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View Full Version : Strange fruit : focus problems on Norma



Axel
12-Jun-2013, 09:50
While doing tests to check on basic functions and film planeity of a DaYi rollfilm back (which I had to return : not plane at all, random view-spacing), I've been experiencing a very strange problem : what I focus on while shooting isn't what ends up being in focus on the film !

Never happened to me in 25 years : 4x5", 8x10", field, studio, portrait, still-life, whatever. Never.


The Sinar is straight : no tilts, no shifts.

My first option was to blame the new lens (Sinaron 55/4,5) - silly, I know. But the problem did happen whichever lens I used : 55 / 75 / 90 / 150 / 180 / 240 / 300 - same. I use the most open diaphragm so I can check exactly where the focus should be.

Even more strangely, the problem is more pronounced when I use wide lenses (55>90) rather than the longer ones.

Second option... my own eyes ! But it is out : did some shoots with a Yashica MAT-124G and they are are sharp as can be (great lens btw).

The problem is that whatever I focus on, the actual focus ends up in front of the desired (and dialed) focus point, closer to the camera. I am as sharp as can be on the ground glass and I even use my three different Norma backs to be sure.
Focus is (re)checked just before taking the image and after as well with a variety of loupes and eyepieces.

Whether I use a 4x5" chassis or the 6x9cm Horseman rollfilm back - don't matter, same problem. Still have to check my old 6x7cm Calumet C2 (just so I can say I've covered all the possibilities !).

I've uploaded a quickie sample made with the DaYi before returning it here (http://www.axeldahl.com/LFPH/test-DaYi-02.jpg) and the Horseman back yesterday here (http://www.axeldahl.com/LFPH/test-HORSEMAN-05.jpg) (zoom in on both).


Simply put : whatever I focus on while making the shot should be the sharpest point on film. Even if the two Norma bodies are acrobatically spread, the focus point I choose becomes the film's sharp(est) spot - right ?

But isn't !

...any ideas ?

E. von Hoegh
12-Jun-2013, 10:00
There's something caught between the GG frame and the back of your camera? Something is moving the film plane farther from the lens than the GG you focus on.

If the GG is properly placed, and if the film takes up the same position as the GG, then whatever you focus on will be sharp.

How do you focus?

Tobias Key
12-Jun-2013, 10:01
The only thing I can suggest is to use a micrometer to check that the ground glass is in the right place. If the error is consistent across everything the ground glass must be to blame.

Sevo
12-Jun-2013, 10:03
Across three backs and five lenses, we can probably rule out the camera. Maybe the onset of presbyopia? The Yashica being immune might merely mean its finder is infinity adjusted whereas your loupes are set for a meter apparent viewing distance (as common). Can/do you see the screen grain and the focused image at the same time? If not, try to adjust your loupes until you can - but many adjustable ones will only adjust the wrong way, towards myopia values, so it might be time to see an optician for glasses and/or corrective eyepieces...

Axel
12-Jun-2013, 10:29
Thanks for suggestions all !

I must add that the Norma hasn't changed a bit since doing the Nouvel and Perrault images last year : same old Norma back I've been using since... 1990. Very tired fresnel, scratched GG but always fine.
The other viewing backs acquired since don't change a thing : sharp on all at the very same spot.

The DaYi required removing the GG and so does the Horseman ; the Calumet, like the 4x5" Fidelity chassis, are slide-in. But that makes no differences, either.

For critical focus, I do not use the Sinar mirror/binoculars so I focus with the same Nikon loupe I've been using all these years which I also use on the GG of the Yashica to check a bit closer (quirky slide in but it works and does help :)
I've never adjusted it ; I put it directly on the GG (or the Fresnel for the backs that have the Fresnel up front) and focus ; I see everything.

Perhaps Sevo has it right. Will try to toy/adjust it tomorrow. And then see an optician :(?((

Tobias Key
12-Jun-2013, 10:55
Have you thought of having a friend or assistant check your focussing?

Axel
12-Jun-2013, 11:02
@ Sevo
Just tested on my main Norma back with the 150mm and toying with the loupe's top piece don't change nothing either : same sharpness to my eyes (and that old 1963 Symmar is a killer, too).

The Nikon I use for focus, the old battered Sinar mainly for wider viewing and composition but also for focus : it "feels" right in it when I am spot-on in focus...

96905

Axel
12-Jun-2013, 11:06
@ Tobias Key
Ah - I work alone now but the last time I did have an assistant was last june ; he did the fine focus which I naturally checked and it was as if I had done it myself : crystal sharp.

If eyesight it is, can it fail so... suddenly, in a matter of weeks ?

Sevo
12-Jun-2013, 11:32
If eyesight it is, can it fail so... suddenly, in a matter of weeks ?

