focus difficulty-FujiGW690-3

[fritz_cole]

This question concerns focusing difficulty with my

wonderfully sharp Fuji GW690III. When this camera is

focused right on, it's awesome, almost 3 dimensional.

But I'm having difficulty getting 100% correct focusing.

I know this is probably user error, but any help

or info. regarding enhancing the rangfinder focusing

capabilities would be greatly appreciated.

Thanks and good shooting!

Fritz Cole

[zonghou_xiong1]

I never had any problems with focusing my Fuji GW690III. I think

someone mentioned testing focusing Fuji sometime ago (this year?) in

the old MFD discussions. If there is indeed a focusing problem, it

is likely to be caused either by the finder or by the lens unit. You

can test both. Finder error can be easily identified by checking the

distance indicator on the lens focusing ring: you can measure if the

distance of an object in focus is right or you can compare the reading

with other cameras. If finder error is eliminated, you can open the

back and use the white plastic sheet that comes with the camera (or

any transparent sheet if you've lost the original) to see if things

are in focus. Use "T" to open the shutter and the camera would

work just like a view camera with a plastic "groundglass". You would

be able to tell if the film plane is accurate. I've done both tests

with mine and they were fine.

[derick_miller1]

I can't do much better than the previous response, since I

have never used the GW690III, but I can point out a general

tip on Rangefinder focusing....

 

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It is better to focus from near to far and not to hunt for

focus.

 

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Near to far means setting the lens so the point of focus is

closer to the camera than the actual subject distance before

focusing. Many Rangefinder users make a habit of setting the

lens to focus on the closest possible point, and then focus.

 

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Hunting means switching between in- and out-of-focus to narrow

the gap, passing the point of correct focus with a narrower pass

until you are in focus. This makes your focus less accurate.

 

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Derick

[john_gaasland]

Derric, I was just wondering what the reasoning is behind your comment that focusing from "near" is better than "hunting"? Thanks, John.

[kim_fullbrook]

I also have a Fuji GW690II and have found it can be tricky to focus. Recommend trying to find an object in the scene that has vertical straight lines which is close to the point on which you want to focus and point the rangefinder "spot" at that. Focus closer than the object and gradually alter the focus "out".

[derick_miller1]

John Gaasland asked why it is better not to hunt with a rangefinder....

 

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On a mechanical level, I don't know the answer to your question.

I have read the advice a few places (including the Mamiya home page user forum), but I have never heard the mechanical reason.

 

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Does anyone here know?

 

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But, if your camera isn't focusing correctly, I presume you want to see if this solution will work for you. I suggest an experiment or two...

 

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On a practical level, put your camera on a tripod and try focusing

from near to far without hunting. Note where you end up by looking

at your lens. Then try focusing by hunting and see if the point

doesn't change.

 

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If you want to pursue this experiment, use a yard-stick (or meter-stick) and place an object next to the stick which

will be the object you focus on. Open your lens wide open (to minimize the depth of field) and try the focusing experiments on

film. It is better to do this with the object relatively close to your camera, since depth of field gets bigger as the distance increases, and you will need a pretty big yard-stick :-) (At a

greater distance, you just need more objects at measured distance

from the object you are focusing on.)

 

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With a field camera (like the speed graphic), the ground glass is

the best way to check this sort of problem. As Zonghou Xiong pointed out, there is an accessory for the GW690III that acts as ground glass. You might be able to make something for other cameras, but

you need to get it in exactly the same plane as the film. If you don't have ground glass, use film and take a series of pictures (with good notes or put something in the picture to say what you are doing).

 

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Finally, evaluate the image on the ground glass or film with a loop and determine what is sharp. If the focus is correct, the depth of field should extend on both sides of the point of focus. In an ideal world, it will extend about the same amount in both directions. (If you don't have a loop, use a normal lens upside down. You can also use big prints, but that adds more variables.)

 

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Derick

[derick_miller1]

I asked on the Mamiya user forum, and got this from Martin Silvermann, a rep for Mamiya (who worked for Leica before he worked for Mamiya, incidentally). He was answering the question about what happens when you hunt with a coupled range finder camera like the Mamiya 7 or the Leica...

 

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"you are using the cam roller mechanism and shifting the critical RF ever so slightly -enough to be off by an inch or so in focus. Going from near and stopping eliminates any mechanical play."

 

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The Mamiya Web page is an excellent resource.

 

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http://www.mamiya.com/

 

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Derick

[neal_anderson]

I also have one of these impressive cameras and experienced some difficulty focussing because of my contact lens prescription. I solved this by replacing the rubber-ringed eyepiece lens with a Nikon eyepiece correction lens of the proper diopter. The ones for the Nikon FM2 fit like they were made for the big Fuji!

 

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Neal Panama City, FL USA

[frank_gross]

not exactly to the point but - I have found that the Nikon DR3 right angle finder is v. helpful - it has lock down intermediate plus and minus diopter/eyepiece correction settings and allows me a more comfortable viewing & focusing position.

Frank