My LF-prints less crisp compared to my MF

Sorry for my silence; been too busy the latest couple of days.

Just to clarify. I did a test to verify that the GG vs film-plane distance is ok. For that purpose I built a test-rig, see below

Attachment 183242

I used a piece of sheet aluminium onto which I glued a high-contrast target. There is also a "ruler" that is slanted by 45 degrees in the z-direction (= optical axis). The zero mark on the ruler is aligned with the aluminum plate (not very clear in this image, but they are). I set-up my camera an focused on the plate/zero mark, using a very sturdy tripod and a focusing loupe (and of course the GG+fresenel combo (Wista original by the way)). After exposure, I verified that the focus was still spot on. Attached below is a close up on the resulting sheet-film negative.

Attachment 183243

It is a quite lousy scan, but as far as I can tell, the focus is pretty spot on, right? I don't think I have a problem with GG alignment!

Next-up to test is my enlarger setup...


By the way, how to verify that the taking lens of the camera is properly assembled in terms of disance between front- and back- module?

Quote:

---

Originally Posted by henpe

By the way, how to verify that the taking lens of the camera is properly assembled in terms of disance between front- and back- module?

---

You can print a USAF 1951 resolution target (http://www.takinami.com/yoshihiko/ph..._test/USAF.pdf) and evaluate the optical performance of your glass. Your lenses (Schneider Symmar-S 135 / Fujinon SW 90 / Fujinon NWS 210) should yield around 50 to 70 Lp/mm, with comparable results like here: http://www.hevanet.com/cperez/testing.html

A short follow-up.

I have not tested my taking lenses yet, but I did run a few tests on my enlargers and found some interesting results.
I was able to acquire a transparency USAF 1951 resolution target. I put the target in both of my enlargers and made prints with both my Nikon 80mm and my Schneider Componon-S 150mm. In all tests, I printed the target to x5 times magnification. When inspecting the prints with a loupe, I found that prints made with my Durst L1200+CLS450 are less sharp compared to prints made on the LPL. This is down to the very fine details of the resolution target. When looking with my naked eye, I cannot spot a difference. I suspect the difference is due to the fact that the LPL is fan-less, while the Durst is not....

Quick question - do you examine the image on the base board (with sample of paper bemeath) using a grain focus device, and if you do, what brand/model number of the device? Thank you.

I made prints on RC paper and then inspected the prints using my eye, but also with a x40 stereo-loupe. When focusing the enlargers, I used both my Peak and my Bestwell Optics Micro-Sight (they both agree with each other, it turned out). I must admit though that obtaining critical focus was a bit tricky.

Next time in my darkroom, I will make new test prints with the Durst but with the fan temporarily disconnected and see if there is a difference....

Quote:

---

Originally Posted by henpe

I made prints on RC paper and then inspected the prints using my eye, but also with a x40 stereo-loupe.

---

To evaluate ultimate resolving power you have to ensure paper flatness. You can place a piece of glass on the easel sprayed with 3M Re Mount glue, this should ensure paper flatness. To test the corners you also have to ensure a perfect alignment, and/or focusing again for the corner.

There's other factors to examine too, like if the film is popping in the neg carrier during exposure, as mentioned paper flatness, easel or other movement issues, is your grain magnifier really right on, etc... Or maybe something about you like not wearing your glasses with your magnifier setting, or not seeing the grain clearly, as it is different looking from smaller formats... And really go over your enlarger settings if something is not set right...

I have also seen on some enlargers when the bellows are extended that they create a pull that changes the focus settings sooner or later, or other locks that drift...

Test, test, test...

Good luck!!!

Steve K

Quote:

---

Originally Posted by henpe

I made prints on RC paper and then inspected the prints using my eye, but also with a x40 stereo-loupe. When focusing the enlargers, I used both my Peak and my Bestwell Optics Micro-Sight (they both agree with each other, it turned out). I must admit though that obtaining critical focus was a bit tricky.

Next time in my darkroom, I will make new test prints with the Durst but with the fan temporarily disconnected and see if there is a difference....

---

The Durst column should really be braced to a solid wall, otherwise you've got a big inverted pendulum wobbling around. May make a significant difference in sharpness, more than any lens.

Quote:

---

Originally Posted by henpe

I made prints on RC paper and then inspected the prints using my eye, but also with a x40 stereo-loupe. When focusing the enlargers, I used both my Peak and my Bestwell Optics Micro-Sight (they both agree with each other, it turned out). I must admit though that obtaining critical focus was a bit tricky.

---

Did you or not place a piece of enlarging paper under your Peak?
After using a focusing device properly do you change aperture? (Do not do that)
Finally, just how accurate is your stereo-loupe?

Enlarger check list:

*Absolute alignment between enlarge head to base board. This is a must and cannot deviated by more than fractions of a mm over the entire travel distance of enlarger head to base board. The planes between enlarger head film holder to base board must be absolutely parallel at all times.

*Enlarger stability. The table supporting this enlarger absolutely rigid and stable? The enlarger column properly supported? Much the same as a flimsy tripod trying to support a view camera vibrations and more is easily transmitted to the optical printing system causing out of focus or appearance of problem like this. This is also why the preference to a floor standing enlarger, the entire enlarger-projection system tends to moves together as a unit which helps negate some of the potential vibration problems.

*Flatness of paper holding easel. If the easel holding the paper to be projected on is not flat some areas will be out of focus.

*Longer enlarging times can help reduce the effects of vibration. This is much the same technique used by the microscope photographer folks. By allowing the projected image information to integrate over time on the projected media, it can help negate some of the vibration problems. Consider using a print time of 20 to 40 seconds.

*Wrong condenser set for a given enlarger lens focal length if a condenser enlarger is used. This can result in light fall off at the edges of the print to poor optical performance of the light source to projected image to the print. The light source must be properly aligned to the condenser systems and enlarger lens. If a diffusion enlarger is used, this does not matter. Based on experience with both condenser and diffusion enlargers, the condenser enlargers when properly set up with the very best enlarging lens can project more optical information on to the printing paper that can be resolved-presented in the finished print.

*Projecting the image to print paper using the near optimal aperture of the enlarging lens. Typical good printing aperture of an enlarging lens is two stops down from full aperture. Avoid stopping down the aperture any more than needed beyond two stops from full aperture. There is no need and will only degrade the projected image. Better to adjust the exposure time to achieve lens projection aperture of about two stops down from full.

*Grain focuser working properly? Thickness of the print paper added when grain focuser is being used?


Bernice