Polaroid 900/Razzle Infinity Stop adjustment

[jonreid]

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*
Jon

[Bill Burk]

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.

[jonreid]

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.
Jon

[Bill Burk]

Wait.

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.

[jonreid]

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.

J

[jonreid]

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.
Jon

[Mick Fagan]

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.

Mick.

[jonreid]

Hi Mick,
Thanks for your input.
I should have added the lens is a 150mm f5.6 Caltar II N (http://jafaphotography.com/affordabl...ard_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.

Jon

[Bill Burk]

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.

[jonreid]

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.