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CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI

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Offline fabri22

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #90 on: 22 / July / 2014, 07:44:49 »
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Quote from: waterwingz on 21 / July / 2014, 18:17:49
The first time through when the script launches,  it does a "half press" in "P" mode (i.e. it lets the camera tell the script what it thinks the correct exposure should be).   This also causes the camera to initialize a property case value that gives the smallest Av setting available - which gets used in all the ND filter calculations.
Nothing to object. The ND filter calculation is indispensable
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So it would be acceptable to do that "half press" as long as the @param default values were then used for Tv,Av,Sv in M mode,  for Tv in Tv priority mode,  and for Av in Av priority mode ?
It would be perfect
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Set focus at infinity?  Or user defined - that would take another on screen control somehow.  I'd need to play with that a lot.
Not asking too much. Also i know that it wouldn't work on my camera.
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If it makes you feel any better,  scripts like CHDKplus.lua, Ultimate.lua or kap_uav.lua would be virtually impossible to write and debug successfully in uBASIC.   And if you could,  forget every modifying them (while you wait for you hair to grow back in).
Actually i've mostly a contemplative approach to your scripts  :)
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Offline waterwingz

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #91 on: 22 / July / 2014, 08:41:19 »
Quote from: fabri22 on 22 / July / 2014, 07:44:49
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So it would be acceptable to do that "half press" as long as the @param default values were then used for Tv,Av,Sv in M mode,  for Tv in Tv priority mode,  and for Av in Av priority mode ?
It would be perfect
Sound like a worthwhile change then - leave it with me.  And thanks for bearing with me through all this.  The UI part is always the hardest - everyone has different preferences.

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Set focus at infinity?  Or user defined - that would take another on screen control somehow.  I'd need to play with that a lot.
Not asking too much. Also i know that it wouldn't work on my camera.
I'll look at that option - the depth of field is so large on these cams that you could probably set focus at 3 meters and use it for almost everything but extreme closeups - removing one more source of shutter lag.   

At some point, we will figure out why some cams (s100, ixus125) don't focus properly - too bad it seems to be the more expensive ones and not something I can pickup cheap on eBay (possibly scratched & scufffed for example).
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Offline fabri22

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #92 on: 22 / July / 2014, 15:37:30 »
Quote from: waterwingz on 22 / July / 2014, 08:41:19
...And thanks for bearing with me through all this...
Are you kidding? There aren't enough "thank you" for all of you CHDK guys
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Offline fabri22

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #93 on: 26 / July / 2014, 10:41:46 »
Today i was playing a bit more with CHDKplus 2.2 (unedited) and noticed overexposed daylight pictures when in Sv mode ... again, even if nd filter @default setted at 2 (as my camera requires).
Reloading CHDKplus 2.1 (with nd filter edited at 2) Sv mode was quite fine (slight overexposition as reported in my previous post)
Could it be related to the new nd96offset=(n+3)*32   vs   the old nd96offset=2*96 ?

your "thorn in the side"  :)
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Offline waterwingz

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #94 on: 26 / July / 2014, 12:00:27 »
Quote from: fabri22 on 26 / July / 2014, 10:41:46
Could it be related to the new nd96offset=(n+3)*32   vs   the old nd96offset=2*96 ?
It does not seem likely unless the rules of arithmetic have changed since my school days. 

In CHDKplus.lua v 2.2,  when you set the ND filter @param value to "2" you are actually selecting the fourth element in the @values array so n = 3 (zero based indexing).  Likewise, if you select the value "3" you get the seventh element in the @values array so n = 6.  (If you select "1" then n=0)


f-stops
CHDKplus 2.2
CHDplus 2.1
1
nd96offset = (0+3)*32 = 96     nd96offset = 1*96 = 96
2
nd96offset = (3+3)*32 = 192     nd96offset = 2*96 = 192
3
nd96offset = (6+3)*32 = 288     nd96offset = 3*96 = 288

Nothing else changed between v2.1 and v2.2.    Can you send me a couple of example pictures (preferably of the same thing at the same time) using 2.1 and 2.2 (with the log file) that shows what you are seeing?  Pick a file sharing site and send me the link via PM ?
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Offline fabri22

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #95 on: 26 / July / 2014, 13:42:32 »
Forgotten to set the Tv max at 1/2000 with the vers.2.2  ::)
Now results are the same among the two versions (overexpos. in Sv mode, but better then before)

Link to test with pics and logs (626 kb)
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Offline waterwingz

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #96 on: 26 / July / 2014, 16:10:52 »
Quote from: fabri22 on 26 / July / 2014, 13:42:32
Now results are the same among the two versions (overexpos. in Sv mode, but better then before)
Link to test with pics and logs (626 kb)
Thanks - the pix and log file are very helpful.  You might not like my conclusions though - I believe your ND filter gives the equivalent of 3 f-stops when it is inserted.  Telling the script that it is only 2 will give exactly the effect I see in those images.

