How about ISO 25 or lower?

Started Dec 6, 2013 | Discussions thread
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Re: How about ISO 25 or lower?
In reply to John Sheehy, Dec 8, 2013

John Sheehy wrote:

Deardorff wrote:

So, start lobbying Canon to put in really slow ISO settings - while keeping qualitiy high.

Current sensors are too efficient to do ISO 50 with the same RAW highlight headroom as ISO 100. It would be nice if a manufacturer could put an LCD shutter in the sensor sandwich to reduce light, for purposes like yours, such that no glare or diffusion will occur.

Another option would be to use a rolling shutter in LiveView, blanking each line only long enough to read it and reset it, and then adding subsequent scans of each line together. I believe that the old Kodak Canon- and Nikon-mount Digital cameras did something like this. There is really no limit to how low an ISO you could get like this, with a minimum of blackout time for each line. The closest you can get now is just take a "burst" of ISO 100 shots in LiveView, with a very stable tripod and remote control, and add them together. The 6D can take 4 shots and add them as a JPEG, but it allows no control of Av and Tv parameters; I don't know if the 1Dx or 5D3 better that in the way that you need. For JPEGs, such is already done in many cameras, especially in compacts and super-zooms, which typical have a "hand-held night scene" mode which takes a few to several shots in rapid succession, and such a function could easily modified to give full control, but they are really designed as extended image stabilizers, and lean towards short total exposure times.

If your needs are for perfect trailing of individual objects, though, these methods will not suffice with too much blackout time between individual exposures. It might be worth trying, though.

Or increase dramatically ("by four folds") the sensor's saturation value, while QE is only increased by 1.2 and these give 88db DR

What would the lowest real ISO be, if we count that the reference is current Panasonic's sensors, ie could be G5 : QE 45%, saturation 12842 at measured ISO 148 ? ..

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