Help with Speed Graphic ground glass/fresnel

Hi everyone

I’m new to LF and the forum.
I recently got my first LF camera, the Pacemaker Speed Graphic. I’ve strictly used the ground glass for focusing. I was pretty satisfied with my camera as it was, but the ground glass had a crack in it, so I bought a ground glass/fresnel from Global Screen on eBay. It came with no instructions. I installed it and my results were awfully out of focus. I contacted the business after reading through a mess of a website. They sent me some scrambled instructions on how to install it. The pictures are still not in focus.
I’ve searched all over the internet and seen some forum say you need to “raise” the glass because of the thickness...?
I was hoping someone out there had the same setup and could tell me what I’m doing wrong, cause I’m frustrated.
Even just point me in the direction of another tradition glass/screen setup that works.

Thank you
-Brian

Brian, did your camera have a fresnel installed with the screen that got cracked?
If you're adding a fresnel, you are adding a couple mm. of thickness, which will put your film out of sync with what you see on the ground glass.
The correct orientation (IIRC) is:
Lens
Fresnel (smooth side towards lens)
Ground glass (ground side towards lens)
Hope this helps.

Hi Dugan

Yes, the camera had a fresnel, but I removed that before installing the new one. The one I ordered has the gg and fresnel in one piece and then a protective screen on top. From the instructions given to me by the Global Screen people, the matte side of the piece should face the photographer.
The fresnel/gg is just way thinner than the original setup and I’m wondering if that’s what’s throwing the focus off...

The order should be from lens to eye:

Fresnel polished side
Fresnel corrugated side
Ground glass ground (frosted) side
Ground glass polished side

This combination requires a proper placement of the GG, as the focus plane is shifted by about 1/3 of the thickness of the Fresnel lens.

If you have an integrated version then you don’t know what thickness the fresnel adds, so you’ll have to try different shims until it’s adjusted and the GG sits on the same plane as the film in the holder. It’s going to be painful unless others have better ideas.

Thank you

Yeah, I understand the original setup.
When I bought this setup I thought I bought a fresnel and a ground glass, since that’s what the description indicated.
Some forums online recommended these, but I haven’t found anyone explaining how they use it.
It seems weird to me that a combination screen that’s half the thickness of the original fresnel would get the same results.
The website is useless.
I guess at this point I should start looking for a new set of ground glass and fresnel.

Quote:

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Originally Posted by Birthbackwards

Thank you

Yeah, I understand the original setup.
When I bought this setup I thought I bought a fresnel and a ground glass, since that’s what the description indicated.
Some forums online recommended these, but I haven’t found anyone explaining how they use it.
It seems weird to me that a combination screen that’s half the thickness of the original fresnel would get the same results.
The website is useless.
I guess at this point I should start looking for a new set of ground glass and fresnel.

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If it’s really thin, like 0.5mm and the older fresnel was like 2mm, you could try using something to temporarily shim back the fresnel by about 2/3 mm or a smidgen less (basically ignoring the new fresnel thickness). That should get you really close. In 2-3 tries you ought to be able to nail it down. That may be cheaper than buying a new one, although i understand its frustrating...
Are you focusing and shooting with the same aperture? Just to make sure the lens is not causing a focus shift when you step down.

Quote:

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Originally Posted by Kiwi7475

If it’s really thin, like 0.5mm and the older fresnel was like 2mm, you could try using something to temporarily shim back the fresnel by about 2/3 mm or a smidgen less (basically ignoring the new fresnel thickness). That should get you really close. In 2-3 tries you ought to be able to nail it down. That may be cheaper than buying a new one, although i understand its frustrating...
Are you focusing and shooting with the same aperture? Just to make sure the lens is not causing a focus shift when you step down.

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It IS really thin.
Half the thickness of one of the screens I removed, which were about the same in thickness. What throws me off is that since this screen is matte on one side and fresnel groove on the other, I'm guessing it should be shimmed so that the matte is located where the matte surface were located on my old setup. Where the matte screen would meet the fresnel, to created a point of focus. Right?
It annoys me I bought this thing. Zero help from its creators and their website looks like it was made in 95', -all the text looks like stream of consciousness, continuously jumping back to bits of info about france and how the fresnel was created there. No help whatsoever.

To answer your other question, I've shot several lenses, different apertures. I didn't have problems focusing before, other than the screen was old, had scratches, pencil notes and cracks in it. I still have that setup and might just go back to it.
But I'm pretty stubborn and I paid $100+ for this bright beautiful piece of frustration.

