How does ISO setting work?
Discussion
D70.
Playing last night, getting pics of my moggy with the 60mm micro, it was reading 1/20th at f2.8 (3.3 when close) so I pumped it from iso 200 to iso800 and it made little or no difference to the exposure. Even when I put it at 1600 it was still only a stop or so better.
How should the iso setting affect the exposure on digicams? I thought it was a full stop per setting.?
Thx
Greg
Playing last night, getting pics of my moggy with the 60mm micro, it was reading 1/20th at f2.8 (3.3 when close) so I pumped it from iso 200 to iso800 and it made little or no difference to the exposure. Even when I put it at 1600 it was still only a stop or so better.
How should the iso setting affect the exposure on digicams? I thought it was a full stop per setting.?
Thx
Greg
Mr Noble said:
The shots I took with the flash on at iso 800 or iso1600, seemed really dark as if the flash fired late or early. Whats that about?
Thx
G
im not sure, but if you want to get decent pictures with a flash use the camera on M mode (fully manual). If you do this an you decide you want more shutter speed, then just turn it up to whatever you want.
Mr Noble said:
D70.
Playing last night, getting pics of my moggy with the 60mm micro, it was reading 1/20th at f2.8 (3.3 when close) so I pumped it from iso 200 to iso800 and it made little or no difference to the exposure.
On Program mode it wouldn't make any difference. The shutter speed and aperture would both rise but the exposure would remain the same. Obvious question, but what colour is the cat? A white cat would tend to underexpose and a black over. Remember the meter assumes it's photographing an 'average' scene, which equals grey. The metering mode will also have some bearing, is it on spot, centre weighted, average? Not familiar with D70 but I'm sure I've read in Simpo's posts that it does tend to under expose.
Using flash in full auto mode won't make much difference, if the camera thinks it's photographing a light scene it will keep the exposure down and the flash out put down. Although, I would have thought you should be able to tell that the flash has fired with some highlights on the fur even if it is underexposed overall. Other thoughts. Are you sure you haven't dialled in -ev and forgotten about it? Can you override the auto on the flash gun? When you switch a flashgun on in program mode, some cameras default to 60th/ sec shutter speed, which would cut down on the ambient exposure. Aperture priority is a better mode for applying fill in flash. If all fails do as dcw suggests and stick everything on manual, then you have complete control of all the individual elements.
HTH
Mr Noble said:
The shots I took with the flash on at iso 800 or iso1600, seemed really dark as if the flash fired late or early. Whats that about?
Ah, that's about the D70 underexposing, combined with the built-in Speedlight (which is only designed to give balanced fill-flash), not doing the job you hoped for. Combine these two and you can be 2 stops under. Incredible but true.
Adjusting ISO and aperture/shutter parameters make no difference because the camera is convinced that 2 stops under is the correct exposure and will keep doing it. So you have to get the thing by the scruff of the neck (the camera, not the cat) and show it who's in charge. In this situtation I'd use flash compensation (new button to learn
) to force the flash to work harder. As for Manual exposure, well, if you're experienced you might get close first time, but for you and I, by the time we've taken the 4 shots needed to get the perfect exposure, the cat will have buggered off!
dcw@pr said:
If all fails do as dcw suggests and stick everything on manual, then you have complete control of all the individual elements.
don't do it if all else fails, do it all the time. no reason not to
simpo two said:
As for Manual exposure, well, if you're experienced you might get close first time, but for you and I, by the time we've taken the 4 shots needed to get the perfect exposure, the cat will have buggered off!
Bacardi said:
If all fails do as dcw suggests and stick everything on manual, then you have complete control of all the individual elements.
don't do it if all else fails, do it all the time. no reason not to
simpo two said:
As for Manual exposure, well, if you're experienced you might get close first time, but for you and I, by the time we've taken the 4 shots needed to get the perfect exposure, the cat will have buggered off!
no, no and no again
when using manual mode, you are NOT setting the exposure. You are setting what result you would like to see come out of the camera with regards to depth of field and camera wobble (or lack thereof). The flashgun adjusts itself to get the correct exposure. don't be scared because the camera says manual, it is not actually being truthful with you
disclaimer - the flash must be set to auto
dcw@pr said:
disclaimer - the flash must be set to auto
Possibly the disagreement is because your original post said 'set everything to manual'.
However, I fear that even with the flash set to Auto, in this particular instance you will get no better result as the D70 still thinks -2 is the correct exposure. Introduce any element of uncompensated Auto and the camera/flash combo will still give you -2.
simpo two said:
Possibly the disagreement is because your original post said 'set everything to manual'.
dcw@pr said:
use the camera on M mode (fully manual)
simpo two said:
However, I fear that even with the flash set to Auto, in this particular instance you will get no better result as the D70 still thinks -2 is the correct exposure. Introduce any element of uncompensated Auto and the camera/flash combo will still give you -2.
that may well be true
dcw@pr said:
no, no and no again
when using manual mode, you are NOT setting the exposure. You are setting what result you would like to see come out of the camera with regards to depth of field and camera wobble (or lack thereof). The flashgun adjusts itself to get the correct exposure. don't be scared because the camera says manual, it is not actually being truthful with you
disclaimer - the flash must be set to auto
So are you saying that the paparazzi boys all have time to adjust their exposure manually before getting their shot?
Bacardi said:
So are you saying that the paparazzi boys all have time to adjust their exposure manually before getting their shot?
im obviously not getting my point across very clearly. im not a paparzzi (thank god) but i do attend a wedding or two, where as you know it is often necessary to grab quick shots, not miss the moment etc, and I have't used my camera with a flash on anything but M for at least a year. It is not necessary to change the exposure for each and every photo - as long as you set the camera exposure so that it would be underexposing without the flash (but this is obvious), and conversley you can't be silly and set it to ISO50 f/22 and 1/8,000th since the flash isn't powerful enough for that. For example, on my 16-35, i normally set about f/5.6 and 1/50, for the 50mm i set f/2.8 and 1/80 and for the 70-200 i set f/4 and 1/125 or 1/200. ISO can be anywhere from 200 - 1600 depending on the available light. If I get desperate I will open up the aperture/increase the ISO until I am happy with the results I see on the back of the camera. Once you have your preffered settings dialed in, you don't need to change them again, unless the lighting changes dramtically, which is rare.
it's true, if i were going for ULTIMATE speed/safety I would go with S mode, on the off chance that maybe just as i was about to take my paparazzi style photo of someone there was a flash of lightning/solar eclipse/angel descending from heaven which would throw off my manually set camera exposure. but the tradeoff would be on the other 99.99% of photos where you would not have control of the aperture leading to sub optimal sharpness/no DOF control and no control of how the un-flashlit backgrounds were exposed.
here endeth the lesson
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