How to install Aptus screen in Contax 645?

[evgeny]

Hi.

The Aptus screen should show an area that fits the Aptus 33x44mm sensor.

Installation: I simply put the Aptus screen on top of the Contax screen, insert Contax screen in the camera, and attached the viewfinder.

The Aptus screen is not fixed when sandwiched between Contax screen and Contax viewfinder.
The screen does move due to its own weight when I rotate the camera from landscape to portrait position and vise versa.
The black rectangle may shift to a side in the viewfinder.
There is a chance that rectangle, if moved, will not be lined with the digital back, and can show an area that is not actually photographed. How to properly install / fix the Aptus screen in Contax 645?

Thanks
Evgeny

[evgeny]

I asked a buddy who uses a Contax with his Phase back and he places the mask on top of the screen. If you put it under then it will give incorrect focusing.

If the mask shifts around, you may need to afix some clear tape at the edges or something. Other option is getting a dedicated Contax screen already etched for the 33x44.

John, thanks. So, I installed it right, will think how to fix the screen.

[cyberean]

is it possible that you have the wrong Leaf mask?
(e.g., one specifically sized for a different cam, than the C645)

another option may be to secure a comparable crop mask,
from one of the other back makers, whose masks are cut
to size for the C645.  (??)

[evgeny]

is it possible that you have the wrong Leaf mask?
(e.g., one specifically sized for a different cam, than the C645)

another option may be to secure a comparable crop mask,
from one of the other back makers, whose masks are cut
to size for the C645.  (??)

I think this is a universal mask.

[andershald]

The instructions from Phase One say that the mask must sit UNDER the foussing screen. I have just checked and the mask will not fit on top of the screen. (P30+ and Contax 645)

[evgeny]

The instructions from Phase One say that the mask must sit UNDER the foussing screen. I have just checked and the mask will not fit on top of the screen. (P30+ and Contax 645)

The Aptus screen must be on top of the Contax screen, Yair confirmed that.

[evgeny]

Some ideas of which I have done.

In Photoshop make a new image file with the 33x44 crop lines centered to a 645 frame. Print on clear acetate and use that as a mask or print the frame image on a white sheet, place on lightbox, overlay a lighting ND .3 or .6 gel (doesn't take much of course) and cut out the mask frame. Then you can customize it to fit as needed. The ND filter is very close to the type provided by Phase One for its backs.

I use dedicated etched screens on my AFDII and RZ which are just the crop lines etched in black and allow seeing a bit outside the sensor size.

I thought about that option.
It's a bit strange to not receive a simple, very simple, plastic screen matching the camera for which the expensive $$ high-tech back is made.

[narikin]

The Phase P series Manual in the Contax section doesn't even mention that the masks are peel-apart, for a year I thought it was grey card, until I was reading the Hasselblad installation section that tells you to peel the cover layers off the mask (not very easy - they are well stuck down). The contax section omits to say that, somehow supposes that you know what Hasselblad installers are told...

more importantly the Phase mask for Contax is wrongly cut out and raises the screen by its thickness, (bad thing) so you have to trim it down enough to allow the fresnel mask to sit on its own four feet, like it should, and the mask not to interfere with that seating at all, for correct focus.