Enlarger alignment - again!

[tkamiya]

Hello.... I need to bring up this subject again.

I've studied what's available. There seem to be two types in the market, one being precision levels and the other being laser type. The latter depends on film plane being parallel to the base board, then lens plane being parallel to the baseboard. In other words, the baseboard is the basis of this alignment.

I've been wondering.... The depth of focus is MUCH shallower between film and the lens. The DOF between lens and the lens, not so much so and since my post is not braced, depending on the height of the head, the "tilt" varies affecting this baseboard alignment.

So.... I'd like to critically align the former.

If I get a front surface mirror and a half mirror (50/50), place the front surface mirror in the neg stage and place the half mirror at the lens mount and look in from the bottom, I should see an image of myself and the same repeated over-and-over. Would it be correct to say, if I can make this image concentric, those two planes are exactly parallel? I can get such mirrors cheaply at a surplus outlet, surplusshed.com. This way, my alignment is not dependent upon the baseboard.

I plan to brace my post later but not at this time.

 

[Worker 11811]

There's a guy I know who used to be a technician for Beseler.
His advice to me was to trap a piece of glass in the film gate so that it sticks out the front of the enlarger.

Level the base using a bubble level, use a builder's square to ensure that the frame and enlarging head is plumb, level and square then, finally put the level on the glass plate and level that with respect to everything else.

If you have some test film, either an Air Force Test Target or a piece of SMPTE PA-35 or similar, you cah use that to make your fine adjustments. If you don't have test film, you can use a piece of regular film that you know has good grain all the way to the edges and use that to focus on the grain.

This is how I got my elngarger straightened out and it's been working fine ever since.

 

[glbeas]

I've used that same infinity mirror arrangement, scrubbing a hole in the silvering in the top mirror to do it. I got very good results aligning the neg stage to the baseboard with it but could never figure a good way to make it work to check the lensboard against the neg stage.

 

[Doremus Scudder]

The whole point is to get centers and edges in focus on the baseboard. Parallel is the best way; otherwise you introduce a tiny bit of parallax distortion.

That said, I usually just stretch an eight-point star of thread across the negative carrier (one thread across each diagonal and one each across the straight sides), affixing it under tension to the negative carrier with tape. Then just use a long lens at its widest aperture and tweak enough to get all edges, corners and the center sharp under the Peak grain magnifier. That seems to be well within working parameters, especially when I stop down to working apertures.

Best,

Doremus

www.DoremusScudder.com

 

[Bill Burk]

I like the sound of the threads in the negative carrier - results-oriented.

I use a long piece of glass in the negative carrier and measure from baseboard to glass. When it came time to level the lens, I used a small fish tank on its side (seemed to measure square) and leveled the lens until it touched the glass all at once.

 

[tkamiya]

FISH TANK!

 

[Neal]

Dear tkamiya,

I built myself something very similar to the Zig-align system with a series of 8 diodes, two front surface mirrors and an old pentaprism. It worked well, but once I got my hands on a Versalab laser unit I threw my old setup away. It is so easy to use I check the alignment on a regular basis now. Until you feel that a laser alignment tool is worth the investment, a good level will serve your needs. Keep in mind that you have to align both the lens stage and negative stage to the baseboard. (If that was obvious I apologize but I couldn't quite tell from your post.)

Neal Wydra

 

[tkamiya]

Neal,

Yes, I understand that. I was trying to avoid using baseboard as a reference, but thank you for your reply.

 

[Leigh B]

I was trying to avoid using baseboard as a reference...

Why?

A reference is just that... a reference.

If you set it level to start with, which is easy because it's readily accessible, then set the film holder and lensboard both parallel to it,
they will be parallel to each other, which is what you want.

I think you're making this a whole lot more complicated than it really is.

What level of accuracy are you trying to achieve (in real measurable units, like angular error or inches per foot)?

- Leigh

 

[tkamiya]

Why?

If you look at ANY enlarger, the head hangs over the baseboard by one or two vertical or leaning posts. There's variability in this leaning forward. Also, as the mechanism to slide up and down has some slack, it moves side-to-side as well. It works because we have DOF working for us between head and baseboard. Little bit of "wobble" really doesn't matter that much.

On the other hand, between lens and negative, we don't have as much DOF. Fortunately, the way my enlarger is made, there is very little slack, wobble, slop, etc.

To me, it makes no sense trying to achieve this precise adjustment with not much of forgiveness factor using a reference far away and not as stable. How do I know, as I make adjustments, it didn't slide in one or more ways? In fact, in my previous attempt, this was a problem.

