Adjusting a Bessa T Rangefinder

[kb244]

So I got my Bessa T today, all "seems" ok, but at infinity regardless of the lens, say if I focus on a Tree off in the distance bout a mile or so away and use the branches to check the double image, the branches are still double image but so close together they touch, almost like infinity shows up in the rangefinder view as being an itsy bit closer than actual infinity. Could this "itsy bit" off mean closer focus is more greatly affected, especially on my 50/1.8?

And if so, how does one go about adjusting the rangefinder just a fuzz?

I know it can merge infinity items cuz I tried using my finger to push on the cam and it can go past infinity point, so probably just a matter of adjustment.

Note the lens I tried were CV 21/4, Canon 50/1.8, and Jupiter-11 135/4 to try out the rangefinder spot. Also all three lens are currently on a Leitz Brand LTM->M adapter, I don't yet have an M lens.

 

[Anupam]

To test focus, put the camera on a tripod, open the back, place a piece of ground glass on the film plane (focussing screens from 35mm SLRs like my Nikon F3 work great for this), and check focus with a reversed 50mm lens or a slide loupe.

It's foolproof and leaves nothing to doubt.

-A

 

[kb244]

I noticed theres a chrome screw on the back under the left LED, normally when you see a shiny chrome screw, it means RF Adjustment. I removed it, but did not see anything in the hole that I could turn. I might try the tip you mentioned above, but rather taping a newspaper to a wall, leveling out the camera on the 3-way head. Cuz I assume you mean focus on the ground glass, then adjust the rangefinder to match.
I am told in regards to RF adjustment ( as told by my co-worker), you test 10 or 15 feet, and you adjust for 30 feet or infinity (I think you adjust for far first, then for closer) since "Back in the day" most shots were 5 to 15 ft when he did weddings and such, and that was the 'critical' range.

I don't have a ground glass or a 35mm camera with a removable screen (that I care to remove) however, I do have in my room a flat-matte focus screen for my EOS-1 Film body that I replaced with a split prism, I can probably just use some masking tape to put the matte screen against the shutter opening with the camera locked into bulb mode and do as you say.

However far as actually adjusting, was I correct in the position, and if so, do I just need to insert a tiny flat-edge screwdriver and find a grip and turn one way or the other? The RF is perfectly vertically aligned, just seems to need horizontal (especially if I confirm it does after the test you mentioned.

And as far as focusing on it, I'll just use my dark cloth and loupe I use for my 4x5 camera.

Edit I'm still at the store, so gona borrow one of the cheap priced (but looks solid) matte focusing screens for one of the Nikon F bodies. (ie: if I scratch it, I'm only out owing 10$, but would probably keep it for the very purpose of focus testing.)

 

[kb244]

Well I been playing with the RF screw and got infinity to look like infinity. So when I get home, I'm gona do the groundglass, newspaper on wall and tripod adjustment as suggested now that I know how to do it with a little screwdriver. Takes a bit of patience getting the screwdriver to contact with the slot.

 

[kb244]

Yep, using the EOS-1 matte screen worked much better compared to the Nikon F focusing screen (Cuz the EOS-1 is flat completely, doesn't have the additonal optics on the other side). I focused on a peice of paper taped to the wall, had two lines vertically, and one diangonally going accross the two in a fine line with an ink pen, focused on the ground glass then adjusted the rangefinder, and checked the RF and ground glass, at several distances between 3.5ft and 10ft, once I was satified they matched, I went outside and checked to see if a large parking lot light nearly a mile and a half away showed up as a single dot at infinity, which it did, then checked that when focusing that it snaped together as one, when it hit infinity rather than before hand, which it did successfully.

Then I snaped a couple frames on the end of a Tri-X roll against the paper on the wall wide open at f/1.8 (the same aperture I used for the ground glass), at several distances using only the RF to focus, then will develop that tonight to see (against my earlier shots and test in the day), and will scan that on the scanner at work (Nikon Super Coolscan 8000 ED, at 4000 dpi) to check it at a finer level.

*Crosses Finger*

 

[pvdhaar]

Don't do anything drastic yet!!!

