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 05/08/2006 01:32:30 PM · #1
ok, this is going to be hard to explain

ok my 5D takes 3 fps

how many 1/100's of a second are inbetween each shot,

same with 30D, and 1ds MK II
 05/08/2006 01:38:01 PM · #2
Originally posted by TroyMosley:
how many 1/100's of a second are inbetween each shot,


That would depend on the shutter speed you used as to how much time was left in each 1/3 of a second. I think.
 05/08/2006 01:39:45 PM · #3
so then i wonder what the minimum shutter speed would have to be to actually get the max shutter speed from the camera 1/100 /200/300 or even 1/1000's
 05/08/2006 01:42:38 PM · #4
oh, now i understand...i've wondered that too

Don't have anything to help though, sorry
 05/08/2006 01:46:37 PM · #5
Let's look at an extreme case. 3fps means 1/3s per frame. If your shutter speed is 1/4s, you've almost used up your frame-to-frame time budget. Obviously, then, as shutter speed decreases, frame rate will drop as well. This will really only be noticable well below 1/30s.
There are a number of other things that affect frame rate as well, and the list varies for each camera. Even some obscure custom functions can have a significant effect.
To estimate the frame-to-frame interval for slower shutter speeds, add the shutter open time to the advertised interval. That will be the fastest possible result.
 05/08/2006 01:48:04 PM · #6
If you are in continuous drive mode @ 3fps then the longest exposure you can have would be something short of 1/3 second, since the camera needs to record the data to the card/buffer at least that often. The only limit on the shortest exposure should be shooting/exposure conditions.
 05/08/2006 01:52:51 PM · #7
Originally posted by kirbic:

To estimate the frame-to-frame interval for slower shutter speeds, add the shutter open time to the advertised interval. That will be the fastest possible result.


Huh? Shouldn't that be something like "multiply the shutter speed by the advertised frames per second figure and if the total is greater than 1 you've passed the limnit."?

And btw, as long as we are talking FPS recycling rates, be SURE you have the in-camera noise reduction turned off, as that DOUBLES the length of time the camera spends shooting/processing. I love noise reduction, but it's a hell of a wait on a 5-minute exposure...

R.
 05/08/2006 01:57:12 PM · #8
Originally posted by GeneralE:
If you are in continuous drive mode @ 3fps then the longest exposure you can have would be something short of 1/3 second, since the camera needs to record the data to the card/buffer at least that often. The only limit on the shortest exposure should be shooting/exposure conditions.


so General, if im reading you right, if i have a shutter speed of 1/300th of a second, in continous drive mode, that would give me my 3fps ratio, and anything abovoe 1/300 is not going to give me any more fps but just a quicker motion stop capabilitie
 05/08/2006 02:16:27 PM · #9
anyone els have a formula for this,
there is 100 1/100ths in a second
im still not understanding,

lets use a 5D as example, how fast does the shutter speed have to be to actually get 3 fps
 05/08/2006 02:18:35 PM · #10
Originally posted by Bear_Music:
Originally posted by kirbic:

To estimate the frame-to-frame interval for slower shutter speeds, add the shutter open time to the advertised interval. That will be the fastest possible result.


Huh? Shouldn't that be something like "multiply the shutter speed by the advertised frames per second figure and if the total is greater than 1 you've passed the limnit."?...


Nope! The max frame rate is just that, a maximum, the actual rate varies. Example:
Canon 1DMkII, advertised frame rate is 8.3 frames/second. Inverting, that's 1/8.3=0.1205 seconds/frame, or 120.5 milliseconds. Within that time, the image must be captured, processed, and written out to the buffer; all these steps are sequential. The max. framerate spec is at some relatively high shutter speed (short open time). For simplicity, I'll assume that the open time required to achieve the spec'd framerate is zero. Now, if my shutter speed is 1/30s (33.3 milliseconds open time), I must add this to the spec'd interval (120.5ms) and will get 153.8ms; that's equivalent to 6.5 frames/second.
The reason it works like this is because the image processing cannot start until the shutter closes. It's a sequential process, which is intuitively "correct" but not something we normally give much thought to.
If one accurately measures the framerate for a range of shutter speeds, it's easy to do linear regression to determine at what shutter speed the advertised frame rate is achieved, if ever.
 05/08/2006 02:24:47 PM · #11
Right, a linear regression. I used to do those all the time with my Uncle Eddy in cub scouts. Easy to do, really fun stuff.

:)

Of course, once our flux capacitor broke down - we had to use the wall stretcher which took more time. Still very enjoyable, though.

Originally posted by kirbic:
it's easy to do linear regression to determine at what shutter speed the advertised frame rate is achieved, if ever.
05/10/2006 04:53:42 PM · #12
do you think its possible that there could be a hack to add FPS or maybe a way to change whatever it is that makes if take 3 fps.
like they did in the original rebel
 05/10/2006 04:55:31 PM · #13
Originally posted by TroyMosley:
do you think its possible that there could be a hack to add FPS or maybe a way to change whatever it is that makes if take 3 fps.
like they did in the original rebel


I think that is more limitted by hardware than software.
 05/10/2006 05:03:09 PM · #14
Originally posted by Bear_Music:
And btw, as long as we are talking FPS recycling rates, be SURE you have the in-camera noise reduction turned off, as that DOUBLES the length of time the camera spends shooting/processing. I love noise reduction, but it's a hell of a wait on a 5-minute exposure...

R.


Doesn't the noise reduction only kick in on exposure times greater than 1 second?

Originally posted by TroyMosley:
do you think its possible that there could be a hack to add FPS or maybe a way to change whatever it is that makes if take 3 fps.
like they did in the original rebel


I'm pretty sure that wouldn't work, and if it did it would still fill up the buffer even faster, so it'd have to stop and write to the card...
 05/10/2006 05:04:34 PM · #15
Originally posted by fotomann_forever:
Originally posted by TroyMosley:
do you think its possible that there could be a hack to add FPS or maybe a way to change whatever it is that makes if take 3 fps.
like they did in the original rebel


I think that is more limitted by hardware than software.


Yep, it is. Specifically, it's limited by how fast the camera can compile a RAW or JPEG file and push it out to the buffer. If I recall correctly, the latest non-1-series cams process about 40Mpx/second, and the 1-series cams process about 64Mpx/s.
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