*istD underexposure?
Posted 17/06/2004 - 14:18
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Jose B,
Yes, underexposing is annoying (and I agree with the focus assist - grrr. However, when you use the AF360 that has a proper AF assist!).
However, there are a few differences between the *istD (and all DSLRs) and the Minoltas you specify (and indeed all consumer digicams):
* The *istD has to meter with a separate system, as in film. The consumer cams do a live CCD read and evaluate the levels directly from the sensor that will capture the image. The *istD meters, then to take the photo operates a mechanical shutter to expose the CCD. The CCDs are fundamentally different (not just used in a different way).
* The consumer cams have built in lenses and are optimised for their own lens. The *istD can use any old lens, and good ones too! For what it's worth, I experienced no end of exposure problems with "compatible" lenses, and have much less of a problem with genuine Pentax glass. What seems to happen, if you've read the whole thread, is the preflash fires and the image is read as if it's brighter and consequently underexposes. Maybe lens-flare has a bearing (ie. bad flare control in a given lens produces a preflash reading that is over, and thus a photo that is under.)
Added to the second point is that, again, the metering is a different circuit to the CCD. If there are colour issues (e.g. lens is cool/warm etc), or even infrared issues - again there could be problems.
I know, for sure, that if you use the *istD in a studio flash environment you don't have these problems... but then you normally manually meter anyway.
Hope that clarifies things!
Matt
Yes, underexposing is annoying (and I agree with the focus assist - grrr. However, when you use the AF360 that has a proper AF assist!).
However, there are a few differences between the *istD (and all DSLRs) and the Minoltas you specify (and indeed all consumer digicams):
* The *istD has to meter with a separate system, as in film. The consumer cams do a live CCD read and evaluate the levels directly from the sensor that will capture the image. The *istD meters, then to take the photo operates a mechanical shutter to expose the CCD. The CCDs are fundamentally different (not just used in a different way).
* The consumer cams have built in lenses and are optimised for their own lens. The *istD can use any old lens, and good ones too! For what it's worth, I experienced no end of exposure problems with "compatible" lenses, and have much less of a problem with genuine Pentax glass. What seems to happen, if you've read the whole thread, is the preflash fires and the image is read as if it's brighter and consequently underexposes. Maybe lens-flare has a bearing (ie. bad flare control in a given lens produces a preflash reading that is over, and thus a photo that is under.)
Added to the second point is that, again, the metering is a different circuit to the CCD. If there are colour issues (e.g. lens is cool/warm etc), or even infrared issues - again there could be problems.
I know, for sure, that if you use the *istD in a studio flash environment you don't have these problems... but then you normally manually meter anyway.
Hope that clarifies things!
Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
(For gallery, tips and links)
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