SF-40 Pre-flash?

[mikelevitt]

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Hey,

I'm considering an SF-40 for my M10.  Has anybody used this combo in TTL and if you have, is there a slow, annoying, bright pre-flash that makes everybody blink for the main flash, like the SF-24D does?  Thanks for your impressions..

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[david strachan]

TTL always uses preflash.  The camera has to calculate how much extra light to add from the flash compared to the ambient light. Unfortunately it's not always good for portraits (blinking), and animal close-ups (fly away).

Sometimes it's better to do manual flash, and know your settings.

...

[mikelevitt]

13 hours ago, david strachan said:

TTL always uses preflash.  The camera has to calculate how much extra light to add from the flash compared to the ambient light. Unfortunately it's not always good for portraits (blinking), and animal close-ups (fly away).

Sometimes it's better to do manual flash, and know your settings.

...

Thanks for the opinion on TTL and photography.   

The reason for the pre-flash is because the surface of a digital sensor is a poor surface to calculate exposure from.  In the film days, TTL actually measured the reflection of the actual flash on the actual film, so no pre-flash was necessary.  When digital was introduced, they needed to come up with a way to meter flash since the sensor did not work as a "gray card" (being too reflective and inconsistent) like film did,  so they came up with the idea of a pre-flash - which lights up the shutter curtain, is measured, and provides the basis for the actual flash which doesn't happen until the curtain is open.

If you've used a professional system like Canon or Nikon, there's no problem with the pre-flash as it occurs just before the actual flash, and is imperceptible.  But with my M-10 and SF-24D, when  used on TTL there is a delay of approximately 1/4 second between the pre-flash and the actual flash.  The pre-flash is also really bright, very noticeable and causes people to blink.  In other words, worthless.  I use the SF-24D in auto mode, which of course works pretty well and has no pre-flash.  Since the SF-40 does not have an auto sensor, that is not an option.

So to restate the original question, I would like to know if anybody has used the SF-40 on the M10, and if you have, if the pre-flash is slow and obvious, or fast and imperceptible?  If you haven't used the combo, I don't need to hear your advice on how to use a flash, or what you would use a flash for.  Just actual information from somebody who has actually used the combo.

Thank you.

[Luke_Miller]

One of the challenges in evaluating the interval between pre-flash and main flash with DSLRs is the main flash is never visible in the viewfinder due to the mirror being up and blocking the view of the subject.  With the Leica M that interval is clearly visible since both flashes are seen in the viewfinder.  I can't tell if that interval is different from that of my Nikons. 

I've used flash with all my M bodies (M8.2, M9, MM, M240, M246).  The flashes used are the SF-24D, SF-58, and SF40.  Since I don't have an M10 I can't answer your question.  The M10 has (presumably) the fastest M processor, so it is possible the interval will be shorter than previous models, since in-camera processing of the pre-flash data determines that interval.

I find Leica TTL flash exposure to be primitive when compared to that of  Canon//Nikon.  With a light source in the scene or a bright background it will often massively underexpose, sometimes to the point of refusing to fire the flash.  I pretty much always use bounced flash and that tends to amplify the issue.  The flash mode that almost always works with my Ms is Auto (auto-thyrister), which is a mode that pre-dates film TTL. No current Leica dedicated flashes support it, but my SF-24D and SF-58 do.  As do many of my Nikon flashes which are perfectly happy in a Leica M flash shoe.

I like the SF-40 and have used flash on my Ms enough to pretty much know when Leica TTL will work and when I need to go to manual.  If I am shooting an event where I need to work quickly I will use Auto mode with my SF-24D, SF-58, or one of my Nikon flashes.

But maybe Leica has improved flash TTL exposure control in the M10 and all of the above is moot.

Edited November 3, 2019 by Luke_Miller
typos

[KFo]

Having both the SF-24D and the SF-40 with an M10-P using TTL mode:

1. I too was surprised by the time gap on the SF-24D between pre-flash and flash.  As you say, it is noticeable.  Easily noticeable.
2. The SF-40 pre-flash/flash time gap is very small. Almost imperceptible.   That time gap is 1/4-1/3 the length of time used by the SF-24D.

I don’t think this should be a huge surprise.  As time goes by, controls improve in speed. The SF-40 should be faster than the older SF-24D.

If you’ve got someplace to receive a video, I can send you a comparison I did to illustrate the difference in time.

