December 13, 2017, 07:51:08 PM

Author Topic: Canon A-1 and speedlites  (Read 5843 times)

CanonFanBoy

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Re: Canon A-1 and speedlites
« Reply #15 on: June 25, 2017, 11:39:38 PM »
Got a pocket meter out and did a quick, simple reverse engineering of the camera and flash contacts on my A1 and 199A. 

As expected the center contact triggers the flash when shorted to the rails holding the flash to the camera.  Also triggers when the center contact is shorted to the back left contact, but not the right contact.  The back contact right tells the camera a flash is mounted with a constant 4.3mv no matter the flash setting.  The back left contact communicates manual versus auto with 135mv for any of three auto settings and 6mv for the manual setting.  Couldn't do any more with my pocket meter.  It wasn't immediately obvious how the specific AUTO setting is communicated from the flash to the camera. 

Mounted my old 420EX on the A1 and the flash triggers as expected.  The flash was recognized (F in the display) from the right contact but the display blinks because it could not decode the aperture sent from the flash via the left contact - no surprise there. 

I taped over the left contact as in the photo and every thing works fine.   The camera recognizes that a flash is mounted in manual mode and triggers it correctly.  The camera display show 60 F 8.0 and M if the lens is not in A mode.  Works with my 90EX and 320EX as well.  Assume it will work similarly with larger Canon flashes, but they weren't handy.
 
Would need a scope for further analysis of the signals.  Just think how much fun it would be to reverse engineer the EOS AF protocols and signals.  Ain't engineering fun?

Thanks for all that. I'll have to try that with the ST-E3-RT because there may be a time when I want to use those in conjunction with the 600EX-RTs. Yesterday I got the same LED camera displays you got, but it would not trigger. I'll try taping. :)

I taped the left contact. I taped the right contact. I taped both the left and right contact.

I can get the camera to recognize there is a flash. It just won't trigger with an ST-E3-RT.

How many contacts total do your old speedlites have each? The ST-E3-RT has 5. It might be that there is another required to trigger and the A-1 just doesn't have the pin contacts to do the job. If that is the case the 600EX-RT is a no go.

Well, one more reason to get another Streaklight.  :)
5D Mark III, Canon A-1, Voigtlander Vito, Tamron SP 15-30 f/2.8 Di VC, 24-70 F/2.8L II, 70-200 f/2.8L IS II, 35 f/1.4L II, 135 f/2L, Helios 58 f/2 (x3), Canon FD 50 f/1.8, 600EX-RT (x7), Streaklight 360ws. Jumping ship to SoNikon any day now.

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Re: Canon A-1 and speedlites
« Reply #15 on: June 25, 2017, 11:39:38 PM »

dcm

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Re: Canon A-1 and speedlites
« Reply #16 on: June 25, 2017, 11:57:01 PM »
Got a pocket meter out and did a quick, simple reverse engineering of the camera and flash contacts on my A1 and 199A. 

As expected the center contact triggers the flash when shorted to the rails holding the flash to the camera.  Also triggers when the center contact is shorted to the back left contact, but not the right contact.  The back contact right tells the camera a flash is mounted with a constant 4.3mv no matter the flash setting.  The back left contact communicates manual versus auto with 135mv for any of three auto settings and 6mv for the manual setting.  Couldn't do any more with my pocket meter.  It wasn't immediately obvious how the specific AUTO setting is communicated from the flash to the camera. 

Mounted my old 420EX on the A1 and the flash triggers as expected.  The flash was recognized (F in the display) from the right contact but the display blinks because it could not decode the aperture sent from the flash via the left contact - no surprise there. 

I taped over the left contact as in the photo and every thing works fine.   The camera recognizes that a flash is mounted in manual mode and triggers it correctly.  The camera display show 60 F 8.0 and M if the lens is not in A mode.  Works with my 90EX and 320EX as well.  Assume it will work similarly with larger Canon flashes, but they weren't handy.
 
Would need a scope for further analysis of the signals.  Just think how much fun it would be to reverse engineer the EOS AF protocols and signals.  Ain't engineering fun?

