First photos with the Crown Graphic and 6x9 back - Focus problems?

[kuzano]

Looking at all that shine...

Looking at all that shine...

THIS POST LOOKS TO BE WRONG. I LOOKED AT THE PICTURES OF THE GG HOLDER AND HAD THE SIDES REVERSED IN MY MIND AS I LOOKED AT THEM

Looking at all the shine on the ground glass, it appears to me that the ground surface of the glass (the focus side) is inside the camera toward the lens. This is correct, and your measurement for matching would be the distance from the inner camera mating surface of the GG holder to the ground surface of the glass. Then matching measurement on the holder would be from the camera mating surface of the roll film holder to the film itself.

Unless I am missing your intention in showing us these images, I think you are using an incorrect measurement on the "GG" holder itself. I see the side away from the lens on both images of the GG holder. The depth you are noting here is the wrong side. Turn the GG holder over so the camera mating surface is up, as well as the rough non shiny side of the Glass itself. Then, the roll film holder should be camera mating surface up, as you are showing it. Those two depths should match, since it appears the ground (focus) surface of the glass is on the inside of the camera. If they do not match, your adjustments have to take place on the GG holder, by shimming or reversing the glass until both depths are identical. I would use a depth micrometer and the more exacting this measurement becomes, the closer you are to correct focus. "close" is not good enough, since enough of these "close" measurements multiply throughout the camera. Kinda makes you wonder how anybody ever got truly good images with the camera. Well, they didn't really, unless they went to this detail and trouble. Have you ever seen old newspaper photos?

Sorry to be such a persistent harp on this, but this is the very critical part of all that you must accomplish to get a start point for using either GG viewing or for calibrating the rangefinder by focusing on the correct surface of the GG.

Perhaps I misunderstood your text, but your pictures make me think you are measuring the location of the GG in it's own holder incorrectly.

I'll shut up now. (very few people ever hear that from me)

 

[Ezzie]

I had trouble with my Graflok back GG when collimating my 4x5 DIY camera and lens. The clue was that the actual plane of focus is on the front face of the GG, but on the rear of the fresnel. Without fresnel the GG will be in front of the film plane and any focusing done on the GG will result in front focusing. If rangefinder is calibrated with this setup, when used will result in back focusing.

 

[kuzano]

OK... I said I would shut up... but I also Lie profusely

OK... I said I would shut up... but I also Lie profusely

There has been a lot of discussion in this thread about placement of the ground glass, front to back placement of the ground (rough) side of the glass, to the point of confusion methinks.

Any Ground Glass viewing or focus camera, with or without a rangefinder suffers one serious technical aspect. They all involve a ground glass to focus or to calibrate a rangefinder to. They all also involve displacing or removing the ground glass to fit either holders with sheets of film, or roll film holders.

This is precisely the place for the most common failure in the system.

This is the over-riding rule in all such types of camera's... First Rule!!!

Replacing or moving the Ground Glass MUST AT ALL times, and in all configurations, place the film surface of the inserted film holder in exactly the same focus location with respect to the position of the focus (rough) surface of the GG.:bang:

The holders themselves (all styles and makes) are rarely amenable to making correction of the holder, AND if you use a holder that does not match all other holders, you may need to correct the GG position again in the future.

It matters not what piece comes before or after whatever other piece.
The First Rule is stated in RED above. Your objective is to make that happen. I go through this on almost every camera I handle. I defy anyone to take any fifty year old, relatively imprecise folding camera and not find a need to reposition the Ground Glass. Sheer luck if you get such a combination of camera and holders. Usually resultant from using the same manufacturers film holders of the same era as the camera.

Now, re the holders, one can shim the holders on the side they mate to the camera, if the GG in the camera is positioned farther back from the lens for whatever reason. Better to get the camera right however, to not have to deal with every film holder.

 

[Johnmcd]

Kuzano, thanks for taking time for such a detailed response. It is greatly appreciated. And the same to all that have posted. But now I am totally confused 🙂

Looking at all the shine on the ground glass, it appears to me that the ground surface of the glass (the focus side) is inside the camera toward the lens. This is correct, and your measurement for matching would be the distance from the inner camera mating surface of the GG holder to the ground surface of the glass. Then matching measurement on the holder would be from the camera mating surface of the roll film holder to the film itself.

