Questions from a Speed Graphic Newbie

[Bravin Neff]

Hello everyone. First time poster here! Great forum. I’ve been searching and reading for days and I’m impressed with the wealth of knowledge shared on these pages.

I just bought a 1953 Pacemaker Speed Graphic (I love it, by the way) and I’m dying to get shooting with it. Before I can do that it needs some work, so I’ve been cleaning it up. I have a few questions for you please.

I compared the Graflok back to the film holder. When I measure (with Starrett scale) from the flange to the glass surface on the Graflok back, I get a value roughly 1mm shorter than when I take a film holder and scale to the film surface. Is this correct? I thought the distances were supposed to be equal to insure focus correlation between the ground glass and the film surface.

Also, I disassembled the fresnel/ground glass assembly. I didn’t initially realize the assembly was two panes. One pane is plain glass and the other has a Fresnel surface. I am not sure I reassembled the surfaces in the correct orientation with respect to each (or with respect to the direction that light travels). Does the orientation matter?

Thank you for your time folks!

Regards,
Bravin Neff

[Jim Noel]

Yes, the orientation matters.
There is a Graflex users group or forum on the web which you should find. They have all the info on your Graphic.

[brian d]

http://www.graflex.org/

Go to the Help Board and search Fresnel there was a good thread a while back.

[Frank Petronio]

You may be screwed up, the difference was probably to compensate for the fresnel....

[BrianShaw]

Does the orientation matter?

The recco to go to Graflex.com is a good one. That site is filled with good info.

The simple answer is, yes... orientation matters. The standard Graflex configuration is fresnel toward the lens, GG toward the photographer... with the bumpy part of the fresnel and the ground part of the GG toward each other in the center of the sandwich.

[BradS]

On the Pacemaker Graphics that were originally outfitted with a Fresnel, the Fresnel lens is mounted behind the ground glass. That is, the Fresnel is mounted closest to the lens. The ground glass goes over it with the ground side facing the lens and smooth side out --- photographer always looks into the smooth side, lens always projects its image onto the ground side. Finally, if I remember correctly, the Fresnel lens is supposed to be oriented so that the side with the ridges faces the photographer. Although, I'm not really sure it matters that much. You are correct that what matters most is getting the ground side of the ground glass facing the lens and at the same distance from the flange (really, the rear nodal point of the lens) as the film. Note that this distance is difficult to measure when the Fresnel is in the way....so you have to measure the thickness of the Fresnel and then add that to the measured distance from the flange to the face of the Fresnel to get the total distance from the flange to the ground side of the ground glass. - Make sense?

[Bravin Neff]

The recco to go to Graflex.com is a good one. That site is filled with good info.

The simple answer is, yes... orientation matters. The standard Graflex configuration is fresnel toward the lens, GG toward the photographer... with the bumpy part of the fresnel and the ground part of the GG toward each other in the center of the sandwich.

Thank you for the details. That Graflex.com site is excellent, but, alas they don't mention the actual details for the glass orientation.

[Bravin Neff]

On the Pacemaker Graphics that were originally outfitted with a Fresnel, the Fresnel lens is mounted behind the ground glass. That is, the Fresnel is mounted closest to the lens. The ground glass goes over it with the ground side facing the lens and smooth side out --- photographer always looks into the smooth side, lens always projects its image onto the ground side. Finally, if I remember correctly, the Fresnel lens is supposed to be oriented so that the side with the ridges faces the photographer. Although, I'm not really sure it matters that much. You are correct that what matters most is getting the ground side of the ground glass facing the lens and at the same distance from the flange (really, the rear nodal point of the lens) as the film. Note that this distance is difficult to measure when the Fresnel is in the way....so you have to measure the thickness of the Fresnel and then add that to the measured distance from the flange to the face of the Fresnel to get the total distance from the flange to the ground side of the ground glass. - Make sense?

Yes, makes perfect sense. Only with the fresnel lens thickness included in the arithmentic will I [you] get the actual flange-to-focus-plane distance properly measured, and this should equal the flange-to-film-surface measure.

The other tricky thing to notice is that the flange has high spots - in the corners, and these surfaces are the only surfaces that make actual contact with the camera body. The rest of the "flange" is actually below the plane and will give you an erroneous reading if you measure from it. Fortunately I'm a machinist by trade so taking these measurements is straightforward for me, but I imagine its not that way for everyone.

I'll take these measurements when I get home, but I'm pretty sure the flange-to-ground-glass measurement is probably right on the money with the flange-to-film-surface measurement.

Thank you for your help.

[Bravin Neff]

If you folks don't mind another question...

The back of the camera has slide-locks that slide inward, presumably to lock a back against the camera. Yet these locks are not positioned at the right height to lock either the Graflock back or my film holders. So what in the heck fits in there that makes these slides useful? Maybe like a Polaroid 550, or perhaps a readyload/quickload type of system?

Regards,
Bravin Neff

[PBrooks]

Readyload and QL fit in just like a film holder. The two sliding locks are for roll film backs. Make sure they are in the up position or they may interfere with your graflock gg distance.

[jbenedict]

If you folks don't mind another question...

The back of the camera has slide-locks that slide inward, presumably to lock a back against the camera. Yet these locks are not positioned at the right height to lock either the Graflock back or my film holders. So what in the heck fits in there that makes these slides useful?

It is also possible to lock in Grafmatic holders. When I was doing a lot of handheld 4x5 with my Crown Graphic, I usually locked in my Grafmatic so I wouldn't pull it out of position when I changed septums.

[Fred Haeseker]

Hi Bravin: About the sliders on the camera back. Only the Graflex and Graflok backs had sliders. The Graflex backs need special film holders that have a groove running down the middle of the sides.
Your camera may have the Graflex back, on which the sliders are oriented differently than on the Graflok back. It's very confusing, but Jo Lommen's press-camera website has an excellent explanation with good illustrations:
http://www.xs4all.nl/~lommen9/

[Bravin Neff]

Hi Bravin: About the sliders on the camera back. Only the Graflex and Graflok backs had sliders. The Graflex backs need special film holders that have a groove running down the middle of the sides.
Your camera may have the Graflex back, on which the sliders are oriented differently than on the Graflok back. It's very confusing, but Jo Lommen's press-camera website has an excellent explanation with good illustrations:
http://www.xs4all.nl/~lommen9/

That link is excellent. Thank you for the information!

Regards,
Bravin Neff

[Jim Jones]

The old ASA diminsion from the face of a 4x5 film holder to the septum between the halves is .0197" +/- .007". The channel for the film is a minimum of .012". Film is typically about .007" thick, although I've seen it from .004" to .01". Sloppy tolerances to a machinist, eh?

Without a fresnel, the distance from the front of the flange to the ground glass should equal the corresponding distance to the film in its holder. However, with a fresnel between ground glass and lens, the optical distance must be the same, but the physical distance will be different, depending on the thickness of the fresnel and its index of refraction. You don't have to be an alchemist or a witch doctor for large format photography, but it probably helps.

[Glenn Thoreson]

The Graflok slides are only there for holding accessories, i.e. roll film holders, etc. They aren't made to hold sheet film holders, which slide under the focus panel. Make sure your focus panel is installed correctly. The spring arms hook under a retainer on the sides of the back opening. They should just snap into place as you slide the focus panel into the back. To remove the focus panel, press down on both arms and slide it to the right. Most accessory holders, etc. require that the panel be removed and the accessory held on by the slides. Some accessory holders, such as the Polaroid 545 will work as a slide in or clip on, either way. Enjoy! :D
Another thought: I don't think you will find a fresnel on the focus panel for the Graflex back. I've never run across such a thing, anyhoo.