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MF and long exposures

J

JohnW

Guest
Could you all help me understand the issues with medium format digital backs and long exposures? What the limitations are and why. And any vendor-specific issues....

I'm considering various lower-end digital MF options, but I'm doing more and more long exposure landscapes (30+ seconds) and don't want any surprises.

Thanks,

John
 

Jack

Sr. Administrator
Staff member
Generally speaking, all MF backs are limited to about 30 - 60 seconds maximum exposure times. Some Kodak sensors with applied software improvements made it to 30 - 60 minutes depending on ambient temperatures -- notably the Phase P25+, P30+ and P45+, P45+ going the longest reliably. I believe the latest Hassleblad 39II back (same Kodak sensor as the P45+) with the latest version of Focus software can also do 60 minutes, but I'd want confirmation of that from some of our Hassy friends before saying for certain.
 

docmoore

Subscriber and Workshop Member
Generally speaking, all MF backs are limited to about 30 - 60 seconds maximum exposure times. Some Kodak sensors with applied software improvements made it to 30 - 60 minutes depending on ambient temperatures -- notably the Phase P25+, P30+ and P45+, P45+ going the longest reliably. I believe the latest Hassleblad 39II back (same Kodak sensor as the P45+) with the latest version of Focus software can also do 60 minutes, but I'd want confirmation of that from some of our Hassy friends before saying for certain.
64 seconds...

Bob
 

kdphotography

Well-known member
Phase P45+ is still the king of the hill for long exposures. If you are consistently doing longer exposures, the P45+ is my first choice....
 

Jack

Sr. Administrator
Staff member
Thanks Bob -- so the 39II is still just over a minute? Thought I read somewhere that was improved --- oh well.

Ken, the OP did mention 30+ SECONDS as a typical long exposure, so may not need the multi-minute backs. I do over 30 seconds with regularity in my landscape shooting, and the P65+ is performaing superbly. Of course this was a big consideration for me when I traded my P45+ in on the P65+. But I agree that if one is planning on regular exposure of over a minute, then the P45+ is the current "king of the hill" for sure.
 

Guy Mancuso

Administrator, Instructor
The max on the P25+ and P30+ is 30 -35 minutes depending on temp. which I had both of these backs. Not sure I would recommend longer on them. The P45 does a 1 hour exposure as Jack has done that several times on workshops . I went as long as 35 minutes on the P30+ and after that not sure it would go longer without noise issues cropping in but I never went longer so hard to say.

The new P65+ and P40+ are rated at 1 minute but I think Doug has tried 2 minutes with success.
 

dougpeterson

Workshop Member
The fundamental issue is heat. Having the sensor on creates heat and in digital imaging [heat = noise].

Generally speaking, all MF backs are limited to about 30 - 60 seconds maximum exposure times. Some Kodak sensors with applied software improvements made it to 30 - 60 minutes depending on ambient temperatures -- notably the Phase P25+, P30+ and P45+, P45+ going the longest reliably.
The improvements from the P series to the P+ that allowed for very, very long exposures had five components
- software processing (better guessing at what is noise or a hot pixel)
- heat sink improvements (industrial design of the back to keep heat from pooling at the sensor)
- firmware improvements involving the method/speed/timing the sensor is read-off to reduce noise introduced in the read-out process
- proprietary black calibration technology which reads out the noise present on the sensor by taking a frame with no exposure (lens closed) [note this sounds simple - but just how good the black cal technology is hugely important to long exposures]

The new P65+ and P40+ are rated at 1 minute but I think Doug has tried 2 minutes with success.
Not so much.

With a P40+ or P65+ 50 seconds at ISO100 is the longest I've ever done at normal temperatures (around 70F in that example). That's the same amount of exposure as 2 minutes at ISO50 so maybe that's where you got that idea. And to be clear the quality was mediocre - depending on the content of the image and your usage it might have been acceptable but I do not want anyone thinking they can do a 2 minute equivalent exposure with a 40+ or 65+ and expect top-quality results. Good quality ends at 1 minute at base ISO (50) with the P40+/P65+ and goes up a tiny bit each time there is a firmware release or software release.

If long exposures are part of your stand-by and you don't want to be limited creatively by the technical capability of your camera then a P45+ would be my strong suggestion. If you're not able to afford a P45+ I'd explore P30+, P21+, P25+, P20+, P45 non-plus in that order. We have a pretty good selection of demo backs right now.

