Dongrappo
Hi everyone
Oh, I hope I’m not stirring up a fuss with this topic and causing unnecessary stress and despair for some of you with my query.
So this is only for the intrepid! ;-)
I’ve been using my enlargers over the last few days and have tried loading some negatives.
Then I took a blank piece of film and used a craft knife to score a grid pattern into the emulsion layer.
In doing so, I noticed that on all the machines, more or less, with the aperture open at f/2.8 or f/3.5 (Liesegang), the plane of focus isn’t 100% accurate either laterally and/or in depth.
With the old Liesegang slide stage for 35mm on glass at the top, a lateral shift in the focus plane is visible to the naked eye. There is nothing to adjust on the device and it is all very solidly and sturdily built, just apparently slightly out of alignment.
With the two Krokus 69s full-glass slide stages, there is only very, very little play in the depth plane. One has slightly more than the other.
The Kaiser VC 60 book stage with glass underside also has a slightly different focal plane at the sides, which I was able to improve by ‘twisting’ it slightly on the lateral axis away from the stop for vertical projection and then tightening it securely. (It could also be down to the open-top negative stage, I suspect.)
The Krokus and the Kaiser were and are in very, very good condition; they have been treated with care and I do not believe that any major mechanical issues have affected the systems. I therefore imagine that this must have been the condition of the equipment when it was manufactured and delivered.
I examined the whole thing visually by, for example, focusing on the front edge and then looking at the rear to see if the sharpness could be increased, or by setting the left side as sharply as possible and then looking at the right to see if the sharpness was better.
With the best Krokus, I have the feeling that, yes, perhaps the sharpness is slightly different, or maybe not, or is it?!?!…. With the others, it’s a little clearer, though still only very, very slightly so, except for the Liesegang, where it’s also very clearly visible to the naked eye (unfortunately!!!).
I’ve now had a look around the forum and read something about how you can test this using a laser setup and a mirror.
My question now is, how precisely do you go about this???
I mean, back in the day, when people were already producing really great enlargements, there were no laser pointers, and not all prints were made on those super-stable, extremely precisely manufactured professional machines.
So how much of a fuss do I need to make of it?
How precisely do you approach this?
How do you solve the problem, if it’s one for you at all?
Adjust the frame? File down the image stage?
In some cases, it’s only a matter of the tiniest nuances that the eye can even distinguish, and of course the problem diminishes when stopping down anyway, but by how much exactly?
Well, I hope I’ve managed to express my question in a reasonably clear way.
I’d be really interested to hear your replies.
Best regards, and I hope I’m not raising an issue for anyone that wasn’t previously a concern, thereby causing any tension.
Well, it’s something that’s on my mind, even though I’d like to take it more in my stride – which I just can’t manage.
Werner
Wolf_XL
… as long as the sharpness of all the corners is maintained when stopping down to the optimal aperture of the enlarger lens, you’re in the clear. It all depends on the enlarger, of course. My Durst Laborator 1000 has been perfectly aligned for years, whereas I have to adjust the Dunco quite often. This is probably also down to the fact that you can swivel the head sideways on the Dunco, which adds another potential source of error. When everything switched over to digital, I bought this bit https://www.versalab.com/PARALLEL.html second-hand very cheaply. With this, adjustment is of course a piece of cake...
KlausWehner
It is important to ensure that all three planes of the enlarger are aligned as precisely as possible.
This should certainly be checked from time to time.
A method using a mirror and a laser is the most accurate – provided you work with precision.
A simple (though not quite as accurate) method is to align all three planes using a spirit level.
Small tolerances are always acceptable, provided you avoid high magnification ratios and always stop down sufficiently.
But of course, you must ensure that the negatives have sufficient sharpness.
That is where I often see the greatest need for improvement.
Best regards,
Klaus
KlausWehner
The device Wolf has shown here looks very professional.
The specified tolerances show just how precisely one has to work.
Of course, one could improvise something like this using a laser and a mirror.
But achieving the necessary precision would be a very laborious task.
Simpler methods are not as accurate.
To be on the safe side, one must stop down sufficiently when zooming in (e.g. by 3 f-stops).
Best regards,
Klaus
