Where it goes wrong in the darkroom? Images printed not sharp enough with new enlarger lens

[DREW WILEY]

Here is why cheap grain focusing devices are sometimes off : Shimmed bases glued on. The thickness of the glue can vary; and sometimes the shim material itself isn't dimensionally stable and can shift in thickness. Second, similar problem with the mirror - there's no guarantee of thickness of the glue, or even the potential for residue back there. Probably not a real front surface mirror either.

 

[Dali]

It's quite easy to mount the lens board incorrectly so that it's slightly tilted. I think this would result in a sharp image through the grain focuser but slightly unsharp prints

I agree.

 

[Lachlan Young]

OK, before this gets any more pointless, here are a few things that should be obvious (but apparently aren't) - if you adjust a Paterson Micro Focus Finder to your eyesight under white light, it is just as accurate as a Peak MK1 (adjusted to eyesight under white light too) - they are capable of getting the grain properly in focus. And this is across more than a dozen random samples of Patersons and more Peak MK1's (in varying states of preservation) than most of you will encounter in your lives. The paper thickness thing is nonsense - if you are getting the image in focus down the magnifier, but it wanders before exposure, the problem is in the head, not on the baseboard - the depth of focus at the baseboard is several times that of a sheet of paper, but not at the neg stage. Backlash from the rack and pinion on the column settling (or the focusing mechanism settling) are much more likely sources of focus error after focusing and before exposure - and nudging an enlarger of the relative lightness of build of the M605 during or between exposures is another potential cause of unsharpness, especially as you cannot guarantee it returning to the point it was beforehand (wall braces for enlarger columns don't exist for the good of people's health) - i.e. if you dial in a different grade to burn highlights, you are potentially knocking the head position out by just enough to affect ultimate sharpness - which may be less than most of you are thinking, but clearly noticeable when compared to working on a machine that isn't affected by accidentally bumping the column while burning-in.

And believe you me, you would really see a visible effect from a slightly tilted lens board without any comparison being necessary, it just would not be over the whole image - and isn't what the OP seems to be talking about.

 

[DREW WILEY]

... or a baseboard or easel sharp in the center, but otherwise misaligned.

Lachlan - a Peak Critical Focus Magnifier is in a whole other league. They really do make a difference. Plus the tilting head allows one to inspect the grain at the corners of the field, not just the central area.

 

[BMbikerider]

OK, before this gets any more pointless, here are a few things that should be obvious (but apparently aren't) - if you adjust a Paterson Micro Focus Finder to your eyesight under white light, it is just as accurate as a Peak MK1 (adjusted to eyesight under white light too) - they are capable of getting the grain properly in focus. And this is across more than a dozen random samples of Patersons and more Peak MK1's (in varying states of preservation) than most of you will encounter in your lives. The paper thickness thing is nonsense - if you are getting the image in focus down the magnifier, but it wanders before exposure, the problem is in the head, not on the baseboard - the depth of focus at the baseboard is several times that of a sheet of paper, but not at the neg stage. Backlash from the rack and pinion on the column settling (or the focusing mechanism settling) are much more likely sources of focus error after focusing and before exposure - and nudging an enlarger of the relative lightness of build of the M605 during or between exposures is another potential cause of unsharpness, especially as you cannot guarantee it returning to the point it was beforehand (wall braces for enlarger columns don't exist for the good of people's health) - i.e. if you dial in a different grade to burn highlights, you are potentially knocking the head position out by just enough to affect ultimate sharpness - which may be less than most of you are thinking, but clearly noticeable when compared to working on a machine that isn't affected by accidentally bumping the column while burning-in.

And believe you me, you would really see a visible effect from a slightly tilted lens board without any comparison being necessary, it just would not be over the whole image - and isn't what the OP seems to be talking about.

About the only post on here that actually makes sense.

There are so many ideas that to be honest some have lost the plot or are scrabbling about to put an idea forward.

My peak focus finder and my tall Paterson finder agree perfectly when looking at various parts of a negative. I never ever had a problem with either except the Peak it is too low to use with a big enlargement. My old joints won't let me dislocate my shoulders to adjust the focus. All enlargers which have a tungsten or halogen bulb will generate heat and with long exposures this will cause the film to 'pop' by a tiny amount, probably less than .25mm but that is enough to knock the focus out, but stopping the lens down by 2 or 3 clicks will allow the d-of-f to compensate.

 

[xkaes]

I believe you do have to adjust the eyepiece of a Paterson finder to your own vision.

Thank you -- what a concept.

