Wista DX focus issues ?

[Fred L]

A friend has my Wista Dx and is now having issues with ground glass focusing. It had been a workhorse for me with no issues so this is a surprise.

The problem he's encountering is that when an image is properly focused on the gg, the image on the film is out of focus. It appears to be back focused about 25' or so (his guesstimation).

I've gone through all I can think of and he's not a lf newbie either. Ground glass is oriented properly, film is loaded correctly and holders sit as they should. I'm stumped. He'd read somewhere that Wistas weren't always calibrated properly which was news to me and he's trying to see if shimming the gg will help.

Any ideas on what the root cause could be ?


tia,

Fred

[Bob Salomon]

The gg is out of position. Who changed it? Marflex can reset it for him.

[IanG]

It's worth checking the dark-slides (film holders).

There were some non-standard MPP dark-slides, these were made to fit the first MPP cameras which had a slightly different register to the usual International type.

I've never heard of a focus issue with Wista's I've had mine about 23 years, and know quite a few others who have used them too.

Ian

[Fred L]

I don't recall anything being changed and it worked fine for me until he took it overseas with him. I was hoping that some jokers at worked played around with the gg as a lark.

I asked about the positioning and he says it's ground glass side facing lens, then on the viewing side there's another piece of glass on top.

Thanks for the ideas, much appreciated, keep 'em coming ;)


@IanG-this is where I'm totally baffled, I've never heard boo about Wistas and focus issues but he's found some references on the internet about this. The holders are mine unless he found some extras elsewhere.

@BobS-see above. I also asked if he thought it could have been knocked out of whack by air travel but I've done the same so can't really see that happening. As well, he's overseas so he would have to ship the thing back here and not sure if that's in the cards right now.


Fred

[Archphoto]

Where is he ? He might get it fixed localy....

Peter

[Steve Hamley]

If you never had a problem with it, try shooting a few sheets with it and see if you can reproduce the results. If you can (fuzzy pics), it's time for a trip to the service station.

If you can't, time to look elsewhere.

Also, have you checked to see that something hasn't shifted during say tightening the locks? Maybe he does this differently than you. Sit down, clear your mind, and watch him use the camera.

Cheers,

Steve

[IanG]

Fred, my Wista has an integral Plastic fresnel/screen then there's a thinner protective sheet of plastic with the grid lines etc on.

It is possible that if your friend changed the screen to a different type then it's out of register. I have heard of this happening with other makes of LF cameras. Bob Salomon could probably give you similar instances with Linhofs.

Ian

[Fred L]

My buddy's in Abu Dhabi so it'll be hard for me to do my own test on it ;) He had the locks tight, everything lined up etc.. He did get some extra holders (Fidelity I think) but that shouldn't be an issue. At first I thought the film wasn't under the rails but he's no stranger to loading holders.

Will ask if he did anything to the screen but I doubt it.

Thanks again for your help. It's frustrating for him since E6 processing is not the most readily available.


cheers,

Fred

[Frank Bagbey]

I am not positive without testing, but I do not think messing around with the ground glass is going to cause results that far off. There are 5 Wista's around here that I know of and none of them have ever had a problem, except for losing the focus locking capnut. I tell people to just take the damn thing off and leave it in the camera bag. If no one has ever messed with the focusing ground glass, I would not alter it. Careful and accurate measuring will determine the problem. Think how much minor variation there can be from using 4 or 5 kinds of film holders, polaroid backs, film backs, lenses, etc. MEASURE accurately, check with loupe, make test exposure!

[Gene McCluney]

Here is my take on this. The ground glass is part of the spring loaded back that seats where a film holder seats. The spring pushes the ground glass back/frame hard against the seat where the film holders goes. When you insert a holder the same spring loading of the back pushes the film holder up tight-in the same place the ground glass back was.
The ONLY way you could get errors is if 1. The ground glass was messed with and is not seating in the frame that holds it, or 2. The film holder is not seating fully. That is all that it can be, one of the above.

[Doremus Scudder]

FWIW, I had a similar problem with my Wista DX. I did tests, shimmed the gg, etc. to get the focus better.

I finally figured out that the problem was my "refurbishing" the back. I had replaced the thin velvet strips that line the face of the filmholder seat. I had put one in the slot for the filmholder ridge. There was none originally, and I thought it had simply been lost. What happened was that the filmholder no longer seated properly; the top was ever so slightly farther out. This put the holder at a slight angle. Strange sharpness issues occurred; in-focus on the bottom, out on the top.

When I finally figured out what I had done, I tore out my velvet strip. Voila!

I now make double sure that the ridge on the filmholder is seated into the slot on the camera back by squeezing to make sure. Often there is a little movement, meaning that the holder was initially not seated properly. I've had no focus issues since removing my "improvement" and making sure the holder is seated.

Possibly, in your case the filmholders are not seating all the way into the slot in the camera back. Have your friend make sure. If this is the problem, it's an easy fix.

Good luck,

Doremus Scudder