Nasty color bleed on pushed A7III RAW (compressed, silent shutter)

Started 6 months ago | Discussions thread
PhozoKozmos Contributing Member • Posts: 698
Re: SONY steep short+wide optical projection to sensor is cause (not file format related)

JimKasson wrote:

PhozoKozmos wrote:

JimKasson wrote:

PhozoKozmos wrote:

SONY steep short+wide optical projection to sensor is cause (not file format related)

anything in foreground out-of-focus will have an expanded blurred ghost

but if it is projected at a very wide-angle onto a very close sensor surface, more of the ghost can be spread farther across more adjacent pixels and pick up the extra light

unlikely, file format related, as ooc (fine only) Sony jpeg paired with Sony RAW will exhibit same effect (regardless of compression or not, and mechanical shutter or not)

This effect is not FFD related here, for even ray-angle related (except the calculation of CoC being focal-plane focus error over f-stop). It is entirely explained by the out-of-focus point spread functions of defocused rays convolved with the objects in front of the lens.

oof point spread is normal, yes

however, i suspect the steep ray-angle may be susceptible in exacerbating a wider spread than usual

Nope. OOF PSF is a function of focus plane error and f stop only, if there are no internal lens occlusions.

it includes exacerbated chromatic aberration spread

You talking LaCA? If so, that is not true, in my experience.

you may simply have chosen better lenses, so you will not encounter it

short ffd only applies for lenses with a short-but-wide lens-sensor dimension LSFD

The FFD doesn't change when you change lenses.

agree. body-flange-sensor dimension (BFSD) never changes, it is fixed 18mm for A7III; but this has nothing to do with lens-sensor focal dimension (LSFD)

not long LSFD

not exceptionally short-but-shallow LSFD (like lenses with 16.7mm back focus, where lens optic rear opening is huge, so projection is shallower)

IMHO, this is a complete red herring.


fujifilm GFX50S have primes like the new 250mm f4, with 57.1mm (minimum) LSFD, even though its body-flange-sensor dimension is a fixed 26.7mm. other fujifilm lenses could have as little as 16.7mm LSFD (minimum) according to fujifilm GFX50S specs

LSFD varies with specific lens


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Sony's new (pending) tele prime has an exceptionally long LSFD, so it will have a normal (good) oof psf (typical for telelenses) and lower LaCA (predictable, as it mimic longer LSFD of dSLRs)

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