Disappointing results with my Crown Graphic

shutterfinger · Nov 19, 2015

Pacemaker graphics, of which the Crown Graphic is a member, were introduced in 1947 with a ground glass only Spring (Graphic) back. The Graflok back was introduced in 1949 on the Century Graphic and became the standard back by 1951. Some early versions of the Graflok may have only a ground glass as the fresnel was introduced a short time after the introduction of the Graflok back. The side rangefinders were replaced by the Graphic Top rangefinder in 1955 and a date code on the bottom side of the front cross member of the rails was added in 1960.

A fresnel from the 1960's-1970's will most likely be thinner than a fresnel from the early to mid 1950's. A factory fresnel (ektalite field screen) will have very fine groves on one side that are hard to distinguish from the smooth side.
Post your serial number for a more precise date if it does not have a date code. Date code-month(letter), year (single digit), revision(letter).

tim48v · Nov 19, 2015

Serial number: 974604; date code: E F4A. I think this puts it in the June of '64. BTW, the grooves in the Fresnel are very fine.

I've taken some more test shots; hopefully I'll get them processed tonight.

shutterfinger · Nov 19, 2015

F4A=June 1964. http://www.graflex.org/helpboard/viewtopic.php?t=3321
The work order for 2500 cameras you serial number is in was entered into the book at the end of November 1963 and yours is mid way of that group.
Sounds like all is correct with the fresnel and gg.

Andrew K · Nov 19, 2015

What does the tranny look like on a lightbox using a loupe? Is it sharper than your scan?

My guess would be the tranny was not flat / or moved during scanning (based on personal experience with a Epson 4750 scanner)

Cheers

Andrew

RobC · Nov 19, 2015

be very very very certain its a fresnel and / or GG position error BEFORE you start trying to adjust their position. i.e. illiminate all other possibilties first before concluding its fresnel/GG position which is wrong because if that wasn't the problem it can be a real bugger to get it back to where it should have been.

For example is your lens mounted properly with the correct spacing between front and rear elements (Probably won't matter too much with that lens). Are the front and rear elements of the lens the correct ones and not a couple of elements someone has thrown together. Is your loupe actually any good and/or focussed correctly etc etc.

tim48v · Nov 20, 2015

Here are some test images from this evening (these are all cropped sections).

shot at about 6 feet, f5.6, 1/10, Ilford 100. Very steady tripod with self timer. I was focusing on the "18".

Side of the building, focus on the electrical box, 1/200, f16, self timer, about 40 feet to the box.

test chart at 6 feet, f16 (I think).

RobC · Nov 20, 2015

The ruler shot does seem to be off about 1.5in on the ruler. So the back need to be a tad further away from the lens to correct it. I can't say how much without precise measurements but approx guesstimate would be 0.16mm. That is about 0.1mm outside of the depth of focus range.

Difficult to say about the electrical box but it would obviously be better if the ruler shot had been spot on.

Again the resolution chart would be better if the ruler shot was spot on.

But with all these shots it could be down to how accurate your focussing is. A single ruler shot gives an indication but to be sure doing 5 ruler shots setting the shot up from scratch each time should show whether the error is consistent and not your focussing error, and if it is, then that would prove its the back being out of whack a tad.

edit:
I assumed ruler was in cm but looking again it looks like inches so I changed figures above to reflect that.

removed account4 · Nov 20, 2015

tim48v said:
Here are some test images from this evening (these are all cropped sections).

shot at about 6 feet, f5.6, 1/10, Ilford 100. Very steady tripod with self timer. I was focusing on the "18".

Side of the building, focus on the electrical box, 1/200, f16, self timer, about 40 feet to the box.

test chart at 6 feet, f16 (I think).

your images look fine to me. a symmar is a plasmat lens design
it has a sweet spot around f16 or so (i'll probably be corrected but g-claron i think is the same lens design )
they are sometimes symmetrical and often used as "convertible" lenses, so you would get 2 focal lengths if one cell is removed.
the 150 usually converts to 235 when the front cell is taken off, and some folks don't like it because the image tends to be sort of soft/pictorial
( schneider suggests using it for portraits or landscapes ) and it is about f12 ( both cells on is 5.6 ) anyways, if you are using your symmar with both cells on
and stopping down to about 16 you should get a nice sharp image ....
also, what you have noticed is how fstops in smaller format correspond to the same fnumber in larger formats ...
i may be wrong but in order to get what was sharp and in focus in 35mm in a 4x5 camera
( lets say f8 for the sake of argument ) it takes around 2 stops closing the lens down more to around f16ish
the way i think of it is 1 stop stopped down / format size. so if you have an 8x10 camera and you wanted
the scene to have the same realitive DOF as f8 in 35mm, you would need to stop down even more, maybe even to f22 ...
it is one of the many things that takes "getting accustomed to" with large format if you are used to small...
have fun with your new camera !
john

tim48v · Nov 20, 2015

Actually, I took two shots of the ruler last night. This one is at about a 45 degree angle; focus point was the "18". Very similar.

