any conclusion about a lens?

Pieter12 · Dec 22, 2023

skahde said:
How sure can you be, that anything done "at a friends place" is comparable to prints done in your darkroom? Is he using the same developer? Was it fresh and unexhausted? Does his darkroom and enlarger have the same level of stray-light? Is his safelight safe? Are all relevant variables under sufficient control to draw any conclusion about a lens?

None of those would affect sharpness.

Roger Cole · Dec 23, 2023

Pretty much all of those can affect contrast though, and fairly small changes in contrast can affect the _perception_ of sharpness.

skahde · Dec 23, 2023

Roger Cole said:
Pretty much all of those can affect contrast though, and fairly small changes in contrast can affect the _perception_ of sharpness.

Thanks, my point exactly. Sharpness is a function of resolution and contrast.

DREW WILEY · Dec 23, 2023

Sharpness is also a function of actually being in focus. One is only as good as their weakest link. But trying to do critical comparisons over the web is futile. Compare actual prints.

Pieter12 · Dec 23, 2023

Roger Cole said:
Pretty much all of those can affect contrast though, and fairly small changes in contrast can affect the _perception_ of sharpness.

skahde said:
Thanks, my point exactly. Sharpness is a function of resolution and contrast.

Sharp is sharp. It is not a matter of perception. Resolution, size and contrast can give the illusion of sharpness, but it does not enhance or produce real sharpness.

DREW WILEY · Dec 23, 2023

Sharpness and perceived resolution are related but not identical concepts. Edge contrast is a factor. But I don't want to go into that here. There are no doubt past threads on that topic.

skahde · Dec 23, 2023

Pieter12 said:
Sharp is sharp. It is not a matter of perception. Resolution, size and contrast can give the illusion of sharpness, but it does not enhance or produce real sharpness.

A rose is a rose is a rose but sharpness is measured as contrast for a given resolution. If you want to ignore this, that's fine with me but still in contradiction to the widely acknowledged concepts: https://lenspire.zeiss.com/photo/app/uploads/2022/02/technical-article-how-to-read-mtf-curves-01.pdf

https://lenspire.zeiss.com/photo/app/uploads/2018/04/CLN_MTF_Kurven_2_en.pdf

And imaging is about nothing but the perecption of a final product, as long as you are interested in any kind of final product. Materials and devices are just means to an end which is somebody looking at a picture.

Pieter12 · Dec 23, 2023

skahde said:
A rose is a rose is a rose but sharpness is measured as contrast for a given resolution. If you want to ignore this, that's fine with me but still in contradiction to the widely acknowledged concepts: https://lenspire.zeiss.com/photo/app/uploads/2022/02/technical-article-how-to-read-mtf-curves-01.pdf

And imaging is about nothing but the perecption of a final product, as long as you are interested in any kind of final product. Materials and devices are just means to an end which is somebody looking at a picture.

Lenses. Not prints. If the grain in a print is sharp but the image isn't, no amount of contrast will make it sharp. The "perception of sharpness" is not sharpness.

skahde · Dec 23, 2023

The print shows sharp grain, the image is unsharp and the lenarging lens should be at fault? Sounds like an interesting concept or an unsharp negative.

MattKing · Dec 23, 2023

Pieter12 said:
Lenses. Not prints. If the grain in a print is sharp but the image isn't, no amount of contrast will make it sharp. The "perception of sharpness" is not sharpness.

As sharpness is mostly a subjective measure - matter of perception, influenced mostly by accutance, followed by macro contrast, followed finally by resolution - that is actually an oxymoron.
Unfortunately, "sharpness" is used by a wide variety of people to mean a wide variety of slightly different things.

Where it goes wrong in the darkroom? Images printed not sharp enough with new enlarger lens

silvercloud2323

koraks

Moderator

Ian C

Lachlan Young

DREW WILEY

Pieter12

DREW WILEY

Pieter12

DREW WILEY

Pieter12

Lachlan Young

skahde

grain elevator

GregY

skahde

Pieter12

Roger Cole

skahde

DREW WILEY

Pieter12

DREW WILEY

skahde

Pieter12

skahde

MattKing

Moderator

Where it goes wrong in the darkroom? Images printed not sharp enough with new enlarger lens

Moderator

Moderator

Privacy & Transparency

Privacy & Transparency