View Full Version : Polaroid 900/Razzle Infinity Stop adjustment

31-Mar-2015, 19:27
Hi all,
I unsuccessfully tried to sell my Razzle after having persistent rangefinder calibration issues.
I spoke to Dean some six months ago and to his eternal credit he offered to look into it.
I decided to try and sell it but having failed to do that am looking at reconfiguring it as a quick carry/bicycle around colour landscape camera, using the GG rather than the rangefinder.
As such I have made a new ground glass as the OEM one was awful. I've then realised that the infinity stop is not allowing infinity focus. Removing the infinity stop allows infinity focus but just as that is achieved the focus mechanism makes a clunk sound and becomes unable to move without resembling it on some sort of out-of-view gear.
This is easy enough to achieve but obviously a pain. There doesn't appear to be any adjustment available in the infinity stop. I only need ~0.5mm I think.
Does anyone have any suggestions as to how to achieve a crisp infinity focus. Attached is a picture of the set up.
The only thing I can think of is finding a replacement screw with the same thread obviously, but a smaller diameter head as that is what it appears to rest against.
Any thoughts appreciated.
*Sorry for the upside down picture*

Bill Burk
31-Mar-2015, 22:15
I removed the screw from my old 900 and it allowed me to pass infinity.

It might be easier to replace the screw... Than file the aluminum stop...

But either action will get you the 0.5mm you need.

31-Mar-2015, 22:24
Hi Bill and thanks for your response,
I was just about to update when you replied.
Yes I can remove the screw and get the necessary extra movement to infinity but like I said, on mine this makes the focus gearing 'fall off the rails' and I have to manipulate it back on in order to focus closer again. Not sure whether this happens on yours or not. It also wants to sit just at that point where it falls off the gear, making it susceptible, I imagine, to unwanted movement past infinity.

What I have just discovered is that Dean Jones had built some adjustment into the position of the front standard. I've gone to the maximum of that possible and it just brings infinity in. For these purposes infinity is a power-pole some 100 metres up the road or more. In order to get a little more I would need to remove the shutter and file the aluminium standard that Dean built. It's certainly do-able but I don't actually have a lens wrench at the moment so its not something I can do immediately.
I've done another test shot and will process as soon as the kids are in bed. At least my new version of the ground glass seems to inhabit the same plane as the film, so that's a plus.

Bill Burk
31-Mar-2015, 22:30

Why would you ever need true infinity? You're not shooting stars are you?

Maybe it would be best to leave well enough alone and allow some depth of field to take you to true infinity.

31-Mar-2015, 22:37
Hi again Bill,
I assumed true infinity was 'the norm'. All of my smaller format gear can focus to a more or less true infinity. And no, I'm not shooting stars but I think a crisp subject, wide open at 100m or so is fair enough.


31-Mar-2015, 22:59
Update 2:
I just processed the second sheet. It's a considerable improvement over the first but still not what you'd describe as crisp focus at 100m.

Mick Fagan
31-Mar-2015, 23:36
Firstly, what is the focal length of the lens on your Razzle?

If Dean built some extra into the front mount, I would gather you must be running a bit close to the wind.

My Razzle has a 150 Fujinon and it goes to a true infinity. I double checked with the GG supplied, which does allow you to adjust, but mine didn't need adjustment. My own Razzle has the same screw in place, but it allows the arrow to go about 1mm past the infinity line.

Thinking out loud here, is there the possibility that the gears have stepped a thread, thereby disallowing infinity focus?

I spoke at length with Dean at a local photographic flea market on this very issue. Essentially, the longer the focal length from standard, the greater the issue. At least that is how I remember the issue. This was one of the reasons I went with a maximum of 150mm, plus the Fujinon lens itself being so compact, allowed the camera to fold with the lens in place all the time. I saw about 6 Razzle cameras over a period of time, usually just after they were finished and prior to Dean shipping them out, about half retained the original lens, with half of the others running something small like my 150 Fujinon, but the other half were running some exotic German lens of usually quite longish length, requiring lens removal for foldability, which to my mind, sort of detracted the compactness of the idea.


