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IQ4 150MP exposure problems in low light

PostPosted: Mon May 27, 2019 1:54 pm
by Roy Prasad
After upgrading from my IQ3 100MP to an IQ4 150MP, I have encountered a consistent and repeatable problem with exposure in low light situations (not darkness, just low light). I have now tested my IQ4 back on two different XF cameras and 6 LS lenses, 4 Blue Ring and 2 non-BR. All my firmware is up to date.

Basically, the camera totally blows it - it comes up with absurd exposure times that range from 2 minutes to a flashing 1:00 hour. A symptom that the camera is getting the exposure wrong is a continually and randomly changing shutter speed in the Av mode. If I click the shutter anyway, I get totally washed out garbage.

So for low light situations, my solution is to use my Sony RX100 camera as an exposure meter. I set the ISO on the RX100 at 100 and the f-stop to match what I have on the XF, and get a shutter speed. I then use that to set an appropriate shutter speed on the XF in the M mode. (Usually, 2x the shutter speed, since I usually shoot at ISO 50).

This method is working pretty well, but it begs the question: isn't it ridiculous that a $50,000 camera + back needs help from an $800 camera for proper exposure?

Perhaps Phase One should consider including a free Sony RX 100 with each IQ4?


For 2+ months, I have been working with Phase One via my dealer, and as of right now, my XF, Prism view finder and one Schneider lens are all with Phase One. So far, no solution to my problem. Phase One has sent me a loaner XF and a Prism VF, but I have the same problem with them, which is why I am thinking the issue may be with my IQ4.

Is anyone else seeing this problem? I would appreciate any insights or suggestions.

TIA, Roy