Leica IIf flash

laptoprob

laptoprob

back to basics
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Hi, has anyone ever tested the behaviour of the flash delay with modern electronic flash? I understood from the Leica FAQ the numbers (red dial on mine) are the delay in milliseconds. Made to time the flash because different bulbs burn differently.
Electronic flashes are meant to be used without delay: setting '0'.
20 milliseconds is the max. delay: that is 20/1000 or 1/50 second, right? So if I take the 1/50 shutter speed, do I get second curtain sync? In other words, does the flash freeze the last moment in a 1/50 sec shutter time when used with electronic flash? That would be really interesting!

thanks, Rob.
 
I think I already found part of the answer. It is not a delay but an advance. To make sure a slow bulb really fires when the shutter is opened. An electronic flash works instantly: no advance needed.
If only I could convert the advance to a delay!

Any ideas?

cheers, Rob.
 
laptoprob said:
Hi, has anyone ever tested the behaviour of the flash delay with modern electronic flash? I understood from the Leica FAQ the numbers (red dial on mine) are the delay in milliseconds. Made to time the flash because different bulbs burn differently.
Electronic flashes are meant to be used without delay: setting '0'.
20 milliseconds is the max. delay: that is 20/1000 or 1/50 second, right? So if I take the 1/50 shutter speed, do I get second curtain sync? In other words, does the flash freeze the last moment in a 1/50 sec shutter time when used with electronic flash? That would be really interesting! thanks, Rob.
Click to expand...

Rob, the delay setting is one value for 1/25th and yet another at 1/50th. I'll have to consult my books when I get home but it should be "0" for one and "20" for the other but I'm not certain which is which. (I THINK it's 20 for 1/50th and 0 for 1/25th but I won't bet my life on it!) Your IIf is obviously a Red Dial model as the Black Dial has the older shutter speeds of 1/30, 1/40 etc.

An electronic flash must fire, of course, when the first curtain has fully opened and the second curtain has yet to enter the film aperture. Electronic flash has a rapid rise time to maximum value while bulbs have a slower rise time, a flat plateau during which the shutter will fully cross the film plane and, once the shutter has closed, a decay time.

If someone doesn't answer specifically by the time I'm home, I'll look it up.

Walker
 
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doubs43 said:
Thanks, X-Ray. Your source doesn't show a delay for 1-1/25th?

Walker
Click to expand...
you are welcome, it is xayraa33 by the way. x-ray is an other RFF member( it is a common mistake lol)
for a red dial at 1/25 sec , use nr. 0 on the syncro dial.
 
My 1955 edition of "Leica Manual and Data Book" by Morgan and Lester, page 167, says to use "0" for 1/25 and "20" for 1/50 with a Red Dial IIIf. For a Black Dial, it is limited to "2" for 1/30.
 
xayraa33 said:
you are welcome, it is xayraa33 by the way. x-ray is an other RFF member( it is a common mistake lol)
for a red dial at 1/25 sec , use nr. 0 on the syncro dial.
Click to expand...

Thanks for varifying what I thought was correct. I haven't used flash with my RD in awhile. Sorry for mistaking you for XRay.

Walker
 
I dont see how 1/50 with a 20 advance would work... unless the flash has the ability to stay bright for an entire time it takes the slit to travel to the end of the neg)

Anything over 1/25 (or 1/30) shutter speed is a travelling slit... so if a flash were to fire, it would expose just that part of the negative where the slit happened to be at that moment.

At 1/25 and below, an entire negative is exposed for a period of time, that is the moment the flash should fire (and thats why you have flash "advance" to make sure the bulb flash does not fire when the shutter is already closing).

correct me if I'm wrong, and my apologies if I misunderstood the discussion
 
Leitz upped the curtain running time on the red dial to 1/50 s , partly to get more accuracy at the highest speed, so it is a wider slit at 1/1000 than the old black dial type at that speed setting . So on a red dial at 1/50 sec. the 2nd curtain is not tripped until the 1st curtain has just finishs its running time in the 24mm x36mm frame. As to why 20 is chosen on the sync dial on the RD and not 0, at 1/50 sec, that req. a bit more research on my part.
 
grifon said:
Anything over 1/25 (or 1/30) shutter speed is a travelling slit... so if a flash were to fire, it would expose just that part of the negative where the slit happened to be at that moment.
Click to expand...

The increase in the top electronic flash shutter speed was made possible because with the introduction of the IIIf Red Dial model, Leitz reduced the weight of the shutter curtains. The lighter weight translated into a higher possible shutter speed with the film aperture still wide open. Pentax Spotmatics - also using a horizontal cloth shutter - syncs at 1/60th with electronic flash. The Copal Square metal focal-plane shutter running vertically permits X-sync at 1/125th of a second as does the Prakticas and other cameras using metal shutters.

The delay setting of 20 miliseconds on the Red Dial IIIf at 1/50th allows for the time it takes the first curtain to fully open.

Walker
 
xayraa33 said:
why is it 2 milliseconds for the black dial , at a curtain run time of 1/30 sec then?
Click to expand...

I honestly can't explain why the difference except that the black dial shutter is heavier and requires a different delay. It's possible that the delay times between the black scale and the red scale aren't the same for a given setting.

One possibility is that the lighter shutter requires no delay at 1/25th - a "0" setting - while the heavier shutter needs those 2 miliseconds at 1/30th for the curtain to begin it's travel from a full stop. But that's only a guess on my part.

