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Thread: P+ ISO or "push" processing?

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    P+ ISO or "push" processing?

    Generally speaking, when hand-holding with available light as the only option, is it better to use the + ISO setting on my P40+ back, or underexpose and push process the file in Capture One?

    I plan on running a few tests on my own, but am wondering if there's a general consensus on this already?
    J R

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    Re: P+ ISO or "push" processing?

    The "+" settings are Sensor+ mode and lower the resolution from 40mp to 10mp while simultaneously raising the native ISO two stops.

    If you can live with the lower resolution (which prints far better than the "10mp" might lead you to think) then it's always better than under exposing a non plus setting.

    This is easy to overlook since no other modern/mainstream still cameras that I can think of employ hardware level pixel binning for higher ISO performance. It was a feature phase one codeveloped with dalsa.
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    Re: P+ ISO or "push" processing?

    What ISO are you trying to achieve? What is the situation? Why not just use ISO800?

    The "+" is simply binning where the signal from four pixels are added together (this is very common in scientific cameras--I have cameras from Nikon, Diagnostic Instruments, and QImaing that can do this). You get an increase in sensitivity or two stops with the compromise of half the resolving power. I guess the question would be is the loss of resolution from noise better or worse?

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    Re: P+ ISO or "push" processing?

    Thanks for the quick reply, Doug.

    I'm sort of surprised, given how much latitude the sensor has in non-Sensor+ mode. I'll have to give it a try.
    J R

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    Senior Member johnnygoesdigital's Avatar
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    Re: P+ ISO or "push" processing?

    Apparently the Phase P40+ does not have the dynamic range for useable images for this scenario. Pixel binning to 10mp, imo, is pointless when you invested in a 40mp DB. The compromise, if possible, is to shoot on a tripod with lower iso. Expose for the highlights. This of course, is just my opinion.

    edited iso
    Last edited by johnnygoesdigital; 3rd June 2013 at 04:55.

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    Senior Member kdphotography's Avatar
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    Re: P+ ISO or "push" processing?

    The difference with Sensor+ pixel binning is that the MFDB still uses the full real estate of the sensor. This is a really nice feature, and images do print exceptionally well. In my experience it depends on what the lighting conditions are (how dim) and balanced against how much resolution you need for a particular image.

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    Re: P+ ISO or "push" processing?

    Quote Originally Posted by johnnygoesdigital View Post
    Apparently the Phase P40+ does not have the dynamic range for useable images for this scenario. Pixel binning to 10mp, imo, is pointless when you invested in a 40mp DB. The compromise, if possible, is to shoot on a tripod with 800 iso. Expose for the highlights.
    Pointless for you perhaps.

    I have shot many actor and professional headshots at 10mp. The tethering is lightning fast, the processing is even faster, and the resolution is still twice what any actor needs for a standard headshot.

    It also prints much nicer than you'd expect for 10mp, probably because the image quality is so much higher than the cameras of yore that were 10-12mp (which I assume set my expectations for what that resolution can do when printed).

    For some kinds of shooting and needs resolution is utterly essential. For other needs its not even in the top ten things if care about.

    If you bought a Porche would you only drive at max speed, peel out every start, and always choose windy roads? Ok - maybe that's a bad example. Back when I had my (cheap) sports car I drove it like I was a madman. Ok, bad phrasing - I might actually be a madman.
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    Re: P+ ISO or "push" processing?

    I understand your point, and the sensor/dof size debate too, but shooting at 10mp and investing in 40mp was my point. I'm not sure the Porsche analogy is appropriate because you could if you wanted to.

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    Re: P+ ISO or "push" processing?

    Depending on the subject and lighting you can "push process" +1, +1.5 and maybe +2 stops no problem. (at least that has been my experience so far with the IQ160). But, the sensor + works very well if you don't need the full resolution of the back for that situation. I used my IQ160 at iso 800 (sensor +) by accident once and the files looked really nice and still have quite a bit of depth.

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    Re: P+ ISO or "push" processing?

    The pixel resolution is overrated. 10MP is only a 50% loss of resolving power from 40MP and 20% more than "Photo quality." You are also getting the advantage of imaging at longer frequencies which will give greater contrast than a smaller sensor of the same pixel resolution. We have a thread all about those 9um backs--pixel number isn't everything. And depending on what you are actually going to do with the image afterward, both in terms of where it will be reproduced and what "look" you want to give it, a 10MP image is plenty. I can imagine a binned MFD back giving some really great results.

    I find it funny that photographers are driven by the technical specs of the sensor rather than the creative process photography is. And this seems to have come along with digital where we pixel peep. Back in the silver age of photography, I never read about optimizing the aperture for the resolving power of the film or DoF changing with film speed.

    It would be nice to know more about what the OP wants to do.
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    Re: P+ ISO or "push" processing?

    Shashin - I'm not looking for any one specific shoot or project. I'm more curious for when I happen to be faced with the situation of shooting at (for example) 1/60 sec, ISO 800 and underexposing 1 stop, or 1/60 sec, ISO 1600 S+ for correct exposure, and which will ultimately produce the better file.

    Neither file will print as well/large as a properly exposed shot at ISO 50 - I think that's a given (at least 99% of the time). Question is, which will be closest.

    And after some testing today, I think the answer is: it depends.