 

[xkaes]

Obviously space aliens. Let's come down to Earth.

 

[DREW WILEY]

I consider the whole discussion futile once glassless carriers come into play. But even doing that right doesn't preclude other potential hurdles. Many easels don't even hold the paper flat.

 

[xkaes]

"Help me, Obi-Wan Kenobi. You're my only hope."​

 

[eli griggs]

I always use the same paper I'm printing on, different runs are OK, but it's always best if you can use a trashed sheet, 'raw' or developed print, even if its only a smaller than full sheet, square that fits the foot on your grain focus device or devices, just put neat notations on each so you know what's what.

Squaring up your table, enlarger, film holder apature, head on rack, and tighten or re-tighten loose joints ( the heating and cooling down of light chambers induces movement that basically, can 'unlock' threaded fasteners) and make sure your easel is also square to the overall squared up enlarger.

It also would matter if only part of a grain focusing padded foot remains on its device.

Replace it or remove it entirely and level it, either works.

An analogy 'dial' type, 360 degree compass device, that is held in the vertical, is my choice of leveling tools, though my Burton compass has this feature built in, for measuring, for example, the hight of trees, and is adjustable and much smaller, so it'll fit better in certain areas of an enlarger.

Lastly, make sure your enlargers head is not tilted left or right, a tiny adjustable wrench is handy for adjustment locks/nuts or bolts.

If such a swing is involved, it's better found out once the table/baseboards are level.

Remember, to check for square in four directions, at each adjustment point and to recheck everything when finished and ready to print, and be aware of any changes over time.

Starting out on level 'ground' is always fundamental to any process or activity and, uneven results with your grain focusing device, can not be properly diagnosed if it's not enabled to do the job it was/is designed for.

Cheers

 

[Lachlan Young]

... or a baseboard or easel sharp in the center, but otherwise misaligned.

Lachlan - a Peak Critical Focus Magnifier is in a whole other league. They really do make a difference. Plus the tilting head allows one to inspect the grain at the corners of the field, not just the central area.

AKA the Peak MK1 that I was referring to. Yes, they have some benefits for specific purposes, but within the angle that the Paterson works in, they are no more or less accurate than each other, if adjusted properly to your eyes. The MK 2 & 3 Peaks are essentially the same idea as the Paterson. The point is that it isn't the accuracy of the focus magnifier that's the problem here.

 

[Lachlan Young]

I always use the same paper I'm printing on, different runs are OK, but it's always best if you can use a trashed sheet, 'raw' or developed print, even if its only a smaller than full sheet, square that fits the foot on your grain focus device or devices, just put neat notations on each so you know what's what.

This will make no difference to accuracy of focus. If it did, every focus magnifier would have been designed and tooled in such a way as to compensate for it. The people who designed them knew what they were doing, unlike an alarming percentage of the end users.

 

[pentaxuser]

This will make no difference to accuracy of focus. If it did, every focus magnifier would have been designed and tooled in such a way as to compensate for it. The people who designed them knew what they were doing, unlike an alarming percentage of the end users.

Good point. Didn't someone, Greg Davis maybe, demonstrate in a video that a sheet of the same thickness or no sheet makes no difference in fact isn't the margin of error much greater than a sheet of paper

However such ideas and others will never die on Photrio and will continue to be cited



pentaxuser

 

[Bill Burk]

Good point. Didn't someone, Greg Davis maybe, demonstrate in a video that a sheet of the same thickness or no sheet makes no difference in fact isn't the margin of error much greater than a sheet of paper

However such ideas and others will never die on Photrio and will continue to be cited



pentaxuser

You might have been one of my 59 views...



I went down a rabbit hole where I proved you do not need to use a scrap of your brand of print paper under the grain focuser.

Then I attached a dial caliper to the negative carrier stage and found that I can measure the depth of focus at the negative carrier in thousandths. And I can split the difference between top down/bottom up focus position. Then I can tell the difference between whether or not that sheet of print paper is under the grain focuser... and it amounts to 10% of the focus "depth of field".

Now I don't like systematically using up 10% of my tolerance in focus when printing, so I have gone back to putting that piece of paper under the grain focuser.

 

[Ian C]

Post #103 is sensible. The statement “the depth of focus at the baseboard is several times that of a sheet of paper” is correct in its intent but is an understatement.

Here is an example:

In a typical enlarging setup using a 50 mm lens at f/5.6 and 9.3X magnification to make a borderless 8” x 10” print from a 35 mm negative and assuming a circle of confusion diameter of 0.029 mm for the negative, the depth of field about the negative is 0.36 mm. The depth of focus about the image plane is 31.4 mm. Roughly half of this field is above and half below the image plane.

