Long exposures limited to the P45+?

[wentbackward]

I actually never intended to get a MF digital camera (I just wanted a back to use on my vie camera) but the deal was just too good to end up with a 645DF and a lens. Anyhow I really like the camera and the ability to use old mamiya lenses... plus I have no choice as I'm still waiting for the 4x5 adapter to arrive here in Hong Kong. I went for the DM33 as the sensor size is quite large (I'd prefer size before megapixels).

Originally I figured with the view camera, if I wanted to do some long exposures I could just pop a sheet of film in my view camera.

I find the noise over a few seconds to be a bit annoying and if I begin to use the DF body more, I really don't want to carry another camera around, this kind of limits some of the stuff I like to do.

I've been checking through the specs and it seems that:
All Leaf/Mamiya backs are limited to 32s
Phase One IQ: 1 min (IQ180 2min)
Phase One P45+ 60 min

However I'm sure I read somewhere about several hour shots on the IQ. Could someone enlighten me?

Thanks everyone
Paul

 

[GrahamWelland]

Paul,

I believe that all of the Phase One backs using xpose+ have the 60 minute exposure capability. I understood that the P30+ & P21+ had this capability in addition to the P45+. However, I've never owned or used either of these backs so I'd have to defer to others to confirm that these do indeed operate as the spec sheets describe.

 

[nightfire]

Some very good practical figures are here:

http://www.captureintegration.com/phase-one/phase-one-tech-specs/

(Scroll down to "Phase One and Long Exposures")

 

[goesbang]

How long are the exposures you NEED to make?
Keep in mind that the "sweet spot" for MF optics is most commonly in the f/6.3 - f/11 range and sensors do not suffer from Reciprocity Law Breakdown.
I am an international architectural photographer and often shoot pre-dawn and last-light images of my clients buildings using P45+, P65+, Aptus 12 and IQ180 backs. I used to occasionally find some annoying noise in P65+ files at around 60 sec, but this has been substantially reduced with recent versions of C1.
The problem exists, but has been hyped completely out of proportion by pixel peepers.
If you are going to regularly shoot beyond 1 min, consider a P45+. Just remember that the IQ180 is rated (at first-release stage) at 2 mins and I fully expect this to improve.
Currently, I still carry my P45+ "just in case" I need to shoot really long exposures, but the image quality of my IQ180 is so superior that I suspect that this habit won't last.
It is healthy to discuss the limitations of our equipment openly, but is is also vital that we process this through the filter of real-world usage.
Cheers,

 

[wentbackward]

Thanks for the comments and link that is very helpful.

I should have been clearer, sorry about that. I mainly use long exposures to remove people from cityscapes, perhaps shooting three long exposures of a few minutes that can be overlaid and ghosts removed or otherwise to blur water movement. I would say max is probably about 7 minutes.

Yes reciprocity is a friend in this case. I have quite a collection of ND filters now.

Well my question is still subjective, but I guess it would be, can I get nice 30x40 print from a seven minute exposure from the new IQ backs, or do they just turn off at 1(or 2) mins?

 

[dougpeterson]

Well my question is still subjective, but I guess it would be, can I get nice 30x40 print from a seven minute exposure from the new IQ backs, or do they just turn off at 1(or 2) mins?

Absolutely not.

The long exposure specs on our website as referenced earlier are the absolute longest you should expect high-quality results from.

The absolute longest an IQ180 can be expected to stretch to is 120 seconds. In our testing so far the quality drops quickly between 100 and 120 seconds. We expect that in the next few months firmware and software tweaks will solidify 120 seconds as usable. But 7 minutes is absolutely not going to happen.

There is no other digital back in the world to recommend for frequent 7 minute exposures (for the purpose of 30x40 high-quality prints) other than the P45+.

At least this means you don't have to do a lot more research.

Doug Peterson (e-mail Me)
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[wentbackward]

Excellent, thanks for that Doug! Now to figure out how to shift my DM33 and get the P45+. It's not so straightfoward in HK!

 

[yossarians22]

Hassy 40 can squeeze 4 and a quarter minutes. And without dark frame subtraction.