Metz 45CT5 & Fill Flash

Discussion in 'Lighting' started by UKJohn, Jul 26, 2006.

  1. UKJohn

    UKJohn Subscriber

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    Hi,

    Recently I have been experimenting with using fill flash and although I understand the principle of how fill flash works I have come up against a slight problem/misunderstanding.

    Over the past day or so I have searched through the various threads and the answers generally reinforce what I know on the subject however, my problem is this.

    Using a Metz 45CT5 flash (I also have a 45CL4) with my Bronica SQA, an incident light reading is taken and the camera's shutter and aperture set accordingly. So say the reading is f16 at 1/250 for fill in flash I adjust the dial on the head of the Metz unit to f11 to give 1 stop less exposure and then to f8 to give two stops less exposure. What I actually did was take three photos one in ambient light (say f16 and no flash), another at f16 (on camera) with f11 set on the flash and a third at f16 and f8 on the flash for comparrison.

    However, I am getting back shadow on the fill in flash images which indicates to me the flash setting choosen is to powerful. Have I misunderstood how the auto dial works on the Metz head (I dont have an instruction manual unfortunately). Does the Metz 45CT5 unit have a single power output and the guide on top simply relate to the flashes power at specific distances? I thought I understood but am now somewhat confused!!

    Therefore knowing what a wealth of knowledge and understanding there is on this site I thought I'd just ask the question in the hope that someone has or has had a Metz flash unit who can possibly help/advise?

    My thanks

    John
     
  2. Nick Zentena

    Nick Zentena Member

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    First off you can likely download the manual for the current Metz 45 model. It'll be very similar to yours and even closer to the CL4 you have.

    The Metz auto mode is fairly good. It can be fooled like any other reflective meter. It can also be fooled if for some reason the flash eye isn't getting the light. This is mostly a problem when doing close ups. At least for me.

    If it seems the flash is putting out too much power all I can ask was the background dark? The other thing was the film speed set right on the flash?
     
  3. Chan Tran

    Chan Tran Member

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    I couldn't find a manual for the CT5 either. Auto aperture setting for the CL4 is with the top dial but I believe with the CT5 it's on the digital display on the back of the flash head.
     
  4. UKJohn

    UKJohn Subscriber

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    Hi Nick and Chan,

    Thanks for your replies.

    What I should have added was that I positioned my girl friend (who acted as the model) at 90 degs to the sun so one side of her was in deep shadow. Just using the ambient light the shadows where dense with no detail. The fill flash both - 1 stop and - 2 stop did give detail in these shadow areas. Also the shadow of her body cast on the ground was given detail by the fill flash.

    The background was pretty normal, not dark at all.

    I would agree that both of these points tends to indicate that the fill flash is doing exactly what it should but I expected the back shadow created by the flash to be no existant. Again, have I misunderstood this.

    Many thanks

    John
     
  5. Nick Zentena

    Nick Zentena Member

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    You added a second light source so it created a second shadow. At least that seems to make sense.
     
  6. Ed Sukach

    Ed Sukach Member

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    I'm not familiar with the Metz setup on the Bronica. Is there a "Fully Automatic" mode where the flash is connected to a sensor within the camera body? There the output will be automatically reset to conform to the new aperture.
    I would guess that the Metz could be switched to "Thyristor" mode, where its light ouput would be contolled independently from the camera settings.

    "Thyristor" would be the way to go. For a -1 stop fill-in, simply set the film speed flash setting one stop higher than the actual film speed, 400 instead of 200; or set the aperture setting to one stop smaller than the one actually used, i.e. f/11 instead of the camera setting of f/8. Make sure that the thyristor sensor is not obstructed.

    Hope this help.
     
  7. UKJohn

    UKJohn Subscriber

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    Sorry Nick,

    I think I missed lead you in my last reply. There was only one light source other than the sun and that was the Metz flash on the camera, but I took two shots for comparison. One at 1 stop less than the camera setting and the second shot at 2 stops less than the camera setting e.g:

    Shot 1 - The camera aperture was f16 the dial on the flash head was set on auto to f11

    Shot 2 - The camera still on f16 with the flash set at f8.

    From visual tests, just by observation, the flash when set at f16 gives what appears to be a stronger light than when set at a wider aperture such as f8. Not very scientific I agree but that was a quick test just prove I was correctly adjusting the dial on the flash head. I did try a more elaborate set up using a Sekonic L588 light meter and infra red connection firing the flash at different auto settings (e.g: f22, f16, f11 etc) but the resultant reading on the light meter proved to be all over the place, so not very reliable.

    Ed hi and thanks for your reply - I have to confess I'm a bit confused with what you have said, especially the bit about shutting down the aperture on the flash from f8 to f11. I would be grateful if you could possibly go over this some more.

    Thanks to you both

    John
     
  8. Nick Zentena

    Nick Zentena Member

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    Ya two light sources. The sun and the flash-) The sun cast a shadow one way. The flash coming I guess at 90 degrees cast the second shadow.

    I think Ed is asking about TTL flash. IIRC the SQA doesn't have TTL worse the CT5 doesn't support the Bronica module. The CL4 does but if the camera won't no use worrying.

    Thyristor is auto mode. I think.
     
  9. Ed Sukach

    Ed Sukach Member

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    I'd be happy to .... but first, what mode was used, "Manual", "Automatic', or ???