Thanks for all that. I'll have to try that with the ST-E3-RT because there may be a time when I want to use those in conjunction with the 600EX-RTs. Yesterday I got the same LED camera displays you got, but it would not trigger. I'll try taping. :)

I taped the left contact. I taped the right contact. I taped both the left and right contact.

I can get the camera to recognize there is a flash. It just won't trigger with an ST-E3-RT.

How many contacts total do your old speedlites have each? The ST-E3-RT has 5. It might be that there is another required to trigger and the A-1 just doesn't have the pin contacts to do the job. If that is the case the 600EX-RT is a no go.

Well, one more reason to get another Streaklight.  :)

The 199A has the same configuration as the A-1.  Three contacts.  The A series of flashes were designed for the A bodies.

The three EX series I tested all have 5 pins and work fine on the A-1. I'm guessing the 600EX's would also work. Don't have one to try.
Shooting with Canon since 1982 - 1DX2, M5, some lenses

Sporgon

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Re: Canon A-1 and speedlites
« Reply #17 on: June 26, 2017, 02:48:19 AM »
Hi Sporgon.
I was thinking this as I read through the responses so I guess we are both on the right track. I do recall reading somewhere (here maybe) that film ISO values don't directly correlate to digital ISO values so might that be a stumbling block to our theory?

Cheers, Graham.

Use your digital camera to get the exposure and balance right !

Correct, but it's not a stumbling block, especially if shooting negative.

Just check out the actual ISO of your camera on dxo. Then work to that. For instance 100 ISO on the 5DIV is 64, the 5DII is 74. These are two I just know from memory. This difference would certainly effect transparency film results.

These differences are real because it you use an accurate hand held meter and set the ISO to the same as your camera, say a 5DII, and then input the aperture and shutter from your meter you will under expose. On the original 5D who's ISO 100 is about 97, you won't.
« Last Edit: June 26, 2017, 02:53:58 AM by Sporgon »

old-pr-pix

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Re: Canon A-1 and speedlites
« Reply #18 on: June 26, 2017, 10:17:27 AM »
Got a pocket meter out and did a quick, simple reverse engineering of the camera and flash contacts on my A1 and 199A. 

As expected the center contact triggers the flash when shorted to the rails holding the flash to the camera.  Also triggers when the center contact is shorted to the back left contact, but not the right contact.  The back contact right tells the camera a flash is mounted with a constant 4.3mv no matter the flash setting.  The back left contact communicates manual versus auto with 135mv for any of three auto settings and 6mv for the manual setting.  Couldn't do any more with my pocket meter.  It wasn't immediately obvious how the specific AUTO setting is communicated from the flash to the camera. 
Interesting observations... I always suspected that the flash command to the body to set the aperture value was via a current loop.  If so, then the flash would need to be mounted for the effect to be measurable.  199-A has 3 selected values of aperture, the 188-A has only two.  The 199-A also can automatically force 1/60 sec. shutter or has a switch to allow slow-sync where the camera body selects shutter speed.  The 199-A also has an indicator on the flash if there was sufficient flash power - I don't recall if that is communicated to the body for viewfinder display. 
Two systems:  Canon & Olympus

Valvebounce

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Re: Canon A-1 and speedlites
« Reply #19 on: June 26, 2017, 07:01:37 PM »
Hi CanonFanBoy.
I still think that the reason the ST-E3-RT won't fire is because it is expecting detailed communication from the camera, don't forget that newer cameras can control the flashes from the menu.
The flashes still fire because, well a flash is still a flash! To prove a point I just triggered my YN-600EX-RT with a key to short the centre pin to the foot (carefully) it said it didn't recognise the camera model but "ok I'll flash"!
I'm curious about this so I just got my 2 YN-600EX-RT's and YN-E3-RT out and tried triggering them with the key! A flash set as a master will fire, but not trigger a slave unit, the YN-E3-RT just played dumb, as in nothing happened!

Cheers, Graham.

