#1  
Old 06-04-2008, 05:54 PM
astroturf (Bryan)
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40D interval timing

Hi
the last couple of times I have been using interval timing (15 secs every 10 secs) on remote shooting, I have been getting a high percentage of failed shots (16 out of 22) for no apparent reason that I can see
does anyone have any idea what is causing this? has anybody experienced this with the 40D?
any input appreciated

Cheers
Bryan
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  #2  
Old 06-04-2008, 07:19 PM
Dennis
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Hi Bryan

If you have In Camera Noise Reduction (ICNR) turned on, here’s what happens:

15 sec light exposure
15 sec ICNR exposure
N sec download time

So, a single light/ICNR set takes at least 30 seconds, therefore you need to set the interval to say, 35 secs to allow for download time.

Cheers

Dennis
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Old 07-04-2008, 01:54 PM
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leon
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Bryan, Dennis is dead right, I had this problem when I first started imaging with the Canon 5D, you need a down load time, in between the image and ICNR, I use 7 sec,s, just add the 5 or 7 sec's to the ICNR gap.

Leon
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Old 07-04-2008, 02:49 PM
astroturf (Bryan)
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Thanks Dennis & Leon for your input

would I be right in thinking the time required for ICNR is whatever time the actual exposure takes , so if the exposure was 30secs the ICNR would be the same then allow say a further 10secs (40 in total) before the next exposure, would that be appropriate do you think?

What I can't figure out with all this, is how have 6 exposures been captured out of 22 when the other 16 failed

thanks
Bryan
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  #5  
Old 07-04-2008, 03:17 PM
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RB (Andrew)
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Also Bryan, what brand/type of CF card are you using and are you shooting in RAW, jpg or both.
These factors, along with ICNR will also influence d/l times.

Also it's a good idea to leave enough time between shots to allow the sensor to cool again before the next shot.
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Old 07-04-2008, 04:16 PM
Dennis
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Hi Bryan

This is what I think may be happening:

The interval is from the start of Exposure 1 to the start of Exposure 2 to the start of Exposure 3……to the start of Exposure N. So, in your example, with ICNR mode (C.Fn II-1 long exposure nose reduction = Auto or 2 = On), then the following sequence takes place:
  • Light exposure 01 – 15 secs is successful (interval 1 of 10 secs causes a failure, interval 2 starts)
  • Dark exposure 01 – 15 secs (interval 2 ends causing a failure. Interval 3 starts, possibly causing a failure)
  • Download time – say 1 sec
  • Light exposure 04 – 15 secs is successful (occurs on interval 4)
  • Dark exposure 04 – 15 secs
  • Download time – say 1 sec
  • Light exposure 07 – 15 secs is succesful
  • Dark exposure 07 – 15 secs
  • Download time – say 1 sec
And so on…
  • Light exposure N – 15 secs
  • Dark exposure N – 15 secs
  • Download time – say 1 sec
So, the interval between exposures is 30 seconds plus download/processing time.

If you set the interval as 10 seconds, then the camera will still be exposing the 1st light and 1st dark exposures after 3 intervals have elapsed (10+10+10 secs) so only the 4th interval will cause another Light exposure to be taken and the 3 earlier attempts at 10 sec intervals will be registered as failed.

Cheers

Dennis
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Old 07-04-2008, 05:05 PM
astroturf (Bryan)
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Hi guys

I think I'm learning something here!
Andrew, I use a Sandisk "extreme IV which I was told was best for the 40D & it's 6.5 fps capability

but being the impatient type I want it all to happen right away lol. giving the sensor a chance to cool makes sense, I also made the mistake of shooting in RAW & jpeg simultaneously(just once)

I think I have to agree Dennis, 6/22 is very close to 1 in every four successful frames
the camera/software is trying to do everything in a shorter timeframe
I think I'm going to allow 40 secs between each capture & walk away for a bit
The 40D is a great camera & I'm really enjoying it, everytime I learn something new with it, it reinforces my interest
Thanks heaps for all your help

Cheers
Bryan
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Old 07-04-2008, 05:53 PM
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skwinty (Steve)
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Quote:
Originally Posted by astroturf View Post
I also made the mistake of shooting in RAW & jpeg simultaneously(just once)
hi Bryan
As a matter of interest, why do you think that shooting in raw + jpg is a mistake?
Are you referring to the extra download time or something else?
I find the advantage of shooting raw + jpg is that you have the instant gratification of the jpg and all the detail in the raw for later processing.
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Old 07-04-2008, 06:41 PM
astroturf (Bryan)
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Quote:
Originally Posted by skwinty View Post
hi Bryan
As a matter of interest, why do you think that shooting in raw + jpg is a mistake?
Are you referring to the extra download time or something else?
I find the advantage of shooting raw + jpg is that you have the instant gratification of the jpg and all the detail in the raw for later processing.
Hi Skwinty
No Big deal I guess
I think it was just all a bit confusing for a beginner like me, especially when it came to combining them all in DSS, the folder seemed very cluttered
I find there's not too much difference between JPeg & RAW to look at anyway
as I say I'm on the learning curve & I may change my mind about this one day
Cheers
Bryan
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Old 07-04-2008, 06:58 PM
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Bassnut (Fred)
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Bryan, I have used the 40D interval timer with no missing subs. I found although RAW is a fixed file size, JPEG can vary. Just allow plenty time for file download and add some.
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Old 08-04-2008, 12:28 PM
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RB (Andrew)
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Quote:
Originally Posted by astroturf View Post
Hi guys

I think I'm learning something here!
Andrew, I use a Sandisk "extreme IV which I was told was best for the 40D & it's 6.5 fps capability

Quote:
Originally Posted by astroturf View Post
but being the impatient type I want it all to happen right away lol. giving the sensor a chance to cool makes sense, I also made the mistake of shooting in RAW & jpeg simultaneously(just once)
Cheers
Bryan
I always shoot in RAW and jpg simultaneously, for both astro and terrestrial.
I like having both files of the same image, I prefer to review the full size jpg photos without opening up the raw file unnecessarily.
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