It won't actually fail in a matter of weeks, but it will appear to suddenly go past the threshold where it affects some particular task - the very moment the screen drifts out of your eyes focal range, you start to focus on the aerial image in front of the screen, and for that purpose, millimetres are critical.

Axel
12-Jun-2013, 11:36
... then I guess a visit to an optician will have to be scheduled for tomorrow :(

E. von Hoegh
12-Jun-2013, 12:09
@ Sevo
Just tested on my main Norma back with the 150mm and toying with the loupe's top piece don't change nothing either : same sharpness to my eyes (and that old 1963 Symmar is a killer, too).

The Nikon I use for focus, the old battered Sinar mainly for wider viewing and composition but also for focus : it "feels" right in it when I am spot-on in focus...

96905

Try this: Take the lens off the camera and point the camera so the GG is illuminated. Focus the loupe so the texture of the GG is sharply defined.

Brian C. Miller
12-Jun-2013, 12:09
Axel, I seriously doubt that it's your eyes. If it was your eyes, you wouldn't see anything as being sharp. Do you know if your camera had shims between the GG-Fresnel set and the frame?

From what it sounds like, your GG-Fresnel combo is out of plane with the film. My Super Graphic's original GG-Fresnel had been replaced with just GG, and so I had to buy a replacement set, test it and shim it. Now it's a camera I won't give up. IIRC, before I shimmed it I had the same front-focus problem as you describe, but a bit worse. As has also been suggested, something may have hung up in the holder path. If your camera has a felt light trap, check to see that it's in its proper place.

Otto Seaman
12-Jun-2013, 12:29
The Sinar's back has milled bosses to position any thickness of ground glass in the proper position without shims or any fuss. The Sinar fresnel is external and only used for composition, not focusing.

I suspect that you gradually began to focus improperly over time as your eyes aged and changed. For me it all occurred in less than a year, and if you use longer lenses stopped down you might never notice that you've missed focus.

Try some reading glasses, try to focus on the ground glass without any loupe, then confirm that focusing with a loupe. What looks good and sharp at a distance should also agree with your loupe. If not then it is time for glasses.

Sevo
12-Jun-2013, 12:31
From what it sounds like, your GG-Fresnel combo is out of plane with the film.

For three different GG/frame combos? You can rule out the Fresnel, by the way, that is a instant removable behind-screen accessory on Sinars.

Brian C. Miller
12-Jun-2013, 13:52
Hmmm, my experience with Fresnel lenses comes from Toyo and Graflex, where the Fresnel is between the GG and the lens. My other cameras don't have Fresnel lenses, just plain GG.

I really think something is funky with the equipment, especially if all of this happened after trying the DaYi holder. On my Graflex and Toyo holders, the backs have clips to seperate the GG and springs from the back, exposing the Graflok clips. So Axel tried three different backs, but I don't know if that is like the small section that pops off the back, or if it is the entire rear standard section that clamps on the rail, and the bellows attach to it. If the "backs" just clip on to the rear standard, then there could be something that is throwing off alignment.

Axel
12-Jun-2013, 14:04
Thank you all again !
(I seriously hope it is NOT my eyes)

The main Norma back... let me take a photo, it'll be easier.

96912

The fresnel rests unattached on the bottom of the Norma frame (ie, the lens side) while the GG rests on the two clear patches (the "milled bosses" ; no shims indeed) and secured by the regular screws and tin bits.
This back is the one I've used since 1990 ; no reason it should suddenly "stop working" ; the other one is the same except it has no fresnel under the GG but the GG rests on the same places and is attached with the same system.
Both frames, fresnels and GGs are absolutely identical ; when I swap them to check for focus, the results are also absolutely identical.


@ von Hoegh
Try this: Take the lens off the camera and point the camera so the GG is illuminated. Focus the loupe so the texture of the GG is sharply defined.
Playing with the loupe, I don't see any difference : it's all sharp to me. But I don't see any "texture", or grain, only the concentric circles (for the one with "built-in" fresnel) or indeed the grain (for the other).


@ Brian C. Miller
As has also been suggested, something may have something may have hung up in the holder path. If your camera has a felt light trap, check to see that it's in its proper place.
I'd then to think the crux would be of that kind but the felt is fine, nothing anywhere, either in the Norma or on the chassis/Horseman/Calumet.


@ Otto
[...]and if you use longer lenses stopped down you might never notice that you've missed focus.
When I see the full-size 4x5" scans of the Perrault and Nouvel images, trust me... I'm on focus :) By that I mean "spot on on focus", not the focus I'd get only because I'm stopped at f16 or f22 : it's exactly where I meant to place it when doing each shot.

@ Sevo
For three different GG/frame combos? You can rule out the Fresnel, by the way, that is a instant removable behind-screen accessory on Sinars.
I have three backs but actually only use two (since this problem crept up) : one has the detachable front fresnel, the other has it under the ground glass. Practically speaking, if I focus with one then check with the other there is absolutely no difference in focus point.


