High Speed Sync
Old 12-30-2017   #1
noeyedear
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High Speed Sync

I've been reading about high speed flash sync, I thought you needed a camera dedicated to system as I believed it was computer controlled. But reading about it I get the impression its just a strobe setting. So does it work with a film based M?
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Old 12-30-2017   #2
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No. The film M has a flash sync speed of 1/50th. High speed sync is exactly what it sounds like, a high speed sync. Especially useful for using full flash outdoors with a wide aperture.
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Old 12-30-2017   #3
noeyedear
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That was a my first thought, but reading how hss works I started wondering if it worked with all focal plane shutters.
It pulses the flash very quickly over a long period to cover the period the slit travels over the film.
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M7 is the only Leica film camera that can do HSS flash
Old 12-30-2017   #4
Robert Lai
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M7 is the only Leica film camera that can do HSS flash

High speed synch works only with the M7 in film land.

I use it at times for fill flash in outdoor settings, when I want to open up the lens for shallower depth of field. Then the shutter speeds have to go up to compensate.

You need the Metz SCA 3502 adapter, and a suitable Metz flash.
I use the Metz 54 MZ-4.

You need to put the M7 camera's shutter speed into 1/250, 1/500, or 1/1000 to activate this mode. On the flash, you need to push the mode button until "M" for "Manual" mode is showing and flashing. Then turn the setting dial UP until "HSS" shows up underneath the big "M". To turn this off, do the same thing and turn the setting dial DOWN while the "M" is flashing.

This procedure is not entirely intuitive, and it doesn't help that you need to read page 115 of the Leica M7 manual (English) AND
page 109 of the Metz 54 MZ-4 manual (English portion) in order to figure this out.

The flash and the electronic shutter of the M7 communicate so that the pulses will overlap exactly, to not cause banding during the high speed flash exposure.

There are things you need to realize:

A) Only those 3 shutter speeds will work (1/250 and faster).
1/125 and 1/60 are mechanical speeds. There is no electronic communication with the mechanical speeds, and the flash will NOT fire if set in HSS mode. It serves you right for not studying the instruction manuals carefully.

1/50 (the lightning symbol) and slower shutter speeds will fire the flash, as they are electronically regulated shutter speeds. But, then you really just have a very limited power manual flash unit.

B) This mode is MANUAL. That is - no TTL flash control, no automatic flash control. You use an electronic version of the "guide number" system. Before you wail and gnash your teeth at the unfairness of the world, Metz gives you an LCD panel at the back. You set your lens focal length (adjusts the flash's angle of coverage), and the aperture that you're shooting at. The panel will show you the correct distance from flash to subject that you need to be at to have the correct exposure.

For ISO 100, 50mm lens, f/1.4, the maximum power distances are:
1/250 shutter speed ---5.7 meters
1/500 shutter speed ---4.5 m
1/1000 ---3.2m

The faster the shutter speed, the more pulses the flash has to put in to give even coverage of the narrower shutter slit as it travels across the film gate. Hence lower overall illumination as shutter speed increases. Remember, in a focal plane shutter, higher speeds are achieved by narrowing the slit distance between the curtains. Narrower slits (faster shutter speeds) require more flashes to cover the 36mm film gate distance. Since the flash doesn't have an infinite capacitor rating, each of the pulses has to have less power in order to put more pulses in.
If you are changing shutter speeds, press the shutter button halfway down to communicate the new shutter speed to the flash.

If you don't want so much power, you can decrease the power level of the flash output in 1/3 stop increments to 1/256 of the original power.
Setting dial cursor to the "1/1" mark on the right bottom of the screen, select, and then dial down. The distance for correct exposure will automatically update as you do this, to shorter and shorter distances.

C) If you want to have a preview of how your subject will look with the flash, hit the "Select" button on the flash, use the setting disk until the "Modeling light" function appears (looks like 3 lightning rods in a cluster). Set that. When you push the test flash button (single lightning rod symbol, with a green flashing LED underneath), the flash will pulse for 5 seconds. You can then see where the shadows and highlights will fall.

D) How do you know when you have achieved the correct subject distance for the right exposure?

Well, the Leica M7 has this miraculous thing in it called the rangefinder. It lets you measure distances accurately and precisely.