What level of accuracy? Accurate enough for 16x20 enlargement.

 

[Leigh B]

OK. You're missing the meaning of "reference".

If you set A parallel to B, and C parallel to B, then A and C are parallel regardless of what you do with B in the future.

This sets your negative carrier and lensboard parallel, after which you can throw the baseboard overboard if you wish.

- Leigh

 

[tkamiya]

No, no, no....

Set A parallel to C. While trying to make B parallel to C, the whole assembly containing A and B moves.

A and B are on the head assembly suspended via a long metal post using rather lose friction roller. There are all kinds of side wobbles.

Have you done this with yours? I have - and encountered this problem. Loosen 4 screws that hold the neg stage base, and another that is attached to the roller that slide up and down the vertical post, moves the AB assembly enough to make this critical adjustment impossible.

 

[tkamiya]

By the way, I have no intention of debating my methodology. With my enlarger (D2 and DII) this IS a problem. If it isn't a problem with yours, great. It won't work for me.

 

[Leigh B]

No, no, no....

Yes, yes, yes.

I'm afraid you don't understand geometry and trigonometry.

Nothing in my methodology is unique to photography. That technique has been used for aligning precision machinery for over a century. It's standard industry practice.
The attainable accuracy with that technique is orders of magnitude tighter than you could ever achieve with an enlarger.

And yes, I have used it to set up my own enlargers.

In the description I gave in post #11, item B is the baseboard. A is the negative carrier and C the lensboard. You could exchange those if you wish.

If your enlarger doesn't hold the position of the lens stage constant relative to the negative carrier, it's broken and needs to be fixed.

- Leigh

 

[tkamiya]

I don't think so, and I do understand geometry and trigonometry. (but I suck at history)

You set L (lensboard) parallel to B (baseboard). Now, make F (film stage) parallel to B (baseboard)
Now, L // B // F. FINE!

In reality with my D2, L // B is easy. Problem arises when setting F // B. Now, I loosen 4 screws on film stage and tap, tap, tap 4 corners of the stage. Remember L and F is one assembly suspended far above B in loosely coupled carriage system? NOW, L//B is disturbed. I just lost my reference parallel.

Nothing I do from this point mean anything.

 

[Leigh B]

I think you mean "L and F is one assembly"...

OK. Set the negative carrier parallel to the baseboard first, disregarding the lens stage. You should be able to lock that adjustment down against the lamp housing.
BTW, on any four-point mount... use three of the screws to set the adjustment with the fourth fully slack. Snug up the fourth after the adjustment is finalized, without changing it.

Then set the lens stage parallel to the baseboard (or to the negative carrier directly).

How are the lens board adjustments made?

Believe it or not... I really am trying to help.

- Leigh

 

[tkamiya]

Yes, I corrected that. I got confused with all those letters.

Have you ever worked with a D2? This enlarger does NOT give me all the adjustment at all 3 stages. (or 2 rather...) I can lock the whole head assembly but it still won't prevent enough wobble. "Lock" is just a clamp on one side that clamps onto the railing of the post.

Thank you for trying to help but unless you know the limitation and intricacy of my particular enlarger, it's just theory. There IS a reason why I am trying to align film and lens stage. I am working with the limitation of this equipment.

 

[Leigh B]

No, I'm not familiar with any of the Omega enlargers unfortunately.

Good luck with it. Have you considered modifying the head assembly to improve the rigidity? Should be a simple job for a machine shop.

- Leigh

 

[craigclu]

5 years or so back, I impulsively bought a Parallel by Versalab after using the mirror system, Bes-Align, levels, Beseler alignment insert, etc. I wish someone 10 years ago would have taken me by the shoulders and shook me until I agreed to a Versalab and saved me all of the trouble. If you have APO lenses and use relatively open apertures, you need the accuracy and incentive to easily check your alignments often as depth of field won't cover your alignment errors. My enlargers tend to stay aligned quite well but confirmation is easy (and actually done) because of the ease of use.

 

[Bill Burk]

Hi tkamiya,

I use DII.

The lens plane can be moved independently of the film plane.

The lens stage is fixed to two focusing rods. These two rods go through two steel rectangular bars. The steel rectangular bars are held by screws that go into the tapped frame and are locked with cap nuts. First reduce the tension on the friction roller. Then remove the cap nuts. Then loosen the screws. Because the holes in the two steel rectangular bars are drilled oversize - now you can move the lens stage freely.

 

[M. Lointain]

Just do what Craig suggested above and get a laser alignment tool. Save yourself hours of grief and insecurity.