Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 03 Jan 2008 (Thursday) 21:44
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

The amazing speed of optical slaves

 
tkoutdoor
Goldmember
Avatar
1,874 posts
Joined Sep 2007
Location: Feeding my camera somewhere in Western Washington
     
Jan 06, 2008 08:13 |  #46

PacAce wrote in post #4639977 (external link)
Are my eyes deceiving me, Curtis, or is the camera syncing at 1/320 at 1/16 power? Even 1/400 doesn't look bad at all. :shock: (Of course, I'm referring to the sync of the flash mounted on the camera).

Nice. 1/500th is still yielding about an 8x10 crop if the camera is oriented to account for the cropping and 1/640th is still yielding about 1/2 a frames worth of usable real estate to the one who could make use of it. All of that is pretty cool for those who might want to experiment with the limits. Thanks for posting those pics, they are truly worth a thousand words.

Curtis your test was demonstrating a comparison of a radio trigger vs an optical slave. If you have any will to take another step with your experiment, I'm curious how a hard wired master flash would compare to your radio triggered slave. At 1/640th I'm guessing the best one might hope for is to get the usable space back down to an 8x10 crop, but that's just a guess that will remain theoretical without actual facts to work with. I think my guess about the usable space left over is optimistic, but who knows without actually testing it? If by chance I'm right though, that could extend the limits of what one could get in half a frame from 1/640th to whatever the next level is...

EDIT - OHH wait... That's precisely what you did with the second test. I got it confused with the first test when I started writing this. This definitely shows a use for a hard wired setup when one would try to push the limits.

PacAce you may recall this was the subject of my first ever post and I pointed this out then... Some guy was wondering how a particular photog was getting sync rates that allowed him to freeze stunt bikes wheels etc. in motion or something like that and this was one of the possibilities we discussed. Now Curtis is showing the results on screen that we talked about in theory then. I love finding a way to "do" what they say can't be done. The Smokey and the Bandit theme song is running through my mind ATM... :-)


Canon ~ 7D, 1D MkIIn, 5D, 20D, 10D, 100-400L IS, 70-200 2.8L IS, 24-105 f4L IS, 17-40 f4L, 135mm f2L, 85mm 1.8, 50mm 1.4, 50mm 2.5 macro, Ext. tubes, TC's 1.4 & 2.0, Feisol 3441-S CF Tpod, Gitzo Traveler Mpod, Acratech ballhead, 550EX, 200EG bag, Epson Pro 3800 printer.

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)
PacAce
Cream of the Crop
Avatar
26,899 posts
Likes: 39
Joined Feb 2003
Location: Keystone State, USA
     
Jan 06, 2008 08:19 |  #47

tkoutdoor wrote in post #4641597 (external link)
Nice. 1/500th is still yielding about an 8x10 crop if the camera is oriented to account for the cropping and 1/640th is still yielding about 1/2 a frames worth of usable real estate to the one who could make use of it. All of that is pretty cool for those who might want to experiment with the limits. Thanks for posting those pics Curtis, they are truly worth a thousand words.

PacAce you may recall this was the subject of my first ever post and I pointed this out then... Some guy was wondering how a particular photog was getting sync rates that allowed him to freeze stunt bikes wheels etc. in motion or something like that and this was one of the possibilities we discussed. Now Curtis is showing the results on screen that we talked about in theory then. I love finding a way to "do" what they say can't be done. :-)

Yes, I remember that discussion very well. You're the "thinking outside of the box" guy. ;)


...Leo

  
  LOG IN TO REPLY
tkoutdoor
Goldmember
Avatar
1,874 posts
Joined Sep 2007
Location: Feeding my camera somewhere in Western Washington
     
Jan 06, 2008 08:49 |  #48

PacAce wrote in post #4641614 (external link)
Yes, I remember that discussion very well. You're the "thinking outside of the box" guy. ;)

Guilty as charged! :cool:


Canon ~ 7D, 1D MkIIn, 5D, 20D, 10D, 100-400L IS, 70-200 2.8L IS, 24-105 f4L IS, 17-40 f4L, 135mm f2L, 85mm 1.8, 50mm 1.4, 50mm 2.5 macro, Ext. tubes, TC's 1.4 & 2.0, Feisol 3441-S CF Tpod, Gitzo Traveler Mpod, Acratech ballhead, 550EX, 200EG bag, Epson Pro 3800 printer.