Based on section (B) above: say you are using a 50mm lens, set to f/1.4, shutter speed 1/1000 with ISO 100 film. You need to be about 10.5 feet away from the subject (3.2m). I would just set my focus ring to 10 feet. Then walk back and forth until your subject is in focus in the rangefinder patch, and FIRE!

E) You do have to balance the exposure with that of daylight. So, use the built in meter of the M7, find out the exposure for the highlights. Now you can decide either to match the intensity with your flash (1:1) ratio, or make your fill flash 1/2 as intense (or whatever highlight : shadow ratio you choose). For example, say you need to be at 11 feet for the flash to match daylight intensity. But you want a 1:2 lighting ratio. If you set your focus ring to 16 feet, and walk back, then your flash intensity is now 1 stop less intense on the subject. Then your highlight (daylight exposure) to shadow (flash exposure) ratio will be 1:2.

Yes, you can use your aperture ring to give you distances for light intensity control with flash!
Wow, what will they think of next??!!

Now that you know that the flash circuitry in the M7 is electronically controlled, let me give you this bonus caveat.

F) If you use the PC flash port, be aware that the circuit remains closed circuit after firing. There is no mechanical flash synch switch inside this camera (confirmed in conversation with Don Goldberg). Even this flash port is electronic in triggering. So, if you are a flash bulb user like I am, you need to unplug the flash cable after firing, in order to let the camera circuitry reset. Otherwise, the next flash bulb you put into the flash holder WILL ignite in your fingers, giving you painful burns. Luckily I was wary of this, and I was wearing winter gloves when I tried this, so only my glove was burnt.

G) M6TTL can't do High Speed Synch. Read the headline above - the M7 is the ONLY film Leica that can do HSS. The shutter on the M6TTL is mechanical, so it has no way of communicating the curtain position to the flash unit, to tell it to fire again, and again, and again as the shutter travels across.
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Old 12-30-2017   #5
noeyedear
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Thank you Robert, i was looking at Elincrom/ profoto, I couldn't see why they would not work with any focal plane camera in HSS but suspected it wouldn't.
Nice to know the M7 can utilise HSS.
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Old 12-30-2017   #6
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Quote:
Originally Posted by noeyedear View Post
... I couldn't see why they would not work with any focal plane camera in HSS ...
The primary reason is that a HSS flash mode can't work with X-sync. It needs its own special sync timing where the flash is triggered when the first curtain starts to open.

With X-sync, the flash it triggered when the first curtain finishes opening. At that time, the second curtain has already closed over part of the image if the shutter speed is set higher than the "maximum X-sync speed", which is 1/50th on classic M Leicas. No amount of pulsing the flash to increase its "burn" time can help when the shutter has already started closing over a portion of the image.
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Old 12-30-2017   #7
Robert Lai
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The M7 does give you the option of first curtain or rear curtain X-synch.
You can choose to have your flash fire immediately once the first curtain has cleared the film gate (first curtain synch).
The alternative is for the flash to wait until just before the second curtain starts its run in order to fire (second curtain synch).

In either case, there is a period of time when the entire frame of film is "open" to the lens, and the flash light bouncing off the subject can hit all of the film surface at once.

At speeds faster than 1/50 on Leica M cameras, there is no period of time when the entire film surface is uncovered by the curtains. The curtains travel at the same speed always. The faster exposure times are obtained by narrowing the distance between the two curtains. At 1/1000, the slit between the two curtains is only about 2-3 mm or so.

If you want to take flash exposures with a focal plane shutter beyond the X-synch speeds, you have two options:

1) flash bulbs
2) Electronic flash with camera / flash circuitry to allow HSS.

For flash bulbs, M class bulbs can be used. You need to refer to the Leica M camera manual to give you the exact settings and shutter speeds for the different type of bulbs.

FP (focal plane) bulbs such as the Press 26, GE #6 have a long burn time, and produce an even amount of illumination during the burning period. This allows the shutter slit to travel with an even amount of light illuminating the subject during the time that you're burning the image on film. With FP bulbs, you can fire up to 1/1000 second.