My Bessa-T was repaired through the official dealer, and my Leica M4 through Wil van Maanen. By using a tape measure and swapping lenses between both, I could verify that they agree on focus within the centimeter in the range of 1.5m to 5m, which seems to indicate that both parties did their job right. The interesting thing though, is both cameras agree that infinity is the same distance about 50m away. Anything further than that does not align completely, but of course, beyond 50m, dof takes care of this.

Now, I'm a perfectionist, and that part of me wants to have the RF line up exactly at infinity. But when I'm in realistic mode, I know that mucking about with the infinity alignment would probably also destroy the perfect alignment in the closer range, which is where focus accuracy is important.

Long story short.. if your pictures are sharp, don't spoil it..

 

[kb244]

Don't do anything drastic yet!!!

Well if you read the last post I already did it. I Developed the roll, thus far seems my final test shots are quite sharp (will know more when I get the neg to work), but the early shots before I even touched the camera were clearly off. For example one of the first shots I took, was of my coworker holding his pentax. I focused on the Pentax logo, the logo was out of focus in the neg with the face and his back in the DOF range (this was shot at 1.8) all the other pre-adjusted shots were soft. But I'll check the test neg when I get to work, as well as fire off a couple test on slower film today and see if the final results are fine. Far distance is usually taken care of by DOF as you said, but I Did not calibrate the rangefinder to make infinity merge, all I did was calibrate it to make the subject on the wall at 10ft match the ground glass, and just so happened that infinity decided to merge from that calibration.

 

[pvdhaar]

Well if you read the last post I already did it...

Ah, yes, reading it again, it's clear.. At first glance I thought you'd just checked with the ground glass whether it's off.. Good to hear that its accuracy has approved though!

 

[kb244]

Ah, yes, reading it again, it's clear.. At first glance I thought you'd just checked with the ground glass whether it's off.. Good to hear that its accuracy has approved though!

My co-worker a few mins ago eyeballed the 50/1.8 @ 1.8 frames under a loupe, saying that if it wasn't there its really damn close. Right now we're putting it thru the dedicated scanner to see if it appears sharp on the grain level or not (or just in the realm of acceptability).

 

[kb244]

Heres the line test, focused on a ground glass for 50mm @ 1.8, though shot on TriX (I woulda probably use a small strip of kodalith or ultratec had I thought of it. )

100% crop @ 4000 dpi

I dunno probably like my co-worker said, if I'm not already there, I'm pretty damn close. The above is at close focusing distance of 3.5ft, scanning the 8ft or so one now.

 

[BillBingham2]

Stupid question, was the adjustment under the silver screw on the back?

B2 (;-?

 

[kb244]

Stupid question, was the adjustment under the silver screw on the back?

B2 (;-?

From my second post.

I noticed theres a chrome screw on the back under the left LED, normally when you see a shiny chrome screw, it means RF Adjustment.

It's threre, but not like you can really see anything.

 

[BillBingham2]

Thanks.

B2 (;->

 

[kb244]

Just got the color roll back this afternoon ( after they spent 4 hours repairing their machine lol). Co-worker looked at the frames with a loupe and was amazed how tack-on they were. Gona have them scanned. I basically did two shots against the brick wall of the store @ 15 feet with some Kodak Gold 200 (shot at 100) 12exp roll.

One with the Canon 50mm f/1.8 shot at 1.8 straight on, then another shot with a Nikkor 135mm f/3.5 Q-C lens @ 3.5 at the same distance. Then I put a usps priority box in between the brick and pipe on the wall and shot down the side of the brick wall at 1.8, 2, 2.8, 4, 5.6, 8 and 11 so that I could see if I have a "sweet spot" on the lens, or if the calibration was off in wihch directly was it going.

Just from the loupe I say I probably got lucky (with the help of a hour or two of tweaking) and got it dead-nut perfect, if nothing else the scanning of it might give me something to brag about.

 

[kb244]

Canon 50mm 1.8 set at 15 ft, wide open.

100% crop at 6 megapixel equivilent (resized to 3072x2048 from 4000 dpi scan)