Unless I am missing your intention in showing us these images, I think you are using an incorrect measurement on the "GG" holder itself. I see the side away from the lens on both images of the GG holder. The depth you are noting here is the wrong side. Turn the GG holder over so the camera mating surface is up, as well as the rough non shiny side of the Glass itself. Then, the roll film holder should be camera mating surface up, as you are showing it. Those two depths should match, since it appears the ground (focus) surface of the glass is on the inside of the camera. If they do not match, your adjustments have to take place on the GG holder, by shimming or reversing the glass until both depths are identical.

This is where I am confused. The images I have shown show the 'mating surface' to the back of the camera of the Graflok back (or the 'inside' of the back). It can only fit that way. The other side shows the flip out dark shades. Therefore the 'shiny side' of the GG is indeed closest to the lens.

What it may mean is my GG is reversed and needs to be swapped around but nevertheless the distance at which the GG is from the lens is still the same (or there abouts) to the film in the roll back (hence my posting of the two images). Just to confirm in my case, the dull (matt) side of the GG faces to the outside of the camera ie. closest to the photographer. From what I can make out this perhaps should be the reverse???

So from what I can work out, I need to do the following.

1. Make sure my GG is facing the right way. Please correct me if I am wrong but that should be dull matt side inside closest to the lens.
2. Ensure that the film plane is the same distance that the inside of GG is from the lens / body.
2. Callibrate the RF against the correct focus of the GG.

Once again I really appreciate the help here, so please don't stop with any advice. Just try not to get too frustrated with me who is definitely a '4x5 virgin' in every respect but eager to learn.

Cheers - John

 

[ChrisN]

Hi John

I just checked my Speed Graphic (with similar rangefinder to yours).

The GG is a sandwich comprising the ground glass and a plastic fresnel lens. The fresnel is towards the front of the camera, between the gg and the lens. The textured side of the fresnel faces towards the gg. The gg itself has the ground side (the surface where the image forms) towards the lens and up against the textured side of the fresnel.

Watch out for the little washers when you unscrew the brackets holding the gg and fresnel in place.

What lens? 127mm?

Are you focusing on the ground glass or with the rangefinder? Keep in mind they are two different systems, but hopefuully both correct and synchronised!

I got started with mine by setting up the ground glass as I described above, (which was given to me either by others here or on the graflex.org site. This should put the ground side of the glass at the film plane.

Second I set the camera on a tripod and focussed it at infinity (actually a radio tower about 5km away). 1. Lock down all movements in their zero positions. 2. Unlock and loosen the infinity stops (tiny screwdriver needed, don't lose the screws) and move them forward. 3. Adjust the focusing wheel to align the infinity marks on the focus scale (beside the LHS focus wheel, front of the sliding track) then lock the track with the little lever beside the RHS focusing wheel. 4. Slide the front standard to find the infinity focus position while checking the image on the ground glass. 5. When you're happy you've found infinity, lock the front standard to the sliding track, check the image again, then slide the infinity stops back and set them in place. You now have the front standard and infinity stops correct for infinity. You can also now set a target at exactly 6 feet from the film plane, focus to 6ft with the focus scale, and check the image on the ground glass. It should be pretty sharp.

Third - the rangefinder. If you have the correct cam for the lens (see post #6) hopefully the rangefinder agrees with what the focusing scale and the ground glass are telling you! If it doesn't you either have the wrong cam, or the camera has been pulled apart and reassembled with things out-of whack, and some more serious work is required.

Also - agree the comment above about f/8 and 4x5. To get reasonable depth of in-focus in the photo with 4x5 you need to be using f/16 or f/22.

 

[kuzano]

OK.. now that I look closer... I see a mistake I made...

OK.. now that I look closer... I see a mistake I made...

The two images of the GG back that you show ARE showing the back (or inside side) of the holder as being UP. I now look at the chrome hooks on each side and see that they are the hooks that face toward the lens inside the camera. Sorry... my mistake... but all the casting areas threw me off until I looked at my extra GG back I have in my parts trove.

That being the case, and looking down on the surface of the glass, the dull side should be the side facing up or inside the camera. The rough surface is where focus takes place, not the shiny side. The Ground Glass is just that, it is ground to be the focus plane.

So, aside from my first error, we should be looking at the dull side, not the shiny side. It looks like your ground glass is in the holder backwards. Throwing the focus point off even the thickness of the ground glass will play hell with your focus, because when you take off the ground glass and mount the roll film holder, your focus is off by the thickness of the ground glass. That is significant and critical focus on the film cannot be obtained this way. If you calibrate the rangefinder to the ground glass with this improper reversal of the glass, the rangefinder will never be matched to the placement of the film.

Does that all make sense, now that I see my original error in viewing the GG back holder again?

