Using grains focuser with or without paper on the easel

[Don_ih]

There's a technical solution for everything. Just put vaseline over the enlarging lens front element and be done with it !

That would introduce the debate of whether it should be on the front or the rear of the lens.

 

[DREW WILEY]

Fine with me. Start a new thread. The debate will really heat up once we start discussing the merits of smearing vaseline over the lens versus applying a nylon stocking.

 

[Bill Burk]

You know, chap stik works in a pinch.

I found my register pins.

Is it ironic, or foreshadowing? I found them in the old card file where I keep pieces of paper to use under the grain focuser.

 

[Don_ih]

Is it ironic, or foreshadowing? I found them in the old card file where I keep pieces of paper to use under the grain focuser.

I'd be inclined to call that coincidental.

 

[MattKing]

Is it ironic, or foreshadowing? I found them in the old card file where I keep pieces of paper to use under the grain focuser.

I'd be inclined to call that coincidental.

Are you sure it isn't a conspiracy?

 

[wiltw]

will Bill be honest and not biased?

 

[Don_ih]

will Bill be honest and not biased?

Look at his picture. You can clearly trust him.

 

[Sirius Glass]

Fine with me. Start a new thread. The debate will really heat up once we start discussing the merits of smearing vaseline over the lens versus applying a nylon stocking.

What about K-Y jelly instead of Vaseline?

 

[Don_ih]

What about K-Y jelly instead of Vaseline?

Whatever you happen to have on hand....

 

[Sirius Glass]

Whatever you happen to have on hand....

ON hand or on ones hand? We have to get a grip.

 

[wiltw]

Another test! ....which works better optically, Vaseline or K-Y? and can you even tell the difference?

 

[Bill Burk]

Look at his picture. You can clearly trust him.

Ah that picture, backyard with my best friends Tom and Jim.

Jim and I were roommates in college and a few years after… he worked at Freestyle. We always had a darkroom, the best was in a bedroom - one bed by the door, another by the window and the whole corner was cordoned off with black plastic stapled to a framework made up of 1x2’s with a box fan over a maze light trap. A bit of plastic over the carpet under the trays that were set on the dresser, we carried water back and forth from the bathroom where we did the film. Hung speakers and listened to the same weird music I listen to today…

 

[Bill Burk]

My conclusion is the range of sharp focus is 0.076 inches. Six sheets in the middle of the test reveal low contrast detail that is camouflaged in noise on the outside sheets.

 

[wiltw]

My conclusion is the range of sharp focus is 0.076 inches. Six sheets in the middle of the test reveal low contrast detail that is camouflaged in noise on the outside sheets.

Your methodology of evaluation...arriving at 0.076" or 1.93mm (which is less than the computed DOF value stated earlier in this thread)

1. Did it include looking at the film grain reproduction, where grain edges appear degraded under examination of the print critically with a loupe?
2. Or did you not use magnification, and assessed the naked eye ability to detect apparent loss of quality, like an ordinary print viewer looking at the enlargement?

...just trying to better understand the criteria used to come to your conclusion.

 

[Bill Burk]

I will try to find a way to present the visual, it’s almost 300mb multipage tiff uncompressed scan at 1200dpi (optical 300 I think). I clicked back and forth looking for any signal. I think I saw some light specks appear and disappear through the page flipping, and the appearance lasts for six pages. Calipered the pages and got the measure.

So although all pages look the same, flipping through them does reveal appearance and disappearance of slight detail. You can’t even see it in the higher contrast parts of the picture.

 

[MattKing]

This question will probably make my brain hurt.
How does the distribution of your results compare with a measurement of the acuity of the entire "eye to the grain focuser" procedure?
In other words, is there variation that comes from the enlarger optics alone, or is it variation that arises because of a combination of the enlarger optics and the grain focuser plus your sight? Would someone else with different eyesight get different results.
I don't expect an answer with numbers. "Hmmm" is probably a good answer.
It is the "eye to the grain focuser" part that I have been posting about in this thread.

 

[Pieter12]

It is the "eye to the grain focuser" part that I have been posting about in this thread.

I'm not sure I understand this. Does the position of the eye to the focuser affect the grain as seen through the focuser? Can it be in focus (when the focuser is properly adjusted, using the reference line) through the instrument and not at the surface the focuser is resting on?

 

[MattKing]

I'm not sure I understand this. Does the position of the eye to the focuser affect the grain as seen through the focuser? Can it be in focus (when the focuser is properly adjusted, using the reference line) through the instrument and not at the surface the focuser is resting on?

It is much simpler than that.
The distances we are talking about here - changes in position of the grain finder one sheet of paper at a time - give results that we are unable to differentiate between, because we can't see a change when the grain focuser moves that small distance.
It is like trying to measure milligrams with a postage scale.

 

[wiltw]

It is much simpler than that.
The distances we are talking about here - changes in position of the grain finder one sheet of paper at a time - give results that we are unable to differentiate between, because we can't see a change when the grain focuser moves that small distance.
It is like trying to measure milligrams with a postage scale.

If I try to paraphrase what I think you're asking, "If you put the grain focuser on the top layer, as you removed each of the layers of double-weight paper, would you be able to detect increase/decrease in focus accuracy as you passed thru the ideal focus plane?" (finding out if the 25X grain focuser would reveal what the naked eye would be fooled as 'in focus')

 

[Pieter12]

It is much simpler than that.
The distances we are talking about here - changes in position of the grain finder one sheet of paper at a time - give results that we are unable to differentiate between, because we can't see a change when the grain focuser moves that small distance.
It is like trying to measure milligrams with a postage scale.

For me, the grain "snaps" into focus when using a magnifier. So, basically you are saying that when I see that sharp grain in the magnifier, when the lens is stopped down it is sharp over a depth of 3-5mm perhaps. I am surprised because there does not seem to be that much leeway when focusing, even stopped down. Disclaimer: I develop in Rodinal and use a condenser enlarger, so grain is quite apparent.

 

[cliveh]

Who uses double-weight paper?

 

[wiltw]

Who uses double-weight paper?

IIRC, Bill did in his testing.

Just found it, Post 221, Bill states, "I am using double weight paper (and Eddie I scribed a cross on both sides but I don’t see the mark on the base)."

 

[cliveh]

Well perhaps Bill should test using single weight paper?

 

[MattKing]

For me, the grain "snaps" into focus when using a magnifier. So, basically you are saying that when I see that sharp grain in the magnifier, when the lens is stopped down it is sharp over a depth of 3-5mm perhaps. I am surprised because there does not seem to be that much leeway when focusing, even stopped down. Disclaimer: I develop in Rodinal and use a condenser enlarger, so grain is quite apparent.

Remember, you are focusing by moving the lens (or the negative), not the easel/paper.
If you are enlarging 8x, it probably takes 8mm of easel travel to have the same effect as moving the lens (or negative) 1 mm.

 

[wiltw]

Well perhaps Bill should test using single weight paper?

I believe his point was to reduce the number of layers in the test, to offset the same vertical distance....removal of 0.015" per layer to have a 0.150" stack takes fewer layers than 0.008" per layer. As it was, he had to do 19 layers...your suggestion would double that count, and only improve the apparent precision of the test by 0.008"