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Thread: High ISO and Long Expoures

  1. #1

    High ISO and Long Expoures

    I am wanting to move from my 35mm format DSLR to a MF DB and I am primarily shooting high ISO shots (1600-3200) and long exposures (20-40 seconds)

    My priorities are low processor noise at both of those settings. I am shooting night sky photography.

    Any recommendations with this type of shooting experience?


    Thanks!

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    Re: High ISO and Long Expoures

    To get above ISO1600, you will need a MFDB with binning--Phase calls it sensor plus.

    A Pentax 645D will give good noise at 1600 and there is no limit to exposure time. Multi-minute exposures are easy enough. The right-angle finder you can find second-hand which fits the Pentax makes working on a mount so much easier. It you are attaching this to a telescope, you will need a 4" focuser. If you are doing wide field, Pentax has a really nice selection of long lenses, both for the 645 and 67 series cameras. The 645D is weathersealed with is great for dew.

    Phase backs can be tethered. Pentax is supposed to be releasing tethering software this year.

    Why not a Nikon D800?

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    Re: High ISO and Long Expoures

    Phase One P45+ would not get you the high ISO's but long exposure times (clear up to an hour or more given right temps) . If you wanted to shoot high ISO long exposures you may want to stick to 35mm as they handle high iso much better. A D800E would be very well suited to your needs at a fraction of the cost.
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    Re: High ISO and Long Expoures

    Ditto to the others: Here is a quote from 2010 from Phase ONe:
    This image is a 40min exposure with a core temp of almost 36 C (35.813 to be precise)

    At this temp we can handle a 13 min exposure at 17 C you can do 60min and at 23C you can do 30min so to be able to do 40 he needs to keep the back around 20C.

    Net, 68 degrees F, or lower to get 40min. And this is at ISO 50. If you go up, which I tried to around 400, you start to see a good bit of noise unless you stay at under 2 min or so.

    As a night shooter since early 2009, I would also agree that the DSLR route is a better one. The CMOS sensor can take longer exposures in higher heat and humidity. Now with the D800, you can get very close to the same resolution as the P45+ and should be able to get to one hour or longer. I quit the single long frame method and now stack as I feel you get much much better depth on the stars, especially if you are working with the moon. With modern DSLR's you can stack without long noise reduction being on.

    When the conditions are right, the P45+ can do a great job, but remember the corresponding dark frame has to be taken, thus, if you shoot for 40min, then the camera has to have enough battery to take the dark frame, so your exposure is really one hour and 20 minutes for a 40min shot. There is no way to disable this either.

    Paul
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    Re: High ISO and Long Expoures

    Agreed. I can shoot up to a 60 second exposure with my IQ140 but it gets noisy fast at anything other than ISO 50 or 100.

    D800e is my new camera of choice for night work.

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    Re: High ISO and Long Expoures

    There are three sensor properties which matter here. You want high sensitivity to light: quantum efficiency. You want low readout noise. And you want low dark noise per second.

    Avoid any Leaf or Phase One back with a Dalsa sensor. It fails on all three properties. Sensor+ (pixel binning) on some backs reduces this to two, as it halves the effective readout noise...but it's still not as low as a DSLR though.

    Only those Phase One P+ backs with Kodak sensors support Xpose+ (dark noise reduction permitting truly long exposures). The P30+ would be a better choice than the P45+ because this domain is really flux-starved, and the P30+ has microlenses which roughly double its quantum efficiency over the P45+. The two Kodak sensors have the same dark current characteristics and presumably Phase One's "Xpose+" is equally effective for all sensors of a given dark current characteristic.

    The Pentax 645D is basically a P30+ in terms of equal quantum efficiency and sensor size. It just divides the sensor into smaller 6 micron pixels as opposed to 6.8 microns. The Kodak sensor in the 645D has even better dark current than that in the P30+, but whether that translates into a less noisy output file depends on how well Pentax have matched Phase One's "Xpose+" technology. I have not seen a comparative test of this (and would love to).

    Now whether either of these 44x33mm sensors gives you that much over a 36x24mm sensor is a moot point. The larger sensors capture more photons, but their readout noise is several times higher than a full-frame Canon or Nikon, so the shadow signal to noise is still going to be poorer in a given exposure time in a night sky photography situation - and astrophotography is all about the shadow detail.

