Chriscrawfordphoto
Real Men Shoot Film.
I don't know. I haven't wet printed in almost 10 years because of my allergies. Thank God for film scanners!
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I don't know. I haven't wet printed in almost 10 years because of my allergies. Thank God for film scanners!
tlitody
Well-known
cop out. Do the math.
Chriscrawfordphoto
Real Men Shoot Film.
I'm an artist, I suck at math. When my son gets up, I'll make him do it. He gets As in math. I got As in everything but math.
Chriscrawfordphoto
Real Men Shoot Film.
By the way, depth of field is irrelevant here. What we need to know is depth of focus.
😛😛😛😛😛
😛😛😛😛😛
tlitody
Well-known
And just so you know cos I'm not expecting an answer...
depth of focus at the paper is:
t = 2Nc(1+m)
where t=depth of focus, N=f-number, c= circle of confusion, m=magnification.
remember an enlarger is a macro camera taking picture of the negative so the negative is the subject and the print is the object. We are not interested depth of field at the negative but rather depth of focus at the paper. As with all macro work depth of focus is at the projected object is large. Depth of field at the subject is small. Very very small in an enlarger because the magnification is so large.
circle of confusion on paper needs to give 8lpmm, I used figure for 10lpmm which is 0.05mm
So using above formula and an 8 times enlargement of negative(which is about right for an 8x10 print from 36x24 neg) we get:
t = 2*5.6 * 0.05 (1+8) = 5.04mm
Which means your depth of focus at the paper will be at least 5mm. And if you use only 5lpmm as a lot of people consider it enough you get a depth of focus of 10mm.
Putting a piece of paper under the focus finder makes bugger all difference.
What is far more important is getting your enlarger alignement correct because the depth of field at the negative is miniscule and if your enlarger alignement is a tiny bit out you will never get a truly sharp print across the image from corners to corners.
depth of focus at the paper is:
t = 2Nc(1+m)
where t=depth of focus, N=f-number, c= circle of confusion, m=magnification.
remember an enlarger is a macro camera taking picture of the negative so the negative is the subject and the print is the object. We are not interested depth of field at the negative but rather depth of focus at the paper. As with all macro work depth of focus is at the projected object is large. Depth of field at the subject is small. Very very small in an enlarger because the magnification is so large.
circle of confusion on paper needs to give 8lpmm, I used figure for 10lpmm which is 0.05mm
So using above formula and an 8 times enlargement of negative(which is about right for an 8x10 print from 36x24 neg) we get:
t = 2*5.6 * 0.05 (1+8) = 5.04mm
Which means your depth of focus at the paper will be at least 5mm. And if you use only 5lpmm as a lot of people consider it enough you get a depth of focus of 10mm.
Putting a piece of paper under the focus finder makes bugger all difference.
What is far more important is getting your enlarger alignement correct because the depth of field at the negative is miniscule and if your enlarger alignement is a tiny bit out you will never get a truly sharp print across the image from corners to corners.
Chriscrawfordphoto
Real Men Shoot Film.
5mm seems like a lot of lattitude for focus at the paper. Wish I still had my darkroom to test it! It would certainly eliminate the need for costly high-mag grain focusers if true. I never did get one of those high-end ones. I used a less costly and lower-magnification focuser called a MagnaSight. People told me when I was a student that I needed a grain focuser (meaning one of those really expensive ones that magnify more) to get maximum print sharpness. I couldn't afford one; if I remember right they cost about $300 back then. My prints were VERY sharp. I doubt I was ever off by 5mm on my focusing though....would be neat to test!
tlitody
Well-known
I have a peak focus finder which cost an arm and a leg. Its no better than my very cheap paterson focus finder at getting accurate focus. The only difference is that I can see right into the corners with it.
Focus accuracy is important because most peoples enlargers are not in alignement so there is less margin for error. But even getting focus spot on is only for the point you check. If alignment is out then you will never get print truly sharp across the whole surface. The depth of focus being at least 5mm 2.5mm each way gives you some margin of error for misalignment. In reality for a 5lpmm print you have enough margin for good enough depending on your standards.
tlitody
Well-known
If you have Barry Thornton's "Edge of Darkness", have a look through it.
tj01
Well-known
Grain focuser would work on all types of paper thickness. It sits on top of the paper and magnifies without blocking the light from the enlarger. Mine is a very good one, sturdy and large view. Bought it at 30 bucks and was still in original packaging, probably sat on the shelf for 30 years.
There's no way I think a loupe or magnifying glass would work, as you would be blocking the light.
Forgive me if I'm wrong.
There's no way I think a loupe or magnifying glass would work, as you would be blocking the light.
Forgive me if I'm wrong.
PatrickT
New Rangefinder User
Well, now I'm hooked on fiber. Damn it looks so good...
Does curl though!
Does curl though!
Chris101
summicronia
PatrickT
New Rangefinder User
Yeah I'm having fun 🙂
Here's a question about a problem I ran into. I've only been printing 35mm negates so far. However, I did try to print a 6x6 negative and found that when I put the negative into the carrier and inserted it into the enlarger (Bessler 23C I believe), it looked as if there was severe vignetting on the corners, like the corners of the image were being cut off.
Any idea why this is and what I can do to fix it?
Also, I was given the option of using a 50MM lens or an 80MM lens. I tried both wit the 6x6 negative and that didn't help.
Here's a question about a problem I ran into. I've only been printing 35mm negates so far. However, I did try to print a 6x6 negative and found that when I put the negative into the carrier and inserted it into the enlarger (Bessler 23C I believe), it looked as if there was severe vignetting on the corners, like the corners of the image were being cut off.
Any idea why this is and what I can do to fix it?
Also, I was given the option of using a 50MM lens or an 80MM lens. I tried both wit the 6x6 negative and that didn't help.
shadowfox
Darkroom printing lives
Patrick what did you do to get the fuzzy borders?
Did you file the inside edges of the negative carrier?
Did you file the inside edges of the negative carrier?
tlitody
Well-known
go back and read the whole thread.
Chris101
summicronia
His carrier was already filed.
Chris101
summicronia
Use the 80mm for medium format. Notice that there is a second bellows above the first one. That bellows needs to be adjusted to optimize the light circle (and get rid of the vignetting.)
There is an indicator for where to set it:
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PatrickT
New Rangefinder User
Use the 80mm for medium format. Notice that there is a second bellows above the first one. That bellows needs to be adjusted to optimize the light circle (and get rid of the vignetting.)
There is an indicator for where to set it:
That would be my problem then...thanks!
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