Never mind now -
I'll see an optician tomorrow and see what, if anything, has to be seen after. And if it ain't my eyes, I guess my old Norma has done its time (I think it's a mid or late 50s model) and I'll either have to go get my P2 (for field work - argh) or buy a decent F2 with no ageing issues.

Will keep you posted - thanks for your help and suggestions.
ax.

Otto Seaman
12-Jun-2013, 14:58
Why not try the back from the P2 on the Norma and vice-versa? Seems impossible that the camera would be the problem.

Ah Yes on the oldest Normas the fresnel was between the ground glass and lens, they claimed the backs were calibrated for it.

Joseph Dickerson
12-Jun-2013, 15:30
Across three backs and five lenses, we can probably rule out the camera. Maybe the onset of presbyopia? The Yashica being immune might merely mean its finder is infinity adjusted whereas your loupes are set for a meter apparent viewing distance (as common). Can/do you see the screen grain and the focused image at the same time? If not, try to adjust your loupes until you can - but many adjustable ones will only adjust the wrong way, towards myopia values, so it might be time to see an optician for glasses and/or corrective eyepieces...

On the contrary, I'd think that all those backs and all those lenses exhibiting the same problem would indicate that it has to be the camera.

I once had a 67mm polarizer that caused a focus shift (it was a Hoya) with all my lenses, I had cleverly adapted all my lenses to 67mm so I could use one set of filters, which meant...the same polarizer. Careful photographer that I am, I focused without the filter then applied the filter factor, and judged the polarizing effect before I put the filter on the lens. Could be something as simple as that.

JD

Jim Jones
12-Jun-2013, 16:24
Polarizers can indeed develop a focus shift. I've had it happen with maybe two 52mm Nikon polarizers. Probably it is because of the sandwich construction of polarizers. Mine had been subjected to extremes of temperature, and a difference in the coefficient of expansion between metal, glass, and plastic might have been responsible.

Lou Baleur
12-Jun-2013, 16:33
Perhaps try focusing with GG and then try inserting a film back but put a piece of tape or frosted/waxpaper in the place of the film and check the focus on that. That can rule out the groundglass being too close. Use Wide open lens and focus on a flashlight or other light source to be sure.

Bob Salomon
12-Jun-2013, 16:40
"The fresnel rests unattached on the bottom of the Norma frame (ie, the lens side) "
Put the Fresnel on your side of the GG not the lens side.

Are you using a Sinar Fresnel or a do it yourself one?

Sevo
12-Jun-2013, 23:41
On the contrary, I'd think that all those backs and all those lenses exhibiting the same problem would indicate that it has to be the camera.


You never had a Sinar, I assume? On Sinars, you swap the entire back frame assembly in its (lens board sized) standard attachment - replacing everything that could possibly cause a focusing difference between the GG and film holders. There is a small chance that could be the holder, but he stated he had used several of them as well.

Axel
13-Jun-2013, 00:06
@ Bob
The three fresnels and GGs I have are all standard Sinar parts : nothing DiY or custom.

The back with "built-in" fresnel is standard Sinar (never opened or touched by anyone) and the one I've been using since 1990 ; if there had been a problem with it, I should have had this focus problem since 1990... but didn't.
On either backs, with or without fresnel, the GG does rest on exactly the same spots so with or without front- or back-fresnel, the focus point is exactly the same.

Struan Gray
13-Jun-2013, 00:20
Your symptoms are exactly right for a situation where the optical thickness of the Fresnel is not being compensated for.

I have an original Norma Fresnel for my 5x7 back which goes between the ground glass and the lens. The manual indicates that the 4x5 one is mounted the same way. Crucially, there are small wings at the edges which go between the ground glass and the milled reference surfaces on the metal frame. This moves the ground glass backwards (by about one third of the total physical thickness of the Fresnel) and compensates for the way the Fresnel shifts the plane of focus.

What worries me is that you said the Fresnel on your Norma was removable. That implies that when you put it in place there is no compensation of the ground glass position. That will lead to exactly the effect you have found: the ground glass is optically too far forward, so when you focus on it the film ends up too far back, and thus is focussed on something closer.

As to why things worked before, I don't know. My 5x7 Fresnel is brittle with age, and the tabs are thin and friable. Something may have snapped, or was already detached and simply finally worked loose from under the clip that holds the ground glass in place, allowing the ground glass to shift from where it has been since you bought the camera.

If the Fresnel really is easily removed, try focussing with it in place, and then remove it. You should see the same shift in the focus point.

The solution is to make sure any bits of old Fresnel tab are removed so that the ground glass locates directly onto the reference surfaces, and then to use one of the Fresnels from your other backs on the outside - i.e. between the ground glass and your eyes.

