Enlarging - Depth of field? Slightly crooked baseboard

zischga · Dec 30, 2019

Hi all,

Today I built myself a baseboard for my Durst M605 enlarger, because the seller of the enlarger did not have the original baseboard anymore.
I used 2 3/4'' plywood screwed together, unfortunately it is not perfectly flat.
It is not warped a lot, maybe 3mm over the whole length of the baseboard.

Does anyone know, if these will have an effect on the sharpness of my prints?
I will probably print 8x10'' with f8 mostly and do not plan to use the open aperture.

Now I'm wondering, if this will still be within the Depth of field, using aperture f8.

Advice would be greatly appreciated.

Ian C · Dec 30, 2019

A baseboard discrepancy of 3mm over its length will have no discernable effect in the situation you’ve described.

ic-racer · Dec 30, 2019

This slight modification of the view camera focusing equation applies to enlargers: (equation #38 in http://www.largeformatphotography.in...DoFinDepth.pdf):

F Number about equal to ( 20 / (1 + m) sqrt(dv))

m = magnification
dv = focusing leeway on the baseboard, represented as the distance on the enlarger column between good focus on the highest and lowest portions. (if 'dv' is zero then your negative is not curved or enlarger/baseboard/easel is not askew)
20 = my personal constant for circle of confusion about 0.15mm on the print

Bikerider · Dec 31, 2019

If you can get hold of a piece of kitchen worktop board, the central core is made up from wood chippings bonded together with resin with heat under pressure and is finished perfectly flat. It is also heavy! This will assist with the stability of the enlarger, because compare to the material I suggest, plywood is quite lightweight. I don't know where you live, if you have small stores that sell 'off cuts' that is where I got mine. A full sheet is very expensive but I only paid £3 (4$) for a piece 600mm x 600mm. It is easy to drill and fit fixing screws or bolts

DREW WILEY · Dec 31, 2019

Either shim your paper frame to make it level or make a better baseboard. No need for math or trying to drive with a deflated tire.

ic-racer · Dec 31, 2019

Does anyone know, if these will have an effect on the sharpness of my prints?

Math is the only way to answer the question. The earth's gravitational pull (level/plumb) is not in the equation.

mshchem · Jan 1, 2020

Start to print. When you have time worry about the baseboard. Don't let this keep you from doing your work,

You will know what to do based on your results.

Vaughn · Jan 1, 2020

Align the enlarger optical system with the baseboard?

koraks · Jan 1, 2020

zischga said:
Does anyone know, if these will have an effect on the sharpness of my prints?
I will probably print 8x10'' with f8 mostly and do not plan to use the open aperture.

That would be sort of on the edge of being a problem for critical sharpness. But obviously it's not ideal. In addition, the effect will compound with all the other imperfections in a real-world situation to make matters worse than they need to be. So as far as I'm concerned this would be undesirable. I'd try to solve it by putting a known-flat, straight & true surface on top of your DIY baseboard. Many options can be thought of; the countertop material mentioned by @Bikerider, a not-too-thin piece of MDF, a piece of high-pressure laminate, etc. etc. Mount it over the current board while making sure it's shimmed in such a way as to be as perfectly aligned as possible to the optical axis.

larfe · Jan 1, 2020

Vaughn said:
Align the enlarger optical system with the baseboard?

How? The column is directly bolted to the board

Vaughn · Jan 1, 2020

Depending on the enlarger, there is usually adjustments that can be made at the head and at the negative platform to make sure everything aligns with the whole plane of the baseboard. I am really only knowledgable about Omega D5XLs ( B&W Condensers and color heads) and Beseler 23CIIs (and a couple 4x5s), as I maintained a bank of each for the university darkroom. But if the plywood is not warped evenly, you'll have no plane to align to anyway. Keep an eye out for a trashed old enlarger getting tossed...it would be nice to replace the plywood with the 'real thing'.

Arklatexian · Jan 1, 2020

zischga said:
Hi all,

Today I built myself a baseboard for my Durst M605 enlarger, because the seller of the enlarger did not have the original baseboard anymore.
I used 2 3/4'' plywood screwed together, unfortunately it is not perfectly flat.
It is not warped a lot, maybe 3mm over the whole length of the baseboard.

Does anyone know, if these will have an effect on the sharpness of my prints?
I will probably print 8x10'' with f8 mostly and do not plan to use the open aperture.

Now I'm wondering, if this will still be within the Depth of field, using aperture f8.

Advice would be greatly appreciated.

I would think that a good magnifier, used for focusing, would show you whether you have a problem or not. One where you focus on the "grain" in the negative. Stopped down to f8, you probably don't have a problem but check it out anyhow.........Regards!

removed account4 · Jan 1, 2020

Bikerider said:
If you can get hold of a piece of kitchen worktop board, the central core is made up from wood chippings bonded together with resin with heat under pressure and is finished perfectly flat. It is also heavy! This will assist with the stability of the enlarger, because compare to the material I suggest, plywood is quite lightweight. I don't know where you live, if you have small stores that sell 'off cuts' that is where I got mine. A full sheet is very expensive but I only paid £3 (4$) for a piece 600mm x 600mm. It is easy to drill and fit fixing screws or bolts

THIS ^^^^
Formica countertop is great and inexpensive ( and level ) --

MNM · Jan 1, 2020

Arklatexian said:
I would think that a good magnifier, used for focusing, would show you whether you have a problem or not. One where you focus on the "grain" in the negative. Stopped down to f8, you probably don't have a problem but check it out anyhow.........Regards!

