Enlarger Alignment, Negative Flatness, and Glass Carriers

[DREW WILEY]

In the real world, people who tend to excuse a bit of sloppiness in one aspect are apt to do the same at other levels, and all these seemingly insignificant little errors add up to something much bigger.

 

[snusmumriken]

As a sticky, this thread should really consist of sound, pithy advice, rather than debate. Huge respect to @Ian C for making us understand the relative importance of alignment behind and in front of the lens. I'm a scientist, so precision has a fascination for me, and it's fun to consider what tools you might use to check alignment. But like @Ian C I'm also a pragmatist, and I am saddened when people believe that they must have expensive or complicated tools to set up an enlarger to give high quality images, especially if - like me - they don't have a professional-level enlarger. There's nothing original in the following, but for the sake of balance and for beginners I think it's worth spelling out a pragmatic cost-free approach.

My reasoning is as follows. Your print is going to be judged by human eyes, not with a grain-focuser, or a magnifying glass. For instance, if I make a 16x12 print, it is likely to be viewed at 4 or 5 feet. So if the enlarger is set up to deliver what appears sharp when viewed at a mere 12 inches from the easel, it is utterly pointless striving for more precise alignment, even if biting sharpness or texture is the whole point of the image. A few people (mostly other photographers) may study your photo at the closest distance the human eye can focus (12-14 inches), but no-one is going to bring a magnifier to your exhibition. This is not sloppiness, you can still be super-critical, but use your eyes to do it.

But it's difficult to judge sharpness from most negatives under the enlarger. You could focus on the grain of the image, but affordable grain focusers don't work near the edges of the projected image, and it's hard to assimilate what is happening across the field by looking successively at tiny parts of it. So a test negative is a pragmatic option, but you really don't need anything fancy. Take a piece of fully exposed and developed film (e.g. from the film leader if you use 35mm) and using the tip of a sharp blade and a straight edge, scratch a grid of lines on the emulsion side. The grid doesn't need to be neat, but the scratched lines do need to be quite thin, and the grid must extend across the whole image area. If you have got the lines too thick or too thin, you will recognise that when you try it, and you can just do it again on another bit of film.

To give yourself the best start, ensure that your enlarger baseboard or bench is horizontal front-to-back and side-to-side. Use any spirit level here, even the one in your phone; but when it reads 'level', reverse the device to check that it says the same thing in both orientations! Then check that the easel placed on the baseboard is also level. If not, stick pieces of sheet rubber or cork under its feet until it is level. These simple checks are perfectly adequate on this side of the enlarger lens.

As far as is possible, check that the enlarger column is also now vertical. If the column is angled forward, that may be impossible. But again, as deviations here affect the less critical part of the projection path, stopping down the lens should mask all but the worst faults. My enlarger column stands straight, but it sagged forward when the head was raised, so I braced the top of the column to the wall (with an adjustment in case of tectonic plate movements).

Now the critical part, the relationship between the lens and the negative. Place an old, flat print of the largest size you intend to make in the easel, emulsion side down: the back side makes a great viewing surface. With any random negative in place, raise the enlarger head so that the image area just covers the paper. Now substitute the scratched test negative, open the lens to full aperture, turn out all other lights, and study the projected image. Use the focus knob to get the lines in the centre of the grid sharp. You will easily notice if all the edges and corners are less sharp than the centre. That could be an issue of film flatness; or possibly a mediocre enlarger lens, and it's fairly obvious what to do about those issues. But if one edge of the grid is sharp and the opposite edge is not, the negative and lens are very likely not parallel. Unless the enlarger is a fancy one with some means of adjusting the lens plane, you will have to shim the negative carrier. As a temporary measure, slip a small strip of thin card (e.g. cut from a cornflake packet) under one side of it. Maybe you will need 2 or 3 thicknesses of card. Mine has 2 (Kelloggs), now glued in place after a trial period. It's worth taking time over this, but at worst it may take you 30 minutes of experiment to satisfy yourself that everything is now sharp (plus a few weeks of printing before you realise you may as well glue the shims in place). Just beware of negative 'popping' if you leave the enlarger on for more than a few minutes - do the job in short spells allowing the negative to cool in between, and apply the same principle when you print.

You should have no need to do this procedure more than once, unless you move house. I have checked mine periodically over several years, and have not needed to change anything.

