relubed J-3

[FrankS]

Well, this evening I relubed the focusing helix of a new J-3 lens I traded with Brett for. Focus action feels great now. I tested the close focus with a scrap of film across the film gate and it seems okay. I've got a cheap roll of colour neg film that I'll use for in-camera testing to see how the lens performs. I may be sending this one off to you, Brian!

 

[JoeFriday]

once Brian is finished with I want it back, please 🙂

I'm actually very anxious to see some photos when it's done.. it was sitting on my shelf for 4 months, only taken out maybe 3 times to look at

 

[FrankS]

The close focus seemed okay, but the infinity was way off. The lense's focussing cam was not extending enough. So I took the lens apart again and tried to tighten things up so the focussing cam would extend farther. When I got it back together, it obviously was't right with the focus ring turning very heavily and roughly. That's enough for tonight though, I'll try again another night.

 

[FrankS]

Brian, the lens could did not get the VF/RF to infinity. I didn't check actual focus at infinity.

Yep, I separated the helical, but I marked the point in rotation where the halves separated and reassembled that part correctly. There was no guarantee that the lens actually focussed properly before my disassembly. I don't think Brett used it at all.

 

[FrankS]

Got it back to operating smoothly but focus (RF patch) is way out. When I focus on something 1 meter away, the lens focus scale reads 1.7 meter. When I focus on something 4 meters away, the lens scale reads 15 meters. When I focus on an object 5 meters away the lens focus scale reads infinity. I've got to play with this a bit more.

Checking the focus at the film plane with a scrap of film and a loup, it seems that when an object is 1 meter away, the focus at the film plane is good with the lens scale-focussed to 1 meter.

Haven't checked infinity this way.

Sounds like the lens RF cam needs to be built up, right?

 

[photodog]

Don't build up the RF cam. It seems to me that the helical was improperly assembled. Try reassembling it again differently. When properly assembled, the RF cam should be flush with the rear edge of the M mount as shown in the photo. This tells the rangefinder of the camera that the lens is set for infinity. The actual focus of the lens can be adjusted by changing the shim as discussed in Brian's earlier posts.

 

[FrankS]

Here's the lens. The RF cam is about 1mm too short of the end of the lens mount.

 

[FrankS]

I am not pursuing that one!

Ouch! It sure hurts when your fail-safe back-up plan falls through!