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Old Oct 7, 2007, 6:31 AM   #1
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I've done some test shots with Kodak z812IS, tests were the following.

noon, of a clowdy day, indoors, composed a composition of stuff. tried to use all the light that was coming from a window, however the day outside isn't sunny.

all shots were done with the same characteristics, except ISO speed.

i was using tripod, and with every shot, i used 2 secs. timer, to avoid shaking.

flash was used everytime, focus was set on macro, distance from objects was about 35-45cm, image stabilization - single.

for all images the settings on the camera were:

Exposure program - Aperture priority

Aperture - F/5.6

Shutter speed - 1/15 sec.

Metering - pattern

Exposure compensation - +1

Light source - daylight

tests were done through ISO 64-1600

now with every reply i'll post the image and it's ISO.
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Old Oct 7, 2007, 6:50 AM   #2
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The first image is ISO 64 full image:



The following images are 100% crops of the original ISO64 image,

the crop form the side of an image:



The crop from the center of an image:


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Old Oct 7, 2007, 6:58 AM   #3
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this image is the same composition ISO400 full image:



Crop of it from the side:



Crop from the center:



any comments, suggestions, tips, etc. are welcomed.
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Old Oct 7, 2007, 7:38 AM   #4
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ups :?

i see that links do not work..

ok then:

ISO 64 full image:

[/img]

Crop 1

[/img]

crop 2

[/img]
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Old Oct 7, 2007, 7:43 AM   #5
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now ISO 400

Full image:

[/img]

Crop 1

[/img]

Crop 2

[/img]
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Old Oct 7, 2007, 8:32 AM   #6
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The brightness of the posted images goes from dark to light as you turn up the ISO.

Either something odd is happening with the metering and/or in-camera post-processing, or your light source isn't as steady as you thought.

It's a very useful series, potentially. A few similar ones for the 612 and 712 have been posted in Steve's Forums in the last 6 months, but I'll take some huntingto find them.

As noise is the big issue, it would be helpful if you posted larger crops (say 600x450), with larger areas of continuous tone, where the nose will be more apparent, as well as the detail (for sharpness inspection).

Thanks, and keep em' coming.

Alan T
(Z712is owner since May, and many thousands of images taken!)
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Old Oct 7, 2007, 11:51 AM   #7
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Alan T wrote:
Quote:
The brightness of the posted images goes from dark to light as you turn up the ISO.

Either something odd is happening with the metering and/or in-camera post-processing, or your light source isn't as steady as you thought.

It's a very useful series, potentially. A few similar ones for the 612 and 712 have been posted in Steve's Forums in the last 6 months, but I'll take some huntingto find them.

As noise is the big issue, it would be helpful if you posted larger crops (say 600x450), with larger areas of continuous tone, where the nose will be more apparent, as well as the detail (for sharpness inspection).

Thanks, and keep em' coming.

Alan T
(Z712is owner since May, and many thousands of images taken!)
well, the light was stable, but i think it's how it should be.. the higher the ISO, the more camera is sensitive to light.. and it spreads all the light that is there..

or you'd say it's a fault, that image gets brighter?

well, i'll try to do more tests, when i'll get my charger and a rechargeable battery, because now, i'm working with the disposable battery, and it's a second day i'm having the camera.

but if you are interested in general photos of z812 you can visit flickr, there, i posted three of them, i'll post more, when i'll have apropriate ones.

http://www.flickr.com/photos/[email protected]/

z812is
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Old Oct 7, 2007, 12:47 PM   #8
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Mystic-grapher wrote:
Quote:
Alan T wrote:
Quote:
...The brightness of the posted images goes from dark to light as you turn up the ISO....
... the higher the ISO, the more camera is sensitive to light.. and it spreads all the light that is there..

or you'd say it's a fault, that image gets brighter?....
As you were on aperture priority, the apertureshould have stayed at f/5.6 unless you changed it. As you increased the ISO value (sensitivity/gain), the automatic metering should have reduced the exposure by increasing the shutter speed proportionately, resulting in an identically exposed image.

It's not necessarily a fault, but it would be nice to know why it happened. Perhaps the characteristic sensitivity curve of the sensor changes in shape with ISO setting.

Any answers, anyone?
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Old Oct 7, 2007, 1:49 PM   #9
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so could you Alan T, or anyone else tell me which program should i use for such experiments, where i change ISO and the camera do the rest, to keep the image as identical as possible..

i mean which of P, A, S, M programs..

or any other?

you have z612, which i wanted to by until got to know that z812 is present.. but the meniu, is more or less the same, so, what can you suggest?

thanks.


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Old Oct 7, 2007, 2:52 PM   #10
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Mystic-grapher wrote:
Quote:
...tell me which program should i use for such experiments, where i change ISO and the camera do the rest, to keep the image as identical as possible..

i mean which of P, A, S, M programs..
'P' might change any of the settings and should be avoided for tests.

'A' (which you said you used) should leave the aperture that you set unchanged, and change the shutter speed (faster) as you change ISO (higher). That's why I'm surprised that you gotdistinctly different brightnesses; you shouldn't have, ideally.

'S' would alter the aperture (smaller) as you changed ISO (higher), leaving the shutter speed as you set it. This would potentially alter the sharpness from shot to shot. You'd also run out of stops at the second step, as f/8 is probably the smallest you've got.

'M' would do, provided youleft the aperture alone and altered the shutter speed so that the 'EV+/-' correctionremained the same. This should give an identical result to 'A'.

Mystic-grapher wrote:
Quote:
you have z612, which i wanted to by until got to know that z812 is present.. but the meniu, is more or less the same, so, what can you suggest?
Actually I have a Z712is, having set out to get a Z612. The Z812 is very similar, I believe, but with even more unnecessary pixels squashed on to the same sensor, as a further salvo in the current silly 'pixel wars'. These are very similar cameras, as you say. You probably have a fine camera, with a good lens and image stabilisation.

Your experiments are very worthwhile, because I haven't seen any othercomparative series from the Z812 round here, and the extra pixels may possibly be relevant in the ISO vs noise issue.

I raised the different brightnesses because I couldn't see how they arose if you did actually set f/5.6 aperture priority and leave it alone between shots. If that's what you did, we'll have to wait for an explanation or a different result from someone else, or just not worry about it.
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