TLR focus problem

[stevebarry]

Hi Everyone, I have an Autocord that seems to have a focus issue.

The focus at infinity is good - the taking lens matches the viewing lens, I assume because everything is sharp on the negative even wide open.

I have never noticed a focus problem, and I routinely look very close at every negative. I usually stop down though, and focus about 7 or 8 feet out to infinity though.

When I notice a problem is wide open at near the close focus limit. Every photo taken this way seems to be focused 3 or 4 inches behind where I focused...and it is consistent on every frame of 2 rolls so I think I can rule out user error.

So my question - could the taking lens and viewing lens be out of sync?

 

[E. von Hoegh]

Hi Everyone, I have an Autocord that seems to have a focus issue.

The focus at infinity is good - the taking lens matches the viewing lens, I assume because everything is sharp on the negative even wide open.

I have never noticed a focus problem, and I routinely look very close at every negative. I usually stop down though, and focus about 7 or 8 feet out to infinity though.

When I notice a problem is wide open at near the close focus limit. Every photo taken this way seems to be focused 3 or 4 inches behind where I focused...and it is consistent on every frame of 2 rolls so I think I can rule out user error.

So my question - could the taking lens and viewing lens be out of sync?

Quite possibly. Is the image uniformly unsharp, or is one side (or top or bottom) sharper?

 

[Tom1956]

Quite probably they are out of sync. Personally, when I set up rangefinders and TLR's, I concentrate on getting my sync at the closest distances and let infinity fall where it may.

 

[ic-racer]

The film may not be held flat in the center.

 

[stevebarry]

IC - ah good point. I put my focus point for all 24 frames almost dead center. BUT - the entire focus plane seems to be constant across the frame.

 

[stevebarry]

E. von - seems to be consistent through the entire frame - but I did not shoot anything 2 d.

 

[Tom1956]

I would say that the viewing lens is a bit out of sync with the taking lens. I've worked on a lot of cameras and have come to expect this.

 

[stevebarry]

Tom, do you know is there an adjustment for this on the camera? Or is it shims and stuff?

 

[Tom1956]

If it's anything like a Rollei, once the face plate is removed, there will be a set screw that is tightened up against the thread screws of the taking lens. Loosen the set screw and you should be able to just turn the taking lens in its threaded mount till it jives. Then tighten the set screw and put the face plate back on. Google up for an assembly or repair manual on the camera.

 

[Tom1956]

I didn't think to tell you, you'll need a piece of groundglass to put on the film plane and use n Agfa lupe or the like. Or get a piece of ordinary picture frame glass of the correct size to put on the film plane. Use thar Scotch translucent tape--I think it's called transparent tape, to use for the groundglass. Concentrate on the close-up end of the focus scale, since that's where errors count most. Infinity SHOULD come out near perfect when you're done.

 

[stevebarry]

Thanks Tom. I know what to do with the gg - but I can't find anything on viewing lens adjustment. I guess I will check gg tonight before I dig anymore for info on viewing lens adjustment.

Sent from my SCH-I535 using Tapatalk 2

 

[Tom1956]

Steve. I've thought about what I've told you, and setting up rangefinders and TLR's are really 2 different animals. On that Minolta of yours, it might be best to set up the infinity end first and then do some checking on how you end up at 3 1/2 feet, which is typically the closest focus of the camera. The taking lens and viewing lens are quite different; the viewing lens usually being a cheapo unit that may never be able to be brought into match to the taking lens. I say this because it takes a lot of turns of the VL at the close distance, which could be disastrous for 50 to 100 feet (near infinity). At the same time, simply setting for a matching infinity and stopping there without seeing where you are at 4 feet is a 1/2 done job. When doing rangefinders like a Kalart, the job is approached entirely differently. At some point, you either go insane, or compromise. GL

 

[stevebarry]

OK well...infinity focus is off at least in the viewing lens. I tried to focus on a street light about 500 yards away, and it gets sharp well before the lever stops. probably 4 or 5 mm before it stops. and when the lever stops it is real blurry. If I understand this correctly that is a good thing for me yes? Hopefully the ground glass is sharp at infinity when the lever stops, and I will adjust viewing - and maybe the close focus will also be relatively close. I can understand this being an issue with a rangefinder, but did not know this was an issue with TLR. I am searching for some small enough glass now.

 

[stevebarry]

Well that took some dexterity. No way to attach camera to a tripod while putting the ground glass on (unless I am real stupid). So balancing the camera upside down, film door open, holding the ground glass on the film rails with one finger, the loupe in one hand, and trying to move the focusing lever. Jesus.

Anyhow, street light is tack sharp on the ground glass when the lever is all the way stopped at infinity. So it would appear the viewing lens is out of sync. I then put the loupe on the focusing screen, and it is more like 2mm that the street light gets sharp before the lever stops.

So, off to find something that will walk me through adjusting the viewing lens.

Correct me if I am wrong, but I can now put the camera on a tripod and forget the ground glass for the time being? Adjust the viewing lens so the street light is sharp on the focusing screen when the lever is stopped at infinity, and then recheck with the ground glass when that is done? And then compare ground glass to focusing screen at close focus?

