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SX260 HS Porting Thread

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Offline mcgd

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Re: SX260 HS Porting Thread
« Reply #460 on: 01 / January / 2013, 09:24:19 »
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To illustrate, here are two sample (downsized) images, both taken with 1/250s, f/5.0, ISO 100, one without ND filter, the other with ND filter in.

Re: SX260 HS Porting Thread
« Reply #461 on: 01 / January / 2013, 09:28:38 »
I don't think so.  ISO would have already been 100, and the minimum effective value on my camera seems to be 80, even when overridden, and 80 vs 100 makes little difference - certainly not enough to account for what I'm getting.
Interesting.  I have to say that ISO100,  1/3200, f8 is one heck of a bright day.  Hope you were wearing lots of sunscreen and good sun glasses :)

EDIT: BTW, activating the ND filter does not affect the preview display until the shutter button is half-pressed, so people testing might think the option has no effect unless they actually take a photo.
That's how it works on all three camera models I own.

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Offline mcgd

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Re: SX260 HS Porting Thread
« Reply #462 on: 01 / January / 2013, 09:41:39 »
Interesting.  I have to say that ISO100,  1/3200, f8 is one heck of a bright day.  Hope you were wearing lots of sunscreen and good sun glasses :)

I'd be in trouble if that was the ambient brightness :-).  This was to take scenes with bright reflections on the sea.  1/3200, f/8 just doesn't cut it sometimes.

BTW from experimenting, it appears that the ND filter reduces exposure by about 2.5 stops (if my calcs are correct).  A photo with 1/100s with ND filter is in between 1/500s and 1/640s without the filter, for the same aperture and ISO (1/500 is brighter then the ND photo, 1/640s is darker).

Re: SX260 HS Porting Thread
« Reply #463 on: 01 / January / 2013, 09:41:55 »
Cameras that have an adjustable aperture and an ND filter (like the G series) generally give you ND control in the Canon firmware.
FYI - neither my A1200 or SD940 have any Canon menu entries related to an ND filter but I can definitely activate it with both.  My G10 (naturally) offers full manual control for the ND filter from the Canon shooting menu.

To illustrate, here are two sample (downsized) images, both taken with 1/250s, f/5.0, ISO 100, one without ND filter, the other with ND filter in.
I get something similar.  When CHDK forces the ND filter in place,  the exposure does not change to compensate.  On my G10, if I use the Canon menu to activate the ND filter then the exposure adjusts (ISO, Tv & Ev) to compensate for the introdution of the filter.

So to get correct exposure when manually inserting the ND filter with CHDK,  you are probably going to need to use a customized script or manual override or an ISO offset if you camera supports it.  Or live with your "P" mode pictures being about 3 stops underexposed.

Update :  did a little experiment with my A1200.  Took a picture of a bright outdoor scene at ISO80 and again at ISO1600.  In the first case,  the camera reported an f3.2 at 1/125.  In the second it reported f9.0 at 1/400.  Both pictures appear to be exposed the same and the A1200 does not have a variable aperature so I can only assume the ND filter made the difference in the reported f-stop difference between the two exposures.
« Last Edit: 01 / January / 2013, 10:11:11 by waterwingz »


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Offline mcgd

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Re: SX260 HS Porting Thread
« Reply #464 on: 01 / January / 2013, 10:10:32 »
To illustrate, here are two sample (downsized) images, both taken with 1/250s, f/5.0, ISO 100, one without ND filter, the other with ND filter in.
I get something similar.  When CHDK forces the ND filter in place,  the exposure does not change to compensate.  On my G10, if I use the Canon menu to activate the ND filter then the exposure adjusts (ISO, Tv & Ev) to compensate for the introdution of the filter.

So to get correct exposure when manually inserting the ND filter with CHDK,  you are probably going to need to use a customized script or manual override or an ISO offset if you camera supports it.  Or live with your "P" mode pictures being about 3 stops underexposed.
Yeah this isn't generally a problem for me, as I mainly use this with HDR bracketed sets, and I'm generally using manual mode anyway in that case.  Only thing is that it would be nice to be able to half-press the shutter to see what my exposure looks like with the ND filter, without having to take a photo to avoid crashing the camera.

But I was mainly posting those to illustrate that the camera definitely has a ND filter, though the menu item for it has gone missing in the release build.  Would be really nice if it were to make a reappearance.

Interesting that some other Canons also have hidden ND filters - didn't know that.

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Offline lapser

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Re: SX260 HS Porting Thread
« Reply #465 on: 01 / January / 2013, 12:18:35 »
Hmm, so the sx260 responds to ND filter commands from a script, but doesn't have an option to use it? That sounds like the typical marketing ploy of disabling hardware features so you can charge more for them in other cameras.

When I activate the ND filter on the G1X, I hear a definite click when it goes in. Then the live screen darkens, and then lightens back up. In AV mode, I then get a 1/10 second exposure with it in, and 1/80 second with it out, so it's compensating for it.

I take a lot of sunset time lapses, sometimes starting out with the sun in the frame, and the fastest shutter possible. An ND filter would be useful for that, but you would need to take it out right after the sun went down.