  
  LOG IN TO REPLY
SolidxSnake
Goldmember
Avatar
1,656 posts
Likes: 2
Joined Nov 2007
     
Jan 06, 2008 10:52 |  #49

Could you do a test comparing an off-shoe test with an optical slave? I'd be interested to see the results.


Troubleshooting 101 (see also: LightRules,perryge):
1) RTFM.
2) Repeat Step 1.

Gear ~ DeviantART (external link) ~ My Heatware (external link)

  
  LOG IN TO REPLY
Curtis ­ N
THREAD ­ STARTER
Master Flasher
Avatar
19,129 posts
Likes: 11
Joined Apr 2005
Location: Northern Illinois, US
     
Jan 06, 2008 11:27 |  #50

SolidxSnake wrote in post #4642227 (external link)
Could you do a test comparing an off-shoe test with an optical slave? I'd be interested to see the results.

I don't know what you mean by "off-shoe".

If you're referring to the Canon Off Camera Shoe Cord, it should give results identical to a PC cord or mounting the flash right on the hotshoe.

Note that a dedicated flash such as an EX Speedlite can't be used at shutter speeds faster than X-sync (without high speed sync), if it's on the hotshoe or connected via Off Camera Shoe Cord. The camera will detect its presence and slow down the shutter speed automatically.

To surpass the camera's X-sync speed as I did in these tests, you either need a non-dedicated flash, a PC cord or radio trigger system.


"If you're not having fun, your pictures will reflect that." - Joe McNally
Chicago area POTN events (external link)
Flash Photography 101 | The EOS Flash Bible  (external link)| Techniques for Better On-Camera Flash (external link) | How to Use Flash Outdoors| Excel-based DOF Calculator (external link)

  
  LOG IN TO REPLY
Curtis ­ N
THREAD ­ STARTER
Master Flasher
Avatar
19,129 posts
Likes: 11
Joined Apr 2005
Location: Northern Illinois, US
     
Jan 06, 2008 11:31 |  #51

tkoutdoor wrote in post #4641597 (external link)
Nice. 1/500th is still yielding about an 8x10 crop if the camera is oriented to account for the cropping and 1/640th is still yielding about 1/2 a frames worth of usable real estate to the one who could make use of it.

Not really.

Remember that if you have the camera in vertical orientation, the black area will be on the right side of the image, making it narrower. To crop for an 8x10 portrait, you would lose some of the top and bottom but need all of the width.


"If you're not having fun, your pictures will reflect that." - Joe McNally
Chicago area POTN events (external link)
Flash Photography 101 | The EOS Flash Bible  (external link)| Techniques for Better On-Camera Flash (external link) | How to Use Flash Outdoors| Excel-based DOF Calculator (external link)

  
  LOG IN TO REPLY
MDJAK
Cream of the Crop
Avatar
24,745 posts
Gallery: 7 photos
Likes: 201
Joined Nov 2004
Location: New York
     
Jan 06, 2008 11:34 |  #52

PacAce wrote in post #4626188 (external link)
No surprise there, Curtis, since the optical slave is working at the speed of light and there's not much to the circuitry--just a photo-sensitive transistor and an SCR semiconductor switch or equivalent, both also working at the speed of light. :)

On the other hand, a digital triggering circuit needs to convert the "fire" signal into digital code which is transmitted in series by the Tx and then received by the Rx, decoded and then converted to a signal that triggers the triggering circuit. That serial conversion before transmission and then after reception is what's slowing the RF triggering devices. Actually, the same applies to the ETTL IR signals, too. :)

I tread with great trepidation into any matters of technical nature, but isn't the speed of light only as fast as it is when measured in a vacuum?

me




  
  LOG IN TO REPLY
PacAce
Cream of the Crop
Avatar
26,899 posts
Likes: 39
Joined Feb 2003
Location: Keystone State, USA
     
Jan 06, 2008 11:39 |  #53

Curtis N wrote in post #4642378 (external link)
I don't know what you mean by "off-shoe".