    I would say: go into medium format for this only if you want to use medium format for a lot of other types of photography as well. I've been a MF user for 20 years and it's a love of the cameras, lenses and usage feeling that keeps me in it, plus its daytime image quality - but I'd be the first to admit that my 5DII - with the same M645 lenses - murders my old Kodak DCS645M digital back for astro shots longer than about 10 seconds. Once the twilight fades, it's time to either swap the Kodak DB with a film back or take out the 5DII, or both.

    To better my Kodak back I'd fancy a microlensed P+ back (P21+ or P30+), with good long exposure dark noise suppression - 2 out of 3 ain't bad, as the song goes. But that 3rd thing, readout noise, will always be a problem as long as medium format backs use CCDs, and unless that changes to CMOS - which also has lower dark current - they will always lag behind FF-DSLRs as astrophotography cameras.

    Now you're probably thinking "what about all those marvellous images taken with CCDs on big telescopes?" - but 1) they are actively cooled to bring dark current to negligible levels, 2) they are read out slowly to reduce readout noise (not quite as good as CMOS, but definitely better than a DB), and 3) they maintain a high quantum efficiency by eschewing the losses in Bayer CFA filters. 2.5 out of 3 ain't bad!

    Ray
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    Re: High ISO and Long Expoures

    Wow guys, thanks! Lots of great info here!!!

    I am currently using a 5D MKII and MKIII but I have a specialized project for an institution which I require a roughly 4k X 4K spherical image. As in mounting a Canon 8-15mm on a MF body with a digital back.

    The task is a night time-lapse and I need a very minimum of 1600 ISO exposure.

    And yes, I have a custom built body that is going to give me full MF señor spherical 8mm image on it :-)

    All I need is the MF back that will get me a 4k x 4k image. The Canons only get me a 2k by the time it fills the frame.

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    Re: High ISO and Long Expoures

    Quote Originally Posted by [email protected] View Post
    All I need is the MF back that will get me a 4k x 4k image.
    Why 4K?

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    Re: High ISO and Long Expoures

    It is being projected on a very large surface and we tested 2k, it didn't hold up.

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    Re: High ISO and Long Expoures

    Where can you get a 4K projector? Don't they cost like $20K?

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    Re: High ISO and Long Expoures

    Yes they do. We have one.
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    Re: High ISO and Long Expoures

    Very cool. Good luck with the project.

    The D800 will give you 4K+ pixels across the width of the frame, so you should be able to get a 4Kx4K image.

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    Re: High ISO and Long Expoures

    I need a Sperical 'negative' the MKI II will give you full frame at 4:3 but with a sperical fisheye it is a 1:1 aspect ratio, it is a 2k X2K image

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    Re: High ISO and Long Expoures

    Sorry to be plodding, but if the D800 has 4k+ pixels across the narrow dimension of the frame, a spherical image will get you the 4k x 4k. And if this lens has a fixed image circle, how does a larger sensor help?

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    Re: High ISO and Long Expoures

    With the need of iso 1600, you may be out of luck with MF

    The Pentax 645D can perform OK here, if the outside temps are Ok, example here in Arkansas at 100% humidity and 105 degrees/95 at 9:00pm you would not be able to shoot any MDFB for a very long period of time as the heat would get to it, (will also get to a 35mm but will take a bit longer). I have seen images taken with the Pentax at 1600 iso and they are not bad, but you seem to need a back, not a full camera, and the Pentax will not give you that. You might look at a zork adatper to see if they make an adapter that would let you use your Canon 8-16 on the Pentax MF mount.

    The P45+ won't work as it's top iso is 800 and for long exposures, I would not take it past 200 iso. 50 is better, 200 gets pretty harsh and I found 400 just not useable. P45+ has a crop factor of 1:1, it will take a bit away from your image.

    You might be able to use a P30+ if you can locate one. This back always had very good low noise performance, but I can't remember if it goes to 1600. Resolution is less than the P45+ and it has a crop factor of 1.3.

    In daylight I have shot the IQ160 up to 1600 in the sensor + mode and actually found the images to be very clean from noise, cleaner than my 5d MKII at 1600, but as already mentioned you are now at 15mp. Smaller than your 5D MKII. The 180 would get you a 20mp image.

    I have no experience with the leaf backs and longer exposures from them.