    In re-reading the message, I see that you've said "auto", that should indicate a Thyristor mode.

    I'm interested in the test with the flash meter; was the meter read relectively, and flash unit pointed at a suitably large target - say a grey (hopefully, but not mecessariy) wall? - Or was the flash pointed drectly at the meter, with an incident metering setup? Or...?
     
  10. John Koehrer

    John Koehrer Subscriber

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    UKJohn,
    From what i've read in your initial post. Your original sequence seems correct.
    Basically your using a point light source that's going to cast a very strong shadow. The crux of the problem is the shadow cast by the subject onto the background.
    Determine which level of fill is your preference and take your model away from the wall. Another solution would be to take the flash off camera and raise it so the shadow is cast below your subjects head/shoulders. You might also try using a diffuser on the flash.
     
  11. UKJohn

    UKJohn Subscriber

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    'I think Ed is asking about TTL flash. IIRC the SQA doesn't have TTL worse the CT5 doesn't support the Bronica module. The CL4 does but if the camera won't no use worrying.'


    Nick,

    Sorry Nick I haven't quite got the gist of your reply so forgive me if I am repeating myself.

    Yes the Bronica doesn't have TTL metering, they way I normally use the flash (which is not that often hence my experimentation and questions) is to take an incident light reading on the subject, set the camera at the specified shutter and aperture and then set the same aperture on the flash. The Bronica has a leaf shutter so it will sync with any shutter speed. This will of course make the flash the dominant light source.

    For fill flash I understanding that you open up the aperture on the flash head by 1 or 2 stops (eg: if the camera is f16 then the flash is set at f11 or f8 respectively) which should make the flash give a weaker pulse of light so that the ambient light source is dominant.

    Am I correct in my understanding of this is how the Metz 45CT5 or the 45CL4 work? From your reply are you saying that the 45CT5 is not compatable with the Bronica SQA (which has no internal metering system - it is totally manual).

    Cheers

    John
     
  12. UKJohn

    UKJohn Subscriber

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    Ed,

    Thanks again for your input. I'm not sure what Thyristor mode is but I'll try and give my explanation as to what I meant by Auto mode...

    45CT5 - On the top of the flash head is a circular dial there is one red 'M' which I believe relates to a manual setting then there are 7 green 'C' which I understand relate to a computerized or auto mode. The auto mode allows you to select 7 different aperture settings subject to the film speed used. For example if a 400ASA film is dialed in the aperture range is from f4 to f22. There is a digital redout on the back of the flash which confirms what has been dialed in such as f no. film speed and distance (which I assume is the effective distance for that setting - I guess???).

    45CL4 - On the top of the flash head there again is a similar dial but the range of settings are different. There is a range set of apertures from 2.8 to 16 which I assume are in the auto mode, there is then a TTL setting, and three manual settings M, M1/2 and M1/4.

    I'm sure I'm only confusing the situation but I have made the positive step and purchased instruction manuals for both flash units (from www.oldtimercameras.com) which I'm sure is a wise move.

    Cheers

    John
     
  13. Nick Zentena

    Nick Zentena Member

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    No I meant the CT5 can't use the Bronica TTL module cable.

    http://www.bhphotovideo.com/bnh/controller/home?A=details&Q=&is=REG&O=productlist&sku=152173

    That won't work with the CT5 but even if it did it wouldn't work with your body.

    I think you understand fill flash just fine.
     
  14. UKJohn

    UKJohn Subscriber

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    Hi Nick,

    Thanks for the reply, the lead from the flash to the Bronica is a bog standard sync lead no thrills, so I would guess that from dialing in the adjusted f no into the flash head the CT5 will work fine for fill-in.

    Perhaps as suggested in a previous response a diffuser across the flash head needs to be incorporated also.

    Once again cheers

    John
     
  15. OldBikerPete

    OldBikerPete Member

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    As previous posts have said, a diffuser will reduce shadows if you are shooting indoors so that light bounced off adjacent walls will reduce the flash shadow for you - watch out for color casts caused by light reflected off colored walls or other objects. You can move your subject away from backgrounds which will catch the flash either indoors or outdoors.
    If that's not good enough then you need to graduate to flash umbrella or other reflectors or multiple flash units.
     
  16. Ed Sukach

    Ed Sukach Member

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    Typing rapidly - hopefully, I can complete this message before this @#$ PC freezes...

    What you have written about using fill-in flash seems to be the "right way".

    If I remember correctly, you are using two flash units .( ...???) which would seem to eliminate any flash sensor circuitry error. I would therefore suspect the exposure meter itself, or the method used for metering.

    Remember that, if you are using the meter in "Incident" mode, the flash sensor will "see" the light refected from that particular scene and a change in the scene itself will affect the output of the flash unit. This could result in differing readings as you move about, holding the meter.

    The best way to try to determine the correlation between the meter and the flash sensor output would be to take "reflective" readings from a large, blank field; a blank wall, or background, and try to eliminate the effect of the different "seeing" angles of the flash sensor and meter; and to keep both flash and meter in stable positions.

    Why changes in the film speed setting of the flash unit should NOT affect the film exposure is beyond me. The only possibility I can think of is that, somehow, the field sensed by the flash unit's thyristor changes between exposures.