I have experimented with doing it from a script with the G1X, and it doesn't compensate for exposure. But my new shot metering method, which calculates exposure from the raw buffer after the shot, should compensate perfectly, on any camera I assume. But, it won't take effect until the 2nd picture after the ND goes in.

I'm working on other stuff now, but I seem to recall a propcase for ND filter? There's one in propcase 4 in the lualib/gen folder called:
  ND_FILTER_STATE=196,     -- 0 = out, 1 = in

Maybe you could experiment with setting it directly on the sx260?

Also, do you hear a click when you swap the ND filter in and out on the sx260? If so, then it's a real filter. If it's real, then my hat's off to you for discovering it. My hat's off anyway, because it should be useful either way. Thanks.


Re: SX260 HS Porting Thread
« Reply #466 on: 01 / January / 2013, 13:47:11 »
Hmm, so the sx260 responds to ND filter commands from a script, but doesn't have an option to use it? That sounds like the typical marketing ploy of disabling hardware features so you can charge more for them in other cameras.
Not any different than not allowing manual control of Tv and Ev when you think about it.

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When I activate the ND filter on the G1X, I hear a definite click when it goes in.
My ears are not that good - no click but the screen does darken on half-press.

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I'm working on other stuff now, but I seem to recall a propcase for ND filter? There's one in propcase 4 in the lualib/gen folder called:
  ND_FILTER_STATE=196,     -- 0 = out, 1 = in
Maybe you could experiment with setting it directly on the sx260?
Might just be easier to re-enable the ND filter option for that camera in the autobuild ?

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Offline reyalp

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Re: SX260 HS Porting Thread
« Reply #467 on: 01 / January / 2013, 15:28:02 »
Cameras that have an adjustable aperture and an ND filter (like the G series) generally give you ND control in the Canon firmware.
FYI - neither my A1200 or SD940 have any Canon menu entries related to an ND filter but I can definitely activate it with both.  My G10 (naturally) offers full manual control for the ND filter from the Canon shooting menu.
Right, but they don't have an adjustable aperture. These cameras do report the ND filter state as aperture. This is all standard stuff for low end, no IRIS/ND only cameras.

I would have expected the SX260, which has other manual controls to let you control an ND filter, but apparently I'm wrong :)

I wonder what the SX260 EXIF says when the ND is in / out? Does it change the aperture value? Is there an ND item in the maker note?
Don't forget what the H stands for.


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Offline reyalp

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Re: SX260 HS Porting Thread
« Reply #468 on: 01 / January / 2013, 15:31:20 »
I'm working on other stuff now, but I seem to recall a propcase for ND filter? There's one in propcase 4 in the lualib/gen folder called:
  ND_FILTER_STATE=196,     -- 0 = out, 1 = in
In my experience, this is read only and just reflects the state of the ND filter.

Note if there is an ND filter, when you call PutInNdFilter, it should take immediate effect. You should hear the click and see the screen darken.

Don't forget what the H stands for.

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Offline lapser

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Re: SX260 HS Porting Thread
« Reply #469 on: 01 / January / 2013, 16:42:04 »
Note if there is an ND filter, when you call PutInNdFilter, it should take immediate effect. You should hear the click and see the screen darken.
Yippee! It works. The screen darkens and I hear a click when it goes in and out.
I set CHDK to display Av in misc, and set the camera in Av mode at 8.0. The misc display shows 8.02

Unlike the G1X, the screen stays darker when ND is in.

When ND is IN, Av changes to 19.16
Then when ND goes out, AV changes to 5.33
It toggles back and forth between these values in the script as ND goes in and out

It stays at 5.33 after interrupting the script. Pressing the shutter half way with <alt> off changes it to 8.02 again.

DOF calculator changes the hyperfocal distance too. I'll have to make sure ND is out when I calculate hyperfocal distance. I'm not sure how exact the Av values are, but they would be a good start to figuring out an exposure correction for the shot, around 2 fstops, it looks like.

I added this at line 36 to platform.camera.h for the sx260:
    #define CAM_RAW_ROWS                        3060        // Found @0xff17db4c
    #define CAM_HAS_ND_FILTER                   1 //added by lapser for testing
    #define CAM_HAS_CMOS                        1

I already changed luascript.c to be able to set exposure in half shoot:

Code: [Select]
static int when()
{
  if(shooting_in_progress())return SET_NOW;
  return SET_LATER;
}
//...
static int luaCB_set_nd_filter( lua_State* L )
{
  shooting_set_nd_filter_state( luaL_checknumber( L, 1 ), when());
//  shooting_set_nd_filter_state( luaL_checknumber( L, 1 ), SET_LATER);
  return 0;
}
Here's the test script:
Code: (lua) [Select]
--[[
@title ND Filter Test
--]]

press("shoot_half");
repeat
  repeat sleep(100) until is_pressed("set")
  print("nd filter IN")
  set_nd_filter(1)
  repeat sleep(100)  until not is_pressed("set")
  print("nd filter OUT")
  set_nd_filter(2)
until false
It looks like a good change to add to the trunk, doesn't it?

[EDIT]The ND filter option in the CHDK menu doesn't do anything. Is there another change that needs to be made?
« Last Edit: 01 / January / 2013, 16:48:40 by lapser »

 

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