    I think your statement regarding photographers being driven by technical specs over creative process is quite harsh and over-reaching. For as long as there have been loupes, there has been "pixel peeping" (or grain peeping). There has always been a healthy debate and discussion over technical merits of equipment. This type of debate has NOTHING to do with digital sensors. It was around when "small" 4x5 film was introduced, and then 120, and 135...all of which I've shot extensively.

    My philosophy has always been to shoot with the highest quality that's practical, irrespective of its proposed final use. Nothing about that has changed with digital. That's why cameras like the Mamiya 7 existed - to give would-be Leica users a medium-format alternative, where an RB67 wouldn't be practical.
    J R
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    Re: P+ ISO or "push" processing?

    Quote Originally Posted by JRBERNSTEIN View Post
    I'm more curious for when I happen to be faced with the situation of shooting at (for example) 1/60 sec, ISO 800 and underexposing 1 stop, or 1/60 sec, ISO 1600 S+ for correct exposure, and which will ultimately produce the better file.
    In signal to noise terms, this is easy to answer.

    In both approaches, you shoot at 1/60 sec, so you acquire the same signal.

    In Sensor+ mode there is 1/4 of the readout noise over the whole detector area as there is in "normal" mode.

    So in the shadow areas, where readout noise dominates over shot noise of the weak signal, you approach 4x better signal to noise. That's a whopping 2-stop advantage.

    So I would unquestionably use Sensor+ in this scenario, unless the look you want is "highly resolved noise", or unless you prefer to filter/denoise the shadows to oblivion.

    Shashin is right to draw attention to the "fat pixel" threads...these would be 12 micron pixels, real fat and juicy...

    Ray
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    Re: P+ ISO or "push" processing?

    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: P+ ISO or "push" processing?

    Also check out this review of sensor plus: HERE

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    Re: P+ ISO or "push" processing?

    Quote Originally Posted by JRBERNSTEIN View Post
    I think your statement regarding photographers being driven by technical specs over creative process is quite harsh and over-reaching.
    I don't think so, at least not those worried about "not using every pixels they paid for," or when someone shoots only at f/8 because that is optimum for MTF. (Actually, I was not talking about all photographers. Just a subset.)

    My philosophy has always been to shoot with the highest quality that's practical, irrespective of its proposed final use.
    I couldn't agree more. And "practical" is the operative word. I imagine you would sacrifice resolution for sensitivity/ISO if it was going to give you better results. I know I would. I really don't think we are really disagreeing or really far apart. I just wanted to know if you had a specific problem because there are different approaches to using MFD in low light handheld.

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    Re: P+ ISO or "push" processing?

    the "obsession" about technical quality is a bit larger now I think though, and especially so in medium format digital, maybe it has something to do with that we want the up-to-10x-price-increase from smaller formats to show as much as possible

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    Re: P+ ISO or "push" processing?

    I would think the majority of photographers who shoot MFD do so because of the ability to print big at native resolution without a compromise.

    Ansel Adams probably wouldn't agree with Shashin's inaccurate assessment of the "optimizing the aperture", because f/64 was a group of photographers whose goal was to do just that.

    Imogen Cunningham's "succulent" from 1920, is a good example of this quest for sharpness and detail, but neither has sacrificed their creative process for technical acuity.

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    Re: P+ ISO or "push" processing?

    Such an interesting topic!

    Obviously, if there were no S+ option, we wouldn't be having this discussion, but since there is that option available to us, it's good to know when to take advantage of it (and when not to).

    Back in my film days, I had to make the choice regularly (particularly in the field when I only had Ilford Delta 400 and 3200 120 film) -- use film A and push for correct exposure, or film B at native exposure, but perhaps with better contrast and larger grain. But with B&W, I find there's SO much more you can get out of a negative with proper darkroom technique.

    And yes, "practical" *is* the operative word...I chose it carefully. Heck, practicality aside, we would probably all be shooting 8x10 or larger Daguerreotypes! lol
    J R

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    Re: P+ ISO or "push" processing?

    From a long discussion at LuLa, as well as some testing, it seems ISO settings on a CCD sensor are metadata settings only, they do not change the signal or the base raw data stored. The advantage to changing the ISO settings is the metadata changed will be picked up by C1 or LR, and the starting image will be closer to normal. However, if you shoot a shot at the same f/stop and shutter speed, one at ISO 35 and one at ISO 400, you can develop the ISO 35 shot to be pretty much identical.

    Certainly changing to sensor+ is different, but there again any higher ISO settings with sensor+ are metadata changes as well.
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    Re: P+ ISO or "push" processing?

    Wayne - that's fascinating...I hadn't heard that before. I'll have to test that out for myself.

    Do you have any examples?
    J R

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    Re: P+ ISO or "push" processing?

    Here's an example I shot after hearing about this.

    Side by side, only difference is ISO setting


    Underexposed shot has a 2.4 stop adjustment in C1, no other changes


    100% view of a section (note some leaf blurring difference is due to movement from the breeze) Note there is no visual difference in noise.


    Here are the 2 histograms compared after the adjustment, with the original 35ISO histo as well. Notice how it looks like shadows are completely clipped yet after adjustment the 2 are almost identical.


    Here's the original LuLa discussion about it
    ISO metadata and ETTR
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    Re: P+ ISO or "push" processing?

    Quote Originally Posted by Wayne Fox View Post
    Here's the original LuLa discussion about it
    ISO metadata and ETTR
    That was a good thread...I was glad to have played a part in it (2nd post).

    Nice tests you've shown here too. I have done something similar, verifying that ISO on my CCD systems is just a flag for image review and RAW conversion.

    Ray

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