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long exposures on p40+

halfFrame

New member
Anyone shooting exposures longer than say 5 seconds with this back?
I think the noise is a problem compared to the 25+ or 45+.

Inclosed is a crop from a 2 second/ 400 ISO file.
 

halfFrame

New member
you'll wonder where the detail went with sensor+ on a long exposure.
The regular sensor at least keeps some detail.
(40+ at 200 ISO on left)
(sensor+ at 800 ISO is on the right)
 

Jack

Sr. Administrator
Staff member
Which latency do you have the back set to, normal or zero? What was the outside temperature when you took those images? Finally, ISO 400 is not the best choice for long exposures, 50 or 100 should be better...
 

thomas

New member
now, that looks bad.

but should you not set the back to ISO50 (base ISO) for long exposure?
than again 2 seconds is not really "long".
 

halfFrame

New member
Temperature was San Francisco mid 50'sF.
Not sure on latency as the back is back at the store.
I also did 50 and 100 tests and all had more noise than expected.
I posted the above as the noise would be more noticeable on the web jpegs.
Basically 100 was extremely borderline and would need retouching of the noise.

I was hoping the P40+ would be better at 100 or 200 ISO, so I could keep the few passing cars out of the frame at 2am.

The sensor+ seems useless for long exposures as it "smears" the info.
50 ISO is fine on the P25 but the exposure time is a problem sometimes.
 

Jack

Sr. Administrator
Staff member
Below are multi-second exposures from the P65+, I have them both printed large in my studio and they are essentially noise free. I suspect something was amiss with your demo back, like it was on the zero latency setting and left on for quite a while before the captures. That is a documented negative of the zero latency setting.



 

Guy Mancuso

Administrator, Instructor
Yea something is wrong. I have gone much longer with great results. Just on iPhone for the next week but will find something. My Salton sea images a lot are pretty long is you want to check my gallery
 

dougpeterson

Workshop Member
Note that the P40+ does not combine high ISO and long exposures very well at all. Also Sensor+ is not a great option for long exposures. Your shot was 2sec@ISO400. The equivalent 15sec@ISO50 would have been very clean and shown some of the best color possible with any back doing long exposures. I'm personally disappointed the dealer you were working with didn't point this out to save you the time and angst of seeing such a poor file out of such a high quality back - but I don't know the situation so maybe you were not working side by side or such.

P40+ long exposure files at ISO50 will look great at 5-30 seconds in most situations and 30-70 seconds depending on temperature. If you absolutely MUST push the maximum limits of the system I've found that ISO100 will give the longest usable (equivalent) exposure. Using higher ISO and even very-modestly long exposures is not going to give good results with a P40+ which is a characteristic of the DALSA sensor it uses.

Whenever dealing with long exposures only process your files in Capture One (rather than PS, LR etc) and play around with the noise reduction settings to customize the default noise reduction to your own personal preferences.

If you want really great really long exposures you'll need to look at the P45+ which can go for an hour (or more depending on temperature). There is no other digital back which comes close for long exposures.

Doug Peterson (e-mail Me)
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Guy Mancuso

Administrator, Instructor
Yea all my long exposure images are ISO 100 and none sensor plus. But I do remember going 30 seconds with excellent results. Also Doug is dead on you really need C1 for long exposure stuff. Totally setup for it. Frankly I NEVER use anything but C1 for Phase files. Nothing processes better
 

Jack

Sr. Administrator
Staff member
thanks Jack,

I'll check on the zero latency issue.
Also we assume you were using C1 to convert and NOT LR or ACR, right? LR/ACR simply suck with Phase files and might also explain your result...
 

halfFrame

New member
Jack _ Guy , Yep I only use the Capture One software for files and have had a Phase One back since the first model way back (the 35mm format version).
I have been using the P25 for a few years now and was thinking of trading up as I am working a lot with the Alpa SWA and with rises and such. In bright daylight the P40+/65+ does great on the lens casts, but I have to work out the night stuff which has a lot of blacks as they are mostly cityscapes. I did try the 50 asa test and the 100 asa test, but I see more noise in them than in the P25 files of similar situations at about 8-20 seconds.
I will try the latency approach on the next time i try the demo back.
 

cly

Member
I have been using the P25 for a few years now and was thinking of trading up as I am working a lot with the Alpa SWA and with rises and such. [...] I did try the 50 asa test and the 100 asa test, but I see more noise in them than in the P25 files of similar situations at about 8-20 seconds.
I will try the latency approach on the next time i try the demo back.
halfframe - did you have a chance to retest the P40+?

BTW, is this an 8-20 seconds example?

--chris
 
Didn't want to start a new thread just for one question, sorry for thread hijack, Its normal to get more hot pixels after several very long exposures yes?
 

Jack

Sr. Administrator
Staff member
Didn't want to start a new thread just for one question, sorry for thread hijack, Its normal to get more hot pixels after several very long exposures yes?
Yes, especially on longer exposures and more especially the warmer it is outside. Also, can increase if you have latency set to "Zero."
 
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