The thickness of a sheet of Ilford FB paper that I measured is 0.012” (about 0.30 mm) thick. Thus, the total DOF about the image in the given example is approximately equal to the thickness of 103 sheets. RC paper is somewhat thinner, usually about 0.009” or 0.23 mm, so the DOF would equal about 137 sheets of RC paper.

In my enlarging, I place a sheet of scrap photo paper upside-down on the easel. This is done to size the image, and to compose and rough focus the projection. Then I place my grain focuser atop the focusing sheet. This is done for the above reasons and the fact that it’s much easier to see the image when it is projected upon a white, reflective surface. You can attain an even more reflective focusing/composing surface by fixing and washing an unexposed, undeveloped sheet of glossy paper and use the emulsion side for composing and focusing. It’s considerably more reflective than the back of the paper.

The thickness of the paper is irrelevant in grain focusing. I’ve calculated the “error” in failing to use a sheet of paper under grain magnifier. It exists but is pointlessly small.

I own and use the following grain magnifiers:

1. French made Thomas Instruments Scoponet

2. Paterson Micro Focus Finder

3. Paterson Major Focus Finder

4. Bestwell Micro Sight

5. Peak 2020 Model II

6. Peak 2000 Model I

I did a comparison in November 2023 using the above list of focusers. I used a well-made Kodak T-Max 100 35 mm negative in a glass carrier in my Beseler 23CII with condenser head and grain focused the image sized for an 8” x 10” print using a 50/2.8N EL Nikkor lens at f/5.6. The grain was nicely resolved in the eyepiece of the Bestwell Micro Sight.

I did not touch the focus control for the remainder of the test. I tried each instrument in turn and was pleased to see the grain crisply resolved in each case. I didn’t see any discrepancy in the point of best focus of the enlarger among this collection of grain magnifiers.

Addendum (December 8, 2023)

With the 0.012” (0.30 mm) thick sheet of paper under the focuser, the distance from the negative to the first nodal point of the lens is 55.3763mm.

If we omit the sheet of paper, the distance is 55.3728 mm, an error of 0.0035 mm.

This distance determines the focus of the projection. The difference is beyond trivial.

 

[warden]

i.e. if you dial in a different grade to burn highlights, you are potentially knocking the head position out by just enough to affect ultimate sharpness - which may be less than most of you are thinking, but clearly noticeable when compared to working on a machine that isn't affected by accidentally bumping the column while burning-in.

While split grade printing I'm always holding my breath while carefully replacing contrast filters on my Beseler 23. I see that time as the greatest chance for focus mishaps, and also the best reason for not engaging in split grade printing in the first place, but people in those debates generally don't mention it. Still I like the split grade approach so I'm as careful as I can be.

Now I don't like systematically using up 10% of my tolerance in focus when printing, so I have gone back to putting that piece of paper under the grain focuser.

I use the paper method when focusing as well. First for the tolerance issue you correctly raise, but also the bright white paper is easier to focus on than the easel.

Where could the loss of sharpness be located ,despite having a very good lens on my enlarger??

Ok listen up because I'm only going to say this once: first you need to rent a helicopter and scout for land for your new darkroom...

 

[pentaxuser]

Posts #114 and#115 seem to point to diametrically opposed conclusions. In one the focus margin is extremely limited and in the other it is so large as to make the need for a piece of paper laughable

So which is it? Could it be that the two parties are measuring different things and on the basis of what they are measuring both are right within the confines of what their measurements are telling them?

What really counts from a practical point of view for all of us is whether the difference between a piece of paper or no piece of paper makes a clear and obvious difference to the perceived sharpness of the print

We never seem to attempt a discussion to see if a meaningful and practical conclusion that a newcomer can use, can be reached.

Does that matter? Well not to me after about 18 years of printing and being a member here but I feel sorry for any newcomer who seeks helpful answers when a focus problem arises and he/she finds him/herself disappearing down a rabbit hole

Incidentally Bill I looked at your video of under a minute but I wasn't sure of what I was looking at with no verbal explanation of what I was looking at or how to relate what I was seeing to what your post said

Not trying to be rude about it but simply honest. Is there any way you could expand on it

Thanks

pentaxuser

 

[Andrew O'Neill]

If not already done, I would focus the image as best as I can unaided, on the back of scrap paper that you use. Then I stop down to my optimum aperture, which is two stops (tested this years ago with Nikkor 150). Make a print and compare it with the grain focussed print.

