I have watched videos on all kind of stuff. Who knows which ones are true. Take the History Channel for example. Did you know aliens built the pyramids?
Using grains focuser with or without paper on the easel
-
A
- Thread starter Mainecoonmaniac
- Start date
Recent Classifieds
-
For Sale FS: Linhof Recessed lens board
- Started by dirkfletcher
-
For Sale Leica M4-2
- Started by chriscrawfordphoto
-
For Sale FS: Toyo Sliding Back for 4x5 Graflok
- Started by B.S.Kumar
Forum statistics
I have watched videos on all kind of stuff. Who knows which ones are true. Take the History Channel for example. Did you know aliens built the pyramids?
probably best if you are kept away from videos if thats your level of discrimination
The mentalité that holds Adams' words on technique to be somehow inerrant is a big (and persistent) problem. In a reasonable world, three independent tests that disprove his statement should be enough to dismiss it completely.
Is there some individual or organization that vets the accuracy of YouTube videos, because it pretty much seems to me that the only requirements are that you have a video camera (or cellphone) and that you know how to upload. I uploaded a video once. I think it was in 2014. It may still be up. Everything in the video is true. Trust me.
Last edited:
I am going to go with Bill's depth of field calculations. I can't tell anything from Bill's or Greg's videos. They say they can't see a difference, but really who knows. Maybe they need a checkup with their opthamologist. Never seen or read about ic-racers test. If it were a life or death decision, and I didn't have Bill's depth of field calculations at hand, I would go with Ansel's opinion. I have never seen any of Bill's or Greg's work up close and personal. It may all be out of focus. I have seen more than a few museum and gallery exhibits where I thought the photographers needed to work on their technique. Besides, I haven't got time to test everything. Have you gotten around to doing that test I suggested about putting your film in backwards?
Last edited:
Thinking more about this question, I concluded that a drawing might better convey what is happening, in comparing the ideal focus with starting off a paper thickness low (no paper on easel). So I made this drawing...
- On it, I start with a blue line representing 'ideal focus'.which is based upon paper on the easel. Using Bill's recent test results, we find a grouping of stack thicknesses falling on either side of 'ideal', represented by the Group A blue dots. The dots represented all the test samples that could not be distinguished as 'out of focus' either by naked eye or under grain focus magnification (10X) Note that only ONE sample was exactly at 'ideal focus' (which was the center of Bill's test stack). Only those sheets which were 'acceptably in focus' are shown in the grouping; 'out of fucus' are excluded from the grouping.
- The pink line represents one paper thickness (bare easel), The grouping of focus error is exactly the same as seen in Group A, for discussion purposes; but they are centered about the pink line Irather than centered about the 'ideal focus' (blue) line.
The distribution of the pink Group B deviates farther from 'ideal focus' at the lower end of the grouping, as there is a one-sheet inherent 'error' built into the results. (It is accepted that there is a range of undiscernable focus error, and our attempts will generally fall within that zone, centered around 'ideal.')
So would it not make sense to start at the 'ideal focus' level, rather than starting with one sheet error (bare easel)?!
Last edited:
yes there is; this site - bill and ic-racer have peer reviewed it.
I wouldn't label it "Ideal Focus", but rather "Paper-focus", since the other is labeled "No-paper focus". They are apparently both "ideal" when one looks at the indistinguishable results on a print.
(I'm a paper-focus man myself, not that it matters.)
I like your drawing, btw, which is a good way to look at the problem.
Fair point.
MattKing
Moderator
And how do you know that you can ever determine (i.e. actually see) which focus is ideal, and which ones are not ideal.
You can assume that the grains focuser accurately positions the image in relation to the image at the paper itself, and that assumption is a reasonable one, but it still is an assumption, which might very well be off slightly.
The "system" (enlarger plus grains focuser plus visual acuity) doesn't permit us to accurately determine where the range limits of your diagram are. In order for the system to do so, it would have to be accurate enough to permit us to see the effect of the sheet of paper.
As warden posted, both with and without paper is equally ideal.
So insert the paper if you like inserting the paper (or not) and use the grains focuser to maximize the accuracy of focus, within the limits that the "system" permits.
The drawing was entirely a conceptual model for discussion purposes. The paper plane is considered the 'ideal' level since the emulsion coated on the paper is the image formation location. Given the very thin thickness of the emulsion (one paper spec states a thickness of approximately 245 µm), it did not really need to be factored into the discussion, especially when 0.070" range of undetectable error has been determined in Bill's test
Last edited:
Certainly, if your concept of "peer review" is two (or three if you include ic-racer whose work to my knowledge no one here has seen) ran some experiments and say they don't see a difference.
Look, I am not saying it makes any difference whether you put paper under your grain focuser or not. What I am saying is that, without Bill's depth of field calculation, Bill and Greg are just a couple of photographers on the internet who have done some tests and, in Greg's case he can't see any difference, and in Bill's case he can see a difference, but only outside the range of a single sheet of paper. If you would like to accept Bill's and Greg's observations as proof positive, you are certainly welcome to do so. They have my gratitude for running their own tests and posting their observations.
And now for the obligatory anecdote:
I remember in my high school physics class about 50 years ago, we did these experiments which involved swinging around some metal balls on strings to determine something or other having to do with acceleration, and all three of us at my table. swinging our respective balls around, came up with the same number (more or less since we were using slide rules). So we slapped each other on the back and congratulated each other for proving without a shadow of a doubt that the number was whatever the number was, and I guess you would say we peer reviewed each others' work. Then the teacher ran the experiment and came up with a different number, which so happened to match the number in one of Newton's laws of motion or gravity or whatever. To the best of my knowledge, scientists are still using Newton's number and getting pretty good results. I am reasonably certain that if NASA had used our number, Apollo 11 would be well on its way to Alpha Centauri by now. On the other hand, it is also possible that NASA did use our number, and that is why they had to fake the moon landing.
