Stupid Questions (forgive me) regarding shooting a SF20 Flash United on a Leica M6

Discussion in 'Rangefinder Forum' started by roberttalbot, Oct 1, 2013.

  1. roberttalbot

    roberttalbot Member

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    A Few Stupid Questions (forgive me and be gracious) regarding shooting a SF20 Flash United on a Leica M6.

    1.) When shooting the flash can one zone focus and/or use hyper-focal distance focusing? I would assume that before shooting the rangefinder with the flash that one needs to focus prior just like one would without the flash.


    2.) Would one need to consider the light meter in the Leica M6 when shot manually? I am wondering if this would apply only for the TTL mode when using the SF20 flash on the Leica M6?


    I have read the manual and searched the rangefinder forums to look for these answers but no luck.


    Thanks and sorry I may have further questions.
     
  2. chriscrawfordphoto

    chriscrawfordphoto Member

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    Flash exposure on any camera is determined by the distance between the flash and the subject. It doesn't matter what distance the lens is focused on. Just set the correct aperture for the distance from flash to subject (or use a handheld flash meter to determine the aperture to use). The meter in the original M6 only measures ambient light. The M6-TTL can do TTL flash metering
     
  3. roberttalbot

    roberttalbot Member

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    I just wrote a quick reply but it is not showing up, so I will write it again. Oh boy, I should have copied it. I will write it all over again, arghh.

    First, thanks Chris Crawford for the interaction and answering the questions.

    So I believe you are saying that one need not care about the focusing because when using the flash unit it is about the distance the flash is from the subject. So in other words, here when using the flash focusing is irrelevant but distance and position with the flash is how it works. Am I right so far?

    Now I would think that the higher number the aperture (i.e., f16, 22) would give the photograph a depth of field.

    I still cannot grabble around the idea that flash users are shooting at 1/50s of a second hand held, would that not cause blur in the photograph or does the flash compensate for that?

    Also, here's a hypothetical situation: I have the Leica M6TTL with the flash mounted in TTL mode, and I am in a low light situation. The ISO is set at 1600, my subject is 3.4 feet (1 meter) away from me. I have the aperture set at 16 which the flash on the back gives me the distance of 23 feet. Now that is a lot of feet that it covers, but my subject is only 3.4 feet. Would the TTL know that my subject is 3.4 feet away and give me the correct exposure or does my subject have to be 23 feet away when I shoot the camera?

    Does the SF20 Flash unit in TTL mode dictate my aperture, or do I choose the aperature and the SF20 adapts to that giving me the correct exposure.

    I hope that I am asking the right questions, and I am not in some other world.

    Also, what is the order. You see the subject, the subject is 4 feet away, in the TTL mode what would one do next. I am a bit confused.

    I'm thinking that since the TTL acts as a automatic flash, I would just shoot the camera 4 feet away from the subject without focusing (because that is superfluous) at f16 with the ISO at 1600 (can't change that) because I am in a low light situation.

    I hope this is right if not, I need correction.
     
  4. MattKing

    MattKing Subscriber

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    I'll see if I can help.

    First, although I've never used an M6 and SF20 combination, I have used other flashes in TTL mode. If my answers are incorrect because of some peculiarity in the M6 and SF20 combination, I'm sure I will be corrected.

    Automatic flashes work by measuring how much light from the flash bounces back from the subject. When the right amount of light has bounced back, the flash is turned off. The full process happens in a tiny fraction of a second - usually much faster than any camera shutter.

    TTL flashes use a sensor in the camera to measure that bounced light after it comes through the camera's lens. Non TTL automatic flashes use a sensor on or attached to the flash.

    In the days of manual flashes, we would measure the distance from the flash to the subject, and that, with the power rating of the flash, would determine what f/stop to set. The closer the flash to subject distance, the smaller the aperture.

    The shutter speed has no effect on the intensity of the flash - you just need to make sure it is a speed that works with flash. Unless you have high ambient light, the shutter speed plays no role in exposure.

    For an automatic flash, the aperture set on the lens does two things:

    1) it affects your depth of field, just like in non-flash work; and
    2) it affects the maximum range of the flash.

    The table or indicator on the back of the flash will, in combination with the film speed, tell you within what range the automatic function will work when the indicated aperture is set.