Sevo
13-Jun-2013, 00:44
What worries me is that you said the Fresnel on your Norma was removable. That implies that when you put it in place there is no compensation of the ground glass position.

He was talking of three backs - a early one (fifties vintage) with a built-in lens side fresnel (presumably distance compensated at the factory). The other two will be regular Sinar style, where a snap-in viewer side fresnel can be attached for viewing (but is not used for focusing).

Struan Gray
13-Jun-2013, 01:16
I could be wrong, but


The back with "built-in" fresnel is standard Sinar (never opened or touched by anyone) and the one I've been using since 1990

Yet the posted image shows a back with no ground glass or Fresnel. And Axel's postings imply that he has not yet realised that a Fresnel between the ground glass and the lens *requires* an adjustment of the ground glass position, especially with wide angles.


On either backs, with or without fresnel, the GG does rest on exactly the same spots so with or without front- or back-fresnel, the focus point is exactly the same.

This is not right.

Doremus Scudder
13-Jun-2013, 01:22
Axel,

It is more than likely not your eyes. Even with presbyopia (age-related nearsightedness caused by the eye's lens losing its flexibility), if something looks sharp, then it's sharp. Presbyopia does NOT change where you perceive sharp focus, it just keeps you from focusing closely with your naked eye and needs to be compensated for using glasses or, in your case, a loupe.

The focus problem you relate means that the film plane and the ground-glass plane are not registered correctly. If Fresnel placement is not the issue (do test this to eliminate or confirm it) and your loupe is working well for you on other cameras (i.e., is in focus for your eyes, but test this too to eliminate it), then there are really no other choices.

If the actual focus is closer to the camera than where you focus on the ground glass, then the film is positioned slightly in front of (i.e., closer to the lens) than the ground glass. The reverse if the actual focus is farther from where you focus on the ground glass.

Time to examine all components carefully to see what the problem is. I'm not familiar with the Sinar system, so I'm just brainstorming here: Look for anything that would prevent the filmholders/roll-film backs from seating correctly. Look for anything that may have caused the ground glass to be out of position.


... The back with "built-in" fresnel is standard Sinar (never opened or touched by anyone) and the one I've been using since 1990 ; if there had been a problem with it, I should have had this focus problem since 1990... but didn't.
On either backs, with or without fresnel, the GG does rest on exactly the same spots so with or without front- or back-fresnel, the focus point is exactly the same.

There is a real problem with the above: If a Fresnel screen is placed between lens and ground glass, there WILL be a focus shift compared to using ground glass alone. For cameras designed to have the Fresnel so positioned, this focus shift has been compensated for. Try your Fresnel back with and without the Fresnel screen, as Struan suggests. In any case, If you have identical Norma backs, with the ground glass positioned in exactly the same place, but one has a Fresnel screen on the lens side, then the focus should NOT be the same between the two. One should exhibit the focus shift caused by the Fresnel.

Edit: The more I read Struan's post above, the more I think he is right on.

Good luck finding your problem,

Doremus

Axel
13-Jun-2013, 01:37
I've added three more images of the back that I actually use :
split up (http://www.axeldahl.com/LFPH/IMG_2006.JPG)
viewing side (http://www.axeldahl.com/LFPH/IMG_2008.JPG)
lens side (http://www.axeldahl.com/LFPH/IMG_2007.JPG)
This a full-factory back : never changed anything.

The other is the same, except it has no fresnel on the lens side (but the GG rests on the same surface so I could add a back fresnel if I wanted to) ; with this one I use the Sinar snapon front fresnel for clearer viewing when using a wide-angle lens.

Again, whichever back I use, the focus point remains exactly the same to my eyes.

If you look at the DaYi sample (http://www.axeldahl.com/LFPH/test-DaYi-02.jpg), focus isn't off by a minimal margin due to a slight thing somewhere but completely out in the woods : zoom in on the image's center.

Other tests done with the Horseman show the same : to focus that much off limits, I'd have to be drunk and high :)

Or in need of glasses ?

Axel
13-Jun-2013, 01:50
Doremus,

Just tried (again) now with a 300, a tiny little delicate thing far away to focus on and swap backs : absolute same.
On the main back I see the added fresnel concentric circles, of course, on the other just the GG's grain, of course again, but the focus point doesn't change between the two.

If there were any focus changes which my eyes weren't able to detect (anymore), it would be of the tiniest kind, something stopping at f22 would entirely cover.

But the samples uploaded show enormous differences : something like 5cm at a 60cm distance or 10m at a 40m distance ! If my eyes were that bad, I couldn't even use my iPhone !
There must be something else - but what ?

Sevo
13-Jun-2013, 02:59
Doremus,

Just tried (again) now with a 300, a tiny little delicate thing far away to focus on and swap backs : absolute same.
On the main back I see the added fresnel concentric circles, of course, on the other just the GG's grain, of course again, but the focus point doesn't change between the two.

