Help with Custom AUTO ISO

dbgg1979

« on: 03 / July / 2009, 12:24:17 »

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Can somebody please explain to me the settings in this section?

Minimal Shutter Speed [Auto] - what is this for?
User Factor (1/FL/Factor) [5] - what is this for?
IS Factor (TV*Factor) [2] - what is this for?
Max ISO Hi (x10) [20] - meaning if if I set it to Auto ISO then HI, this would be the highest ISO value the camera will use?
Max ISO Auto [10] - if set to AUTO (not AUTO HI), the ISO will go from 80 to 100?
Min ISO (x10) [8] - if set to AUTO (not AUTO HI), the ISO will go from 80 to 100?

The settings in MAX ISO HI, MAX ISO AUTO, and MIN ISO were set by me.

If setting the camera to P mode. In what sequence does the camera choose the correct values for exposure? example. Aperture first, then camera decides the correct shutter value to get a correct exposure, then if picture is still too dark, choose a different ISO?

My flickr is showing weird ISO values with photos taken while custom AUTO ISO was enabled. I'm getting ISO 300, 200, 250. Is this because flickr can't identity the proper ISO because of CHDK?

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whim

2041
A495/590/620/630 ixus70/115/220/230/300/870 S95

Re: Help with Custom AUTO ISO

« Reply #1 on: 03 / July / 2009, 12:44:00 »

This is described in the latest user guide here: http://images1.wikia.nocookie.net/chdk/images/3/33/CHDK_UserGuide_April_2009_A4.pdf

check pages 11 & 12

hth,

wim

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dbgg1979

Re: Help with Custom AUTO ISO

« Reply #2 on: 03 / July / 2009, 13:02:33 »

thank you so much!

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dbgg1979

Re: Help with Custom AUTO ISO

« Reply #3 on: 06 / July / 2009, 04:32:26 »

So I've been experimenting with custom auto iso.

These are my current settings:

Enable custom iso:

Minimal Shutter Speed: 1/60s
User Factor: [5]
IS Factor: [2]
Max ISO Hi (x10): [20]
Max ISO AUTO (x10): [20]
Min ISO (x10): [5]

But when I check my photos, the ISO says 304? I also saw one that went as high as 600. The max ISO AUTO doesn't seem to be working. I assume that the settings above means that if I take a photo and the camera detects a shutter speed slower than 1/60s, it will automatically adjust the ISO to attempt to get a 1/60s shutter speed but limited to the value set in Max ISO AUTO right?

Here's a sample of the photo Katrina Halili at Gaisano Country Mall, Cebu City

Is this normal? Or is it just Flickr no reading the ISO right because of the CHDK?

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nonno

Re: Help with Custom AUTO ISO

« Reply #4 on: 06 / July / 2009, 05:02:07 »

i think that's because real ISO and camera ISO aren't the same. Canon writes in EXIF and prints on screen not real ISO values but some standard ("market") values, while with CHDK you set real ISO values. So you can check the correspondence between the real ISO and the market (canon) ISO values enabling "Show real ISO" in "OSD parameters" -> "miscellaneous values" of chdk menu and setting the autoISO override accordingly.
You can make some more tests changing the camera ISO from canon menu to see the real ISO and overriding the ISO value with the CHDK option to see the corresponding market ISO.

In my a650 the market ISO is shown by canon deafault info screen on the display, but if you can't see it just enable "Show market ISO" in "OSD parameters" -> "miscellaneous values" of chdk menu.

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dbgg1979

Re: Help with Custom AUTO ISO

« Reply #5 on: 06 / July / 2009, 23:45:41 »

I see the real and market values now. that's better. I have set my chdk/real iso settings just enough so I can get a maximum market ISO of 250 which is just enough noise for my taste

Thank you so much nonno.

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