 

[DREW WILEY]

More nonsense stereotypes. I've displayed quite a few big prints, and if the detail is there, people will approach just as close as they can to examine it. 12X16 is comparatively tiny. Are they supposed to use binoculars to view that, rather than walk up close? "Normal viewing distance" is largely a useless myth unless you're selecting the size of print type in a book, or the size of content on a highway billboard.

And by "affordable grain focusers" you apparently mean junky ones. And here is where logic falls apart. Lots of photographers will spend hundreds or even thousands of dollars for yet another camera body or tempting lens they don't even really need, but then squirm at the thought of buying decent darkroom accessories. But one is only a good as their weakest link. And if you think just any spirit level is actually level, just how many of them have you ever checked?

Trying to achieve critical focus via just stopping down more is a lazy cop out, and has distinct disadvantages.

Hydroscopic cornflake box shims? - now that does sound corny. Even the average kitchen garbage can holds better shim alternatives than that. And if negative are capable of "popping", it means you don't have an adequate carrier to begin with. How is ANY of this "scientific"? I guess your idea of an "ordinary" enlarger is one made of cardboard itself, that cost less than a recycled old tire. Never mind - anyone that cheap when it comes to choice of darkroom equipment probably can't afford film anyway.

 

[snusmumriken]

More nonsense stereotypes. I've displayed quite a few big prints, and if the detail is there, people will approach just as close as they can to examine it. 12X16 is comparatively tiny. Are they supposed to use binoculars to view that, rather than walk up close? "Normal viewing distance" is largely a useless myth unless you're selecting the size of print type in a book, or the size of content on a highway billboard.

And by "affordable grain focusers" you apparently mean junky ones. And here is where logical falls apart. Lots of photographers will spend hundreds or even thousands of dollars for yet another camera body or tempting lens they don't even really need, but then squirm at the thought of buying decent darkroom accessories. But one is only a good as their weakest link. And if you think just any spirit level is actually level, just how many of them have you ever checked?

Trying to achieve critical focus via just stopping down more is a lazy cop out, and has distinct disadvantages.

Hydroscopic cornflake box shims? - not that does sound corny. Even the average kitchen garbage can holds better shim alternatives than that. And if negative are capable of "popping", it means you don't have an adequate carrier to begin with. How is ANY of this "scientific"? I guess your idea of an "ordinary" enlarger is one made of cardboard itself, that cost less than a recycled old tire. Never mind - anyone that cheap when it comes to choice of darkroom equipment probably can't afford film anyway.

You have evidently read but not comprehended my post, because you are railing against things I have not said. To take your first paragraph as an example: as I said, whatever size a print is, your audience cannot view it closer than you can view it on your enlarger baseboard (or perhaps darkroom wall in your case), unless they use a magnifier. I use reading glasses, hence my closest sharp focussing distance is about 11 inches. For most people without glasses, it's in the 12-14 inches range. Normal viewing distance doesn't come into it.

 

[DREW WILEY]

Whatever. It's still hard to salvage much that's actually helpful in your post. Sure shims can be necessary; and a scratched negative can make it easier to adjust focus or alignment. But just how ridiculously penurious does all this need to be?

Even if someone can't afford a serious $50 or $75 torpedo level, any self-respecting hardware store would allow them to briefly borrow one of those to check cheaper levels, and find that one out of twenty or so $10 one worthy of their intended application.

 

[snusmumriken]

Whatever. It's still hard to salvage much that's actually helpful in your post.

Thank you. I am content to let future readers be the judge of that.

 

[DREW WILEY]

Well, some people, including myself sometimes, like to find the most cost-effective simple means to juggle practical problems. But that can also sometimes become a long-term dependable cure if one is thoughtful. For example, to shim an older Omega enlarger chassis level, I reached for a very cheap clip of "feeler gages" - essentially an assortment of shims, in this case, too cheap for any serious machinist or auto mechanic, but when clipped off with a tinsnip, ideal and permanent for my purpose. Of course, there is no need for that with precise column enlargers like Durst commercial ones, which have built-in adjustments. But it potentially comes into play with leaning column more ordinary units. You might say I have a phD in Jerryrigging. Doing things affordably doesn't necessarily mean they aren't done well. But one often needs to think "outside the box".