What you call the matte surface should face towards the lens, thus the thickness is not of consequence.

Quote:

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Originally Posted by Jon Shiu

What you call the matte surface should face towards the lens, thus the thickness is not of consequence.

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Do you have experience with the combo screen, cause that would mean the fresnel groove is pointing towards me, doing the opposite of the instructions I've gotten from the creators.
At least that's what I understood from the email.

"1, You must remove all the original ground glass and Fresnel lens.
2, what you received is 2in 1 combination of ground glass and Fresnel lens. The transparent grid piece is a protective for the Fresnel/gg
3 the combination piece should face the camera taking lens with matte side facing photographer. And the grid transparent piece put above the combination piece."

Brian, check your PM's.

Yes, I have a stock Tachihara combo screen. Their instructions do not make sense to me.

I would go back to your original fresnel screen and ground glass parts, or source new old stock replacements.

Quote:

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Originally Posted by Jon Shiu

Yes, I have a stock Tachihara combo screen. Their instructions do not make sense to me.

I would go back to your original fresnel screen and ground glass parts, or source new old stock replacements.

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Yeah, that’s what I’m gonna do.
Thank you for your help.

Ebay seller "photofinder" , Stephen Shuart, AKA "The Rev" knows just what you need to set up your camera, with or without Fresnel. I never liked the Fresnel in my Graphics because I frequently use very wide lenses like 65 and 58 and much prefer the plain ground glass. If you remove the Fresnel, thin spacer strips have to be placed on top of the ground glass to move it forward. Turns out, the thickness I determined for the spacers (I think around .0300, and much thinner than the Fresnel) is the same as a grey plastic material sold in big hobby shops for model railroad use. This modification is only a sure thing for the original Graphic ground glass. It will not work work for a ground glass of different thickness. I think Shuart has a thicker, "drop in" ground glass that needs no spacers.

Neal, the ground glass' thickness is irrelevant. The image is formed on the ground surface, which should face the lens.

Tbhe OP is somewhat cooked. Graflok backs made by Graflex Inc. for Graphic cameras' ground glasses sit on bosses on the focusing panel casting. Graflex Inc. intended their fresnels to sit between the GG and the lens. Graflok backs' focusing panels made by Graflex Inc. for Graphic cameras and intended to be used with Graflex' own fresnels have lower bosses than focusing panels made to be used without a fresnel.

There's no guarantee that any fresnel or fresnel-GG sandwich made by a third party will be the right thickness to work properly in a focusing panel made by Graflex Inc.

The OP's best option is to toss his $100 mistake -- or return it for a refund if possible -- and get a new GG the right size and use it with the fresnel he removed from his focusing panel.

Here is what you want.
https://www.ebay.com/itm/4x5-Graflok...YAAOSw65FXqitK
Beg to disagree Dan. The ground surface of the glass needs to be on the same plane as the surface of the film in the film holder when the film holder is in place. This can be determined by measurement with a dial gauge. The thickness of the ground glass does make a difference if the Fresnel is to be removed. You are correct that on Graphic backs designed for use without Fresnel have different dimensions.

In cameras where the Fresnel is in front of the ground glass, between the ground glass and the lens, the Fresnel, which is a lens, affects the focus on the ground glass, effectively moving the focusing surface forward. If in cameras where the Fresnel is behind the ground glass, but in the frame, then removing it will could throw focus on the film off depending on the design. On Linhofs, the ground side of the glass is always held in the correct plane, regardless of its thickness, and a Fresnel if used is mounted on top from behind. On cameras with frames like Deardorff, the ground glass is mounted in the frame from behind and the ground surface is always on the correct plane regardless of glass thickness. A Fresnel, if used has to go on top like in the Linhof.

Neal, you are writing from general principles, not from Graflex Inc.'s practice. Please read the manuals.

Yeah, I was cooked, but I did get a new ground glass and returned to my old setup.
It’s all back in working order.
I had absolutely no idea what I was buying, since the post was very misleading, but had good reviews.
Anyway, thanks for putting the record straight.
Have a nice day

Hi Neal
Thank you for your help and input.
I got a ground glass and am now back to my old setup, it’s not perfect or the brightest, but it works and I’m happy about that. I should have bought a new ground glass from the beginning, but I pulled the trigger on a very misleading eBay ad and that was a mistake.
I’m happy where I am and will keep it as it is