Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies. Read More.
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 20 May 2006 (Saturday) 14:29
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

optical trigger

 
ahmadof
Member
102 posts
Joined Jun 2003
     
May 20, 2006 14:29 |  #1

I just bought an optical trigger to use with a 420EZ flash. It will fire once properly if I fire a flash with my 550EX. After that, though,it does not fire again unless I turn the flash off or take the trigger off and put it back on. Am I missing something? I have tried all the setting I know (full manual) etc. Is this how they are supposed to function?




  
  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
26,853 posts
Likes: 20
Joined Feb 2003
Location: ABE, PA USA
     
May 20, 2006 17:00 |  #2

Nope, you're not missing anything. Evidently, the Canon Speedlite flashes have some current flowing through the hotshoe after it's been fired. Other flashes that work fine with optical triggering units do, too, but the current flowing through those is not as high as that of the Speedlites. The characteristic of an SCR (Silicon Controlled Rectifier, which is the component in the trigger unit that basically acts as an electronic switch turned on optically) is that once it is triggered, it will stay turned on for as long as the minimum holding current required to keep the SCR turned on is flowing through it. So, the net effect of the higher current flowing through the Speedlite hotshoe is that the SCR does not turn off. If it doesn't turn off, then you can't trigger it again to fire the flash until you disconnect and then reconnect the flash or turn off the flash and then turn it back on again.

I just spent an hour and half this afternoon with my Speedlite connected to my home made optical trigger with a digital multimeter connected across the sync wire and ground (to mearure voltage) and an analog VOM connected in series with the sync wire (to measure the current through the sync wire). That's how I came up with the above observation.


...Leo

  
  LOG IN TO REPLY
ahmadof
THREAD ­ STARTER
Member
102 posts
Joined Jun 2003
     
May 20, 2006 17:06 as a reply to  @ PacAce's post |  #3

wow, thanks. I guess all optical triggers won't work then. I was going to try one of the more costly ones (i have a$14 ebay one). Which is a shame as I think that was the only peice of the puzzle keeping me from going pro :)




  
  LOG IN TO REPLY
Curtis ­ N
Master Flasher
Avatar
19,129 posts
Likes: 4
Joined Apr 2005
Location: Northern Illinois, US
     
May 20, 2006 22:19 |  #4

ahmadof,
See if you can pickup an old flash unit at a camera shop, pawn shop or wherever. Better if you can get one with variable manual settings. They usually go pretty cheap and most will work fine with a slave trigger.


"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
RLRiley
Member
116 posts
Joined Oct 2005
Location: Santa Clarita, CA
     
May 21, 2006 03:32 |  #5

I had the exact same problem with my 420 and optical triggers, fortunately I have several old flashes that will work just fine with them. Still, I wish the 420 would work, but at least thanks to PacAce's description above, now we know why they won't work more than once. That was the part that always confused me, why they would fire one time correctly, but never again unless you turned it off and then back on.


"Knowledge, Sir, Should Be Free To All"
Harcourt Fenton Mudd--- I, Mudd

  
  LOG IN TO REPLY
akiwi
Cream of the Crop
Avatar
6,900 posts
Gallery: 3 photos
Likes: 44
Joined Jun 2005
Location: Munich, Germany
     
May 22, 2006 07:05 |  #6

Metz has an optical trigger that works.
I tried it out at my local camera store a few weeks ago and it worked perfectly. Other tests with Hama triggers didn't work.


Peter
www.PeterHansenPhoto.d​e (external link)
Gear:: Canon 7D & 350D :: EF 24-70 F2.8L :: EF-s 17-85:: 50mm 1.8 ::70-200 F4L ::100 F2.8 Macro:: Sigma 10-20 :: 580EX:: Elinchrom studio lights:: loads of other bibs & bobs.

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

3,053 views & 0 likes for this thread
optical trigger
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?
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 2.0forum software
version 2.0 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is HBGPhotos
736 guests, 461 members online
Simultaneous users record so far is 6430, that happened on Dec 03, 2017

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.