I was thinking that when scientists invent time travel, maybe I could travel back in time with my cellphone to my high school physics classroom, and make a video of me and my friends conducting our experiments and announcing our conclusion, and then I could travel back to the present and post it on YouTube. Your doppelgänger over on the physics forum might even claim that our peer reviewed experiments proved that our number, rather than Newton’s number, was the correct number. Wouldn't that be hilarious.
Last edited:
- Joined
- Feb 9, 2010
- Messages
- 9,308
- Format
- 4x5 Format
I’ve cut, punched and numbered about 50 sheets for the next test.
Next thing I need to do is make a print for BPX 37, I am going to select a high contrast, sharp 35mm negative with fine detail in the middle. Once I get a good print to send out, then I will use the same negative and settings to make the stack of fifty.
Next thing I need to do is make a print for BPX 37, I am going to select a high contrast, sharp 35mm negative with fine detail in the middle. Once I get a good print to send out, then I will use the same negative and settings to make the stack of fifty.
Bill demonstrated a group of photos that, although KNOWN to have elevational issues, could not be identified with certainty. In my conceptual chart, those were the graphed points, which fell to either side of 'ideal'.
Certainly there is measurement error to consider, which might bias results one way or the other. But the conceptual chart assumes that the error is factored out, as all assumptions about measurement...do we assume the micrometer is checked for accuracy? Yes. but we also do recognize error can creep in.
So the 'ideal' might be better represented by a thicker line, for 'nominal' rather than 'precise'. Yet, again this is a conceptual drawing and not a plot of actual results observed in Bill's experiment.
To please those for whom a conceptual chart is not precise enough, I offer this modified chart for discussion. The translucent thickness conveys that some measurement errror can arise (the drawing tool does not permit thicker than shown!)
It is not meant to be exact...a concept!
Both 'with paper' and 'without paper' cannot be 'ideal', if perfect focus is at a precise distance from the lens node! which theoretically is at a perfect distance from the negative. The distance from node-to-emulsion (A') is determined by lens actual optical FL and the distance of node-to-negative (A)...there cannot be two 'ideal' distances.
Last edited:
- Joined
- Feb 9, 2010
- Messages
- 9,308
- Format
- 4x5 Format
Left hand doesn’t know what right hand is doing.
Butterfly in my series was shot on Double-X not TMY-2.
It makes me happy to realize I cannot see the grain of Double-X on my standard 11x14 enlargements because that was the entire goal of my idea to try Double-X in the first place.
But next test is going to be from TMY-2 because that’s what I had intended to test. Hang tight, we might see the grain.
Butterfly in my series was shot on Double-X not TMY-2.
It makes me happy to realize I cannot see the grain of Double-X on my standard 11x14 enlargements because that was the entire goal of my idea to try Double-X in the first place.
But next test is going to be from TMY-2 because that’s what I had intended to test. Hang tight, we might see the grain.
You might want put one of those plus or minus symbols in front of that 0.070" since the accuracy of Bill's vision is an unknown. Wouldn't want any false precision sneaking in. I am not saying it would change the result, so everyone can get back in their seats.
The other thing you might want to do is add a couple of green lines on each side of the paper/non-paper lines representing the near and far distances from Bill's depth of field calculations.
Last edited:
That is left as an exercise for the student. QED
One point that has not been raised is, how accurate is a grain focuser? It seems to me it depends on how well it has been made so the mirror image actually represents the image projected on the paper surface. The peak magnifiers have front-surface mirrors so they won't introduce errors from the mirror glass, I don't know if that kind of care is found in others or if it is even all that necessary.
As restated countless times by many, "you cannot tell the difference, so it does not really matter"!
I can certainly tell the difference when using an enlarger that is not aligned or a lens that has poor definition at the edges. Why shouldn't I be able to tell if a faulty grain focuser results in a soft image?
It might obviate the need for Bill to do his fifty sheet extravaganza.
MattKing
Moderator
You cannot tell, if the "fault" in the grain focuser is of an order of magnitude less than the thickness of a few sheets of paper.
The tolerance is much narrower for faults in alignment, because the enlarger magnifies ("enlarges") the effect of those faults.
The same applies to lenses.
We've really got to see the grain. Comparing flower stems seems a little iffy to me.
Bill's test (and other tests by posters here) showed that some degree of error cannot be identified, either by naked eye or by 10X grain focuser. If the alignment is bad enough, or if the elevational error is large enough, it can be visualized, as shown in Bill's testing. So within the zone of undetectability, 'it does not really matter'
Matt already addressed the alignment issue, "The tolerance is much narrower for faults in alignment, because the enlarger magnifies ("enlarges") the effect of those faults. The same applies to lenses."
Perhaps the enlargement for the next test needs to be 16X, where so many of us will not enlarge to a greater degree because Tri-X grain became too apparent. And eny errors get magnified more, too.
Last edited:
| Photrio.com contains affiliate links to products. We may receive a commission for purchases made through these links. To read our full affiliate disclosure statement please click Here. |
PHOTRIO PARTNERS EQUALLY FUNDING OUR COMMUNITY:  |