31-Mar-2015, 23:44
Hi Mick,
Thanks for your input.
I should have added the lens is a 150mm f5.6 Caltar II N (http://jafaphotography.com/affordable_largeformat_standard_lenses.htm).
Dean advised me to get a 150mm, and this was what I picked up at a good price. Lovely lens. It fits in the folded Razzle without a problem. There is a little 'play' with the front standard and with a small amount of pressure I can pull the front standard back, only by a tiny amount, and the focus comes in. The problem is though that at a resting position it is slightly out.
"Thinking out loud here, is there the possibility that the gears have stepped a thread, thereby disallowing infinity focus?"
- yes possibly, but I can't see the gear mechanism to understand how it works.


Bill Burk
1-Apr-2015, 07:37
The rack block is hitting the infinity stop.

If you simply lower the bed and don't pull out the lens, you'll see the gear is fully toothed all around. You'll also see the limit you hit.

2-Apr-2015, 20:09
Update: Attached picture shows the adjustment that Dean built into the front standard.
He seems to have glued the bellows on front and back, so I don't want to mess with that. And because of that it seems that I will need to file it by hand. :(
The good thing about taking some extra here is that I won't run into the issue of the focus disengaging from the gear. I'll obviously lose something at the close focus end but wonder how much it will be. I thought briefly about replacing the hex bolts Dean used with wing nuts or something that might allow some quicker adjustment. This could be handy if the change in close focus distance was significant - the camera could be changed from landscape mode to portrait mode.

Bill Burk
2-Apr-2015, 21:36
Oh good, you have a good plan. Just file the front of the slots until you can lock down the lens board closer to infinity. I'd stay with strong bolts and/or use some Loctite to set it once you have it adjusted right. I wouldn't really want wing nuts.

Mick Fagan
2-Apr-2015, 23:04
I would agree with Bill, keep the nyloc type of nuts that Dean used, although to be technically correct, they are a one use item as far as I know.

I wouldn't think of using wing nuts myself, I don't think you can get a strong enough lock down on the bolt thread.

I presume you haven't used your Razzle that much, one thing I can tell you is, with regard to racking the bellows right out. When I rack things right out for a closer type of shot, usually a portrait, I find with the 150 lens I get a slight vignetting, something the original shorter lens would not have done. The vignetting isn't that bad, but if one wishes to do a contact or full negative print, then it doesn't look the best. Closest good focus for no vignetting, is sort of about 3.5 metres. That measurement is a bit flexible though.

If you are back far enough to take a full length portrait in the vertical, just that is, you are close to vignetting, or at least mine is with my 150 Fujinon. I pretty much work on a vertical portrait in the frame distance, then keep myself around that distance, whether I do a portrait or landscape format. With a Grafmatic back, this set-up is pretty good for 4x5 portraiture or as a walk around 4x5 camera, allowing 6 sheets of film before re-loading is required.


2-Apr-2015, 23:19
Hi gentlemen,
Well, feeling pretty pleased with myself. Happened to have a round file of exactly the right diameter and filed a small amount out of the ends of those channels. Seems I took the exact right amount out as the focus on my chosen pole is now spot on. Shot & processed a sheet an it looks good. I measured that distance on Google Earth and it is 91m. I could file out a touch more to drop it back even further but I'll see how it goes for a while.

Following this I once again tried to calibrate the rangefinder but couldn't. Seems there's something fundamentally awry with my rangefinder. At some stage though it was fine, as one of my favourite portraits is of my daughter, shot on the Razzle a few years ago. It's confusing, I can't think what might have changed.

Anyway, thanks for your input Bill & Mick, with the new GG I think it will be a nice little landscape camera.


Mick Fagan
3-Apr-2015, 01:34
Jon, have you adjusted the cam mechanism?

I had to do a bit of thinking with this, but on my Razzle there is a small black rubber plug on the right of the rear of the camera head, the viewfinder is in the left rear of the camera head. The centre of the rubber plug is 20mm from the right side.

