Using infrared flash units

Discussion in 'Q&A for better images' started by mloufrost, Mar 23, 2004.

  1. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    I own both the Canon Rebel 2000 and the digial Rebel. I also own the 420EX speedlite. I am planning to purchase the ST-E2 transmitter. I know that the transmitter works with the 420EX but I am wondering if it might also be useful in firing other (non Canon) infrared flash units. It would be helpful, at times, to add small flash units to obtain light from different angles. Thanks for your input.
     
  2. mike_nunan

    mike_nunan Guest

    Hi Mary Lou,

    I would recommend you just get a 550EX instead. The ST-E2 will only work with Canon flashes (to answer your main question) and offers inferior triggering range compared to the 550. You also lose the option of having a direct fill light.

    With the 550 you can set the master unit not to fire for the actual shot, giving exactly the same effect as you get with the ST-E2. If you do this, you will see a burst of pre-flash as the unit sends out its instructions to the slaves, but it won't actually fire while the shutter curtain is open. As I say, it has better range, so you can get away with tricks like having the slave flashes behind the camera provided there is enough reflection from the scene for the control flashes from the main unit to reach the slaves. This works fine in most domestic interiors.

    If you want to save some money, consider the Sigma equivalent to the 550EX. I understand they have recently brought out a new unit to provide full compatibility with the later digital bodies.

    HTH

    -= mike =-

    PS. You might want to take a look at the following very comprehensive FAQ, if you have some time:

    You must be logged in to see this link.
     
  3. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike, thanks for your info and for sending me to photonotes. Wow, I got the answers to lots of questions I have had plus.....many answers to questions I hadn't thought to ask!

    I need to be more specific before you can decide if the 550 EX or a Sigma equivalent is what I want.

    I do not plan to use the flash equipment in a studio setting. My immediate interest is that I will have the opportunity to explore the possibilities in cave photography during a trip to Missouri in April. Indirect lighting is especially important in this environment. What are your thoughts? Thanks, Mary Lou
     
  4. mike_nunan

    mike_nunan Guest

    Yes there's not much missing from that FAQ that I can think of! Regarding cave photography, I've never done anything like that, but I would suspect you're gonna have to be careful about the master unit's coverage if you want to use a wireless setup. If you just want to position one unit away from the camera, things may not be so bad, since you can point the head of the master unit straight at the slave. You'll also want to make sure that the receiver window on the slave is facing towards the master, as per Canon's instructions.

    Caves are pretty large things, so power output may become an issue. If you can't get enough light out of a hotshoe type unit, then your only way ahead would be battery-powered studio strobe, such as those made by Lumedyne. It's a significantly more expensive option, but it may be your only option if you want to use any kind of reflector, diffuser or other light modifier which will cost you stops of output. It all depends how seriously you want to take this, really. Are you planning to sell the images, or are you willing to invest money in equipment specifically to allow you to get the best quality?

    Also, if the caves are dark (i.e., we're not talking about the open-to-the-public tourist attraction kinda caves where they have permanent lighting) then you may be able to play some other tricks, such as using a very long exposure and manually triggering the flashes from different positions to get the lighting you want. That way you can fire multiple pops to bump up the effective power. Or, you could use a l& to achieve the "painting with light" technique -- this can be the best way to evenly illuminate complex interiors and I can imagine it would work well in a cave, provided you could manage to get around the dark corners without breaking your neck in the process! ;)

    Anyway, some things there to consider. If you give a bit more info about your intentions and budget then I'll have a shot at coming up with a few more.

    Best regards,

    -= mike =-
     
  5. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike you wrote:

    "Or, you could use a l& to achieve the "painting with light" technique -- this can be the best way to evenly illuminate complex interiors and I can imagine it would work well in a cave, provided you could manage to get around the dark corners without breaking your neck in the process! ;)"

    I have been considering multiple exposures on the same frame instead of keeping the shutter open. This would allow me to use a flashlight to get around and place the flash in different locations.

    I went after the information on the Sigma EF-500 DG Super. One question I have that I don't think I found an answer for is whether the Sigma offers the same kind of exposure compensation that the Canon 550EX has. Do you know the answer to that?

    The reason for this interest is that another thing I want to be able to do with nature photography that I can't do with the 420EX on either of my Rebels is to use flash fill where I want to control the amount. Currently the only way I can do that is to take an ambient light reading with the ISO set correctly, set the Fstop and shutter with manual controls, and then raise the ISO to fool the flash into giving less output. This is obviously pretty awkward in situations where nature doesn't sit around and wait (animals?).

    Incidentally, I checked with B&H Photo in NYCity and they sell the SigmaEF-500 DG Super for $179.95 and the Canon 550EX for $299.95(imported)

    Any other thoughts? Thanks, Mary Lou
     
  6. mike_nunan

    mike_nunan Guest

    Hi Mary Lou,

    Taking multiple exposures is fine, but much depends upon whether your camera is able to cock the shutter without any film movement. In practice few 35mm cameras are able to do this so I'd stick to the Digital Rebel instead, it ought to work well. I don't know the answer to your question re flash exposure compensation (FEC) on the Sigma, and I guess from the way you put things that the Rebel bodies don't allow FEC to be set on the body. I've only used Canon flashes with the EOS-3 and 1v, which both allow compensation to be set on the camera, even with the most basic of flashes such as the 220EX. If you don't know your camera inside out, then it might be worth going back to the user guide to see if that feature is buried in there somewhere.

