werid issue, 7d shooting very slow frame rate

[paul_jones]

hi guys,

i am wanting to purchase a 7d, as i cant wait for the long over due 1dsmk4 to do video.

but i will also want to do fast fps with the motor-drive. on the specs it says it can shoot 8fps.

last night i rented a 7d to try to shoot some action at 8fs.  everything we tried (several hours of mucking around with it), we couldn't get the camera to shoot faster than 4fps when shooting dark subjects, but got 8fps when shooting bright light.

we aren't new to canons, and know most of the controls that effect frame rate (ive used almost every canon professional camera, over 20 years).


here are the settings tried with no success at improving the frame rate-

- lens set at manual focus- so no slowing down for camera to focus.
- camera set on manual, with faster that 250th sec shutter speed.
- we tried raw only
- we tried small jpegs only.
- all testing was done at the first part of the buffer -ie, waited for the buffer to clear before trying again.
- we used a sandisk extreme 4 card (one of the fastest available).
- i also tried a different card.
- of cause- the camera was set at "H" on drive settings


we wondered if lots of noise would be causing the slow down from shooting the dark stuff, but when i tested with well exposed flash lit subjects with the modeling lamps off with very fast strobes(capable of over 12fps recharge), the camera still went very slow . so that throws out the idea of noisy files slowing things down.

the issue isn't an isolated one, and appears to do the same with the latest firmware.
http://photography-on-the.net/forum/showth...9335&page=5

reading this thread, apparently there is no slowdown when using only live view. this of cause isn't an answer to the problem though.

have you guys got any answers (hidden custom functions??)? i really want this camera to shoot at the speed that the canon specs say they do.


thanks paul

[DarkPenguin]

High ISO noise reduction turned on?

[paul_jones]

High ISO noise reduction turned on?

hi, not sure, but i doubt it shot effect a raw shot? i will try this when i get my hands on the camera again (i not buying one, until this mystery gets solved).

i got this reply off another forum-

RobjDickinson wrote:
The issue is meetering, canon decided to give meetering priority on the 7D, it cant meeter fast enough in manual mode (or tv / av etc) for 8fps in realy dark conditions.
The workround is NOT to use manual mode, use Tv or Av and use * for exposure lock that should give you fast burst mode for a bit.
Complain to canon, hopefully this will be fixed.
(note meetering is stil used in manual mode, but shouldnt prevent shooting!)

so, this could be the reson. but i sucks- canon has inaccurate specs.

cheers paul

[Ken Bennett]

hi, not sure, but i doubt it shot effect a raw shot? i will try this when i get my hands on the camera again (i not buying one, until this mystery gets solved).

The high ISO noise reduction does affect raw files, and it affects how many shots you get in a burst on the xxD cameras. Not sure if it affects the 7D or not. I learned this the hard way with my 40D cameras.

I can't imagine it would affect frame rate, though. Hmmm.

[DanielStone]

if you want to get 8 frames a sec, you'll need to be using at least 1/125 of a second, actually more like 1/250

this gives the mirror enough time to return and lift again for the next exposure.

8fps in bright light is easy if you're shooting at 1/1000 vs 1/15.

also, in dim light, AF sensors don't have as much contrast to work with vs bright light conditions. AF uses contrast to focus, more contrast/texture, easier to focus, less texture/contrast=slower af

-Dan

[Sheldon N]

This issue was discussed pretty extensively here...

http://www.fredmiranda.com/forum/topic/823708/0

Basically when the light levels fall below a certain point (ISO3200, f/2.8, 1/100) the metering system slows down the frame rate, something to do with DIGIC 4. It doesn't have anything to do with shutter speed settings (once the speed is actually fast enough to allow 8fps) because it will still happen even in manual mode when the light level drops. It's also not the AF settings, since it will slow even in manual focus mode.

[paul_jones]

if you want to get 8 frames a sec, you'll need to be using at least 1/125 of a second, actually more like 1/250

this gives the mirror enough time to return and lift again for the next exposure.

8fps in bright light is easy if you're shooting at 1/1000 vs 1/15.

also, in dim light, AF sensors don't have as much contrast to work with vs bright light conditions. AF uses contrast to focus, more contrast/texture, easier to focus, less texture/contrast=slower af

-Dan

all my test were higher than 250th of a sec. the lens was switched to manual and exposure was on manual- there shouldn't be much for the camera to do.


cheers paul

[paul_jones]

This issue was discussed pretty extensively here...

http://www.fredmiranda.com/forum/topic/823708/0

Basically when the light levels fall below a certain point (ISO3200, f/2.8, 1/100) the metering system slows down the frame rate, something to do with DIGIC 4. It doesn't have anything to do with shutter speed settings (once the speed is actually fast enough to allow 8fps) because it will still happen even in manual mode when the light level drops. It's also not the AF settings, since it will slow even in manual focus mode.

thanks, ill have a read now.

iso wasn't higher than 400, but the lens was at 1.2- so low setting for the exposure. but exposure shouldn't really effect frame rate when its set to manual. if it does, then the specs that canon advertise are false.

paul