M9 and Leica SF 20

[fotografiejc]

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Does anyone know if it is possible to use the SF 20 flash on the M9. If so does it work with TTL?

[250swb]

You need to set it to 'Auto', it won't do TTL. It seems to under expose by about two stops (well mine does, but it can easily be compensated for), but otherwise it works OK.

 

Steve

[kipdent]

I bought an SF 20 for my M6TTL and the few times I use flash it has worked very well. What I want to know is, what is technically different about the SF 24 that allows it to be used in TTL on the M9 but not the SF 20? And conversely, can the SF 24 be used in TTL on the M6TTL camera? If so, it's a head scratcher...

[eritho]

Can anybody explain why the SF-20 in "auto" mode underexpose 2 stops on the M9 but not on the M6

[lars_bergquist]

I bought an SF 20 for my M6TTL and the few times I use flash it has worked very well. What I want to know is, what is technically different about the SF 24 that allows it to be used in TTL on the M9 but not the SF 20? And conversely, can the SF 24 be used in TTL on the M6TTL camera? If so, it's a head scratcher...

 

TTL on a film camera is control on the fly. With the M8/M9 digital cameras, the flash executes a pre-exposure trial flash to set the following exposure flash.

 

The reason is that TTL on a digital camera must bounce the light from the shutter, not from the sensor front which, being highly polished, not matte, would lead to exposure errors. Hence the first 'trial flash'.

 

The old man from the Flash Powder Age

[Brian Bower]

Eritho. Just tried an SF20 on my M9. It works fine in Auto (but NOT TTL) . With the SF20 you need to remember to set the lens stop and the ISO speed that you are using.

 

By the way,in Auto, the SF24 does pick up the ISO setting from the camera but not the lens stop of course. The SF24 can also be set in 1 stop increments in AUTO but the SF 20 can only be set in 2 stop increments.

 

Hope this helps.

 

Brian Bower

[jaapv]

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The SF24D works fine on the M9/8 if set to GNC,The mechanism of the preflash is explained in an erlier post. The camera will set the shutterspeed and it will work at all apertures ( within the working range of course). The SF20D will only work on auto, then you must set the aperture manually. It will switch to flash shutterspeed, afaik.

[eritho]

Eritho. Just tried an SF20 on my M9. It works fine in Auto (but NOT TTL) . With the SF20 you need to remember to set the lens stop and the ISO speed that you are using.

 

By the way,in Auto, the SF24 does pick up the ISO setting from the camera but not the lens stop of course. The SF24 can also be set in 1 stop increments in AUTO but the SF 20 can only be set in 2 stop increments.

 

Hope this helps.

 

Brian Bower

 

As far as I remember (I use flash very seldom) The SF20 will pick up the ISO setting from the M9.

 

But what really bothers me is the question I have asked several times in this forum:

Why the SF-20 in "auto" mode underexpose 2 stops on the M9 but not on the M6

[Brian Bower]

The SF20 does automatically set the shutter speed in accordance with what you have set in the 'Auto slow synch' item in MENU. i.e. 'Off', 'Lens dependent' 'Down to 1/8s' etc.

 

Brian Bower

[Brian Bower]

Erik,

 

I have just rechecked. You are quite correct the gun does adjust the ISO setting. I think that I forgot to partially press the shutter release to get the camera to transmit the changed speed to the SF20!

 

I do not understand why there should be such a big difference between the M6 and the M9. The camera is not involved with the exposure calculated by the flashgun sensor.

 

I have just tried a few more shots with the M9 and SF 20 with different subjects, at different distances and ISO speeds and they are all OK. In some cases it could be argued that ideally maybe they are a half or quarter stop underexposed but they are comfortably inside the histogram. A lot depends on the subject and personal preferences and I do remember that in my Kodachrome 25 days I would often do a second shot at + half a stop when this was possible.

 

Take care

 

Brian

[eritho]

Erik,

 

I do not understand why there should be such a big difference between the M6 and the M9. The camera is not involved with the exposure calculated by the flashgun sensor.

 

I have just tried a few more shots with the M9 and SF 20 with different subjects, at different distances and ISO speeds and they are all OK.

 

Brian

 

Are you sure?

You are the first I have heard not stating the SF20 underexpose with approx 2 steps when used in auto-mode on the M9.

Are you sure the camera is not involved?

I don't understand either. That is why I have asked in this forum numerous times. Untill now I have had no answer.

So: Why is the SF-20 in "auto" mode underexposing 2 stops on the M9 but not on the M6

[bocaburger]

If anything I'd think an SF20 might overexpose in Auto mode on an M8 or M9. My experience is the ISO values of the M8 are conservative compared to the film standard most flashguns were programmed for. Eg ISO 640 on the M8 is more like ISO 800 in film, so the camera's sensitivity is really 800 while the flash "thinks" it's exposing for 640 because that's what the camera is "telling" it. I use my SF24D and Metz 54MZ3 (with the older SCA3502-M3 module) in AUTO mode on the M8 and get more consistently good exposure than my SF24D in GNC-TTL mode. I've found the same thing with Canon, I get better exposure consistently with the Metz 54 in AUTO vs the dedicated Canon ETTL.

[eritho]

If anything I'd think an SF20 might overexpose in Auto mode on an M8 or M9. .

 

Its underexposing two steps.

[bocaburger]

I understand. I just don't know why. When I first got my M8 and before I found a used SF24D I still had an SF20 and mine did not underexpose on the M8 when set in the AUTO mode. (Silly question but you did make sure it isn't set to TTL, right?)

[250swb]

Its underexposing two steps.

 

And its not just the SF20, my Olympus FL36 and FL50 flashes both underexpose by two stops (approx) when set to auto and mounted on the M9 (they also pick up the same info from the camera as the SF20).

 

Steve

[eritho]

I (Silly question but you did make sure it isn't set to TTL, right?)

 

Sure!!!

[eritho]

And its not just the SF20, my Olympus FL36 and FL50 flashes both underexpose by two stops (approx) when set to auto and mounted on the M9 (they also pick up the same info from the camera as the SF20).

 

Steve

 

Now, does this mean we can be sure the flash is somehow controlled from the M9?

The ISO setting of the flash is controlled from the M9 and it looks to be the correct value shown on the flash dispaly.

If I dial in two stops exposure compensation on the camera it works al right, but what is really happening when you dial in exposure compensation.

Aperture is set on lens and is not changed.

Shutter speed is set and is not changed.

ISO is set and is not changed.

To change the exposure you must change either aperture, shutter speed or ISO-settings.

I don't understand

[kipdent]

With the M8/M9 digital cameras, the flash executes a pre-exposure trial flash to set the following exposure flash.

 

The reason is that TTL on a digital camera must bounce the light from the shutter, not from the sensor front which, being highly polished, not matte, would lead to exposure errors. Hence the first 'trial flash'.

 

Thanks, Lars! I now understand the only difference between the SF 20 and SF 24 is the latter's ability to pre-flash. I guess it's time to sell my SF 20!