If you're referring to the Canon Off Camera Shoe Cord, it should give results identical to a PC cord or mounting the flash right on the hotshoe.

Note that a dedicated flash such as an EX Speedlite can't be used at shutter speeds faster than X-sync (without high speed sync), if it's on the hotshoe or connected via Off Camera Shoe Cord. The camera will detect its presence and slow down the shutter speed automatically.

To surpass the camera's X-sync speed as I did in these tests, you either need a non-dedicated flash, a PC cord or radio trigger system.

Curtis, I think he wants to see a side-by-side comparison of the optical slave and the flash connected directly to the camera to see how much of a difference, if any, there will be. The first post has the optical slave compared with the SkyPort.


...Leo

  
  LOG IN TO REPLY
PacAce
Cream of the Crop
Avatar
26,899 posts
Likes: 39
Joined Feb 2003
Location: Keystone State, USA
     
Jan 06, 2008 11:41 |  #54

MDJAK wrote in post #4642417 (external link)
I tread with great trepidation into any matters of technical nature, but isn't the speed of light only as fast as it is when measured in a vacuum?

me

For all practical purposes, down here on Earth, the difference is so slight that you won't be able to tell the difference. :)


...Leo

  
  LOG IN TO REPLY
SolidxSnake
Goldmember
Avatar
1,656 posts
Likes: 2
Joined Nov 2007
     
Jan 06, 2008 11:44 |  #55

PacAce wrote in post #4642438 (external link)
Curtis, I think he wants to see a side-by-side comparison of the optical slave and the flash connected directly to the camera to see how much of a difference, if any, there will be. The first post has the optical slave compared with the SkyPort.



Right, that's what I was looking for. Instead of a directly connected flash compared to a RF trigger, I was asking for a comparison of a directly connected flash to an optical slave.

And I know it's not practical for a test, but couldn't you put the 580EX II into HSS mode and raise the shutter speed past the X-Sync?


Troubleshooting 101 (see also: LightRules,perryge):
1) RTFM.
2) Repeat Step 1.

Gear ~ DeviantART (external link) ~ My Heatware (external link)

  
  LOG IN TO REPLY
PacAce
Cream of the Crop
Avatar
26,899 posts
Likes: 39
Joined Feb 2003
Location: Keystone State, USA
     
Jan 06, 2008 11:52 |  #56

Curtis N wrote in post #4642378 (external link)
I don't know what you mean by "off-shoe".

If you're referring to the Canon Off Camera Shoe Cord, it should give results identical to a PC cord or mounting the flash right on the hotshoe.

Note that a dedicated flash such as an EX Speedlite can't be used at shutter speeds faster than X-sync (without high speed sync), if it's on the hotshoe or connected via Off Camera Shoe Cord. The camera will detect its presence and slow down the shutter speed automatically.

To surpass the camera's X-sync speed as I did in these tests, you either need a non-dedicated flash, a PC cord or radio trigger system.

Or, you can do what I did and that was to place a piece of tape over the 4 dedicated contacts. :)

SolidxSnake wrote in post #4642468 (external link)
Right, that's what I was looking for. Instead of a directly connected flash compared to a RF trigger, I was asking for a comparison of a directly connected flash to an optical slave.

And I know it's not practical for a test, but couldn't you put the 580EX II into HSS mode and raise the shutter speed past the X-Sync?

Shooting in HSS is not going to give you the apples-to-apples comparison you were asking for because in HSS mode, the flash will always since up with the shutter.


...Leo

  
  LOG IN TO REPLY
SolidxSnake
Goldmember
Avatar
1,656 posts
Likes: 2
Joined Nov 2007
     
Jan 06, 2008 12:03 |  #57

PacAce wrote in post #4642507 (external link)
Shooting in HSS is not going to give you the apples-to-apples comparison you were asking for because in HSS mode, the flash will always since up with the shutter.



I mentioned that ;)


Troubleshooting 101 (see also: LightRules,perryge):
1) RTFM.
2) Repeat Step 1.