If there were any focus changes which my eyes weren't able to detect (anymore), it would be of the tiniest kind, something stopping at f22 would entirely cover.

But the samples uploaded show enormous differences : something like 5cm at a 60cm distance or 10m at a 40m distance ! If my eyes were that bad, I couldn't even use my iPhone !
There must be something else - but what ?

1. Forget the main back for a while - fresnels may have their own issues regarding focusing, you should work this out with a bare ground glass.

2. (Bright) ground glass focusing often is partially diffuse, partially off an aerial image. If presbyopia moves the ground glass out of your sharp viewing range, you will lose the visual anchor on the diffuse image and ground glass texture, and may start to focus on the floating aerial image somewhere to the lens side of the ground glass. Aerial images have no depth of field, regardless of aperture, so stopping down does not improve focusing in that particular case.

3. The described focus errors are not enormous, at least for the images you have shown so far - for a 55mm lens, the extension is around 5mm at 60cm distance, so a 5cm focus shift would be caused by a mere 0.5mm register error at the back.

Axel
13-Jun-2013, 03:18
Sevo,

I have friends coming over this afternoon : will ask both of them to focus for me (with the "bare" no-fresnel back) and then will check with my own eyes. Will repeat several times with 55mm, 300mm, long-distance, close-distance etc.

Now, if their focus corresponds to mine every time... it must mean something happened to my Sinar and not my eyes, right ? (??)

ax.

Axel
13-Jun-2013, 09:37
Test done with other people focusing for me and nothing here : I focus exactly where they do, no difference.

So there must "something" between GG and Norma back(s) ; will go tomorrow morning to the only LF shop in Paris, Norma in hand, to see and hear if they have a clue.

Thank you all for your patience and input.
ax.

Jerry Bodine
13-Jun-2013, 11:04
I've added three more images of the back that I actually use :
split up (http://www.axeldahl.com/LFPH/IMG_2006.JPG)
viewing side (http://www.axeldahl.com/LFPH/IMG_2008.JPG)
lens side (http://www.axeldahl.com/LFPH/IMG_2007.JPG)
This a full-factory back : never changed anything.

Axel, if I may muddy the waters a bit more. My late 60s 4x5 Norma back has no fresnel on the lens side and has the clips to attach the removable fresnel to the eye-side and has never exhibited any problems. These uploaded images show a configuration which employs a fresnel on the lens side AND the clips for the removable eye-side fresnel. Since one would never use BOTH fresnels at the same time, it seems odd that a full-factory back would be supplied this way. So I would ask whether this back was in fact supplied by the factory, or whether it was purchased "new" from another outlet and assumed it was a factory configuration?

Joseph Dickerson
13-Jun-2013, 13:49
You never had a Sinar, I assume? On Sinars, you swap the entire back frame assembly in its (lens board sized) standard attachment - replacing everything that could possibly cause a focusing difference between the GG and film holders. There is a small chance that could be the holder, but he stated he had used several of them as well.

Actually a Sinar user (F1) for twenty years. The OP mentioned sample images from Horseman and Dayi roll film backs, and multiple lenses. Ergo my suggestion that multiple backs and lenses indicated a camera problem.

Maybe it would be less confusing if he had referred to them as roll film holders. Either way, it's a puzzlement, and I feel his pain.

JD

Sevo
13-Jun-2013, 13:56
As roll film holders do not come with a variety of fresnels, I assumed that backs meant backs - and the photographs posted later on confirm that. Now, I can believe in grown variations across different backs, but there is no place where a uniform focus error on all of them could have grown by mere old age on Sinar type backs, as the register distance is permanently milled into them, and not subject to shims or adjustment screws. It must either be an issue with the holders, or the Dayi holder (after whose purchase the troubles apparently started) damaged all backs the same way - but I am absolutely stumped as to how it could have done that.

Joseph Dickerson
13-Jun-2013, 16:01
Sevo...you made the right assumption, I didn't! Sure hope he sorts it out, a lot of us will be losing sleep over this one.

"Curiouser and curiouser"!

JD

Otto Seaman
13-Jun-2013, 17:19
As roll film holders do not come with a variety of fresnels, I assumed that backs meant backs - and the photographs posted later on confirm that. Now, I can believe in grown variations across different backs, but there is no place where a uniform focus error on all of them could have grown by mere old age on Sinar type backs, as the register distance is permanently milled into them, and not subject to shims or adjustment screws. It must either be an issue with the holders, or the Dayi holder (after whose purchase the troubles apparently started) damaged all backs the same way - but I am absolutely stumped as to how it could have done that.

I agree, it is hard to imagine this stemming from the camera itself. It should be repeatable with the Sinar P he mentions owning, ruling out the camera.

Perhaps it an Absinthe problem?