In any event, if you get the rough, dull side of the glass pointed into the camera, The measurement of the glass to the mating surface of the camera, MUST be equal to the measurement of the mating surface of the roll film holder down to the film itself.

There, I hope that clarifies the confusion I probably caused in this.

As far as hanging in there to assist, I am certainly willing to do so until it all comes together.

I just looked at those images of the GG and the film holder again, and am pretty sure, I have this right. All my other points about creating a system whereby the film sits in exactly the same location as the displaced ground glass after focus, should give you good focus on the film, even after you calibrate the rangefinder to the properly positioned GG and switch to rangefinder use.

This measurement is tenable and should remain workable UNTIL you switch to another film holder. Always check new holders as you acquire them to the one that you made the original adjustments with, or get a dimension for the GG back offset and apply it to future holders.

If you ever get another 4X5, of any other manufacture, this is a common first checkout procedure. The closer the two dimension are to being identical, the better the focus. There is not much room for difference at this first point of getting registration of the focus distance identical.

If you still have any questions on this we can continue on either on this thread, or you are welcome to PM me. I have a spare Crown Graflock back frame and ground glass holder, and will dig it out and may include some pictures as demo. I do not currently have a roll film holder, but I have a lot of various DDS (two sheet Double Dark Slide holders) and a late Pro model Kodak Readyload holder to get sample measurements from.

Hang in there. The WOW you get when you start seeing properly focused sheets of film is way worth the trouble. The first really great sheet of film I shot was a lake in the high Cascade mountains, with a lot of green reeds in the foreground, the lake and a rocky mountain peak in the background. I remember my jaw hitting the floor when I saw the processed print on Fuji Velvia 50. It was the most amazing surprise I have ever had with film, and validated large format for me ever since.

Oh yes, and John, I am not frustrated with you. I remember every step of sorting this out myself years ago, with an old Crown Graphic bought used at Columbus Camera Group in Columbus Ohio. 1989, no instructions and no internet.

I am frustrate however that the internet also poses it's own problems with getting this information to you in an orderly manner, and at my own errors in looking at the images you posted.

You seem correct in that your ground glass may indeed need to be turned over putting the dull ground side toward inside the camera. That could surely explain those original images you posted.

LASTLY HERE, I PUT A CORRECTION NOTE AT THE TOP OF MY POST THAT WAS WRONG ABOUT THE FIRST TIME I LOOKED AT YOUR GG HOLDER IMAGES, AND NOW THINK THE GG IS SHINY SIDE IN... NOT FOCUS SIDE IN.

 

[ChrisN]

Kuzano - does your ground glass have a fresnel lens?

...

So, aside from my first error, we should be looking at the dull side, not the shiny side. It looks like your ground glass is in the holder backwards. Throwing the focus point off even the thickness of the ground glass will play hell with your focus, because when you take off the ground glass and mount the roll film holder, your focus is off by the thickness of the ground glass.

...

Looking at this photo ...

... I think we are looking at the plastic fresnel lens, not the shiny side of the ground glass. See the reflection pattern - star shaped from the middle - that's the fresnel pattern reflection. I think the fresnel is certainly in backwards - it needs to be shiny side forwards and textured side towards the back of the camera and the ground glass.

Kuzano is certainly right about the placement of the ground glass in the frame being critical, and again the position of the fresnel is critical in spacing the gg at the focal plane. See also http://www.graflex.org/articles/sanz-cervera/.

 

[Keith]

The first thing to do with this camera IMO is forget the roll film back and sort out the rangefinder once it's established the screens are in the correct order.

 

[Johnmcd]

Kuzano - does your ground glass have a fresnel lens?



Looking at this photo ...

... I think we are looking at the plastic fresnel lens, not the shiny side of the ground glass. See the reflection pattern - star shaped from the middle - that's the fresnel pattern reflection. I think the fresnel is certainly in backwards - it needs to be shiny side forwards and textured side towards the back of the camera and the ground glass.

Kuzano is certainly right about the placement of the ground glass in the frame being critical, and again the position of the fresnel is critical in spacing the gg at the focal plane. See also http://www.graflex.org/articles/sanz-cervera/.

Hi Chris,

I believe it is the plastic fresnel lens we are seeing in the picture as you have said.

So let me get this right.

Do I need to take apart and flip the fresnel over so that the textured side is against the GG. The plastic fresnel lens stays between the lens and the GG. With regards to the GG, it is the dull side that is facing me, the photographer?

