Phase One P+ long exposure recommendation chart

[sanvandur]

I have a Phase One P21+ back that just got repaired. It was having some issues with long exposures. The problem is now solved. Phase One sent my dealer this extremely useful chart showing the longest exposure possible at a given temperature.
Here it is:

Please use this chart to let your "long exposure" customers know what to expect with P+ backs.

Temp/ C and F: Max. exposure time/minutes

41 105 8
35 95 13
29 84 20
23 73 30
17 63 60
11 52 90
5 41 135
-1 30 200
-7 19 300
-13 9 450
-19 -2 675
-25 -13 1000
-31 -24 1500
-37 -35 2250
-41 -42 3375
-47 -53 5000
-53 -63 7600
-59 -74 11400
-65 -85 17000
-71 -96 25600
-77 107 38400 (26 days)

[EgillBjarki]

Very usefull! Thank you very mutch

[ternst]

I guess I don't get it. The plus backs are advertised to be able to do an exposure of up to one hour but no longer. The regular backs up to 30 minutes. I don't have the plus back yet but my normal P-45 will do a 30-minute exposure, but no longer, so I suspect the plus back will be limited to one hour as advertised. If that is indeed the case then this chart doesn't really mean anything - am I missing something?

It is true that higher "room" temps will create more noise, or that lower temps will create less noise, so long winter photos should be less noisy than those in the summer, but at some point the sensor heating up would be well above the room temp anyway.

[mahleu]

It is true that higher "room" temps will create more noise, or that lower temps will create less noise, so long winter photos should be less noisy than those in the summer, but at some point the sensor heating up would be well above the room temp anyway.
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A cooler room temp will mean a cooler sensor. A cooler sensor means less noise. So yes, long winter photos should be less noisy, although moisture forming on the lens can be a problem in cold places.

[sanvandur]

It is my understanding that the + backs do not shut off after one hour (unlike all other MFDB's). You can make as long an exposure as you want. The only limitations are noise/temperature and battery power running out on the camera body and/or the back itself.

[ternst]

The specs for the plus backs say max one hour exposure, which is double of the 30-minute exposure of the regular backs. I tried to do longer than 30-minute exposures with the P-45 and it would not let me, in fact it messed up the image badly - I posted the results in another thread here a couple of months ago. I could have easily gone 2-3 hours with the battery, but I know the plus backs use up a lot more juice so probably an hour is about it with them...