Gear ~ DeviantART (external link) ~ My Heatware (external link)

  
  LOG IN TO REPLY
Curtis ­ N
THREAD ­ STARTER
Master Flasher
Avatar
19,129 posts
Likes: 11
Joined Apr 2005
Location: Northern Illinois, US
     
Jan 06, 2008 12:09 |  #58

SolidxSnake wrote in post #4642468 (external link)
Right, that's what I was looking for. Instead of a directly connected flash compared to a RF trigger, I was asking for a comparison of a directly connected flash to an optical slave.

Ok. Well I don't have time to set thing up again today, but I think you can figure this out.

The first post shows how fast the optical slave reacts to the master. Post #37 shows the speed of the PC cord vs. Skyport system. Logically if you combine what we've learned from the two, we can assume that the optical slave will react fast enough to not make a difference, and the shutter speeds attainable via PC cord will be equal to the left sides of the images in post 37 (assuming the same flash duration).

When you see the rest of the test shots in my thread on the Skyports, you realize that flash duration can make quite a difference in the practical maximum shutter speed.

And I know it's not practical for a test, but couldn't you put the 580EX II into HSS mode and raise the shutter speed past the X-Sync?

Sure. But HSS has its own set of limitations, and it really wasn't the point of this thread. ;)


"If you're not having fun, your pictures will reflect that." - Joe McNally
Chicago area POTN events (external link)
Flash Photography 101 | The EOS Flash Bible  (external link)| Techniques for Better On-Camera Flash (external link) | How to Use Flash Outdoors| Excel-based DOF Calculator (external link)

  
  LOG IN TO REPLY
PacAce
Cream of the Crop
Avatar
26,899 posts
Likes: 39
Joined Feb 2003
Location: Keystone State, USA
     
Jan 20, 2008 15:13 |  #59

bieber wrote in post #4626289 (external link)
The current front-page article on Strobist, I believe, is about a guy who found that the only way he could get remote Speedlights to keep up with his 1DII was to use optical slaves; ETTL and radio triggering didn't work fast enough...

PacAce wrote in post #4626605 (external link)
I couldn't get my flash mounted on the camera (1Dmk3) and set to power level 1/128 to pop on the 9th frame either at the highest burst rate. For some reason, the flash always stopped firing after the 8th frame. Tomorrow, I'm going to use an external power source and see if I can get the number of frames passed 8.

I did try with the PW units and at 10 fps, the flash fired every other frame although every once in a while, it did fire two in a row. I have a feeling that if I had two MultiMax units, I wouldn't have a problem firing the strobes at 10 fps because the MM can be set to 30 fps. Unfortunately, the PW Plus units can't go that fast. With the Plus units, the flash fired once every 2 or 3 frames.

I just wanted to post an update to the fps speed test (1Dmk3 + 580EX + PW) I started two weeks ago.

With the 1Dmk3 set to 10 fps and a PW Plus Tx mounted on the hot shoe, and a 580EX II connected to a PW Plus Rx unit via the PC sync terminal, I was able to shoot at 10 fps for 13 consecutive frames without missing a single frame at 1/16 power.

The 580EX II was attached to an external power pack. Without the external battery pack, the flash could only keep up at about 9 fps without missing a beat and only with a fresh set of batteries.

At 1/8 power, the flash couldn't keep up with the camera even at 8 fps.

When the 580EX II was attached to the PW unit via a hotshoe adapter, it could only manage 8 fps without missing a frame.


...Leo

  
  LOG IN TO REPLY
Double ­ Negative
*sniffles*
Avatar
10,533 posts
Likes: 11
Joined Mar 2006
Location: New York, USA
     
Jan 20, 2008 15:49 |  #60

^ Impressive!


La Vida Leica! (external link) LitPixel Galleries (external link) -- 1V-HS, 1D Mark IIn & 5D Mark IV w/BG-E20
15mm f/2.8, 14mm f/2.8L, 24mm f/1.4L II, 35mm f/1.4L, 50mm f/1.2L, 85mm f/1.2L II, 135mm f/2.0L
16-35mm f/2.8L, 24-70mm f/2.8L, 70-200mm f/2.8L IS, 100-400mm f/4.5-5.6L IS, Extender EF 1.4x II & 2x II

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

20,500 views & 0 likes for this thread
The amazing speed of optical slaves
FORUMS General Gear Talk Flash and Studio Lighting 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is Mareseatoats
288 guests, 227 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.