Minolta Autocord Focusing Problem

[Javonimbus]

I bought a Minolta Autocord III from eBay as my first medium format camera. It seems to be in good optical and mechanical order, except for an issue with focusing. With the focus set to infinity on the distance scale, the image on the viewing screen is focused beyond infinity by a considerable amount. I need to move the focus lever to approximately 12ft on the scale to bring distant objects into focus on the screen.

The taking lens does not seem to be affected, I used an improvised viewing screen on the film plane with the shutter open, and found distant objects to be sharp with the focus lever at infinity.

Is this likely to be an issue with the focusing screen, the mirror, or something else? What steps can I take to diagnose the cause of the issue and fix it?

 

[Dan Daniel]

If the taking image is in focus, then the viewing lens is out of adjustment. It is on a screw mount. See if you can get it to screw forward (counterclockwise from the front). If it won't move farward, you'll need to remove the lens shroud to access the set screw.

You can check the mirror by looking through the viewing lens from the front with the hood open. Maybe the mirror is loose.

 

[F4U]

Evidently someone has tampered with it. If the film plane is actually in focus at infinity, either the reflex mirror or ground glass positons have shifted postion, or somebody has opened up the camera and removed the viewing lens, possibly for cleaning. And then screwed it back in completely, thinking that;s the way it should be. In actuality the factory likely made provisions for the viewing lens to be screwed in until proper viewing distance was achieved through a collimator, and then secured with small set screws to keep it from screwing in further or backing out. I just diagnosed it. Now you fix it. If it's anything like a Rolleiflex, the front panel screws are underneath the leather. Take off the front panel so you can get to the front lens element of the viewing lens.

 

[blee1996]

I will probably diagnose in this sequence:

1) Make sure your taking lens and distance scale are matching: you need a high powered magnifier to look at your "ground glass" on film plane for critical focus. A visual inspection might not be enough.

2) Take off the waist level finder by unscrewing several screws. Check if the focus screen is installed properly: matte side down. Give it a gentle clean with lens cleaning fluid and Q-tip while you are at it.

3) Check if the mirror is installed correctly. It should be front facing: silver side on the outside. Give it an air blower cleaning while you are at it.

4) If the focus still off, then work on the viewing lens. There might be set screws to remove, and then fine-tune the viewing lens to match your film gate.

 

[F4U]

I will probably diagnose in this sequence:

1) Make sure your taking lens and distance scale are matching: you need a high powered magnifier to look at your "ground glass" on film plane for critical focus. A visual inspection might not be enough.

2) Take off the waist level finder by unscrewing several screws. Check if the focus screen is installed properly: matte side down. Give it a gentle clean with lens cleaning fluid and Q-tip while you are at it.

3) Check if the mirror is installed correctly. It should be front facing: silver side on the outside. Give it an air blower cleaning while you are at it.

4) If the focus still off, then work on the viewing lens. There might be set screws to remove, and then fine-tune the viewing lens to match your film gate.

Excellent post. Do these, in this order and the problem is solved.

 

[250swb]

Maybe a replacement focusing screen that isn't shimmed properly, or even a screen put in upside down after a service may cause this, but also look at the viewing lens mount inside the camera and see if it may have been recently taken out for cleaning, looking for scratches on the lock ring etc.

 

[F4U]

One last thin. go on ebay and buy one of those small sets of Vessel JIS screwdrivers. Do not attempt to une normal small screwdrivers. They MUST be JIS, or you'll end up with nothing but a bunch of chewed-up screws you can't get out.

 

[Alex Varas]

I will probably diagnose in this sequence:

1) Make sure your taking lens and distance scale are matching: you need a high powered magnifier to look at your "ground glass" on film plane for critical focus. A visual inspection might not be enough.

2) Take off the waist level finder by unscrewing several screws. Check if the focus screen is installed properly: matte side down. Give it a gentle clean with lens cleaning fluid and Q-tip while you are at it.

3) Check if the mirror is installed correctly. It should be front facing: silver side on the outside. Give it an air blower cleaning while you are at it.

4) If the focus still off, then work on the viewing lens. There might be set screws to remove, and then fine-tune the viewing lens to match your film gate.

You are becoming an expert on this, I love it!!
Well explained!!

 

[Dan Daniel]

2) Take off the waist level finder by unscrewing several screws. Check if the focus screen is installed properly: matte side down. Give it a gentle clean with lens cleaning fluid and Q-tip while you are at it.

Be careful using any fluid with the Autocord focus screen. If it is the original screen, it is a two-part sandwich. Ground glass to the top/viewer, plastic fresnel below. Liquid could get in between the two and make a mess. Nothing difficult, just need to remove the screens, separate, and let dry, but be forewarned.

 

[aconbere]

I will probably diagnose in this sequence:

1) Make sure your taking lens and distance scale are matching: you need a high powered magnifier to look at your "ground glass" on film plane for critical focus. A visual inspection might not be enough.

2) Take off the waist level finder by unscrewing several screws. Check if the focus screen is installed properly: matte side down. Give it a gentle clean with lens cleaning fluid and Q-tip while you are at it.

3) Check if the mirror is installed correctly. It should be front facing: silver side on the outside. Give it an air blower cleaning while you are at it.

4) If the focus still off, then work on the viewing lens. There might be set screws to remove, and then fine-tune the viewing lens to match your film gate.

Came to say this much less eloquently. I had one recently where the mirror was wildly out of position.

 

[blee1996]

Thanks @Dan Daniel for the additional warning about the focus screen. Autocord had the more advanced focus screen + fresnel, so it needs to be extra careful.

@Alex Varas thanks for the encouragement: I did a few simple and cheap Rolleicord Is and Seagull TLRs recently. For the complex and exotic stuff, I will continue to send them to you and Dan for proper CLA.

 

[Alex Varas]

I think we all started this way... some gets pro, some decides not to, skill and knowledge is there and you always get better for every screw you take out