InitializeAdjustmentSystem and exposure control on M3 (was Help!)

pigeonhill

1164

InitializeAdjustmentSystem and exposure control on M3 (was Help!)

« on: 07 / August / 2022, 05:50:46 »

Advertisements

I've spent a morning trying to sort out an issue that I've never seen before.
I'm in manual mode, ISO 100 and in my script I take two images.
One at ISO 100 and one at ISO 3200.
The images get taken OK and the in camera review, after taking, the ISO value has clearly shown to have changed.
BUT the exposure has stayed the same, ie the histogram is the same.
I'm mystified.
Does anyone have any ideas what is going on?

« Last Edit: 07 / August / 2022, 20:45:59 by reyalp »

Logged

philmoz

3450

Re: Help!

« Reply #1 on: 07 / August / 2022, 07:12:32 »

Is the shutter speed and aperture the same in both images or have these changed to compensate for the altered ISO?

Logged

CHDK ports:
sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
g12 (1.00c, 1.00e, 1.00f & 1.00g)
sx130is (1.01d & 1.01f)
ixus310hs (1.00a & 1.01a)
sx40hs (1.00d, 1.00g & 1.00i)
g1x (1.00e, 1.00f & 1.00g)
g5x (1.00c, 1.01a, 1.01b)
g7x2 (1.01a, 1.01b, 1.10b)

pigeonhill

1164

Re: Help!

« Reply #2 on: 07 / August / 2022, 07:15:56 »

No both the same.

The code I’m using works fine in an other script.

The only thing I’m doing different in the new script is using FA.create, but I can’t see how that would impact image capture.

As I say, ISO changes in the EXIF, ie displayed by Canon, but exposure remains constant.

Logged

c_joerg

1250

Re: Help!

« Reply #3 on: 07 / August / 2022, 08:22:58 »

Does Image with ISO 3200 have more Noise?
What about JPG size of both Images?

Logged

M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

pigeonhill

1164

Re: Help!

« Reply #4 on: 07 / August / 2022, 08:38:38 »

I'm shooting RAW.
Looking at the captured images in Lr, they both look the same in IQ.
But the ISO values are different!

Logged

pigeonhill

1164

Re: Help!

« Reply #5 on: 07 / August / 2022, 08:41:11 »

BTW here is the relavant code:

Code: [Select]

function myshoot()
    local prevcnt = hook_shoot.count()
    local rawprevcnt = hook_raw.count()
    press 'shoot_full_only'
    repeat sleep(10) until prevcnt ~= hook_shoot.count()
    release 'shoot_full_only'
    repeat sleep(10) until rawprevcnt ~= hook_raw.count()
end

function snap() -- single image capture
    press("shoot_half")
    repeat sleep(10) until (get_shooting())
    myshoot()
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
end

function check_buttons_etc()
    wait_click(50) -- check for a button press
    if (is_key("print") and get_alt_mode()) then 
        if isoval > 0 then
            local iso = get_iso_mode()
            set_iso_mode(iso)
            sleep(100)
            snap()
            local isov = iso
            isov = isov + isoval*3
            if isov > 16 then isov = 16 end
            set_iso_mode(isov)
            sleep(100)
            snap()
            set_iso_mode(iso)
        else
            snap() 
        end
        last_count = focus_count
        image = true
        dirty = true
        grabp = true 
        pdof = pj
    elseif (is_key("display") and get_alt_mode()) then 
        if show then
            draw_clear()
            show = false
        elseif not show then
            draw.overdraw()
            show = true
        end
    end
end

Logged

c_joerg

1250

Re: Help!

« Reply #6 on: 07 / August / 2022, 08:45:51 »

Quote from: pigeonhill on 07 / August / 2022, 08:38:38

I'm shooting RAW.

RAW has an Embedded JPG....
You can export with LR as well.
An Image with ISO 3200 is larger because of noise

Quote from: pigeonhill on 07 / August / 2022, 08:38:38

Looking at the captured images in Lr, they both look the same in IQ.
But the ISO values are different!

Looks like ISO overwrite das not work...

Logged

M100 100a, M3 121a, G9x II (1.00c), 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

pigeonhill

1164

Re: Help!

« Reply #7 on: 07 / August / 2022, 08:55:50 »

Another strange thing I've noticed.
With both Canon and CHDK histograms showing, as I adjust the shutter (Tv), between 1/60s and 2s the histograms 'freeze', ie they only change either side of this shutter speed zone.