That was the conclusion I came to. I checked with the lens wide open figuring it would make a misalignment easier to spot. Was fine at 8x10. If it was OK wide open, then stopped down is certainly not an issue.

RalphLambrecht · Jan 1, 2020

zischga said:
Hi all,

Today I built myself a baseboard for my Durst M605 enlarger, because the seller of the enlarger did not have the original baseboard anymore.
I used 2 3/4'' plywood screwed together, unfortunately it is not perfectly flat.
It is not warped a lot, maybe 3mm over the whole length of the baseboard.

Does anyone know, if these will have an effect on the sharpness of my prints?
I will probably print 8x10'' with f8 mostly and do not plan to use the open aperture.

Now I'm wondering, if this will still be within the Depth of field, using aperture f8.

Advice would be greatly appreciated.

I canned you the mathematics if you wish but, You are well within the DOF in your setup nothing to worry about. It's more important that your enlarger is stable and without vibration; wall-mounting is the way to go.

Bikerider · Jan 2, 2020

jnantz said:
THIS ^^^^
Formica countertop is great and inexpensive ( and level ) --

I didn't use the name Formica because I was not sure it was known under that name over the pond. But yes, that is what I have used. In UK it comes in various thicknesses, the piece I have for my LPL 7700 is 40mm thick, consequently heavy but very stable.

removed account4 · Jan 2, 2020

Bikerider said:
I didn't use the name Formica because I was not sure it was known under that name over the pond. But yes, that is what I have used. In UK it comes in various thicknesses, the piece I have for my LPL 7700 is 40mm thick, consequently heavy but very stable.

yeah its great stuff ! and it works great as a deadweight too when one is flattening stuff, or gluing / pasting stuff ( book making ). &c.

Ian Grant · Jan 2, 2020

I'm with other, get a piece of Kitchen top and bolt the bottom column fitting to it. You can get an off-cut cheap as already mentioned and no alignment will be needed. You'll need to add feet or two strips of wood to allow space for then two bolts.

I've not seen much (if any) new Formica in years, this was a material laminated to kitchen tops and also table tops, trays, cutting boards etc. These days much cheaper wrap around plastic/synthetic materials are used instead of Formica, they are thinner and not as hard wearing but fine for a baseboard..

Ian

Jim Jones · Jan 2, 2020

Vaughn said: ↑
Align the enlarger optical system with the baseboard?
Larfe said:
How? The column is directly bolted to the board

Every enlarger I ever used would let me loosen the bolts, slide shims between the column and baseboard, tighten the bolts, and check for alignment. Repeat until the alignment is good.

Ian Grant · Jan 2, 2020

Jim Jones said:
Vaughn said: ↑
Align the enlarger optical system with the baseboard?
Larfe said:
How? The column is directly bolted to the board

Every enlarger I ever used would let me loosen the bolts, slide shims between the column and baseboard, tighten the bolts, and check for alignment. Repeat until the alignment is good.

Normally not need with Durst's I have 4 and they all sit perfectly aligned.

Ian

john_s · Jan 7, 2020

I made a baseboard once and I found that the weight of the enlarger caused a small tilt between the optical plane of the head and the baseboard. I rectified it with some square steel tubing, four pieces, two under the enlarger foot and one at each side of the board, all oriented front-to-back.

Mainecoonmaniac · Jan 7, 2020

I don't think you'll know until you first level your enlarging bench, the the baseboard, next the lens then the negative stage. All should be level and parallel with each other. If the baseboard is warped, it might cause you problems. Stopping down is only a bad fix.

DREW WILEY · Jan 7, 2020

Trying to compensate for a gross adjustment flaw by stopping way down is indeed a "bad fix" - kinda like squinting your eyes at someone you don't like. It worked for Clint Eastwood at least.

larfe · Jan 7, 2020

Jim Jones said:
Vaughn said: ↑
Align the enlarger optical system with the baseboard?
Larfe said:
How? The column is directly bolted to the board

Every enlarger I ever used would let me loosen the bolts, slide shims between the column and baseboard, tighten the bolts, and check for alignment. Repeat until the alignment is good.

Well of course, this is however a rather clunky hit and miss manner of aligning a "precision" machine... same goes for lens stage etc

DREW WILEY · Jan 9, 2020

New baseboards are pretty darn easy to make if you have the right materials. In the meantime, certain temporary solutions have been mentioned. But those are like the advice to drive slow if you have a nearly flat tire. Better to fix the actual problem.

Enlarging - Depth of field? Slightly crooked baseboard

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