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

[kuzano]

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?

Originally Posted by kuzano

...

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]

Originally Posted by ChrisN

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]

Originally Posted by 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.

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

Getting there slowly

[ChrisN]

Originally Posted by Johnmcd

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]

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]

Originally Posted by 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.

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]

Originally Posted by 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

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]

Originally Posted by Keith

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.

[Keith]

Originally Posted by kuzano

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.

It does indeed ... I drive a six year old Ford Falcon ute. It also runs a dedicated LPG engine! (LPG currently 75 cents per litre)

[kuzano]

Originally Posted by ChrisN

This tells me the ground glass in the Graflok is sitting about 0.3mm too far back. Cheers!

Not sure how much effect .3 mm will make on focus, but it can be tested. If you conclude that the GG is back from the lens .3mm, more than the film holder, you can make a .3mm mask around the camera mating surface of a film holder. Insert a loaded holder in the camera and shoot some test shots. Perhaps a formal focus target. A couple of shots without the shimmed holder and a couple (Or a few) with the shimmed holder.

You will have your answer.

Such fun these old camera's... simple. Not a chance.

[Johnmcd]

Hey Chris if you can email that manual to me that would be great. I think you have my email from a previous film purchase.

Cheers John

[sevo]

Originally Posted by ChrisN

This tells me the ground glass in the Graflok is sitting about 0.3mm too far back.

Maybe. A fresnel in front of the ground glass will alter the focal plane - so the ground glass is offset to compensate that. To know whether these 0.3mm are the proper displacement, we'd really have to know its focal length and the distance between its nodal point and the ground glass, and calculate the focal plane displacement from them.

Personally, I think that 0.3mm are wrong. As described, it would be a offset into the wrong direction, and about a magnitude too small - in the cameras where I recalibrated front fresnel arrangements, I came up with forward offsets around 2mm. But the Graphic (other than German view cameras) was designed around a front-mounted fresnel, so that the needed displacement may already have been considered in the back design.

[graywolf]

In fact Pacemaker Graphics are set up with the fresnel from the factory. If it is not there, then one has to fabricate a spacer to put the ground glass at the film plane.

Properly set up Graphics make fine images whether focused from the ground glass, the focus scale, or the rangefinder. But it all starts with a properly set up ground glass. Once that is properly set up you then set up the scale focusing, and then the rangefinder focusing. Those set ups hold nicely, and you should not have a problem again unless someone gets in there and "fixes it".

Once the GG is set up the only other thing that is not pretty obvious is that infinity is not with the rack all the way back. Because the camera is wood, and thus has a tendency to swell and shrink a bit, the camera is properly set up with infinity set with the rack about 1/8" (3mm) forward. That also allows for the adjustment hat the RF needs.

There is nothing really difficult to setting up the camera, it is just that so many were "fixed" by someone without a clue.

Once you know which way the GG/Fresnel sandwich goes in, and about the 1/8" of slack, everything else usually falls into place unless there is actual damage.

Most plastic "Graphic" film holders will be in close enough tolerance for commercial work. Old wood film holders may not. "Graflex" holders will not work correctly at all, they will not seat properly.

I have read that the factory had focusing target a 100' and 6' to set up the camera. The Kalart (sidemount) RF also needed a target at 15' to verify the setup.

There is more info out there & more people using press cameras than there was when I set up my webpages about them. Back then there was only graflex.org and a couple of collector sites, and nothing about using a press camera as they were originally intended to be used, as most people that bought them wanted a cheap view camera.

Yours looks like a nice clean camera. I hope you get it working and have a lot of fun using it.

[sevo]

Originally Posted by graywolf

Once the GG is set up the only other thing that is not pretty obvious is that infinity is not with the rack all the way back. Because the camera is wood, and thus has a tendency to swell and shrink a bit, the camera is properly set up with infinity set with the rack about 1/8" (3mm) forward.

I don't think it is that. The tropical wood from which Graflex bodies were made is quite moisture proof (I've seen many with leather eaten off by mould and metal parts badly corroded, where the bare body still was restorable). It even is much less vulnerable to temperature drift than metal constructions (tropical and polar expedition cameras remained mostly wood, with no leather and minimized metal, long after metal cameras had become standard).

If there is a factory designed 3mm rearward slack, that will simply be the space needed to accommodate a no-fresnel or rear-fresnel groundglass.

[graywolf]

It is for sure needed with the side mount RF, it does not start to register until the lens is racked out a bit. I do not know about the top mount RF (I have never worked on one). But the instructions did say it was for the wood expanding and contracting.

The wood is mahogany (South American, I believe, not African), by the way. Fairly dimensionally stable, but not as stable as maple (for instance).

[Johnmcd]

Thanks again to all that have added to the discussion. Might get a chance to take another roll this weekend and check the results. Fingers crossed.

John

[Johnmcd]

By using the manual (thanks Chris) I was able to re-adjust the RF to infinity. Not an easy task as the act of tightening the locking screw of the RF mirror always twisted the mirror away from the proper position. Fiendishly frustrating. Anyway with more luck than anything I got it set.

Took a quick walk down to the bay and shot 8 focused images All at F16 and 1/250th. HP5 in Rodinal.

Thanks to all those that helped. Much appreciated.

[graywolf]

Nice!

Glad you got it all sorted out.