Rich1939 wrote:
Does it look better? NO!
Does it look just as good? YES! And that is the point of the exercise. Gene demonstrated it with his photos, I needed to prove it to myself. Noise ,not apparent
DR, the day didn't lend itself to judge that. IQ, equal.
Try it, you might like it.
Rich and Ron,
I’m not trying to be a spoiler here. We’re having a technical discussion here over the advantages/disadvantages of a technique, and if that is “pushing my luck”, then so be it. If you propose a particular technique, then I think you’d be open to an unfettered technical discussion. I haven’t insulted anyone, just questioned the premise behind it, and if you find that disagreeable, you can ignore me on future posts if you wish, but that’s hardly in keeping with a free and open forum.
This particular technique isn’t useful to me and many other shooters because I/we don’t have an ISO invariant System, but I am quite interested in the technical aspects, and since I don’t “have a dog in this hunt”, I’m perfectly willing to adopt your position if you demonstrate an advantage. My point is under what circumstances does it actually IMPROVE the shot over just setting the ISO appropriately? From Gene’s postings and from every thing I’ve read (referenced earlier in the thread), the advantages accrue mostly in low light or night scenes (the referenced article specifically mentions this) and offers the the following benefits: 1) it allows you to accidentally underexpose and save the image in post (2) it allows you to selectively edit the photo and potentially increase the DR in specific sections by masking, curves, etc. What neither you or Gene or the author of the article Gene referenced earlier in the thread have demonstrated (yet) is that it actually IMPROVES an image taken under normal circumstances.
Again, the premise is that ISO and DR (and noise) are inversely related, (and this is shown in any ISO vs DR graph), so shooting at a lower ISO results in lower noise. The point that is missed is that raising in post accomplishes has exactly the same effect as raising the ISO - when you multiply the signal, you multiply the noise as well, and if you do this in SW, then multiplying the individual pixel values or gamma has exactly the same effect on both whether you do it in-camera or after the fact. Further, if the particular camera uses an amplifier between the sensor and the A/D, then not using the ISO amplifier decreases the signal to the A/D and actually diminishes the DR since the maximum DR of an A/D is realized when the signal just reaches the most significant bit (MSB) - anything less just “wastes” the DR of the A/D.
This will be my last comment since it seems to be redundant, but my challange still goes: post an unaltered shot underexposed by 5 stops (or whatever) at base ISO, the same “correctly” exposed shot, and the underexposed shot changed ONLY by increasing the overall gamma - no masks, curves, etc., with EXIF information and demonstrate an improvement, not merely that you can “save” an underexposed shot. If you demonstrate an IMPROVEMENT, I will gladly reconsider my position. Ron, I thank you for an interesting technical discussion and hope my critical comments haven’t been unwelcome.
Cheers,
Chris