Canon 7D & Off Body Flash - Got a Question....

12/03/2009 08:30:47 PM · #1

Does anyone know or can they check what the actual fastest sync speed on the 7D is via sync port or a radio trigger without any part of the shutter curtain in the image???

No - I don't mean the published 1/250 for an on camera flash.... For example my 20D is really 1/320 without any part of the shutter in the frame when a flash is triggered from a sync port or most radio triggers (once it's in the hot shoe it's limited to the published 1/250). I know the 5D is limited to the published 1/200.

Am thinking of a wee upgrade and trying to flip between a 5d classic and the 7d (cannot swing a 5d2... not sure I can swing a 7d either yet :-/... but having bad thoughts about picking up a 1D classic for the sync speed ).... but a 2 stop difference is hard to go from a 20d to a 5d.... and if the 7d can also do 1/320.... well...

12/04/2009 10:40:04 PM · #2

Anyone??

Tez

Canon EOS-5D Mark II

Canon EF 85mm f/1.8 USM

12/05/2009 12:17:00 AM · #3

if you're really bothered you can get a canon flash cord, extend it by splicing a cable into it (however long you like), then you can keep the ETTL, high speed sync function and whatever else and your flash can be as far away as the cord will allow, so theoretically 50ft away and at 1/8000 sec for example.

As for an answer to your question... I'm not sure. It also depends on the flash/light being used as well as the camera.

Melethia

Canon EOS-80D

12/05/2009 03:31:01 AM · #4

No, it does NOT work at 1/320 with off camera flash/pocket wizard combo. The shutter is seen across the bottom quarter of the picture at 320.

TrollMan

Fujifilm X-T4

Fujifilm XF 35mm f/1.4

12/05/2009 04:01:46 AM · #5

It mostly depends on the flash you're using and not the sync speed of the camera. If you for example use this pack from Profoto you'll get down to 1/8000th.
But keep in mind that at 1/8000 flash you only get 1/8th power so you need a powerful flash. At 1/2000 the flash gives half power and you'll get a full power shot at 1/1000th.

I'm not sure however if a radio trigger will keep up with this or not. But I have heard a buzz about the speed being reduced to 1/800th when using PW's (due to a delay). I can't confirm this though but just ordered a set of PW Flex TT5's today so I guess I'll find out soon! :)

TrollMan

Fujifilm X-T4

Fujifilm XF 35mm f/1.4

12/05/2009 04:05:20 AM · #6

And just to add to this... on the more professional flash units you can actually set the flash speed digitally right on the pack. What you see Melethia I believe is a limitation of your flash - not camera nor PW.

Melethia

Canon EOS-80D

12/05/2009 04:23:02 AM · #7

And it's not a Pocket Wizard - it's a cheap knockoff. The flash is a Canon 430EX - I meant to mention that. It all does work just fine at 1/250th, though.

TrollMan

Fujifilm X-T4

Fujifilm XF 35mm f/1.4

12/05/2009 05:37:06 AM · #8

And keep in mind that the sync speed and flash speed are two different things. In the picture below with the model jumping on a trampoline the sync speed was 1/125 on my camera while the flash speed was set to 1/4000th. The actual 'freeze' effect is then equal to 1/4000. 1/125 would not have been sufficient.

Just thought I'd mention before someone are finding out that their camera will show the curtain (black band) at speeds higher than their camera's x-sync (1/200 on 5D2) regardless of flash units.

I'm by no means an expert on this so feel free to correct me anyone.

Canon EF 24-70mm f/2.8L USM

12/06/2009 10:52:25 AM · #9

Thx - bummer that it seems you get the curtain on the 7d at 320... Yeah guys I know the flash duration and sync affect different things.... I do a bit of the strobist thing against the sun where the sync speed DOES matter to knock down the exp on the sky some. I was hoping the crop body could cheat the advertised 1/250 by a stop since my 20D does. Yeah... I cannot do HSS since only one of my flashes is a real canon with that feature... This is all manual not eTTL. Hummmm....

Message edited by author 2009-12-06 10:53:44.

Ken

Canon EOS-7D

12/06/2009 12:36:56 PM · #10

Can't you switch Shutter sync. to Hi-speed? I know you can do that for a mounted flash and use whatever shutter speed you want without seeing the shutter in the photo. I just did a test shot @ 1/2000 with no shutter in the frame.

Canon EF 24-70mm f/2.8L USM

12/06/2009 06:42:03 PM · #11

Ken - Yeah, if you own all Canon/Nikon/Whatever strobes and use the auto function (eTTL, iTTL, pTTL, whatever) with White/IR communications. Some other issues with HSS is that it's pulsing light not a freeze like (as troll said, the actual elapsed of the flash burst is VERY fast on battery strobes... far slower on most studio strobes) single flash, so depending what your doing that can make a difference and it also kills the power of the flash because it's not doing a single pop - it's doing one for each portion of the frame as the 2 curtains move, so is FAR less powerful. It's basically a work around the sync-speed limit with some fancy timing from the computers on these things now [I swear, I will not be surprised when one of these things forces you to hit 3 buttons to start or stop it :-)].

Ken

Canon EOS-7D

12/06/2009 06:59:04 PM · #12

Originally posted by robs:

I thought the Hi speed sync was actually a single pulse that is open the entire time the shutter is open. Are you referring to Multi flash?

Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II

12/06/2009 07:33:35 PM · #13

Originally posted by Ken:

I thought the Hi speed sync was actually a single pulse that is open the entire time the shutter is open. Are you referring to Multi flash?

Nah, It's not a single pulse (Tech link from Canon - See the wave form diag part way down). I don't mean what your calling Multi - although for simplicity, it's very similar at faster rates. Anyways... WAY off topic here :-) I don't got the option of HSS..... and that extra stop helps sometimes and since it's APC and less travel distance for the shutter, I was wondering if it could cheat like my 20D does.

MattO

Nikon D4

12/06/2009 07:52:38 PM · #14

Not sure if this helps or not, but I can only get 1/320 on my 1DMKIII using Cybersyncs from AB. Published flash sync on my 1DMKIII is 1/300 and once I step to 1/400th I get a black streak.

Matt

Canon EF 24-70mm f/2.8L USM

12/06/2009 08:27:48 PM · #15

Yeah thx but it seems to be body specific and I should not expect anything over the published # I know. I can always shoot wider and crop out the curtain but just trying to see what I would be in for - I want it all basically :-). Seriously tempted to get a 5D classic and an old 1D for the sync speed only.... Very tempting instead of the 7D and probably a wash for the $. Thx for the info guys.....

Ken

Canon EOS-7D

12/06/2009 10:43:19 PM · #16

Originally posted by robs:

Originally posted by Ken:
I thought the Hi speed sync was actually a single pulse that is open the entire time the shutter is open. Are you referring to Multi flash?

Nah, It's not a single pulse (Tech link from Canon - See the wave form diag part way down). I don't mean what your calling Multi - although for simplicity, it's very similar at faster rates. Anyways... WAY off topic here :-) I don't got the option of HSS..... and that extra stop helps sometimes and since it's APC and less travel distance for the shutter, I was wondering if it could cheat like my 20D does.

It looks like you're right, thanks for the link.