    Most TTL flashes will let you choose a range of apertures - you just need to remain aware of the range of distances that will give you.
     
  5. roberttalbot

    roberttalbot Member

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    Matt King,

    Thanks for chiming in. "the right amount of flash that bounces back off the subject," learn something new every day.

    So the aperture is the depth of field when using the flash unit just like without it. It's just the shutter speed is set to the side.

    So the shutter speed is irrelevant and that is why it is set a 1/50s of a second. I wonder why they set it there, but that is going away from the topic if we tried to answer that.

    The back of the flash does not give me the range of the flash but gives me the distance.

    Matt, so my ISO is at 1600, I'm in a low light situation, I have the flash on TTL. The subject is 3.4 feet away from me -- yet the back of the flash stats f16, 23 feet. When I shoot the subject at 3.4 feet, I am wondering if it will give me a correct or right exposure of the subject.
     
  6. MattKing

    MattKing Subscriber

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    I've now looked at the manual for the flash, so I can better help.

    You first determine what aperture you intend to use. Than you set that aperture on both your camera lens and the flash.

    When the flash is set to an ISO of 1600 and an aperture of f/16, the "23 feet" you see displayed is an indication of the expected maximum flash-to-subject distance you can expect to work with. Changing either the ISO or the aperture will affect that maximum, but the TTL circuitry in the flash and camera will automatically adjust the light output for shorter distances.

    You can adjust the "f/16" by using the controls on the back of the flash. When you do, you will see that the "23 feet" will change.

    Maximum range calculations are somewhat dependent on the scene - low, light coloured ceilings and reflecting floors and walls really assist a flash. A flash confirmation function is available on the flash.

    Here is a link to the manual: http://www.summilux.net/documents/LeicaSF20.pdf

    The pages are quite small, but they work with the zoom function.
     
  7. roberttalbot

    roberttalbot Member

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    Matt King thanks again, you're very kind. I read the same manual, yet either I am very slow at learning or the manual writes as bad as I do. Probably both and hence my confusion.

    Now, when the manual says "expected" maximum it means that I can shoot the subject from anything under 23 feet. Now, you're saying that the TTL circuitry automatically adjusts the light output for distances. Wow, then the manual mode may be superfluous, except in scenes where the TTL may have a hard time reading.

    So, I can conclude since the photographer chooses the aperture in the TTL mode, the flash increases in output or descreases the flash depending on the aperture the photographer chooses. So the SF20 flash in the TTL mode adapts to the photographers desired f-stop setting.

    I think it is clicking.

    Matt is this correct?
     
  8. MattKing

    MattKing Subscriber

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    So, I can conclude since the photographer chooses the aperture in the TTL mode, the flash increases in output or descreases the flash depending on the aperture the photographer chooses. So the SF20 flash in the TTL mode adapts to the photographers desired f-stop setting.

    I think it is clicking.

    Matt is this correct?

    Close. The exposure isn't determined by how bright the flash output is (it doesn't actually vary), but rather how long the flash fires.

    The photographer chooses an aperture and ISO and then sets both on the camera and the flash.

    Then, when the photographer releases the shutter, the flash starts firing and the TTL sensor in the camera starts measuring the light from the flash as it bounces back from the subject and goes through the lens. When enough light has bounced back from the subject, the TTL sensor in the camera turns the flash off.

    For close distances, the flash duration may be really, really short - e.g. 1/30,000 second.

    Even for maximum exposure the flash duration is quite short - 1/400 second.
     
  9. roberttalbot

    roberttalbot Member

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    ahhhh I see. Makes sense in regards to when you say "how long the flash fires" and you're saying that the TTL is able to read the distance, so the TTL capability on the flash knows how far the subject is from the flash therefore applying the particular length of time the flash fires?

    This is very interesting, and this makes the most sense to me in our exchange. I need to go out shoot in different light situations in the TTL mode, and wait for development. For me I need to know as much as I can before shooting with a new "tool"

    I've been reading other forums which I cannot link here because the moderators think that is spam or something, where they are having a similar conversation...let me quote from it:

    began quote from the i-camera-forum
    The 1/50 sync speed means that low-power flashguns like the SF24d are almost useless in bright light.

    The main use for a portable flashgun in daylight is as "fill-flash" to lighten deep shadows in a sunlit subject.