Here is a chart of the longest clean exposures expected for a P45+ which varies by ambient temperature. The gist is
8 minutes at 105F (41C) [yikes thats hot!]
20 minutes at 84F (29C)
1 hour at 63F (17C)
5 hours at 19F (-7C)

Doug Peterson (e-mail Me)
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J

JohnW

Guest
Thanks, everyone. Very helpful, although I'm looking at entry-level systems -- new or used. I'm a hobbyist, and there is no 39II or P45+ in my near future.

It sounds like a P25+ or P30+ is the way to go. What about the older Hasselblad's, such as the H3DII-22? Or the new Mamiya DMs?

Is this spec published with the backs?

John
 

Steve Hendrix

Well-known member
Thanks, everyone. Very helpful, although I'm looking at entry-level systems -- new or used. I'm a hobbyist, and there is no 39II or P45+ in my near future.

It sounds like a P25+ or P30+ is the way to go. What about the older Hasselblad's, such as the H3DII-22? Or the new Mamiya DMs?

Is this spec published with the backs?

John
30 seconds MAX - All Leaf and Mamiya products
30 - 60 seconds Max - All Imacon/Hasselblad products
Up to 4 minutes - H4D-40
Up to several minutes - All Phase One P products
Up to 60 Minutes - All Phase One P+ products

This is my best guesstimate (with regard to including the Imacon/Hasselblad products, since I used to sell them, but no longer). Mr. Grover can fine tune my guesstimate.

I believe that you cannot physically perform an exposure longer than 30 or 60 seconds with the Leaf/Mamiya/Imacon/Hasselblad (except H4D-40) products. In other words, the exposure will quit of it's own accord at the max time. So if you want to try a 120 second exposure even though you'll realize the noise will be higher, you cannot.

If it's a Phase One non-Plus model, the P45 will give best results for multi-minute exposures compared to P20,21,25,30. So if going for a P25 range product, I would try for a Plus model and the multi-minute exposures will be superior to the non-Plus P25.

We may have a few P25+ pre-owned units available...


Steve Hendrix
 

Steve Hendrix

Well-known member
"Up to 60 Minutes - All Phase One P+ products?"

Shouldn't that be all Phase One P+ products, except the P40+ and P65+?

Ahh - yes, thanks for that Stephen. Wish I could edit that.

P40+ and P65+ would be grouped in the non Plus group as far as capability goes. You can perform longer exposures than 60 seconds but (as Doug Peterson has noted) the results are not great. We talk more in 30 second ranges with those products in terms of getting optimal results.


Thanks,
Steve
 
J

JohnW

Guest
Thanks again, everyone. Especially to you, Steve, for the summary. Just what I was hoping for.

John
 

Nik

Member
30 seconds MAX - All Leaf and Mamiya products
30 - 60 seconds Max - All Imacon/Hasselblad products
Up to 4 minutes - H4D-40
Up to several minutes - All Phase One P products
Up to 60 Minutes - All Phase One P+ products

This is my best guesstimate (with regard to including the Imacon/Hasselblad products, since I used to sell them, but no longer). Mr. Grover can fine tune my guesstimate.

I believe that you cannot physically perform an exposure longer than 30 or 60 seconds with the Leaf/Mamiya/Imacon/Hasselblad (except H4D-40) products. In other words, the exposure will quit of it's own accord at the max time. So if you want to try a 120 second exposure even though you'll realize the noise will be higher, you cannot.

If it's a Phase One non-Plus model, the P45 will give best results for multi-minute exposures compared to P20,21,25,30. So if going for a P25 range product, I would try for a Plus model and the multi-minute exposures will be superior to the non-Plus P25.

We may have a few P25+ pre-owned units available...


Steve Hendrix

Steve, as far as LEAF goes, I think APTUS II 10 can go up to 60 minutes
http://www.leaf-photography.com/products_aptus2645df.asp Cheers, Nik
 

Nik

Member
Do you mean seconds?

That could be. Definitely not minutes.


Steve
Copy from the "Features" section :

"Unbeatable combination
With Capture speeds as fast as 1 frame per second, the combination of the Phase One 645 and the Leaf Aptus-II provides freedom and flexibility to realize your creative vision.

* Fastest image transfer speed, using the latest FireWire 800 technologies
* Open platform for maximum choice and compatibility
* Durable, proven platform for secure operation
* Ergonomic handling and ease of use
* Use Phase One digital lenses, Mamiya AF/AFD or Hasselblad V lenses
* Guaranteed up to 300,000 captures or 3 years (VA)
* Exposures from 1/4000s to 60 minutes
* Flash synchronization up to 1/1600 sec.
 
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