Axel
14-Jun-2013, 03:40
Well, weirdness continues :
I show the LF shop owner both my Norma backs and right off the bat he points one out and says "That is not right."

One very american acronym is creeping up in my head, WTF ?, because "that" is the one I've been using since 1990 with no focus problems whatsoever, whether studio, lifestyle, portrait, close, far, up, down and diagonals ! The one with the fresnel sandwiched under the ground glass !

Then he points to the other back and says "But THIS is right" - "this" being the one I bought recently with only the ground glass and removable framed fresnel...


So I guess I'll be making (another set of) tests this weekend on 4x5" and 6x7 and 6x9 with THIS back, the one that's RIGHT, in hope of getting all this right AGAIN.

The P2 is in Lyon and I'm in Paris ; I don't know when I'll go get it back but since I don't do studio anymore, I'd rather stick to the simple and somewhat more lightweight Norma. And if THIS back is RIGHT, then I really don't need to go get my P2 for a simple test... right ?
Come to think of it, I also have the 8x10" Polaroid developing machine - no use for that anymore either :(


Anyway - I never did drink absinth :)

(or maybe I did ?)
(but maybe I should ?)

Sevo
14-Jun-2013, 04:00
Well, weirdness continues :
I show the LF shop owner both my Norma backs and right off the bat he points one out and says "That is not right."

One very american acronym is creeping up in my head, WTF ?, because "that" is the one I've been using since 1990 with no focus problems whatsoever, whether studio, lifestyle, portrait, close, far, up, down and diagonals ! The one with the fresnel sandwiched under the ground glass !

Then he points to the other back and says "But THIS is right" - "this" being the one I bought recently with only the ground glass and removable framed fresnel...



A poster here on the thread already pointed out that this at the very least suspicious, as that is a frame with the recess for a rear fresnel, which is quite unlikely to be factory made with a front side fresnel. Sinar components are milled to fit and the ground glass is placed on forward rests, so there is no way to place a fresnel between the original rests and ground glass without screwing up focusing. You'd have to grind down the frame to make room for the fresnel - impossible at least on my Norma frames, as the ridge forward of the rests is not strong enough to cut away the about 3mm taken up by the fresnel and air space on my front-fresnel cameras.

Did you perhaps in the past use only a holder that came with that camera and back (at least for your positively in-focus results)? If so, it might be worth checking whether the film plane on that holder has not been modified to match that apparent fresnel hack on the frame.

Axel
14-Jun-2013, 04:15
Sevo,

The only rollfilm holder I used with the Norma is the old Calumet C2 - in focus.
What I mostly used this Norma with were and still are my three dozen 4x5" chassis - in focus.


... that is probably why I should start drinking absinth :)

Struan Gray
14-Jun-2013, 04:18
My 4x5 Norma has the same clips, and the accompanying 5x7 back - which was bought by the original owner at the same time as part of a 5x7 'Expert' kit - has the early style Fresnel which goes between the ground glass and the lens.

Something is placing Axel's rollfilm holders further back from the lens than the ground glass position. Axel's statements here about the Fresnel are not consistent with each other, or the picture of the disassembled back he posted. That's not a personal attack, but a gentle reminder that there may be factors here which he does not (yet) appreciate. You should not be able to pop the internal Fresnel on and off while maintaining focus. If you can, and do, something is wrong with that Fresnel or the way you are using it. It's not rocket science.

If the back with the internal Fresnel truly does agree with those with external Fresnels, then something else is shifting the filmholders backwards. My Normas had some loose and dodgy light sealing cork/black string around the attachment to the format frame which needed to be sorted out before lensboards (front standard) and the international back (rear standard) would seat correctly on the milled reference marks. However, the roll film backs Axel is using attach to the international back, so any such misalignment should be common for the ground glass and film. If something is fouling the film holders but not the ground glass the most likely culprit is the groove at the insertion end of the back - crud here will lever one end of the rollfilm holders backwards.

Axel
14-Jun-2013, 04:59
Struan,

I suppose my "main" Norma back (the one shown above) also was part of an "expert" kit because it came bundled in a big Sinar with 5x7" and 8x10" backs and all sorts of accessories (not at hand ; all in Lyon).
As far as I know it never was modded by anyone, at least not me as I wasn't even born in '57 :) I've always used it like that and it always worked...
However, I cannot "pop" the fresnel out but have to unscrew the top clips, pull the gg/fresnel duet, leave the fresnel on the table, re-screw the clips.

The other Norma back is the same, except there is no fresnel held under by the ground glass ; that's the one I will test now, in hope all this goes away.


I see and agree with your logical path but all grooves, frames, ends, sealing velvet are fine : no dirt, no crud, nothing.