 

[DREW WILEY]

Lachlan - my Thomas Scoponet was so far off that I threw it in the trash can. The shims below the base and underneath the mirror were both susceptible to humidity swelling. The assumption that manufacturers know what they are doing is naive. Some mass produced items never are quality control tested prior to distribution. You get what you pay for. Precision accessories inherently cost more to make to begin with.

As far as paper thickness being a factor - again, generalizations do not apply. The shorter the focal length of enlarging lens, the more thickness and spacing differences factor, just like in a camera. Some papers are thicker than others. And, for gosh sakes, take most of the web video jockeys with a grain of salt. Their methodology is often sloppy as heck.

 

[Bill Burk]

The video shows a set of prints one frame per print made at a locked focus setting. The jig is a speed-ez-el on top of a 4x5 film box containing all the paper for the test (with the bottom of the box upside-down so the box never closes all the way). For each sheet taken out of the box, the easel goes down the thickness of the sheet.

It’s best if you download the video so you can swipe back and forth and see the “focus” come in and out.

It’s about a 5/8 inch stack of prints. They are all pretty good. I don’t remember exactly but it’s something like 5 sheets each side that look bad, but only about 20 sheets in the middle are as good as it gets.

For that interpretation, if putting the sheet under the grain focuser gives perfect focus, omitting the sheet throws the focus off from the “middle of best” by 1 sheet out of 20. That one sheet amounts to an error of 5% of tolerance.

Insignificant but measurable. I’m using a dial caliper these days. Focus up, move dial to zero. Focus down, read the dial. Move focus to the midpoint.

Grain focuser on the scrap sheet of paper.

Including the sheet is insignificant, but it’s effortless to be measurably more precise.

So I include it.

 

[pentaxuser]

Thanks Bill That would seem to fit with my theory that reconciles your explanation and conclusion with the conclusion drawn by the poster immediately prior to your post

pentaxuser

 

[Don_ih]

There's nothing wrong with focusing with a piece of paper in the easel. It's virtually impossible that it could matter, though, No paper is actually thick enough to make a difference, and no enlarger lens has a large enough aperture to make a difference. Maybe if you decide to put that otherwise useless Canon 50 0.95 ltm lens on your enlarger, you'd notice something.

I'm afraid the answer to this entire thread is likely that the guy's negatives are fuzzy.

 

[silvercloud2323]

When you find a solution please post it here. We will be interested to hear the results.

ok

Jus a few questions and thoughts to consider (but not necessarily the cause of your problem):

If, in any case, there is an Anti Newton glass in the negative carrier, is it mounted on top, and not below?
If, in any case, it is a glassless negative carrier, does the negative is held flat, and not 'bulged' [convex (I suppose I don't know the correct word in English)]?
Is possible that the negative is bulging (plopping?), after focussing or during exposure, due to temperature fluctuations caused by the heat of the enlarger's lamp?
Are the negative carrier plane, the lens mount plane and the paper/easel plane parallel?

Hello

It was on Baryta paper that i am now printing for the first time. I saw that the paper was slightly curved on the easel.

About planeness of negative carrier , lens mount and easel. Do you mean alignment
I do think they are aligned. When i check with focus magnifier left and right side are sharp.

Btw.; Ben jij van Belgie..?

 

[silvercloud2323]

Some good suggestions above.


Here's my two pennorth.

As you have access to another darkroom, would it be possible to try your lens on the enlarger there that produced good results?

Has the negative been placed in the holder the correct way up? That is glossy side up.

Also, when I started out, I read in a few books that the red swing filter could be used to make the exposure.
The method was with the filter in, switch the enlarger on, keeping an eye on the stop clock swing the red filter out of the light path, then when the time was up swing the filter back in to stop the exposure. A better cause of vibration in the enlarger column would be hard to find.

Good luck in your quest. Some here should hit on the solution for you.

As you have access to another darkroom, would it be possible to try your lens on the enlarger there that produced good results?
Yess i will try to attach that other lens to my DurstM605

 

[Sirius Glass]

There's nothing wrong with focusing with a piece of paper in the easel. It's virtually impossible that it could matter, though, No paper is actually thick enough to make a difference, and no enlarger lens has a large enough aperture to make a difference. Maybe if you decide to put that otherwise useless Canon 50 0.95 ltm lens on your enlarger, you'd notice something.

I'm afraid the answer to this entire thread is likely that the guy's negatives are fuzzy.

Even though I know that the thickness of the paper should not matter, I still use it as part of my process. It turns out to be useful for notes if I ever want to write something down.