I hope you know what I mean 🙂

John

 

[Johnmcd]

The first thing to do with this camera IMO is forget the roll film back and sort out the rangefinder once it's established the screens are in the correct order.

Hi Keith - yep that's the plan, I think mate.

Getting there slowly 🙂

 

[ChrisN]

Hi Chris,

I believe it is the plastic fresnel lens we are seeing in the picture as you have said.

So let me get this right.

Do I need to take apart and flip the fresnel over so that the textured side is against the GG. The plastic fresnel lens stays between the lens and the GG. With regards to the GG, it is the dull side that is facing me, the photographer?

I hope you know what I mean 🙂

John

Hi John - getting there!

Fresnel - textured side towards the photographer (towards the back).

Ground glass - dull, textured (ground) side towards the lens (towards the front).

I've just found pdf versions of the service manual for the camera (6.4MB) and the top-mount rangefinder (0.5MB). PM me with your email address if you'd like a copy.

Cheers!

 

[kuzano]

That's possible... Fresnel...

That's possible... Fresnel...

However, that complicates the issue a little bit. If there is a fresnel, the way to find out is take the GG out and see if there are two pieces. Fresnels are a separate viewing aid from the ground glass. However you put it back together, again the final result does not change. the focus (dull) side of the actual ground glass is still paramount as the final measurement compared the film holder.

The fresnel has nothing to do with focus itself, but lightens the viewing a bit for better view brightness.

That said, the fresnel is a nice feature accentuating focus viewing. I would make the determination about the GG measurement in the holder first.

once that is determined, the fresnel can then be added to the mix, but only if it does not change the measurement that matches the film holder. If the GG holder measures out to match the film holder when it is alone in the holder, then the fresnel should be toward the inside of the camera, inside the Ground Glass.

If putting the fresnel first in the GG holder, and then the GG itself with the dull side inside the camera makes the focus surface match the film holder, then that would be an appropriate configuration.

An alternative configuration would be if the fresnel alone in holder matched the depth of the film plane in the film holder, then the dull side of the ground glass could be place in the holder against the fresnel, in which case the dull surface of the ground glass would face away from the inside of the camera, BUT it would be in the proper measurement location. So very many variables with one required result... placement of the focus surface (dull side of the GG) compared to the film plane of the holder.

This is getting very sticky to explain again....

So, it is again paramount that the final result must be the ground surface of the ground glass in the matching location to the depth of the film in the film holder.

To take the fresnel out of the equation temporarily, do your testing in very good light, without the fresnel in the camera. (UNLESS THE FRESNEL IS INSTRUMENTAL IN MAKING THE DEPTH CORRECT). Do all testing without the fresnel if it can be done to get a correct match on the GG and the film plane.

Then mount the fresnel in a location that does NOT change the location of the focus (dull) surface... On whichever side of the gg that does not change the measurement.

WOW...

I'm sure there are varying opinions on placement of the fresnel IF THERE IS ONE. Some of these cameras did not have fresnels or they have been removed.

Without a doubt a fresnel is a real plus on improving the viewing, but plays no part in the focus as a function of a fresnel.

 

[ChrisN]

I'll only add that if the camera (which must be a post-1955 model) was originally built with a fresnel, then the fresnel needs to be there, in the correct place, to act as a spacer for the ground glass. If you take out the fresnel you're moving the gg forward about 1mm.

 

[kuzano]

Understood...

Understood...

I'll only add that if the camera (which must be a post-1955 model) was originally built with a fresnel, then the fresnel needs to be there, in the correct place, to act as a spacer for the ground glass. If you take out the fresnel you're moving the gg forward about 1mm.

forward being which way, toward the lens, or toward the back of the camera?

Sorry, but while forward would seem to mean toward the lens, then taking it out if it's behind the ground glass would mean moving the GG back away from the lens the thickness of the fresnel... 1mm, while putting it on the inside of the camera next to the GG won't affect distance of the GG. However, reversing the GG will move the focus side the thickness of the GG forward (toward the lens) or backward (away from the lens)

So I go back to my original Rule One. Physical Measurement.

Color me a trouble maker, but again, the bottom line is to measure it all out. Thicknesses of both the pieces, and final location of the focus side of the GG as to matching the distance on the film holder.

I majored in A-Hole throughout my educational experience. I would like to agree 100% with you on this, but it's dependent on the meaning of "forward".

 

[ChrisN]

Forward being towards the lens. And the fresnel is between the lens and the GG.

The Graflok back is assembled from the back, with the fresnel going in first, then the ground glass. I've just measured my fresnel at 1.84mm thick, so if we leave out the fresnel then we move the ground glass forward, towards the lens, by 1.84mm.