When I attached the DaYi, now the Horseman, fixing has typical "swiss" quality : firm, direct, secure, ie. no fiddling or forcing necessary.
The Calumet C2 goes in like a chassis : slide-in, like the million 4x5" in Fidelity chassis and Polaroid 54/55/59/Fuji in 550/545 holders I must have used since 1990 - all in focus.




btw, off-topic, this on your website is masterfuly formulated : "I will always take a wash of subtle secondaries over any amount of primary fire."

Doremus Scudder
14-Jun-2013, 05:36
Axel,

This is getting ever stranger. However, since there is a discrepancy between your focusing and the focus on the film, there must be a discrepancy between ground-glass plane and film plane or your focusing plane and the ground-glass plane. I agree with Sevo above; eliminate the Fresnel screens from the equation for now and spend some time with the back that just has the ground glass.

Although I am a bit skeptical about presbyopia causing any problems, make a pencil mark or stick a piece of tape on the frosted surface of the ground glass and check to see that you are indeed focusing on the plane of the surface of the ground glass (do this with no lens mounted). Adjust your loupe if needed to make sure you've got the right focus.

Also, waste a bit of film (use scrap if you have it) and measure the best you can from the inside of the dismounted back to the ground glass surface. Then, insert a loaded filmholder or rollfilm holder, pull the darkslide and measure to the film surface. You are just comparing here, so use a sturdy and true straight edge as a bridge and something smaller but equally stable as a crosspiece to rest on the ground glass/film and cross the bridge piece. Any discrepancy here must be significantly smaller than 0.5mm to be acceptable.

If film plane is aligned with the ground-glass plane, and you are indeed focusing on the frosted surface of the ground glass, then there can't be a problem.

FWIW, I had a felt strip slip out of place on one of my cameras once. It ruined focus on negatives from an entire trip. The error was very small.

Best and good luck (and keep us posted),

Doremus

Axel
17-Jun-2013, 14:33
Ah, well, tests #5 received and the results are so inconclusive that this borders on madness.

Big files uploaded : zoom inside the squares.

4x5 with the 90mm (http://www.axeldahl.com/LFPH/4x5-90mm.jpg) : all is almost fine
4x5 with the 55mm (http://www.axeldahl.com/LFPH/4x5-55mm.jpg) : argh !

6x9 with the 240mm (http://www.axeldahl.com/LFPH/6x9-01.jpg) : perfect, as it should be.
6x9 with the 90mm (http://www.axeldahl.com/LFPH/6x9-02.jpg) : as was in the gg, although it seems the focus area is "displaced" to the left...
6x9 with the 90mm (http://www.axeldahl.com/LFPH/6x9-03.jpg) : not as sharp as it was in the gg and the actual in-focus area can be seen in the cloth, forward of the center point...
6x9 with the 90mm (http://www.axeldahl.com/LFPH/6x9-04.jpg) : focus is again forward - the green cushion is more detailed than the Ellington record strip !
6x9 with the 150mm (http://www.axeldahl.com/LFPH/6x9-05.jpg) : focus is again left field of wherever forward.
6x9 with the 75mm (http://www.axeldahl.com/LFPH/6x9-06.jpg) : focus is again left field of the next... galaxy ?
6x9 with the 55mm (http://www.axeldahl.com/LFPH/6x9-07.jpg) : focus is again strangely spread across elsewhere.
6x9 with the 55mm (http://www.axeldahl.com/LFPH/6x9-08.jpg) : focus is again slightly forward (the top of the knobs is in focus but it is their bases that should be).

I'll spare you the 6x7 made with the Calumet C2 : some are perfect, some are completely off as well.

I have several days of shoot at the Fondation Cartier end of this week so I'll rent the back of a Sinar F2 or P2 because this is impossible to figure out ; as I don't see myself making sixteen-hundred test sheets and rolls, I think I'll go get my P2 back in Lyon next week !


@ Doremus
Pencil test done and and I am focusing indeed on the frosted/gridded surface.

Sevo
17-Jun-2013, 14:45
All over the place does not sound like a ground glass issue, by the samples and the description where their focus should have been you have swing/tilt as well as forward/backward errors, so the glass cannot simply be off into one direction. And you should notice if the glass is loose in its frame, or the frame is obviously wobbly. Perhaps the camera breaking loose from its locks when you insert a holder? I've had a F that grew increasingly unreliable through a similar issue...

Axel
17-Jun-2013, 22:10
Sevo,

Tight and straight everywhere, no wobbly ground glass or frame.
After each shot is done, I reattach the gg and check with my eyes and two loupes : everything is like it was before putting the rollfilm or chassis in.

Otto Seaman
17-Jun-2013, 22:29
At least you are checking and not making the mistake of shooting assignments and trusting!

Good luck, I am as confused as anyone here, anxious to discover what the problem is!

Struan Gray
18-Jun-2013, 02:02
Long lenses have more depth of focus - they won't show the effect as clearly as the shorter ones.

