Shen Hao 612 back forward focusing?

[joshdaskew]

Hi, I have recently bought a Shen Hao 612 multi format back off Ebay and after some test shots realise that it seems to be forward focusing from what i focused on my groundglass. I am using a Chamonix 45N-1. I had this same problem when I first got my Chamonix and shooting on regular film holders and it drove me insane! Like many others i came to the conclusion that it was the fresnel placement on the original Chamonix that was causing focus areas when shooting wide open. I was doing my tests with a 150mm Xenotar 2.8. I have had since had this back replaced with a Maxwell screen and had my back aligned by Bill Moretz at Pro Camera. All tests after these additions to my camera have been spot on! With the roll film back, all my tests show that the film that is coming back has the focus forward of what was focused on the groundglass. I have done a test of shooting close up at a 45 degree angle on some newspaper print and these results were actually not bad, the worst seemed to be focusing on something on the ground at a distance of around 3-5 metres. Any thoughts?

I mainly plan to shoot some architecture with this back and would be stopping down to around f11-f16 so this shouldn't really matter but i would still like to know that what I am focusing on is correct?

If anyone has any thoughts at all it would be greatly appreciated! Best Regards Josh

[joshdaskew]

Anyone have any suggestions? Could i be putting the back on incorrectly? I am taking the groundglass off and then inserting the holder.. Anyone?

[Gordon Flodders]

Have you tried shooting with standard double dark holders? If they exhibit a similar focusing problem, then obviously the ground glass/freznel relationship is at fault.
Very unlikely that the Shen is out of whack, (although it's a possibilty) it sounds more like the GG is not positioned correctly.
Someone should certainly come up with a fix for this. Remember that The Xenotar has an insanely narrow DOF wide open (as when you're focusing with it), so maybe try a different lens and see what happens?

GF.

[joshdaskew]

Thanks for the response, much appreciated! I have actually tested the back with standard double darkslides when I first received it back from Bill Moretz at Pro Camera and they came back perfectly in focus (shot wide open at 2.8 on the 150mm Xenotar). So the only thing I can attribute it to is that the Shen Hao back is out of whack. As mentioned before, the worst type of shots seems to be mid distance type of shots ( anywhere from 3-5 metres ) while the close up shots of newspaper print seem to be Ok. Am totally lost on this one... Any other thoughts or other ideas for tests would be really appreciated! Best Regards Josh

[Lachlan 717]

I have one more suggestion: let's run a film through it on my camera. That'll let you know if it's the camera or the back.

[joshdaskew]

Hey nice one! To the rescue again! Will give you a call tomorrow and see if I can track down a time to meet you westside! Thanks again.

[Lachlan 717]

Pleasure.

No idea why we didn't think of it last week!!

I also should have the Horseman back in action soon, so we can try that as well. It should be accurate.

[verney]

Is there setting for 220-film on the Shen Hao back?

[joshdaskew]

Hi, To my understanding, the back only takes 120 film, it is a fairly basic device. If you use 220 there is no way of knowing what frame you are up to as you wind on according to the numbers on the back of the backing paper.. I don't think 220 film has this. Thanks for the input.

[vinny]

I had an early shen hao back (shortly after badger began selling them) and my shots were soft with it so I measured the depth of the film plane vs. the ground glass. quite a ways off, returned it and got a new one which isn't off.