    However, in the context you're talking about, I'm not sure you want to go down the road of ETTL metering anyway. If you are using the multiple exposure idea, I'm not sure you'll get enough control. It might be better to control the flash power manually and use a wireless slave to trigger the off-camera unit, either by radio or more cheaply just by using a simple optical slave. In that case you'll need to have a small flash mounted on the camera itself, but I would suspect you're going to want a bit of direct fill anyway so that might be just fine. Perhaps the best option would be a pair of Sigma guns, which would allow you the option of leaving the on-camera unit switched off for the exposure if you wanted to, plus you can set the remote unit into manual mode if ETTL isn't giving you what you want. I'd suggest using the image review and histogram to judge the exposure, rather than getting into flash metering with a handheld meter.

    One thing I would definitely recommend is taking a good selection of light modifiers, especially diffusers. The rough textures of rocks and the boldness of cave formations will need a gentle touch on the lighting if you are to avoid a harsh look. A couple of collapsible circular diffusers would be a good start. If you get the bottletop type you can use them as handheld reflectors too.

    Going back to the business of making multiple exposures, I think the biggest problem you're going to have is visualising how the frames will combine in the final image. If you have the option to use your camera in "tethered mode" (directly connected to a laptop -- assuming the Rebel allows this) then you can combine the images in Photoshop while you work, in order to see exactly how the final result will look. It'll also let you evaluate the individual images without touching the camera, which means that you won't have any alignment worries. Whichever way you approach it, I think you've set yourself a considerable challenge. It should be easy enough to get acceptable results, but to go to the next level and get sensational results will require a lot of care in the planning and execution. If you go down the route of compositing the images while you're there, then inevitably that will soak up quite a bit of time, so I guess you'll have to pick your approach based upon the amount of time you have at your disposal and the number of final images you're hoping to make. It sounds like a fascinating project though, I wish you the very best of luck with it. I hope you'll post some results here, it would be great to see them.

    Best regards,

    -= mike =-
     
  7. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike, we didn't have nearly enough time to experiment with the cave photography, buy I learned a lot. I used two flash units. My new Sigma 500 DG Super was mounted on top of my camera and I lowered its power (probably too much). A second flash, a Canon 420EX was held away from the camera providing light at a different angle and sometimes illuminating the back areas of the photo. My biggest lesson was that I shouldn't use the LCD image as the judge on the exposure. The histogram would have been a better indication. The pictures were, in general, too dark even though they looked fine in the LCD panel. If I had paid better attention to the histogram, I would have known that the image was underexposed. I made adjustments in Photoshop. I'll post one at a time.
    Mary Lou[​IMG]
     
  8. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike, here is a second image. Here I think that the placement of the second flash gives a weird illumination to the back of the picture which isn't very natural.
    Mary Lou[​IMG]
     
  9. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike here is another shot. In this image the second flash was not aimed at the back of the image and the result is a bit more natural. Mary Lou [​IMG]
     
  10. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike, there was a lot of iron in the soil at this cave and this is what gives the reddish hue to the cave features. This is the last shot. It brings out a few more features and is probably my favorite. Mary Lou
    [​IMG]
     
  11. mloufrost

    mloufrost Active Member

    Joined:
    Jan 10, 2008
    Messages:
    36
    Likes Received:
    0
    Mike, as you can see, I didn't have time to explore multiple exposures. I would like to return to this cave, "Crystal Cave" near Springfield, Missouri. It is very interesting because it is privately owned by a couple in their 80's. The man (86 years of age) still crawls around discovering new rooms and then takes his shovel and pick ax and opens the room up to those of us who don't want to crawl in on our bellies! He has also put in a small amount of lighting which helps immensely in focusing the image. He has recently discovered some rooms with very intricate decorations that make curlicues out from the ceiling or walls. They would make good macro shots. Maybe I'll arrange to go back and spend an entire day underground!
    Mary Lou
     
  12. mike_nunan

    mike_nunan Guest

    Hi Mary Lou,

    You already got some nice results there, way to go! I agree that the last one is the best. The first one is pretty good too, but the other two have fallen prey to some very hard shadows. That's always going to be a risk with this kind of flash setup, I guess.

    I think for the next visit you should get hold of some simple light modifiers for the off-camera unit. A diffuser bottle-top with a white or silver cover would be a good start, then you can either fire the flash through the diffuser or bounce it off the cover. I'd say it would be very worth trying a double exposure, with the flash off-camera to (say) the right on the full power needed for the exposure, then off to the left with the power reduced by a couple of stops. That will stop the shadows blacking out without leading to strongly visible cross shadows or overexposure of the foreground. It looks to me like the on-camera unit is set about right, if you went any further it would worsen the "cardboard cutout" effect that is already coming into play in the third image. Re the second image, I think you might have got away with that if you'd used a stop or two less light in the background flash.

    You've made a great start there, and thanks for posting the images. I'll look forward to seeing more from your second visit.

    All the best,

    -= mike =-
     
  13. sjprg

    sjprg New Member

    Joined:
    Jan 10, 2008
    Messages:
    2
    Likes Received:
    0
    I use an ST-2E with two EX550s and one EX420. One of the tricks I use is to use several makeup mirrors I purchased at the drugstore, and set them up so that the control signals can be reflected onto the remote flashes regardless of their position. I usually put the EX 420 behind the subject pointing stright up, as a local bounce light. By placeing a mirror off to the side I can control the EX420.
    These mirrors are only about $3.00 each so it a cheap control system.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice