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Tv override problem with sx50hs

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Tv override problem with sx50hs
« on: 14 / January / 2015, 20:50:00 »
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I've been using CHDK for three years on my sx10is, with few difficulties and with plenty of satisfaction.  Thanks to everyone involved for more making my life more enjoyable!

I've never needed to write before, but my new sx50hs has me stumped.  I can't get Tv override to work consistently.  Last night I wanted to compare it to my sx10is with a series of shots in low light at ISO80, f5.6, efl 560mm, and shutter times increasing incrementally (1/3 stops) from 4s to 16s.  Worked fine with the sx10 - but doing the same thing on the sx 50, after a shot at 4s and the next at 5s, every other one cut out at one second!
 
I've re-tried a couple of times since, and had a couple of (seemingly) random shot come out as dialed in, but almost every one winds up being a one-second exposure, regardless of how I program it with CHDK. (Settings were identical to those for my sx10.)

Can't be a common problem, as it doesn't come up in any search I've done on this site or on google - but maybe someone here has a suggestion?

Thanks!

Re: Tv override problem with sx50hs
« Reply #1 on: 14 / January / 2015, 21:36:13 »
What camera mode are you using?   

The sx50hs does not work well with CHDK in HiSpeed_Burst mode (for example). http://chdk.setepontos.com/index.php?topic=11272
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Tv override problem with sx50hs
« Reply #2 on: 14 / January / 2015, 23:20:56 »
Thanks for responding!

Not burst mode.  No raw.  Camera on a tripod, aperture priority set for f5.7, IS off, one shot with timer; then to ALT, to CHDK menu to change exposure time, then out of menu, ALT off, and next shot using timer.
 
Each new exp. time was always visible in red on the screen.  The first run through, I only saw the problem after playing back the whole series at the end, so thought maybe I hadn't activated the white dot beside the new times? or had disabled the override?.  But re-doing it, and double-checking all that, changed nothing, except on a couple of occasions which I can't explain.  They came after a long pause, so I thought maybe the subsequent failures were because those early longish exposures had over-stimulated the sensor?  But when I tried using a FAST shutter speed - 1/3 sec. - I still got a one-second exposure!   

Hope that helps...

Re: Tv override problem with sx50hs
« Reply #3 on: 14 / January / 2015, 23:36:46 »
Not burst mode.  No raw.  Camera on a tripod, aperture priority set for f5.7, IS off, one shot with timer; then to ALT, to CHDK menu to change exposure time, then out of menu, ALT off, and next shot using timer.
So each shot is taken using the Canon self timer ?   Just the 10 second or 2 second self-timer?  ( S100 timer modes - don't have my SX50 handy at the moment).   Or are you using the custom timer (with variable delay and # of shots)?

When I get access to my SX50 I can test but I need to repllicate exactly what you have done.

What happens if you take your shots without using the timer but with CHDK overrides set?
Ported :   A1200    SD940   G10    Powershot N    G16


Re: Tv override problem with sx50hs
« Reply #4 on: 15 / January / 2015, 00:51:15 »
I've been working on this for another bit, and indeed the problem seems to be the self-timer!

I can get the sx50 to stay open as long as I want when I push the button myself - but using the timer (whether 2 or 10s), the exposure always defaults to 1 second. 

My exif data doesn't register self-timer use, so I can't be sure (and can't remember) whether the few shots that worked before tonight were the result of having pushed the button rather than using the timer.  It seems quite possible.  Funny that this isn't the case with the sx10, though.  Its timer doesn't cause this problem. 

Any chance someone could overcome it on the sx50?  I'm already a LOT happier now that I know how to get the long exposures I want - but it would be great if the jiggle from pushing the button could be avoided...

In any case, thanks a lot for such a quick and accurate analysis of the situation!

Re: Tv override problem with sx50hs
« Reply #5 on: 15 / January / 2015, 08:20:09 »
I've been working on this for another bit, and indeed the problem seems to be the self-timer! I can get the sx50 to stay open as long as I want when I push the button myself - but using the timer (whether 2 or 10s), the exposure always defaults to 1 second. 
In any case, thanks a lot for such a quick and accurate analysis of the situation!
Can you get the CHDK override and the self timer to work together at faster shutter speeds?  1/15? 1/500 ?

Quote
Funny that this isn't the case with the sx10, though.  Its timer doesn't cause this problem. 
Every Canon camera has different firmware so every CHDK port is unique.  The placement of the hooks CHDK makes into the Canon firmware is not an exact science - things that work for one camera may not work for the next.  This is probably the case with the SX50 - AFAIK this sort of thing works fine on most other CHDK enabled cameras.

Quote
Any chance someone could overcome it on the sx50?  I'm already a LOT happier now that I know how to get the long exposures I want - but it would be great if the jiggle from pushing the button could be avoided...
There are only a couple of people who can really do this and I might be the only one that actually owns the camera.  If I can pry a few moments free I'll try the most obvious things and see what happens.

In the meantime,  you can use a simple script to insert a delay between pressing the shutter button and the actual exposure (with or without overrides enabled).   In fact,  the simple shoot.lua script included with every CHDK distribution will do that for you.
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Tv override problem with sx50hs
« Reply #6 on: 15 / January / 2015, 14:24:41 »
I took some indoor daylight shots just now, programming for exp. times of 1/60 down to 1/500 - all worked when I triggered the shutter myself, but all defaulted to 1/25 when the self-timer (2s) triggered it.

I tried the script, though.  It takes a couple of extra steps compared to using the timer, but it worked, and resolves the issue of potential camera jiggle.  Thanks for the suggestion.  Great service on this board!

   

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Offline philmoz

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Re: Tv override problem with sx50hs
« Reply #7 on: 15 / January / 2015, 16:05:42 »
I took some indoor daylight shots just now, programming for exp. times of 1/60 down to 1/500 - all worked when I triggered the shutter myself, but all defaulted to 1/25 when the self-timer (2s) triggered it.

I tried the script, though.  It takes a couple of extra steps compared to using the timer, but it worked, and resolves the issue of potential camera jiggle.  Thanks for the suggestion.  Great service on this board!


Can test if other overrides are affected - e.g. enable CHDK DNG file saving and see if a DNG image is saved when you shoot with the timer.

Also please post exactly which version of CHDK you are using.

Phil.
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)


Re: Tv override problem with sx50hs
« Reply #8 on: 15 / January / 2015, 19:15:08 »
Last night I wanted to compare it to my sx10is with a series of shots in low light at ISO80, f5.6, efl 560mm, and shutter times increasing incrementally (1/3 stops) from 4s to 16s.  Worked fine with the sx10 - but doing the same thing on the sx 50, after a shot at 4s and the next at 5s, every other one cut out at one second!
 
I've re-tried a couple of times since, and had a couple of (seemingly) random shot come out as dialed in, but almost every one winds up being a one-second exposure, regardless of how I program it with CHDK. (Settings were identical to those for my sx10.)
I found my SX50hs ( CHDK 1.4.0 -3885 ) and  tried your workflow :

  • Camera in Av priority mode
  • f5.6
  • IS off
  • CHDK Tv override set to 5.00000
  • Canon self timer set to 2 seconds

Press the shutter,  the two second self timer runs, the shot starts, and five seconds later the shot completes.   Repeated this several time for different shutter speeds.

I can't reproduce your problem. All image are exposed for the time requested - based both on timing with my watch and on the EXIF reported values.

Can save DNG file every time as well and can also do all of this in P mode.

So right now, it's going to be hard to make changes if I can't reproduce the problem. Sorry .
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Tv override problem with sx50hs
« Reply #9 on: 15 / January / 2015, 21:16:42 »
Philmox, waterwings

Thanks.  Tried again tonight, with RAW turned on.  Still had the same problem when using the self-timer (2s) - whether recording DNG's or not, the camera defaulted to 1s exposures, despite being programmed for 10s.  Only got my 10s exposures when triggering manually.

My build is 1.3.0-3913 - it's what came out using the ACID/STICK apps to download the "right" one, on Jan 12th.  Would you suggest trying 1.4.0. instead?  (Little leery of "unstable" builds...)

 

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