You see the same sort of thing with the 55 and the 90, so it's unlikely to be the lens attachment. However, just for sanity's sake it's worth checking that they are firm, and that the lenses cannot tip or shift between focussing and exposure. I, for example, have had minor problems with a Norma-era Sinar-Linhof adapter board.

Something is placing the film plane further away from the lens than the ground glass. The 4x5 55 shot suggests that the film is tilted/swung too: if you line up the things in focus in 3D space you get a tilted plane.

The focus placement could come from two causes. Either something is fouling the mating surfaces so that all or one side of the filmholders is levered away from the back. Enough to show focus shifts, but not enough to prevent the Graflok slides from working or to create serious light leaks. That the effect is variable suggests that you could be looking for something soft - a stray piece of light sealing material, for example.

Were these shots taken with the ground glass assembly which has the Fresnel? I'm not obsessed, but an alternative explanation would be if one side of the Fresnel was not moving the ground glass backwards by the correct amount.


Incidentally, the Norma manual at Camera Eccentric

http://www.cameraeccentric.com/html/info/sinar_1.html

suggests that the 4x5 Fresnel does not have tabs like my 5x7 one, but instead uses a second reference surface behind the one used with no Fresnel in place. In that case, if the Fresnel has become compressed with age, it would lead to the effects you are seeing.

Axel
21-Jun-2013, 02:27
Well... the Sinar repair shop here in Paris couldn't find anything wrong my Norma !
This really escapes me (and everybody else :) so I won't bother trying anyhting else with it.

I'm renting an F2 for this weekend and next week's shoots.
As the P2 is, for me, out of the question for field work, I'll be buying another Norma or F2 rear standard for the rest of the summer's work.

And if whatever I buy still gives focus problems, then I can make a TV show about the-mystery-camera-with-eyes-of-its-own !

Axel
21-Jun-2013, 07:22
Further chatting with the repairman lead to one possible answer which actually makes sense to me.
Here goes :

1) This wandering focus point problem cannot be pinned on lenses - seven crazy lenses all of a sudden ? Acid-crazy indeed.

2) It cannot be traced down to the Sinar frames (http://www.axeldahl.com/LFPH/IMG_2094.JPG) as it would then be precisely located and would show similar symptoms and results every time.

3) It isn't the rollfilm backs or the chassis either as they all seat the same way in the Sinar frame.

4) It isn't my eyes or my loupes as all four work ok with other cameras.


The variability of the problem, thus, can only be traced to a moving part.
And that's the spring-back on which the g-g and fresnel are fixed on. This would mean that the spring-back rails (http://www.axeldahl.com/LFPH/IMG_2095.JPG) which rest on the Sinar frame are worn out enough to have me focus wrongly.
In other words : the chassis/rollfilm are where they should be but the gg/fresnel is not. Or not anymore. Or not all the time.

Solution : an entirely new spring-back ?

Does this make sense to any of you ?

Sevo
21-Jun-2013, 07:24
The variability of the problem, thus, can only be traced to a moving part.
And that's the spring-back on which the g-g and fresnel are fixed on. This would mean that the spring-back rails (http://www.axeldahl.com/LFPH/IMG_2095.JPG) which rest on the Sinar frame are worn out enough to have me focus wrongly.
In other words : the chassis/rollfilm are where they should be but the gg/fresnel is not. Or not anymore. Or not all the time.

Solution : an entirely new spring-back ?


Didn't you say you already tried several of them? And would not that be the primary thing the Sinar shop checked?

Axel
21-Jun-2013, 07:34
Sevo,

I tried both my back assemblies together (ie. spring-back + frame) but didn't swap spring-backs separately.

The repairman told me he couldn't really check much because both assemblies were/are too worn out.
That Norma has seen three professional photographers since the early 1960s - maybe too much for one spring-back !


I'll be making a simple visual test now that I have with me the rented F2 : do focus with the Norma, exchange the spring-back/frame and see where focus rests.

Axel
24-Jun-2013, 10:20
Ok, after a real-life test at the Fondation, it is obvious the crux was my old Norma rear standard.

I don't know why nor do I have a clue as to what could have happened to it during the 6 months of non-use in its bag but the use of a Sinar F2 rear gives images that are sharp like they should be.

See a raw scan made with my Epson V700 here (http://www.axeldahl.com/LFPH/FCIII-A-02-05.jpg).
(1s /f22 ; it's an image I'll be redoing btw : I'm too high there)

I don't like the way the gg/frame of the F2 kicks off (to Graflock a rollfilm back), nor do I like the two posts protruding down but I'll keep that rented rear for a week while finding a replacement.

Would love to remain with a Norma - but what if the strange fruit reappears ??
______________________________


Thank you all for your patience and suggestions !
ax.

Otto Seaman
25-Jun-2013, 17:32
It makes sense, although I can't imagine using the camera so much that you'd remove that much metal.