Durst M670 Alignment

Hi all.
Trying and failing to get my M670 aligned. Anyone have experience with this enlarger? I can’t see any adjustments for lens board to neg stage so I’m assuming they are fixed. Therefore I have been shimming the easel but this isn’t making a difference re sharpness corner to corner.

Thanks in advance

Unless you restrain the negative between the sheets of glass in a glass carrier to keep the negative flat, you’re wasting your time and efforts in trying to align the negative stage perpendicular to the lens axis. That’s because a negative that is not so restrained can temporarily take on a “dome” shape due to the heat of the lamp.

Thus, the projection of a negative not restrained in a glass carrier can be focused in the center, but slightly out-of-focus in the corners.

If the negative stage and lens axis are out of square with each other, tilting the easel won’t help.

The relationship between the negative stage and lens axis is most likely correct as is.

If the lens-to-negative alignment is out, the shims under the baseboard will need to be quite large. You could make a 'false baseboard' with adjustable feet like below. However, if the lens field is curved also (as seen in the last image), simple planar baseboard corrections will not make the situation entirely in focus.

Ian C said:

Unless you restrain the negative between the sheets of glass in a glass carrier to keep the negative flat, you’re wasting your time and efforts in trying to align the negative stage perpendicular to the lens axis. That’s because a negative that is not so restrained can temporarily take on a “dome” shape due to the heat of the lamp.

Thus, the projection of a negative not restrained in a glass carrier can be focused in the center, but slightly out-of-focus in the corners.

If the negative stage and lens axis are out of square with each other, tilting the easel won’t help.

The relationship between the negative stage and lens axis is most likely correct as is.

Click to expand...

Ok so I have anti Newton glass for the top side and mask for the bottom. Just tried it and I think it’s improved but not certain. I’m going to see if I can get a glass carrier for this enlarger and see if it solves the problem.

You should be fine with negative insert/mask and AN glass on the top.
What device you are using for alignment?
With my Dursts M605 and &800 I have only to put one bigger Olfa razor (maybe 0.5mm thick) under the front of the column to have everything aligned.

No device, just checking the focus of the projected negative at centre and corners on the easel. I haven’t been concerned with the level of the head, just trying to get the easel level with it using bits of card.

Ian C said:

Unless you restrain the negative between the sheets of glass in a glass carrier to keep the negative flat, you’re wasting your time and efforts in trying to align the negative stage perpendicular to the lens axis. That’s because a negative that is not so restrained can temporarily take on a “dome” shape due to the heat of the lamp.

Thus, the projection of a negative not restrained in a glass carrier can be focused in the center, but slightly out-of-focus in the corners.

If the negative stage and lens axis are out of square with each other, tilting the easel won’t help.

The relationship between the negative stage and lens axis is most likely correct as is.

Click to expand...

I’ve looked around but can’t find any glass carriers for the m670 other than the AN glass I already have. I’ll get one made to go on the bottom, under the AN glass. What kind of glass should it be made from?

Posts 18 & 19 of the thread whose link is given below discuss making a usable glass carrier for an enlarger for which you don’t have a commercially-made glass carrier. I’ve made such carriers out of two sheets of the thinnest window glass available.

While not as convenient to use as the enlarger-maker’s carrier, it keeps the negative flat during projection, which is essential to making uniformly-focused projections, and that is essential in analyzing the lens-axis-to-negative alignment. Such a carrier is inexpensive and easily made.

https://www.photrio.com/forum/threads/faulty-lens-on-agfa-enlarger.170968/

This might not be made to work in all machines, but I have done so for a variety of enlargers for which no glass carrier was readily available.

Posts 2 & 10 in the post whose link follows discuss the making of a mask/spacer to prevent Newton rings without necessarily using an ANR upper glass:

https://www.photrio.com/forum/threads/giving-up-on-the-v35-back-to-the-23c.171651/

I assume both the negative carrier and easel have true plane surfaces. If so, when all four corners of the image on the easel are in sharp focus, the enlarger is adequately aligned. In that case, if the center of the image is unsharp, the problem is likely curved film. Of course a more remote possibility is a poor lens. Proper storage of film reduces the problem of film curvature, although enlarger heat can distort an originally flat film. When aligning an enlarger with no mechanical adjustments, shimming the negative carrier with adhesive tape is a convenient and semi-permanent cure.

Many Durst enlargers often have the ability to tilt the enlarger lens standard, there should be a knob on the rear this can sometimes be out of alignment there's a ball bearing that locates when it's in the correct position. I think the M670 is similar in this respect to my M601 & M605.

Ian

Just found this on a British forum.
Possibly the solution you are looking for.


Better late than never.

It is a fix by Nat Polton for the M670 lens adjustment.
If the link does not work look at FADU PHOTO in the UK under DARKROOM.

Couple thoughts on alignment:

The neg, lens, and baseboard have to be parallel on both axes (for and aft, side to side). Some enlargers have adequate adjustments for this, some don't and require shimming.

A "Besalign" style lens board can make lens alignment a piece of cake. Here's a PDF I made on DIYing one.

The Versalab Parallel (or the DIY version in the appendices of "Way Beyond Monochrome") is utterly fantastic for aligning and worth every penny IMO.

To make the Parallel much easier to use, get a cheap filter for each enlarger lens thread - anything like a skylight or light-colored color filter. Tape a scrap of white paper to the center of the inside surface. This presents a flat and reflective surface for the laser to bounce off of and is much faster than Versalab's glass and rubber band solution, by a mile.

The minute you try a Parallel, your days of sheets of glass and levels and rulers will become a grim and distant memory. I can align my enlarger for wall projection in under 5 minutes.