Behind this plug is an adjusting screw. Now I havenít needed to do this to my camera, but Dean explained this to me when I picked up my camera. I cannot at this stage, unless I start pulling things off my camera, tell you exactly what is behind that rubber plug.

But from memory, you need to use the GG to focus correctly on something, say, around 5 metres away, then adjust the screw until the yellow focusing images fuse. That is, adjust the cam screw if the yellow images arenít fused, until they are fused.

Then check infinity, my betting is that your focus will be correct when the yellow images fuse.

The rangefinder cam on various rangefinders can move if the camera is bumped, or as happened to me with my Canon in the sixties, when I dropped it from my pushbike rack, where it was balanced as I removed stuff from a bag.


Mick Fagan
3-Apr-2015, 01:36
Oh, I just re-read your last post, seems you have been adjusting your viewfinder mechanism.



3-Apr-2015, 03:05
Hi Mick,
Yeah, it's easy enough to remove the top and get access to both horizontal & vertical rangefinder adjustment screws. Only the horizontal one is reachable through the rubber cap. These control the angle of the right hand mirror and therefore one of the images in the yellow patch. I think the issue with mine is that either;
a) the cam has been ground incorrectly - unlikely since I had no issues with it when I first got it.
b) the position of the cam has changed.
There is a line running vertically on the cam which I took to be the infinity mark, since it was near there when my camera was (supposed to be) at infinity. There's also a small hex driven grub screw which may have the job of holding the cam in the correct position. I might have another look at it tomorrow. I briefly toyed with the idea of removing the whole rangefinder assembly, to reduce size & weight and turn it into a real frankencamera :)
Will post some phone pics of the RF set-up tomorrow.


3-Apr-2015, 20:48
I've just had the top off the camera again and confirmed that the rangefinder is unable to be calibrated. if I adjust it for infinity it is increasingly out at closer distances and vice versa.
Some pics of the set up. The hex-head grub screw appears damaged and I can't loosen it. Perhaps its my hex key, hard to tell at such small sizes and difficult angular access.
Left upper: Horizontal adjustment screw. Right lower: Vertical adjustment screw.
The hex-head grub screw from the rear.
The cam (with infinity line on top?)
Top view of the cam

I think I'll stick with my idea of only using it via the GG and giving up on the rangefinder.


Mick Fagan
4-Apr-2015, 02:40
Hmmm, interesting.

Having never pulled mine apart, and I'm not in a hurry to do so, I just wonder, if, as you say, your cam has moved slightly? If the Allen Keyed bolt is unable to be moved by your Allen keys, perhaps it was either too tight, or if Dean had replaced it, maybe it was metric. Dean was English and he grew up with their imperial system, but converted to metric as this was a requirement for machining, which I'm thinking was what he was doing before he became semi retired and started fiddling around converting old Polaroids. Australia went metric in about 1974, when the USA did, but we sort of did it, where as I understand it, the USA didn't, although they have decimal inches, which is something I have yet to see in the flesh.

I would be attacking that bolt with a small Pederson locking Vice Grips tool, that should do the trick. Then it should be a simple thing to replace that bolt, then again it may not be that simple. Polaroid was an American company, if the camera was manufactured in the USA, it would be non metric, I would assume, but if manufactured almost anywhere else, it could be metric.


Bill Burk
4-Apr-2015, 13:18
My thought is that you may need a custom cam.

It might not be too hard to calculate the required dimensions because you could work out the radius required to make the rangefinder coincide at any specific focus.

For example, focus using ground glass on 15 feet. Note the degrees of rotation at that point where the follower touches the cam, because you "know" that is where the mechanism needs to be when the subject distance is 15 feet. Then rotate the focus until the rangefinder coincides. Now note the radius of the cam where it meets the follower. That's what you have to grind the previous mark down to. Repeat the measurements for many different focus distances. At this point you should have dots outlining a new spiral for your custom cam specifications. Take to someone to grind, or file yourself until you meet the dots and have the cam you need for that lens.