Which brand of 4x5 filmholder is best?

[rdenney]

True statement. But hey, I'm only human. They told me so when they disconnected the wires.

No worries. Membership in the lunatic asylum is assumed on this forum.

Let's do a little math. Assuming a simple lens, the angle of light approaching the film through a 47mm lens, at the lateral edges of a 6x12 frame at a shallow 37-degree angle. Each .001" that the film is out of position will create a lateral shift of .0008". But that is not important--what is important is how much lines from different parts of the subject diverge in that distance. Those lines come from the edges of the projected shape of the aperture. At f/5.6, the projected diameter of the aperture is 8.4mm, or 0.33". The angle subtended by the projected aperture is therefore 6 degrees. Each .001" of positioning error would cause those lines to diverge by (pause for calculating several similar triangles) .000085". If our desired circle of confusion was .001" (0.25mm, or a demanding 1/5000 the image diagonal in 6x12), we would need an error of .006 to undermine half the circle of confusion. An error of .005 might not have that much of an effect, even for a lens this short, unless we were enlarging so much that we needed an even more demanding circle of confusion goal.

The effect would be less for longer lenses, of course, because they approach the film at a steeper angle and it therefore takes more longitudinal movement to achieve a given lateral error. And the effect would be much less for smaller apertures.

Thus, I can't figure out how to defend the notion that a .005" positioning error would cause a large focus error. Maybe noticeable at very large magnifications, perhaps, but certainly not large.

Rick "numbers are facts" Denney

[Brian C. Miller]

Thus, I can't figure out how to defend the notion that a .005" positioning error would cause a large focus error. Maybe noticeable at very large magnifications, perhaps, but certainly not large.

Not large, but noticeable. And I mean noticeable with a 22x loupe on the film, which is visible on a 16x20 (4x) enlargement. And what does +/- 0.007-in. mean? How about a potential 0.014-inch difference?? That's still within specified tolerance, but could you really make tack-sharp pictures with that?

Here's the test sequence I used:
1. Load holders with Techpan (may it rest in peace, amen)
2. Open 2nd story window, remove window screen, and position big fat heavy Bogen tripod firmly, without camera going out window.
3. Focus with 8x loupe on ground glass, and move focusing knob ever so gently. Lock down the focus.
4. Carefully insert holder, and make exposure. Develop film, and then compare to image on glass.

How close does it look? Is it "all right!" or "Huh??" quality? If the quality is "huh?" then take dial calipers, and make many measurements and adjustments. Repeat until quality is "all right!" So I continued to get it down to 1mil off from the Graflex holder.

Yes, Lachlan, a dial caliper can be opened to 1mil, easily. You can see a 1mil gap between the jaws, easily. Magnetic tape is 1mil thick.

I don't think that it's necessary to measure every holder. Could the manufacturing tolerances be that out-of-whack from holder to holder? I think that the holders would look warped if that was the case. One sample is good, and then move on.

How many line pairs does my 135mm Wollensak Optar lens resolve? I have no idea. All I know is that at two blocks, I can count all of the spokes on a bicycle wheel. The bricks on the wall are like etchings. Somebody else can do the trigonometery, all I care about is that I like what I see.

Beyond that, it is sharp enough for me, and off I go to make photographs.

[Cor]

Brian,

What is the lens-subject distance?

At what f stop did you use that 135 mm lens?

best,

Cor

Not large, but noticeable. And I mean noticeable with a 22x loupe on the film, which is visible on a 16x20 (4x) enlargement. And what does +/- 0.007-in. mean? How about a potential 0.014-inch difference?? That's still within specified tolerance, but could you really make tack-sharp pictures with that?

Here's the test sequence I used:
1. Load holders with Techpan (may it rest in peace, amen)
2. Open 2nd story window, remove window screen, and position big fat heavy Bogen tripod firmly, without camera going out window.
3. Focus with 8x loupe on ground glass, and move focusing knob ever so gently. Lock down the focus.
4. Carefully insert holder, and make exposure. Develop film, and then compare to image on glass.

