H20 issues

[Ganesh6667]

Dear Friends,
Just started using a Phase One H20 back on a Mamiya Rb67 Pro S.
Some issues I have been facing recently is the image sent from the back is just black like an unexposed frame. Tried different settings and finally the 90mm lens at 1/4 of a second at any aperture works. I am using a Macbook for the shoot and a C1 version 6 or 8 - i am not sure. When I tried with my other lenses, the wide 50mm and the tele 250mm, I only get an unexposed black frame even at 1/4 or 1/2 of a second. Sorry to take you back by a few years, but I am hoping for some explanation on this issue.
Kindly share some info as to how to get over this problem. I am unable to shoot at any other shutter speed other than 1/4 or 1/2 sometimes, Is it the rear shutter or sync problem? or what?
Thank you.

[Doug Peterson]

Underexposed, nothing but noise, or 100.00% black?

I'm assuming it's the last option (e.g. making a +3 exposure adjustment in C1 does not show any image nor noise). If so, most of the time you get black frames the cause is insufficient power coming from the firewire port. Work with the Phase One back from whom you purchased to troubleshoot. In all likelihood they will start by having you try a powered hub and a normal length Phase One firewire cable.

[Chris Livsey]

Would it not be easier to test that by using a CF card instead of tethering, if that works then the firewire is suspect?

[Doug Peterson]

Would it not be easier to test that by using a CF card instead of tethering, if that works then the firewire is suspect?

H20 was the generation before CF card slots were added.

[Chris Livsey]

That's going to be a problem then