Guide numbers, especially for M class bulbs will vary with the shutter speed that you use, as you effectively cut off a portion of the bulb's light output that you're using for exposure. Guide numbers for different shutter speeds are on the box that the bulbs come in. The alternative for bulb fanatics such as myself is the Norwood Flashrite Meter. It's a little rangefinder which have curves for the flash output of different bulbs on its calculator dial. You match up the curve for your bulb with your shutter speed, sight the target, and voila, the dial will tell you the aperture you need to use. I suspect this was designed for leaf shutters, but it works accurately enough for focal plane shutters.

For HSS, as I mentioned above, the shutters uncover part of the film with the slit, and the flash fires to expose that section of film. The next section of film is then uncovered and the flash has to fire again. If you don't coordinate this perfectly, you could have sections where the film was not exposed to flash light at all, giving a Venetian blind vertical banding pattern on the film image. Or, if the sections overlapped, the overlap portion would be overexposed, giving rise to a different type of banding.
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Old 12-31-2017   #8
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Quote:
Originally Posted by Robert Lai View Post
...
For flash bulbs, M class bulbs can be used. You need to refer to the Leica M camera manual to give you the exact settings and shutter speeds for the different type of bulbs.

FP (focal plane) bulbs such as the Press 26, GE #6 have a long burn time, and produce an even amount of illumination during the burning period. This allows the shutter slit to travel with an even amount of light illuminating the subject during the time that you're burning the image on film. With FP bulbs, you can fire up to 1/1000 second.

Guide numbers, especially for M class bulbs will vary with the shutter speed that you use, as you effectively cut off a portion of the bulb's light output that you're using for exposure. Guide numbers for different shutter speeds are on the box that the bulbs come in. The alternative for bulb fanatics such as myself is the Norwood Flashrite Meter. It's a little rangefinder which have curves for the flash output of different bulbs on its calculator dial. You match up the curve for your bulb with your shutter speed, sight the target, and voila, the dial will tell you the aperture you need to use. I suspect this was designed for leaf shutters, but it works accurately enough for focal plane shutters.
....
Very good info.

It should be noted that true M class bulbs will not work well at the higher speeds with FP shutters, especially those with slow X-sync speeds. The old M3 bulbs, while officially classed a M, had a significantly longer burn time. They didn't meet the old FP class spec, but would work fine with miniature format (35mm FF, etc) cameras like M Leicas at the higher speeds up to 1/500th and, with some acceptable uneveness, 1/1000th. Medium- and Large-Format cameras with FP shutters need real FP class bulbs for anything over their maximum X-sync speed.
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Old 12-31-2017   #9
Robert Lai
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I didn't want to get too deep into this issue, but there is a point with FP bulbs.
According to the Leica instruction manual for the M4, you can use class M bulbs using the bulb synch port, and AG-1 or M2 bulbs using the X-synch.

For the latter two classes of bulbs, to accommodate the firing and illumination time, you use a shutter speed 1/30 or slower.

With the M3 bulbs, you can indeed use up to 1/500 shutter speed.

Officially, you can't use the FP class bulbs. They require about a 5ms delay, which is available on your trusty Nikon S2, SP, S3, or F, but not the Leica M cameras.

However, if you use M synch (and thus waste a bit of the light from the bulb), you can fire up to 1/1000 shutter speed with FP bulbs. Since these FP bulbs are costly and hard to find, I'd rather just keep them for use with my Nikon F and F2.

Walter Emanuel in his Leica Guide from the 50s to the 70s, gives extensive guide number tables for all classes of flash bulbs for all of the Leica cameras with flash synch, including the IIIF, IIIG, and M cameras.
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Old 01-01-2018   #10
noeyedear
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I don't fancy using flashbulbs for what I have in mind. I do wonder that if they can make the electronic flash pulse to burn longer for HSS its a shame they can't mimic flash bulbs.
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FP bulbs
Old 07-14-2018   #11
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FP bulbs

To clarify a point that DWIG made:
#6, Press 26 bulbs (same bulb, different manufacturers), were made for the "miniature" (i.e. 35mm film) focal plane shutters.

For medium format and large format (e.g. Graflex) focal plane shutters, you need a very large bulb that burns for considerably longer. These are the General Electric #31, Sylvania / Wabash 2A, or the Phillips PF 45.
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