    Paul

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    Re: High ISO and Long Expoures

    Most leaf Aptus backs are limited to 32 seconds ^
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    Re: High ISO and Long Expoures

    Quote Originally Posted by Paul2660 View Post
    I have seen images taken with the Pentax at 1600 iso and they are not bad, but you seem to need a back, not a full camera, and the Pentax will not give you that. You might look at a zork adatper to see if they make an adapter that would let you use your Canon 8-16 on the Pentax MF mount.
    You cannot adapt a smaller-format lens to a larger-format body and maintain infinity focus. The mirror-box of the camera body gets in the way. That's one of the advantages of having a digital back rather than a digital MFdSLR - you can use the sensor with lenses of any flange-distance (provided they cover the required sensor size). See also: tech cameras and the Hartblei H-cam.
    Doug Peterson , Digital Transitions | Email
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    Re: High ISO and Long Expoures

    Quote Originally Posted by [email protected] View Post
    Wow guys, thanks! Lots of great info here!!!

    I am currently using a 5D MKII and MKIII but I have a specialized project for an institution which I require a roughly 4k X 4K spherical image. As in mounting a Canon 8-15mm on a MF body with a digital back.

    The task is a night time-lapse and I need a very minimum of 1600 ISO exposure.

    And yes, I have a custom built body that is going to give me full MF señor spherical 8mm image on it :-)

    All I need is the MF back that will get me a 4k x 4k image. The Canons only get me a 2k by the time it fills the frame.
    Everyone here knows how much I love medium format. But this is not right for you.

    [ISO1600 + long exposure + sustained shooting] is not something you'll get good results from with any current medium format back. The closest would be a P30+ or P45+ or H4D-40, but even the most evangelical of us would not claim they would do what you're asking with any decent final quality.

    Long exposure - yes.
    ISO1600 - yes.
    Sustained Shooting (time lapse) - yes.
    Great Quality - yes.

    All four at the same time: no.

    I'd try a D800 or working out a multi-camera stitching which would require a lot of hardware customization (i.e. camera mounts with specific spacing) and software expertise (i.e. preset geometric mapping algorithms to take two overlapping rectilinear ultra wide angles and create a single spherically mapped image out of them - with enough consistency to avoid flicker or artifacts when presented at the required frame rate for time lapse video).
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
    Office: 877.367.8537. Cell: 740.707.2183
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    Re: High ISO and Long Expoures

    Quote Originally Posted by [email protected] View Post
    Wow guys, thanks! Lots of great info here!!!

    I am currently using a 5D MKII and MKIII but I have a specialized project for an institution which I require a roughly 4k X 4K spherical image. As in mounting a Canon 8-15mm on a MF body with a digital back.

    The task is a night time-lapse and I need a very minimum of 1600 ISO exposure.

    And yes, I have a custom built body that is going to give me full MF señor spherical 8mm image on it :-)

    All I need is the MF back that will get me a 4k x 4k image. The Canons only get me a 2k by the time it fills the frame.
    Ah, now these extra details change things. As Doug says, you can't use a MF SLR with this 35mm format lens and get anywhere near infinity focus.

    This special project is crying out for the use of a cooled, high q.e., medium format astronomical CCD camera.

    What I would ask is - does this need to be in colour? Because if B&W will suffice...we use a Finger Lakes Imaging (FLI) Proline 16803 on our campus telescope. It's got a - wait for it - 4k x 4k sensor! - the Kodak KAF-16803, consisting of 9 micron pixels with no Bayer CFA and quantum efficiency which is about double that of even the microlensed MFD systems. It operates with regulated thermoelectric cooling at 50-55 degrees Celcius below ambient temperature, so exposures can be arbitrarily long and still almost noiseless (and of course dark frames can be taken and subtracted separately for the little bit of dark current which does arise). The CCD is has a read-noise of just 9 electrons (the best MFD systems are poorer at 12 electrons). The back focus is short and the front of the unit has a wide threaded flange, so you can get a Canon mount to screw onto it from FLI. (It probably won't operate the aperture, but you want to shoot the lens wide open anyway, right?) It is operated tethered over USB and a 12V power source. Price around $10-12k, depending on any promotions, which in MFD terms is very much at the "cheap" end.

    And if you can afford it, there are other Proline models using colour sensors - the KAF-31000 and KAF-50100, the same sensors as the P30+ and Hasselblad H4D-50 respectively. What you gain over those cameras/DBs is the extremely deep cooling, plus lower readout noise (again 9, instead of 13 to 16 electrons). The KAF-50100 has no microlenses though, so its q.e. (which is a major contributor to high ISO) is not as good as the KAF-31000.

    I think any of these units will give you "All four at the same time: yes".

    FLI Quality Cooled CCD Cameras Home

    Ray

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