I think that's where the confusion lies - in that the GG/fresnel is fitted into the Graflok back from the back, not from the front. If it was made to be assembled from the front and the GG was at the back, of course the GG position wouldn't change if the fresnel was omitted. But as it is assembled from the back, with the fresnel going in first between the lens and the GG, then the fresnel acts as a spacer to locate the GG.

And all of this may be moot anyway with the variation in film holders. I've just measured five holders picked at random. The 10 sides measured with clearances from 4.75mm to 5.35mm from the face to the centre of the plate. Of course that ignores the thickness of the film and the question of whether the film bows away from the plate. The wooden holders probably warp and shrink or expand as the humidity changes.

But generally most people would get best results by assembling the ground glass and fresnel the way the designers intended, and in accordance with the service manual.

 

[Keith]

I wonder of John ever suspected a 4x5 Crown Graphic was going to be so much fun! 😀


I meant to mention I spent a bit of time with a set of vernier calipers measuring my best film holders and comparing them to the ground glass in it's correct position ... and I might add I measured to the actual surface of the film and not just the holder backing. It was actually a few thousandths out!

 

[ChrisN]

Kuzano - you are perfectly right of course about the penultimate test being measurement (and the ultimate test of course is making a photo!).

As I mentioned above I've measured five film holders, and got an average face-to-film plate measurement of 5.12mm. Add 0.2mm for the film and I have a measurement of 4.92mm that I want my ground glass frosted side to be sitting at.

Now my Graflok back is a little difficult to measure directly as the plastic fresnel is between the face and the frosted side of the ground glass. So I started by taking a measurement of the ground glass on my Ebony 4x5. That's simpler as the GG is actually plastic, covered with a glass sheet on the outside and no fresnel needed. And being Japanese it's beautifully and I expect very accurately made. That measures 4.85mm from the face to the GG frosted side. 4.85mm is pretty close to the 4.92mm average for my film holders. Results with the Ebony have been consistently pretty good, allowing for my ability to focus solely on the ground glass. I do like to use the smaller apertures.

Finally I measured the Graflok back, both by measuring from the face and allowing for the thickness of the fresnel, and also by setting the Graflok face to a flat surface and measuring from the flat surface to the shiny side (rear) of the ground glass and subtracting the thickness of the ground glass to get to the frosted side. That came to 5.2mm. This tells me the ground glass in the Graflok is sitting about 0.3mm too far back. This will be difficult to correct unless I shave that amount off the corners of the Graflock where it sits against the camera. If I removed the fresnel I'd move the GG forward 1.84mm, which would be way too far.

Will 0.3mm make any difference to my photos? Only one way to tell - I need to load some film!

Cheers!

EDIT to add: apparently the correct depth for the film holder face-to-film is 3/16 inch or 4.7625mm. Source - Large Format Photography Forum info pages.

 

[Johnmcd]

😱

Still has less parts than any other camera I own 🙂

And it's a very interesting learning curve. I'll report back soon when I have digested all the latest posts as I really need to be sitting at home with the camera in my lap rather than thinking about it when I should be working...

Cheers - John

 

[Keith]

😱

Still has less parts than any other camera I own 🙂

And it's a very interesting learning curve. I'll report back soon when I have digested all the latest posts as I really need to be sitting at home with the camera in my lap rather than thinking about it when I should be working...

Cheers - John

I have to admit messing around with a Crown Graphic is a lot of fun ... I really enjoyed the process. So far I've also dismantled and cleaned the lens and shutter. It's a bit like like having an old Holden ute in the shed that you go and work on occasionally when modern technology gets the better of you! 😀

 

[kuzano]

Firm Proof That You are in fact in Australia....

Firm Proof That You are in fact in Australia....

I have to admit messing around with a Crown Graphic is a lot of fun ... I really enjoyed the process. So far I've also dismantled and cleaned the lens and shutter. It's a bit like like having an old Holden ute in the shed that you go and work on occasionally when modern technology gets the better of you! 😀

Your reference to a Holden Ute.....

As I understand it a Holden is an Australian GM car/truck. A Ute is a utility vehicle. Ford in Australia was first to rise to the request from farmers wives for a vehicle that could take produce and goods to market during the week, and yet be presentable to take the family to church on the weekend. I think it was 1934 when Ford introduced the Ford Coupe Utility. Essentially a Coupe body which could seat five, with a utility bed (like a pickup) faired into the body for market duty.

The "ute" utility concept survives today if I am correct.