Walker
 
the curtain material is the same, for RD and BD, the springs in the curtain rollers may be stronger or set to a higher tension, the curtain drum may be a bit lighter on the RD and it also uses ball bearings and the BD does not use ball bearings at the bottom axis of the curtain drum. Like I said , the higher curtain running speed was partly to get more accuracy on the high speed and as a bonus, less chance of ghosting with flash because of the higher sync speed on the RD. most horizontal focal plane shutters trip the switch to fire the electronic flash, by making the SW contacts as soon as the 1st curtain completes its travel across the film plane gate.
this is done regardless of what the 2nd curtain is set to, thats why one gets a half or quarter frame or less exposed if the sync speed is set higher than the curtain running time
maybe Leitz used the 2nd curtain to trip the flash sw contacts to get more control to fire flash bulbs a bit before to build up light and FP bulbs need a different firing time because they burn for the duration the traveling shutter curtain slit, and FP bulbs can be used at a higher shutter speed.
remember, in the early to mid 1950s most people used flash bulbs more than electronic flash, so a camera maker had to make the flash system flexable in their cameras.
 
xayraa33 said:
the curtain material is the same, for RD and BD, the springs in the curtain rollers may be stronger or set to a higher tension, the curtain drum may be a bit lighter on the RD and it also uses ball bearings and the BD does not use ball bearings at the bottom axis of the curtain drum. Like I said , the higher curtain running speed was partly to get more accuracy on the high speed and as a bonus, less chance of ghosting with flash because of the higher sync speed on the RD. most horizontal focal plane shutters trip the switch to fire the electronic flash, by making the SW contacts as soon as the 1st curtain completes its travel across the film plane gate.
this is done regardless of what the 2nd curtain is set to, thats why one gets a half or quarter frame or less exposed if the sync speed is set higher than the curtain running time
maybe Leitz used the 2nd curtain to trip the flash sw contacts to get more control to fire flash bulbs a bit before to build up light and FP bulbs need a different firing time because they burn for the duration the traveling shutter curtain slit, and FP bulbs can be used at a higher shutter speed.
remember, in the early to mid 1950s most people used flash bulbs more than electronic flash, so a camera maker had to make the flash system flexable in their cameras.
Click to expand...

This is what is said in "Leica - The First Sixty Years" by G. Rogliatti. Rogliatti, BTW, had full access to factory records and personnel who worked for Leitz so it's reasonable to believe that his information is accurate.

The ball bearing shutters began with military production of the model IIIc during WW2 so why the BD IIIf wouldn't have them is certainly curious. Not all IIIc's seem to have gotten ball bearings but when production started once again in 1946 they at least had provision for retrofitting the ball bearings. (Page 67)

The IIIf Black Dial was produced from 1950 and in 1952 a new type of shutter with lighter design was introduced and the IIIf Red Dial was born beginning with serial number 615,001. New shutter speeds of 1/25, 1/50 and 1/75 replaced 1/30, 1/40 and 1/60.

The Red Dial IIIf was simply an improvement on the existing camera. It was the policy of Leitz to continue making improvements of their products and while all of the benefits you state are likely true, the RDST IIIf and the IIIg improved the Leica camera even more.

If you go back to the 4th post of this thread you'll find that I gave a pretty good explanation of how a bulb works. I've burned many hundreds of flash bulbs and I understand their use quite well. FP bulbs weren't really necessary when M-sync bulbs and a Compur Rapid shutter on a Miniature Speed Graphic did just fine up to 1/500th and did it cheaper too.

Walker
 
delay or advance?

delay or advance?

doubs43 said:
The delay setting of 20 miliseconds on the Red Dial IIIf at 1/50th allows for the time it takes the first curtain to fully open.
Click to expand...

This is the confusing bit: Delay or advance?Nemeng Leica FAQ website states setting '0' advance is meant for electronic flash, regardless of sync speed. If 20ms advance with an electronic flash is used, the flash will be fired in the 1/50th second advance: before the first curtain opens.
Right?
Because of this mixup I was thinking of using the dial as a delay setting, bit this is not possible without tinkering. I don't know how the system works so I don't know if this tinkering is possible.
I don't have the extensive books, sadly.

Thank you al for your answers.

cheers, Rob.
 
laptoprob said:
This is the confusing bit: Delay or advance?Nemeng Leica FAQ website states setting '0' advance is meant for electronic flash, regardless of sync speed. cheers, Rob.
Click to expand...

Rob, perhaps your local library has the 15th edition of "The Leica Manual". A complete flash sync setting guide is on page 94. For the black dial IIIf Leica, electronic flash is synced at 1/30th with a delay setting of "2". For the IIIf Red Dial Leica the settings are "0" for 1/25th and "20" for 1/50th. This agrees with what has already been posted. Your shutter speed dial will tell you which is correct for your IIf. Let us know how it turns out.

Walker
 
Thanks again Walker, I just wiched I could understand this.
0ms flash advance at 1/25 means an electronic flash will fire directly at first full opening.
Setting 20, 20ms means a 1/50th second advance. This means the flash sync is triggered by the second curtain: otherwise the flash would be before full opening.
If this is correct, setting '0' at 1/50 second would mean no advance, thus second curtain sync! Flash at the end of the 1/50 exposure!

True?

thanks, Rob.
 
Here is where my cunfustion comes from:

This means there can be no 2nd. curtain sync. Too bad!

a report made at greenspun


Here's what happened:

I tried the white paper test...Interesting trick: it creates an intense visual afterimage and you can "see" exactly what's happening after the flash has fired!

1/25 at 0 setting...full white image through lens port. 1/50 at 20 setting...no white image. 1/50 at 0 setting only 2/3 white image. Different increments until about 10...then nothing.

Regardless of what the Leica charts indicate, on my camera (IIIf RD) the only electronic flash sync that works is 1/25 at 0 setting.

I can live with that. Thank you all for your help and suggestions.

-- Todd Frederick (fredrick@hotcity.com), August 22, 2000.greenspun.com
 
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