    You set the shutter speed to (for the M6) 1/50, then set the aperture to get the correct daylight exposure or maybe half a stop underexposed.
    (With ISO400 film, in sunlight would mean 1/50 at about f/64, so already you're stuck. Switch to ISO50 film so the exposure is something a Leica can do - say 1/50 at f/16.)
    To get a good "fill" effect, lightening the shadows but not too much, you need the flashgun to deliver two to three stops less light than you'd need if the flash was the only source of light. So (if the flash is in Auto mode) you tell it that the aperture is f/8 not f/16.

    Unfortunately, the maximum working distance of the SF24D at ISO50 is about 2m, which severely limits its usefulness. For longer distances you need much a more powerful flashgun.
    (The problem is that that the flashgun's 1/1000 second flash has to balance what the sun delivers in 1/50 sec. If the camera has a faster sync speed, like the 1/180 of the digital Ms or 1/500 of a traditional Hasselblad, fill-in flash is much simpler.)
    As an alternative to switching to slow film, you can use a neutral density filter on the lens. This solves the problem of getting a usable aperture at 1/50 sec in bright light, but does not alter the other problem of getting a little flashgun to balance the power of the sun.

    PS: if you don't have the manual for your SF 24d, an internet search will find a scanned copy.

    end quote from the i-camera-forum

    The SF-24D I hear on an m6 is exactly the same as the SF20D only that it was meant primarily for the m7. The SF24D I hear works exactly like the SF20 on a M6.
     
  10. roberttalbot

    roberttalbot Member

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    Here, the author of the quote is taking into account the shutter speed 1/50 that you have to set the M6 to in order to trigger the flash from the SF20 and SF24D models. Yet is not the shutter speed constrained when the flash unit is being used?

    Elsewhere, I read that the light meter in the M6 should be ignored. Now this statement of the light meter being ignored makes sense especially when using the TTL mode because the flash adjusts to the distance and aperture.

    I'm sticking with this "Most TTL flashes will let you choose a range of apertures - you just need to remain aware of the range of distances that will give you."
    ----

    It just dawned on me now, sorry, that the m6 classic is different from the m6TTL so the m6 classic would have to be shot in manual mode because the classic does not come with the TTL. Yet both have to be shot under 1/50, so it being TTL or not does not answer what the author in the quote is talking about.
     
  11. cowanw

    cowanw Member

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    Also, if using flash, the ISO need not be set at 1600 because of low light situation. You are providing a high light situation with the flash. using your post #3 hypothetical you could easily use ISO 100
     
  12. Chan Tran

    Chan Tran Member

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    The 1/50 isn't too low a shutter speed for hand holding unless you use a telephoto lens. With flash and if the ambient light is low then the shutter speed won't make a different as the entire exposure is done with the flash that has short duration. The 1/50 is the fastest shutter speed to use with flash on the M6. You can use slower shutter speed if you wish. At ISO 1600 which is very fast film the ambient light would play a rather important role.
     
  13. MattKing

    MattKing Subscriber

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    Your ability to link will be limited on APUG until you have been around a bit longer and made a few more posts. That was instituted to help stop the robo-spammers.

    TTL doesn't read distance. It just measures how much light from the flash has bounced back from the subject. When enough has bounced back to properly expose the film, it turns off the flash.

    The distance affects how much light from the flash reaches the subject and how much light bouncing from the subject reaches the camera - if you are far away the light spreads out more.

    Are you using the flash as your source of light, in situations where there isn't enough ambient light to work? If so, the TTL flash will work great.

    If you are trying to use TTL flash to "fill" or balance lighting in situations where there already is enough light to expose the film, you will most likely just get frustrated. The focal plane shutter on the camera limits your flash use to speeds of 1/50 second or slower. This means that apertures need to be small and/or films need to be slow in order to expose properly for ambient light. If you do that though, the flash will often need to be too close to the subject.

    In addition, the ambient light will tend to confuse the TTL metering, and cause the flash to shut off prematurely.

    If you are going to use fill flash with a camera that requires a 1/50 second shutter speed for flash, most often you need to use the flash in a fixed position, in manual mode, using either a guide number calculation or a flash meter.
     
  14. MattKing

    MattKing Subscriber

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    +1

    The only reason to use ISO 1600 is if that is the film you have. If you are choosing a film for use with flash, I'd recommend a slower film.