 

[gone]

In all likelihood, you just need to shim your focus screen, or someone replaced the focus screen and did not re ck the focus afterwards. If the focus screen was replaced w/ a non Minolta screen w/o a fresnel, you may have to adjust things to get it right. The standard Autocord screen has a large circle in the center that is used to give you an easier focus area to see when you focus. Someone also could have replaced the mirror and not gotten it locked down all the way. I know what you mean about the camera being difficult to hold w/ the back door open and a ground glass on the film rails. You can tape the GG to the film rails, and just balance the camera on the tripod as best you can. It works well enough this way to get a focus ck on the GG on the film rails w/ a loupe.

Simply pull the 4 screws out that hold the top hood on, carefully pull the hood up and off, and ck to see if the mirror's 2 screws are tight and the mirror is lying flat. If someone replaced the mirror w/ one that is a different thickness, that's your problem. Ck to see if the focus screen has a fresnel under the focus screen (if it has the stock Minolta focus screen installed). It should be on the bottom of the camera's focus screen. If everything looks OK, put the back on the camera, lock the camera down on the tripod, place the focus on infinity, put the top hood back on w/o the screws, unfold the magnifying glass, and carefully pull the hood up a little and see if the image gets sharper on the focus screen. If it does, place 2 little shims of cut paper cards (playing cards work great) on either side of the top hood on the bottom, place the hood back on the camera, hold it down snug, and see how the focus now looks. Keep shimming and checking as needed until you get a sharp image, then lock it down w/ the 4 screws (they don't have to be snugged down too tightly) and reconfirm that the image on the focus screen is sharp at infinity. Since you already confirmed that the taking lens is properly focused at infinity, you're now done.

Nearly every time you have a focus issue on a TLR it's related to the focus screen or mirror. Unless the camera has been dropped and the lens board is visibly bent, it's doubtful the two lenses are out of sync.

 

[stevebarry]

I found A service manual. On the last page it talks about adjusting the taking/viewing lens.

Dead Link Removed

If I am not mistaken I need to remove the leather covering to get to this stuff? I may be out of my league here. The camera is mint condition. May be worth me shipping somewhere.

 

[stevebarry]

momus, yes. I did not see your post, and was just playing with the camera, seeing if I could find a way IN. I got to thinking maybe the answer might be that simple, the focusing screen.

There is a little down play in the focusing screen....almost like it is on a spring. Playing with it - focused at infinity, it seems like if the screen came up just a splinter it would come into focus on the screen.

I will do like you say and disassemble the focusing hood/screen and inspect. Certainly much easier and within my mechanical abilities.

The lens board does not appear to be damaged. Focus is smooth and it comes into the camera parallel on top/bottom/sides as close as I can tell. No dents. The camera really is mint condition.

I can look at the mirror but no way of knowing if the thickness is correct, I will make sure everything is tight.

 

[Tom1956]

I had never seen the name momus before, but he sounds like he's on-the-ball, and I concur. Either way you do it, by screwing the viewing lens in and out on it's mount, or shimming the screen is a viable way. And he is correct in the likelihood of physical changes in the mirror and/or screen that have caused this problem. At the same time you know another thing I've found in working on cameras?--They never got it right before it left the factory in the first place. In all my days of working on cameras, this has been the most common problem.

 

[stevebarry]

Is this mirror supposed to be seated all the way into the clip on the narrow (bottom) end of the mirror?

 

[Tom1956]

I've never torn the leather yet. Yes it's tedious, and yes you can tear it, or scratch the camera finish, but to date I have never done any damage you could tell with the naked eye. Take your time and use your sense, and you won't tear it. If you "send it to somebody", what do you think THEY are going to do? They could be a boob. How do you know whether they were a boob until your camera comes back fixed, but with torn leather? If you want anything done right, you have to do it yourself.

 

[Tom1956]

Is this mirror supposed to be seated all the way into the clip on the narrow (bottom) end of the mirror?

View attachment 71046

Seems like it should. Do the screws look chewed or scratched to give evidence a knucklehead has been working on the camera? That's my first indicator. I'll tell you when the time was in my life that I knew I was on my way to being a good self-taught repairman. When it occurred to me to practice "forensic" repair. Find the telltale signs of clowns who weren't paying attention and using their brain, putting me in the position of repairing their "repair".

 

[stevebarry]

Hey Tom - seems like it should to me too. Seems like it would fit perfectly and also the mirror is just sort of hanging there unsupported on the narrow end. And also the wide top end seems like it is sticking up too high. But I don't see how seating it down in the clip would affect the focus. Right? It would not move it closer or further from either the lens or the screen.

 

[Tom1956]

Well, one thing's for sure--you already found one problem that must be corrected before proceeding. It's not always just one problem; it could be several working additively. I'm not a fan of groundglass shimming. I still prefer seeing if the groundglass had been tampered with, and barring that, proceeding to turning the viewing lens in its setting. How do you know you are not just now getting sensitive to a problem that was there from the factory? Just yesterday I threw a Nikkormat FTn in the garbage because the factory failed to tighten a pentaprism hold-down screw, and thart screw eventually backed itself out and fell down in the copal shutter and ruined it. My forensic disassembly method convinced me I was the first person that ever opened the camera up. It was a virgin.

 

[stevebarry]

Well here is the screen:



It appears to be the original screen, as momus described it? There is NO fresnel however - maybe it needs one, if that was factory? The screen is very bright and easy to focus as is.

The screws holding the mirror are tight.

 

[stevebarry]

actually, looking at this photo I posted of the screen, it does have a fresnel attached, not sure how I missed that. Looking around the internet at other Model L autocords, it would appear to be the stock screen/fresnel combo.