Black calibration on Phase One P45+

[jamesdfloyd]

Can someone point me to a post, or a link that shows me how to do a "Black Calibration" for my Phase One P45+?

I have seen a few references to the process as a "thing", but not how to do it.

Thanks,

J.D.

 

[drevil]

the feature was introduced with the IQ2 series, afaik.
so the P and P+ backs do not have this feature.

 

[dougpeterson]

the feature was introduced with the IQ2 series, afaik.
so the P and P+ backs do not have this feature.

This is not correct.

Black calibration has been part of the Phase One architecture since at least the H20 (probably earlier, but that predates my specific technological experience with Phase One).

Dark frame on the P45+ is automatically performed when required. No user action is required.

Are you trying to solve a specific issue or experiencing some unusual noise? If so I would suggest contacting your dealer for analysis.

 

[drevil]

ok you are referring to dark frame substraction, sure, that does exist for a long time.
but according to a video on youtube, the iq2 series made it possible to turn it off?

https://www.youtube.com/watch?v=22uezADFNHI

 

[Paul2660]

Can someone point me to a post, or a link that shows me how to do a "Black Calibration" for my Phase One P45+?

I have seen a few references to the process as a "thing", but not how to do it.

Thanks,

J.D.

I am curious, are you trying to do a calibration file for the back?, or do a dark frame subtraction?

As far as I know all Phase one backs, need a calibration file which is stored in the back, this file with a 60mp and 80mp backs helps to remove tiling and other issues. Not really sure what it does on the P45+ besides removed errant pixel errors and column errors. The file can become corrupted. I believe that a dealer can help create a new one over the phone, but it's been a while since I used the P45+ so it may have to be done by Phase One. You also need to be using the latest firmware, which can be downloaded from the Phase One site. I would also talk with a dealer before updating your firmware if you are not at the latest version.

On any exposure @ 1 second or longer, the P45+ will take a 2nd exposure for the same time, i.e. a 1 second exposure, the back will take a second 1 second exposure. There is no way to turn this off the the 2nd exposure is very important to the file. So as you grow the exposure time, you need to make sure you have a fresh battery, as a 30 minute exposure will take a total of 1 hour to write.

On the IQ2 and 3 you can turn this feature off by shooting in Aerial mode, but only on a tech camera or other non DF or XF style camera. Not sure if the IQ1 had aerial mode or not.

Paul C

 

[dougpeterson]

ok you are referring to dark frame substraction, sure, that does exist for a long time.
but according to a video on youtube, the iq2 series made it possible to turn it off?

https://www.youtube.com/watch?v=22uezADFNHI

The wording in that video is quite poor. Likely a lost-in-translation between the marketing and technical teams. In "normal" mode the back still takes dark frames as needed. "Extended" just lowers the threshold for when "as needed" is considered to be.

 

[Paul2660]

The key is the wording as needed, as it's been made clear on this site and others, that before 1 second, the back may use a prior dark frame several times, and for sure the user doesn't see anything on the LCD, where as a 1 second or longer, the back shows the dark frame process being done each time, thus possible confusion. I will also assume that at 1 second or longer the back is taking a fresh dark frame each time, not reusing one since each time the photographer is not able to shoot again until the follow up dark frame processes. Also no buffering is used either to free up the back, something that IMO should be possible, at least by now with the CMOS backs, as Canon has figured out a way to process the dark frame in the background for years now. Eventually you will buffer out with Canon especially on longer exposures, but not on 1 sec to 20 seconds.

Paul C

 

[dougpeterson]

I will also assume that at 1 second or longer the back is taking a fresh dark frame each time, not reusing one since each time the photographer is not able to shoot again until the follow up dark frame processes.

Not correct. Timed multi-second exposures can also re-use previous dark frames when suitable. This is more common for the CMOS backs since the the threshold for "as needed" with those backs is higher. For example if you set an IQ3 100mp to 2 seconds and take several frames in a row it will typically only do a new dark frame on the first of those captures.

 

[Paul2660]

Doug,

I was referring to the P45+, as mine always took a fresh frame each time, no matter what. Maybe that changed in the last 2 years with firmware, but I used mine plenty of times for exposures 1 sec or longer and it always took a dark frame, and thus control of the back for an additional period of time. That I know is correct as I owned and used the P45+ for 3 years or so.

So far the times I have used either a IQ150 or 100 CMOS back for longer exposures, (not in Aerial mode), I have always seen the corresponding dark frame fire after the initial shot. In fact just 2 weeks ago, I watched for 16 or so exposures all at 10 seconds to 20 seconds and waited for a CMOS back IQ100 to fire a full corresponding dark frame for same time and remember wondering out load to myself, why this still has to occur with CMOS.

I would agree that on 1 second to 3/4 seconds, it does seem that the back is not always firing a dark frame each time.

Paul C

 

[f8orbust]

I've used a P45+ for years, and it always takes a dark frame.

That's not to say that it doesn't reuse a previous dark frame* rather than the one it's just taken, but that in itself would be weird given what I just said.

Jim

*Where does it store them ?