How close does it look? Is it "all right!" or "Huh??" quality? If the quality is "huh?" then take dial calipers, and make many measurements and adjustments. Repeat until quality is "all right!" So I continued to get it down to 1mil off from the Graflex holder.

Yes, Lachlan, a dial caliper can be opened to 1mil, easily. You can see a 1mil gap between the jaws, easily. Magnetic tape is 1mil thick.

I don't think that it's necessary to measure every holder. Could the manufacturing tolerances be that out-of-whack from holder to holder? I think that the holders would look warped if that was the case. One sample is good, and then move on.

How many line pairs does my 135mm Wollensak Optar lens resolve? I have no idea. All I know is that at two blocks, I can count all of the spokes on a bicycle wheel. The bricks on the wall are like etchings. Somebody else can do the trigonometery, all I care about is that I like what I see.

Beyond that, it is sharp enough for me, and off I go to make photographs.

[Gordon Flodders]

Yes, Lachlan, a dial caliper can be opened to 1mil, easily. You can see a 1mil gap between the jaws, easily. Magnetic tape is 1mil thick.
.

My tapes measure around .015mm thickness..I think 1mm must be pretty heavy duty stuff
I'm perplexed by the attitude here, it's only a question regarding which film holder is best and we're only talking poofteenths after all.
The problem is not if some holders vary a little, because there's far more chance of the ground glass screen telling lies than anything else. In low light, it's damn near impossible to ascertain correct focus even with a decent loupe. I always shoot wide open for portraiture, no matter which lens... doesn't everyone?

I recently tried this: Low light portrait shoot with a Sinar 4x5 using the GG. Hit rate for accurate focus using a 4X loupe was two out of six. Using a rangefinder equipped 4x5 the accurate focus hit rate was 8 out of ten. I used the same holders, so that has no bearing on the results.

How often is there indecision about where the focus is at it's best using a ground glass screen? How long does one mess about checking focus while the model's pose goes on the wane?

Anyone who can adjust their focus to make a .005 difference would do better to build an atomic clock.

Give me a rangefinder any day

GF.

[Lachlan 717]

Yes, Lachlan, a dial caliper can be opened to 1mil, easily. You can see a 1mil gap between the jaws, easily. Magnetic tape is 1mil thick.

Brian,

I think I mentioned 0.127mm, not 1mm...

[Robert Hughes]

Mils, millimeters, microns, the designations get confusing...
I have a home made 8x10 box camera that slides on wooden rails. No way could I tweak that box to within 0.001" focus. But it seems to take good pictures. My guess is that one's sensitivity to depth of focus issues may be a distraction from the general goal of photography. Just take the d@#m shot and be done with it.

What's the best 4x5 filmholder? The one I've got at hand. Wooden, plastic, old, new... as long as it's square and doesn't have a light leak I'm OK.

[Brian C. Miller]

Um, guys, 1mil is not 1mm. A mil is 0.001-inch, and "mil" is exactly how it is spelled. (link)

Cor: I don't know the exact distance, but I'm guessing 1,055ft based on Google maps. All I know is that the subject matter was two blocks from my window. I think I shot at f/4.7 or f/8.

[emmett]

Hofman metal master worth looking at?

If you can findem
They where great.

[evan clarke]

Hi Evan,

I must confess I don't know what the "automatic slide stop" is. Could you expound, please.

Thanks.

- Leigh

There is a little buton which locks thendark slide. When placed in the camera, the button is activated and the darkslide automatically unlocked for removal. Much more convenient than manipulating L screws and I like to have the slides locked...Evan

[Bob Salomon]

There is a little buton which locks thendark slide. When placed in the camera, the button is activated and the darkslide automatically unlocked for removal. Much more convenient than manipulating L screws and I like to have the slides locked...Evan

Only on some cameras A Linhof does not release the lock.