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  1. #1

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    Strobe Power for 4X5

    Good day,

    I have been using 2 Alienbee B800 (320WS) flashes for a few years now with my DSLR, but I want to start doing portraits with my 4X5 camera. I plan to use Kodak Portra 400 film and I was wondering (roughly) if my flashes are powerful enough (18% grey looks 18% grey)?

    My typical shot is 1-2 persons, with 1 flash going through a softbox just outside the frame of the photo (no more than 6ft away), with the second strobe used for separation/background lighting either with a reflector or through an umbrella - I may use window light as well, if it is strong enough.

    I am guessing for portraits on 4x5, F16-F22 would be where I want to be (not a big fan of super shallow depth of field).

    I may invest in another flash soon, however, I like the B800 for their compactness, as I do plan to throw everything in a Kelty Redwing 50 (tried it, works great) so that I can move around (I typically take pictures at a friends home or some other interior space).

  2. #2

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    Set your *slr to 400iso at f/16 and f/22 and see what happens. Better yet, do it in a film SLR with 400iso film, since digital and film iso designations are not an exact match.

    Some of the answer to your question also may depend on the lens focal length you intend to use with your 4x5 camera. At 6 feet, you're at the edge of needing to figure bellows extension factor into your exposure with a 210mm lens, which is a good basic portrait focal length. And, if you're accustomed to working close-and-tight to your subjects, you may find you need to spread your lighting setup out a little in order to make room for the bigger camera or you may have to move the camera back a ways and move the lights out of the scene.

    There are a lot of variables at work here, so it's a little tough to make a guess. I personally would not want to have a main light with less than 800w/s in a LF portrait setup at f/16. You might find you can work at f/11 if you're careful with focus and camera movements.

    Peter Gomena

  3. #3
    Two23's Avatar
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    I've been shooting Portra 400 lately in a 1951 Rolleiflex. I used two White Lightining X3200 monolights (1320ws each) and shot f8. I placed the lights about 100 ft. off the rail. Last night I again used the Rollei with Portra 400 and used only four Nikon SB-28 flash, placed 20 ft. off the rail. I was getting ISO 400 and f6.3. I think you'll be OK since you'll be shooting indoors and the light will reflect back onto your subject, and you will place the flash much closer than I can. Did I mention I photo freight trains running at track speed at night?


    Kent in SD

  4. #4

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    I went through my archives, and found a few shots taken at f22, and it looked good at ISO 200 (default for my camera) with just one light at full power (these where from 2008 and I only had 1 strobe at the time). I also just did a test at ISO 400 with the flash at the back of a room (10'x15'), pointed at the ceiling (white), and I was able to get a good exposure.

    So, it may still be a stretch as I wouldn't have any power in reserve, but it is workable.

    Honestly, I am having doubts about using 4x5 for portraits. It can be done, and lots of people do it, but there are many challenges:

    - Takes a relatively long time.
    - Exposures are more expensive.
    - Bulky to set up.
    - Very limited in the types of images I can take.

    But, it does have some massive advantages:

    - I tend to be more careful and methodical, and as a result, my images look better to me.
    - I have to plan to take pictures long before I actually take anything, so I have to be more pro-active and less lazy.

    I have been considering using the 4X5 for landscapes and probably just going medium format for portraits, but I really don't want to spend any more money and also, looking through the big ground glass at your composition is beyond words.

    Slightly off topic, but any advice?


    @Two23 - I thought it was a typo when you said 100ft - thanks for clearing that up! Where can I view your images, very interested.

  5. #5
    36cm2's Avatar
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    I feel most comfortable with LF in front of something large that doesn't move quickly. I feel most comfortable with portraits in back of something smaller that I can move quickly if I have to.

    That's what I feel; it doesn't have to be what you feel. I think each format has its ideal subject and for me it's LF for landscape, MF for portraits and macro and 35 for sport and street.

    As for your original question, get a main light at least 1000 w/s and work the rest of the lights from there, if you decide to stick with LF.

    Best of luck,
    Leo
    "There is a time and place for all things, the difficulty is to use them only in their proper time and places." -- Robert Henri

  6. #6
    Two23's Avatar
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  7. #7

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    Did some soul searching, and decided I want to stay with 4x5 for the moment. Sounds more serious than it really was, but I have a good DSLR that I enjoy using as well, so whenever using my Cambo isn't workable, I'll just use my DSLR - and I have no issues with that and if I need to get another more powerful strobe, I will at some point.

    Thanks for all the help - and sorry for the nervous breakdown - was frightened by the cost for Polaroid 405 holders on eBay which shook my believe in humanity to the core

  8. #8

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    @Two23 - Really like! My father used to be a train driver and mechanic ("modern" diesel trains) and I've always loved them. Had a lot of trains where I grew up and no greater way to get around than travelling the island on a slow train, across hills, valleys, rivers, tunnels and along the coast - some of my best memories! As a side note, don't the drivers get alarmed when they see the strobe light, and then you emerging from the darkness?

  9. #9
    Leigh B's Avatar
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    Power requirements for a strobe system depend only on the film speed and lens aperture.

    For example, an exposure with a particular flash using ASA 100 film and f/22 will look exactly the same
    regardless of film format or lens focal length.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  10. #10
    Steve Smith's Avatar
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    Quote Originally Posted by laroygreen View Post
    As a side note, don't the drivers get alarmed when they see the strobe light, and then you emerging from the darkness?
    I wondered about this too. I suppose it must be a bit of a surprise to them but unlike someone driving on a road, they are not going to lose control and crash into a tree.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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