Regards,

Kevin 

Edited November 3, 2019 by KFo

[Luke_Miller]

On 11/2/2019 at 6:23 PM, mikelevitt said:

.... is there a slow, annoying, bright pre-flash that makes everybody blink for the main flash ...

If the goal is to eliminate the blinks from the TTL pre-flash - I am unaware of any camera/flash combination that is free of the issue.  The human blink reflex is just too fast.  What works for me is to bounce the flash, which not only provides softer light/shadows, but generally eliminates the blinkies.  The bounced pre-flash is apparently not strong enough to trigger the blink reflex in most subjects. 

With Leica, if I can't bounce I would go to Auto/Manual, or chimp until I got the shot without the blinks.  That can be a challenge with larger groups.

It is easy with Nikon by using the FV Lock feature.  That does the pre-flash and sets the flash exposure, but does not trigger the main flash or trip the shutter.  Then subsequent flash exposures have no pre-flash until FV Lock is disabled.

[mikelevitt]

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On 11/3/2019 at 12:09 PM, Luke_Miller said:

One of the challenges in evaluating the interval between pre-flash and main flash with DSLRs is the main flash is never visible in the viewfinder due to the mirror being up and blocking the view of the subject.  With the Leica M that interval is clearly visible since both flashes are seen in the viewfinder.  I can't tell if that interval is different from that of my Nikons. 

I've used flash with all my M bodies (M8.2, M9, MM, M240, M246).  The flashes used are the SF-24D, SF-58, and SF40.  Since I don't have an M10 I can't answer your question.  The M10 has (presumably) the fastest M processor, so it is possible the interval will be shorter than previous models, since in-camera processing of the pre-flash data determines that interval.

I find Leica TTL flash exposure to be primitive when compared to that of  Canon//Nikon.  With a light source in the scene or a bright background it will often massively underexpose, sometimes to the point of refusing to fire the flash.  I pretty much always use bounced flash and that tends to amplify the issue.  The flash mode that almost always works with my Ms is Auto (auto-thyrister), which is a mode that pre-dates film TTL. No current Leica dedicated flashes support it, but my SF-24D and SF-58 do.  As do many of my Nikon flashes which are perfectly happy in a Leica M flash shoe.

I like the SF-40 and have used flash on my Ms enough to pretty much know when Leica TTL will work and when I need to go to manual.  If I am shooting an event where I need to work quickly I will use Auto mode with my SF-24D, SF-58, or one of my Nikon flashes.

But maybe Leica has improved flash TTL exposure control in the M10 and all of the above is moot.

Luke, thanks for the first hand account.  I shoot my canons with both eyes open, and still can't see a pre-flash.  And I agree with you on the auto flash, that's what I am doing now with the SF-24d, or whatever I happen to throw on the Leica - they all work on auto.  Thanks!!

[mikelevitt]

On 11/3/2019 at 3:17 PM, KFo said:

Having both the SF-24D and the SF-40 with an M10-P using TTL mode:

1. I too was surprised by the time gap on the SF-24D between pre-flash and flash.  As you say, it is noticeable.  Easily noticeable.
2. The SF-40 pre-flash/flash time gap is very small. Almost imperceptible.   That time gap is 1/4-1/3 the length of time used by the SF-24D.

I don’t think this should be a huge surprise.  As time goes by, controls improve in speed. The SF-40 should be faster than the older SF-24D.

If you’ve got someplace to receive a video, I can send you a comparison I did to illustrate the difference in time.

Regards,

Kevin 

Kevin, thank you!!!!  This is exactly what I was hoping to find out.  I'll give it a try.

[mikelevitt]

20 hours ago, Luke_Miller said:

If the goal is to eliminate the blinks from the TTL pre-flash - I am unaware of any camera/flash combination that is free of the issue.  The human blink reflex is just too fast.  What works for me is to bounce the flash, which not only provides softer light/shadows, but generally eliminates the blinkies.  The bounced pre-flash is apparently not strong enough to trigger the blink reflex in most subjects. 

With Leica, if I can't bounce I would go to Auto/Manual, or chimp until I got the shot without the blinks.  That can be a challenge with larger groups.

It is easy with Nikon by using the FV Lock feature.  That does the pre-flash and sets the flash exposure, but does not trigger the main flash or trip the shutter.  Then subsequent flash exposures have no pre-flash until FV Lock is disabled.

I would argue that Canon works just fine.  I can go to an event at night, shoot hundreds of shots, and get just a handful of blinks.  I can't see the pre-flash...  I'm guessing that it's very dim, and very close to the main flash.