RF calibration

[rogue_designer]

I have a Canon P that took a short fall, and I think got knocked a bit out of alignment. No other damage luckily.

I know where the adjustment screws are... what I don't know (and don't laugh) is how I know when it's back in alignment. What am I looking for - and how do I test as I go. Is there an easy way, or do I need to make a makeshift optical bench and target? And run test rolls to see how it's coming along?

*feeling really stupid... I would usually send out, but if it's an easy process, I'd like to know.

 

[airds]

Rangefinder calibration

Rangefinder calibration

The info under the Canon P section of Karen Nakamura's website should help - approx halfway down

 

[Reprosteve]

Talking to my camera repair person,you align the rangefinder at
infinity.Once that is done ,and nothing is Stuck(your rangfinder)everything
should fall in place.There is only one adjustment.

An example.If you have a 70-200mm zoom lens.If you focus in manual on a subject at 200mm, when you zoom back to 70mm theoreticaly everything should be in focus.It's the same pricipal as
adjusting the rangefinder

 

[John Shriver]

There are other adjustments, but they're not likely to be messed up by dropping the camera. The effective length of the cam follower arm is adjustable in some way, either by bending it, or by the roller being mounted on an eccentric stud. This adjusts the "rate" of the rangefinder. (Consider the infinity setting the "zero intercept", and the arm length the "slope".)

 

[rogue_designer]

There are other adjustments, but they're not likely to be messed up by dropping the camera. The effective length of the cam follower arm is adjustable in some way, either by bending it, or by the roller being mounted on an eccentric stud. This adjusts the "rate" of the rangefinder. (Consider the infinity setting the "zero intercept", and the arm length the "slope".)

I think I see...

Can I set it via the viewfinder and lens distance setting only then, and not have to worry about the ground glass/tape along the film rails stuff?

Do I gain anything by doing an optical set up with ground glass at a closer distance?

 

[venchka]

I think I see...

Can I set it via the viewfinder and lens distance setting only then, and not have to worry about the ground glass/tape along the film rails stuff?

Do I gain anything by doing an optical set up with ground glass at a closer distance?

I bounced my IV-S? off the marble floor of the Heidelberg train staion one might running to catch the last train back to Worms. The top plate got a nasty ding and the rangefinder was knocked out of alignment. Not having a clue as to how to fix it, I bought an auxilliary rangefinder. I got brave one day and removed the top cover. Found the adjustment screw. I put the camera and 50mm lens on a tripod. Set the lens at infinity. Pointed the rangefinder at a light pole about 100+ yards away. Turned the screw until things were lined up. Worked like a charm. I still have the rangefinder. I sold the camera and lens. :bang: :bang: :bang:

 

[AndersG]

There are other adjustments, but they're not likely to be messed up by dropping the camera. The effective length of the cam follower arm is adjustable in some way, either by bending it, or by the roller being mounted on an eccentric stud. This adjusts the "rate" of the rangefinder. (Consider the infinity setting the "zero intercept", and the arm length the "slope".)

[Sorry, this is a bit off topic]

On the Canon 7 the cam follower roller is mounted on an eccentric stud and I think it might be the same on the P. Do you or anyone here know where I could find the sort of tool needed for changing this adjustment?
I did mess with this adjustment on my 7 and discovered that using a screwdriver it can be adjusted in one direction only - and that was the wrong one... :bang: :bang:

(The Canon 7 service manual identifies the proper Canon tool as a T06A-C151-747A/B, but that doesn't help finding the right equivalent tool.. It ought to be some kind of very thin spanner.)

/Anders

 

[John Shriver]

The "try this at home" RF adjustment is to mount a known good lens on the camera, focus it at infinity, and then get the RF image to align when looking at something at least 1/4 mile away. The more "official" thing is to use a special jig "lens" that is machined from a billet of metal, and has exactly the right 7.5mm cam projection. (Canon used to make one.) But a normal lens in good condition should be fine. (Just don't use an Elmar with a worn focusing helical!)

As for the eccentric cam follower on the Canon 7, make your own tool. Tomosy's approach is to make a custom wrench from a peice of hacksaw blade, using a Dremel (TM) tool and a cutoff disk. Any sort of spring steel would actually be suitable, but a hacksaw blade is very easy to source.

 

[rogue_designer]

Thanks for all the help gents! Worked a treat, and the P is sharper than ever.

I put on the old 50/1.8 that was so sharp before and used the infinity method (focus on the moon) and got that as close as I could. Then checked the results at closer range using a tripod, a point light source a meter away, and a bit of groundglass on the rails. Image was perfect, and on checking new negs tonight, all seems to be well again.

Much obliged to this forum. What a great resource you all are.

Cheers,
Liam