Thanks for all that. I'll have to try that with the ST-E3-RT because there may be a time when I want to use those in conjunction with the 600EX-RTs. Yesterday I got the same LED camera displays you got, but it would not trigger. I'll try taping. :)

I taped the left contact. I taped the right contact. I taped both the left and right contact.

I can get the camera to recognize there is a flash. It just won't trigger with an ST-E3-RT.

How many contacts total do your old speedlites have each? The ST-E3-RT has 5. It might be that there is another required to trigger and the A-1 just doesn't have the pin contacts to do the job. If that is the case the 600EX-RT is a no go.

Well, one more reason to get another Streaklight.  :)
7DII+Grip, 1DsIII, 7D+Grip, 40D+Grip, EF 24-105 f4L EF-S 17-85, EF-S 10-22, EF 70-200 f2.8 L IS II, EF 1.4xIII, 2xIII, EF 100-400 f/4.5-5.6l IS II, Σ17-70 f2.8-4 C, EF 50mm f1.8, YN600EX-RT, YN-E3-RT, Filters, Remotes, Macro tubes, Tripods, heads etc!

1DsIII, 20D, 24-105, 17-85, Nifty 50 pre owned

CanonFanBoy

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Re: Canon A-1 and speedlites
« Reply #20 on: June 26, 2017, 07:47:14 PM »
Hi CanonFanBoy.
I still think that the reason the ST-E3-RT won't fire is because it is expecting detailed communication from the camera, don't forget that newer cameras can control the flashes from the menu.
The flashes still fire because, well a flash is still a flash! To prove a point I just triggered my YN-600EX-RT with a key to short the centre pin to the foot (carefully) it said it didn't recognise the camera model but "ok I'll flash"!
I'm curious about this so I just got my 2 YN-600EX-RT's and YN-E3-RT out and tried triggering them with the key! A flash set as a master will fire, but not trigger a slave unit, the YN-E3-RT just played dumb, as in nothing happened!

Cheers, Graham.

You must be right. I can live without triggering the 600s. I am thrilled I can use the Streaklight. :)
5D Mark III, Canon A-1, Voigtlander Vito, Tamron SP 15-30 f/2.8 Di VC, 24-70 F/2.8L II, 70-200 f/2.8L IS II, 35 f/1.4L II, 135 f/2L, Helios 58 f/2 (x3), Canon FD 50 f/1.8, 600EX-RT (x7), Streaklight 360ws. Jumping ship to SoNikon any day now.

Valvebounce

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Re: Canon A-1 and speedlites
« Reply #21 on: June 26, 2017, 08:18:10 PM »
Hi CanonFanBoy.
Not sure about I 'must be right', but I might be right, but I could be wrong, ??? I'm only guessing here, :o (with a little bit of very crude experimentation).  ;D

Cheers, Graham.

Hi CanonFanBoy.
I still think that the reason the ST-E3-RT won't fire is because it is expecting detailed communication from the camera, don't forget that newer cameras can control the flashes from the menu.
The flashes still fire because, well a flash is still a flash! To prove a point I just triggered my YN-600EX-RT with a key to short the centre pin to the foot (carefully) it said it didn't recognise the camera model but "ok I'll flash"!
I'm curious about this so I just got my 2 YN-600EX-RT's and YN-E3-RT out and tried triggering them with the key! A flash set as a master will fire, but not trigger a slave unit, the YN-E3-RT just played dumb, as in nothing happened!

Cheers, Graham.

You must be right. I can live without triggering the 600s. I am thrilled I can use the Streaklight. :)
7DII+Grip, 1DsIII, 7D+Grip, 40D+Grip, EF 24-105 f4L EF-S 17-85, EF-S 10-22, EF 70-200 f2.8 L IS II, EF 1.4xIII, 2xIII, EF 100-400 f/4.5-5.6l IS II, Σ17-70 f2.8-4 C, EF 50mm f1.8, YN600EX-RT, YN-E3-RT, Filters, Remotes, Macro tubes, Tripods, heads etc!

1DsIII, 20D, 24-105, 17-85, Nifty 50 pre owned

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Re: Canon A-1 and speedlites
« Reply #21 on: June 26, 2017, 08:18:10 PM »