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12-22-2012, 02:31 PM   #31
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QuoteOriginally posted by Ben_Edict Quote
IDM works off the film surface. That is not possible with the sensor surface of a DSLR - otherwise the old players with these film-based measurement systems would also have stuck to it, like Sony (Minolta held the original patent for this technology), Olympus (the first on the market) or even Nikon (F3 and later).

Sensors have completely different reflective properties, which are obviously not so easy to manage and create a whole set of problems, which did not exist in film days. The istD was the last Pentax DSLR, which sported flash-TTL metering and it was of not really much use - at least I did not find it any more realiable than P-TTL. Simple A flashes work best anyway...

Ben
The difference in reflection is a calibration issue only, the *istD was just as good in TTL and P-TTL. I have shot both with no issue.

12-22-2012, 03:21 PM   #32
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With the *ist cameras, TTL works only with an M lens ( or A lens off A position) and in M Mode. Also I think it has to be in iso 200.
The flash is controlled by quench circuitry in the camera.
The AF360 flash shifts into TTL mode when activated with a half press of the *ist's shutter button
With speeds in range 1/45 to 1/125 or so, the TTL mode considers the ambient light, so the *ist s will chop the flash right down to be fill flash for the correct exposure.
12-22-2012, 03:45 PM   #33
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QuoteOriginally posted by wombat2go Quote
With the *ist cameras, TTL works only with an M lens ( or A lens off A position) and in M Mode. Also I think it has to be in iso 200.
The flash is controlled by quench circuitry in the camera.
The AF360 flash shifts into TTL mode when activated with a half press of the *ist's shutter button
With speeds in range 1/45 to 1/125 or so, the TTL mode considers the ambient light, so the *ist s will chop the flash right down to be fill flash for the correct exposure.
Not so, it can work on an A lens with a TTL flash like the AF500FTZ.

It can be in any ISO, I often worked at ISO400 because there was no noticeable noise increase and I got further flash range

I always shot in M and set exposure to what I wanted with natural light so I never had exposure issues, it was always spot on
12-22-2012, 04:15 PM   #34
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IMO there are no excuse for Pentax. This is a plain removal of a useful feature just to cut industrial costs (of just a few dollars) per camera.

Admitted that Pentax/Ricoh wants loyal customer I think should fill these gaps.

12-22-2012, 06:34 PM   #35
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QuoteOriginally posted by seppstefano Quote
IMO there are no excuse for Pentax. This is a plain removal of a useful feature just to cut industrial costs (of just a few dollars) per camera.

Admitted that Pentax/Ricoh wants loyal customer I think should fill these gaps.
No disagreement. The top of the line camera at least should support both, like the *istD does
12-25-2012, 06:42 AM   #36
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QuoteOriginally posted by Lowell Goudge Quote
Not so, it can work on an A lens with a TTL flash like the AF500FTZ.

It can be in any ISO, I often worked at ISO400 because there was no noticeable noise increase and I got further flash range

I always shot in M and set exposure to what I wanted with natural light so I never had exposure issues, it was always spot on
Lowell,

TTL in the older Pentax bodies had a couple of limitations, one of which was a limited ISO range of 200-400 for the istDS, 200-800 for the istD

The other was underexposure near minimum aperture and overexposure near maximum aperture when using fast lenses for the istDS. This issue is not noted for the istD.

I never found an official explanation of the problem with TTL and digital, but it's certainly gone from all of the DSLR brands as far as I know.

Ray
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