I didn't post any comments yesterday; wanted to see what others thought. But I agree that the focus seems to be off by about 1.5"

tim48v · Nov 20, 2015

RobC,
You're saying that the gg needs to move back .16mm (0.006")?

thanks,

RobC · Nov 20, 2015

well the second one seems to be off by about 4 inches so as I suspected there is some of your focus error going on here as well as gg correction needed. so I would do another 3 setting up from scratch each time and we can take the average error which will iron out your focussing error.

DWThomas · Nov 20, 2015

At least it looks plenty sharp somewhere -- that's the first step to encouragement!

Ian Grant · Nov 20, 2015

tim48v said:
RobC,
You're saying that the gg needs to move back .16mm (0.006")?

thanks,

If the GG is moved back then when you focus the lens will be slightly nearer the camera body by the same difference - for the same distance, so when you then shoot a test shot focus will be further out.

It's possibly the combination of a non Graflex (Ektalite) fresnel and the back is throwing up this focus error, the focus frame is correct for a GG screen and Ektalite fresnel so don't modify it.

Ian

shutterfinger · Nov 20, 2015

In the second ruler image, post #34, the 18 and 25 are about the same sharpness with 21 to 21 1/2 the sharpest.
#24 bond printer paper is .11mm thick, card stock is .25mm thick, common to use similar for shims for gg.
Ian is correct the gg/fresnel needs to move forward to correct the focus error.
By using paper shims and moving the gg sandwich back .1mm then shooting the ruler from the same position as before at f5.6 you can then know how much change in focus has been achieved then notch the fresnel accordingly so it sits a little deeper onto the focus panel bosses. Do Not grind down the focus panel bosses.

RobC · Nov 20, 2015

I think Ian is right. The film needs to be further away from the lens and to get that to happen, you need the GG moved forward towards lens so that when you focus you will need to extend lens further to get the 18" mark in focus than you do now. Sorry for the confusion, I was thinking the GG needs to be further from the lens rather than the film.

But do further tests to be able to average out the error before changing anything. Two tests is not enough.

tim48v · Nov 20, 2015

I've shot two more with the camera "as is".

It would be pretty easy to shim the film holder, moving it back 0.1mm and 0.2mm and see what happens.

BrianShaw · Nov 20, 2015

Why not send it to a pro to have it set up correctly? I did that once and would do it again. Money well spent.

MattKing · Nov 20, 2015

tim48v said:
I've shot two more with the camera "as is".

It would be pretty easy to shim the film holder, moving it back 0.1mm and 0.2mm and see what happens.

Just a reminder that you need those shims to be light tight all around.

John Koehrer · Nov 20, 2015

It would be hard to believe that in the life of the camera, someone else wouldn't have had the same problem. The error would have had to been introduced after it was made.

Ian (post 38) said the lens and GG need to be closer together, not further apart. Rob then corrected himself and agrees with Ian.

So lens back or GG forward.
But. Let's say you move the GG forward(X mm) and then move the lens(Xmm) to focus, aren't you just moving both the film plane and lens the same amount and not really changing anything?
Hey! I don't use LF but I'd take a whack at swapping out the fresnel and GG one at a time & check it that way. Make a GG from a picture frame(Goodwill store) glass & lapping compound/600 grit wet or dry sandpaper.

RobC · Nov 20, 2015

At 40 feet using f16 the depth of focus is +or- 0.35mm so the error you have in GG distance is well within that at landscape distance with F16. The GG position error is more pronounced at close focussing distances with wide aperture. The point being that altering the GG position is not going to make a significant difference to your landscape shots unless you are using widest apertures. Having said that, if you ever want to use that lens for close up work then it probably is worth getting it spot on or just focus a tad closer using the average error you're working on at the moment.

Sirius Glass · Nov 20, 2015

BrianShaw said:
Why not send it to a pro to have it set up correctly? I did that once and would do it again. Money well spent.

45PSS at www.graflex.org does Crown and Graphic repairs.

BrianShaw · Nov 20, 2015

So does Steve Choi at Steve's Camera Repair in Culver City CA

BrianShaw · Nov 20, 2015

It's a shame that Fred Lustig is no longer with us. I miss him.

Sirius Glass · Nov 20, 2015

BrianShaw said:
So does Steve Choi at Steve's Camera Repair in Culver City CA

I think so, but I am not sure. Give him a call.

BrianShaw · Nov 20, 2015

That wasn't a question.

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