Here's a little table of the four shots ( I used the 2.1 version but 2.2 is exactly the same).



  • The first line shows the settings the camera wants to use - 1/250 second @ f8.3 & ISO90.
  • Notice that the av value it wants to use is f8.3.  The only way to get that is to add 3 full stops to the f2.7 lens opening your camera uses when it is at full wide angle (like in your test shots).  This tells us the ND filter effect is three f-stops - not two.
  • The first shot uses "P" mode - the script does not set any exposure parameters itself. The resulting image I used as the "reference" going forward.
  • The second shot is in Tv priority mode.  It show up slightly over exposed because the script hits the lower limit of ISO100 that you set  (vs ISO90 in P mode).
  • The third shot is in Av priority mode.  It show up slightly under exposed because the script thinks it is using f5.9 using the ND filter when the actual f-stop is f8.3.
  • The final shot is in Sv mode.   Here the script pulls out the ND filter to get as high an shutter speed as it can for the lowest ISO setting that works.  It thinks that gives two fstops increase in exposure but it actually gets three.  This results in the over exposure you see

ixus125 info :  zoom range 4.3 - 21.5 mm  gives aperture f/2.7 - f/5.9

Does this makes sense?  What if you reshoot that sequence with the f-stop value at 2 and then 3 and see what happens?

Update : looking at this some more, it makes less and less sense.  The correct shutter speed for the Sv mode should have been 1/3500.   This is above your set limit so it should have clamped at 1/2000. Instead it stuck at 1/800.  Bizarre - unless it thinks the ND filter is inserted but then maybe forgets to do so ... oh ..wait ...damn ...

However, I believe that my comments about the other three pix are still valid.
« Last Edit: 26 / July / 2014, 19:35:16 by waterwingz »
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Offline waterwingz

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #97 on: 26 / July / 2014, 19:09:24 »
Okay - thanks once again to fabri22 for finding a bug.  One that I was sure was not there.  And of course,  it was.   :-[

link >  CHDKplus2-3beta.zip

Fixed the ND filter handling once again - and hopefully for the last time. The code handling that has actually become a lot cleaner - usually a good sign when you are looking for stabilty.

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Offline fabri22

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #98 on: 26 / July / 2014, 19:44:38 »
Quote from: waterwingz on 26 / July / 2014, 16:10:52
I believe your ND filter gives the equivalent of 3 f-stops when it is inserted.  Telling the script that it is only 2 will give exactly the effect I see in those images.
I measured the nd filter of my camera with the ndf_cal.lua as you suggested. It returned 2 in more then a test.
However i agree with you in believing it should be at least 3.
From a logic point of view an "2 f-stops only nd filter" seems too low to cover a sufficient ev range in a camera with an f/2,8 lens, 1/2000 as max shutter speed and 80-100 ISO min.

I'll test again in daylight swapping the nd96offset value, but i doubt to get different results from what i reported here when nd96offset was 3 on chdkplus 2.1.
Definitely my cam is allergic to some chdk functions and reacts with bizarre behaviours. Here another one.
Is it time to buy another canon p&s model?  ???

EDIT
I was posting just when the 2.3 "was born" :) :)
I'll test tomorrow in daylight.




« Last Edit: 26 / July / 2014, 19:49:40 by fabri22 »
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Offline waterwingz

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Re: CHDKplus.lua : adding M, Tv, Av, ISO+ exposure modes with a GUI
« Reply #99 on: 26 / July / 2014, 20:28:44 »
Quote from: fabri22 on 26 / July / 2014, 19:44:38
I measured the nd filter of my camera with the ndf_cal.lua as you suggested. It returned 2 in more then a test.
It gives a 3 on all my cameras but it's temperamental.   I'll look at the code again "just in case".
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