 

[EHM2]

Unlike photography of subjects where there is a lot of depth and therefore errors in best focus will
usually result in focus on something you are pointing at, enlargement involves copying one flat subject
(negative)to another (print),and should these two planes not be parallel, grievous softness will ensue
(don’t say Scheimpflug!).
You are already in trouble if you cannot get the four edges of your negative masking edges of your
empty negative carrier in simultaneous focus at the target level of magnification and with the lens
stopped to working aperture. You will see the consequence in your prints and that will bug you. I am
assuming that you care about sharp. Is your lens flat field? If not, you have even more problems.
Before you give up you should, with very modest equipment, be able to get a 4x enlargement without
epic effort. Unfortunately, that limits you for example to a 4x6 inch print from your 35mm negative, and
most workers aspire to bigger.
So there is the quantification of necessary degree of alignment, much discussed already, and tools,
materials and procedures for achieving your lofty goal. Without discussing the math part, left in better
hands than mine, I would like to point out a few things I have tried on multiple enlargers over a
sustained period of time. Much of it is reiteration, but I have some specific suggestions that may
interest some.
Everything is easier if you start from flat; your baseboard is probably flat enough for use, but it not
usually flat enough for the tools you will use. The tools I use for everything are a six inch machinist level
and a Versalab laser alignment tool. Yes they are expensive, but you will use them more than once, in
different capacities, they retain resale value, and, most importantly, they free your hands up to make
adjustments “live” and allow you to work with the lights on.
The machinist level is probably too sensitive to read reliably on many baseboard materials, often no
more than a thin piece of melamine inaccurately glued to a mishmash of poor quality wood chips or dust
and hygroscopic glue or inaccurately planed plywood of unstable wood species.

So level your easel. Yes, you can use a cheap level if you want to telegraph your error up through the
chain.
Next, level your negative stage to the easel with glass plate supplied by Versalab or your enlarger’s glass
carrier and the Versalab on the easel, and, of course, no lens. I often use adhesive paper labels on the three (or one) upper
glass surfaces to suppress multiple laser reflections. Very easy (with built in adjustment screws) on a
Beseler 45M2 or later; more difficult on the two Saunders enlargers I used. For the latter you have to
shim the column. In fact for these I have a specific recommendation- a Small Parts Plastic Shim
assortment, 5x20 inches,0.0005”-0.03 “. These are color coded, dimensionally stable, easy to cut with a
clean edge using scissors and/or a rotary trimmer. Lifetime supply for $40. I used to use brass when it
was cheaper and I had access to a lab grade shear, but with my present cutting tools I get a serrated,
work hardened edge on the metal cuts that defeat me before I start. For the Omega D series, you will
hopefully just have to fiddle with your wall brace. Do not let the presence of die cast and machined
metal components lull you into thinking that the manufacturer of your enlarger took care of this, even if
it is new. I was perhaps lucky, but if you level the enlarger head to the easel at the top of its travel, it is
usually good enough. Also, this is where the laser is particularly apt.
Finally, the most critical alignment must then be done - that of the lens to the negative stage. Once
done, it is usually stable upon adjustment for focus with most enlarger head designs. On my Beseler I
mounted the lens on the adjustable double lens board foam sandwich provided by Zone VI (I’m that old), later Delta
made one; not too hard to find or fabricate with hacksaw, drill and tap. My addendum to this is to
consider using four adjustment screws instead of three, a la old optical transits. Your adjustment with
four screws in a square pattern will be a little fiddly but will match up with the geometry of the
construction of the enlarger head. These lens boards are ideal if you have one and you can still focus
your lens with the additional thickness of the modified board (at high enlargement). For the laser reflector I used a good
quality deep blue filter on the lens with a paper tape label attached on its upper surface.
Beseler claimed with their later 4x5 enlargers that you could do this alignment without additional hardware, but I
didn’t find it to be fun. Saunders 4x5 the same claim. The tiny Saunders lens board does not lend itself
to adjustable modification, and this is where the dreaded shims return for consideration. That said I
have had at least one enlarger (a Saunders medium format) that was almost impossible to align and
then changed with focus. I found that the focus stages of Omega and Beseler 4x5’s, where the parts
traverse a machined, dovetailed piece of metal, to be more stably aligned wrt to focusing.