Alternatives to Canon Speedlite Transmitter ST-E2?

Dear Lazyweb,

I shoot with a Canon EOS 5D and an f1.4 50mm lens. This combo takes great photos in the dark, but the auto-focus sucks.

One solution it to put a flash on it and set it to "emit, no fire" so that the flash uses a red light for focus assist, but doesn't actually flash. I don't like this solution because the flash doubles the size of the thing I'm lugging around, and I bang it into things all the time.

Another solution is the Canon Speedlite Transmitter ST-E2, which is basically a flash without the flash part: it does focus assist and does it well (it also does other things that I don't care about).

Here's the problem: unlike a real flash, it doesn't run on AA batteries. It runs on these shitty 6v "2CR5" batteries, the disposable version of which are around $5 each. They don't last very long, maybe 1500 or 2000 shots.

I've bought rechargable 2CR5 battery kits from two different manufacturers, and guess what, they don't work. More specifically, they seem to not fit. I can only get the ST-E2 to function with them if I keep the lid open and manually jiggle the battery. They're not making contact somehow. I've tried the obvious things, including taping shims around them, to no avail. Maybe my ST-E2 is defective, but since it always works fine with the disposable batteries, that seems unlikely.

What I'd like is something that plugs into the hot-shoe and does focus-assist, but that runs on AA batteries. Failing that, a rechargable 2CR5 that actually works with the ST-E2. Any suggestions?


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27 Responses:

  1. Seriously, I have had the exact same problem and have yet to find a good solution that doesn't involve the following:

    -Shooting on a super super super high ISO and low shutter speed while camera is on a tripod.
    -Taking a test shot.
    -Getting the auto focus to generally focus on what I'm shooting and then switching to manual focus.
    -Take the photo.

    And that BARELY works. :(

    For the record, I also shoot with a 5D with that same lens.

    Did you buy the ST-E2 new or used? Mine was used and I suspect that was the problem with my batteries. Bollocks.

    • Woops, meant to add in my terribly-written how-to that after I get the proper focus, I adjust the ISO and shutter speed to more desireable levels. Strange, but if I lower the shutter speed and raise the aperture, my autofocus on the f/1.4 seems to work better. MAGIC.

    • jwz says:

      It was new.

  2. I don't mean to be facetious, but once you get used to manually focusing based on distance estimates, you can get pretty damn good. It's a good skill to have, and you don't have to bother with these tech issues.

    • jwz says:

      That doesn't work real well when you're shooting at f1.4 and your depth of field is 6".

      • laptop006 says:

        You really would be surprised. I've shot a fair bit recently with the Canon 50 & 85 f/1.2's on an E-P1.

        Despite being fully manual (when using FD lenses) with no focus assist (other then a zoom) it's not hard to get in-focus shots in a few seconds, even in dark clubs (with no flash).

        The other crazy thing you could do would be to dig up a Canon EF 50mm f/1.0 L, that, combined with a newer body should focus and shoot in environments your eye's can't handle.

  3. babbage says:

    I avoid the problem by using a body that contains a built0in AF-assist lamp. Of course, emitting a bright light is not a way to subtly take a photo, and does tend to dazzle anybody looking at the camera. I haven't got a solution that's great on every axis.

  4. iampivot says:

    Is it a Canon EF 50mm f/1.4 USM Lens that doesn't focus correctly, or an aftermarket one?

  5. rog says:

    I've had the same problem, but mainly in situations where I can switch on a torch while I set the focus. The other problem with the ST-E2 (or a flash) is how much it costs if you _only_ want the use of focus-assist functionality.

    This would be a good question to ask on my Q&A site: , or I can ask on there on your behalf if you like?

    I imagine it would be possible to hack something together, either a red LED/battery deal hooked up to the right hotshoe pins, or perhaps an adaptation of the ST-E2 to wire in an 4 x AA or 9V battery clip w/ a voltage regulator.

    • rog says:

      Scratch that last paragraph, looks like the hotshoe pin hackery required would be significant.

      Instead, if you use a plug-in style remote shutter trigger, you could wire in a focus assist light for the "half-pressed" state.

  6. ppezaris says:

    The best quote on the subject that I have heard, which I read a while ago at goes something like this:

    For improved focus assist, attach a 1D to the rear of the lens.

    • edlang says:

      Or borrow a 50/1.0L for a few days to see how the faster (albeit chunkier) lens handles the lowlight AF?

      • edouardp says:

        More light, but less depth of field it has to hit the focus for. At 10 feet the focal plane is 12 inches at Æ’/1.4, and drops to 9 inches at Æ’/1.0.

        No. I have nothing actually useful to add. Sorry.

        The Canon 50mm Æ’/1.0 lens *is* super cool though.

  7. tkil says:

    I don't like the idea of throwing stuff away either, but it seems like most of the rechargeables have sketchy reviews (e.g., amazon user reviews).

    Also, the rechargeables seem to have 600mAh (most) or 800mAh (top-flight) capacity; the disposable ones have 1500mAh.

    Looking at getting a charger plus an extra battery, that's about 45$ (or 90$, since you've gone through two kits already).

    You can get disposables for 3$/ea in bulk (20-packs, with 10-year shelf life). Just recovering the cost of the initial kit would pay for 15 disposables (or 22.5Ah of use, which would take ... 35+ charges of the 600mAh cells?).

    And since it seems that the 1500mAh disposable is rated for 1500 shots, that's 22.5 thousand shots before you're even close to breaking even on the rechargables. (That's assuming the cells keep their capacity that long; I saw one brand claiming a 5yr cell life, but I wonder if that's even to 80% original capacity...)

    The lithium cells can be recycled, too. Not as good a solution as rechargeables (from an idealistic environmental point of view), but it beats landfill. (Who knows; if electric cars really take off, lithium might become a demand metal, and the disposables might actually earn you a bit back, or have a nickel deposit, or something. That last would be very ironic...)

    Finally, is it possible to run that attachment with camera power? If so, many people on the boards say that putting hi-capacity NiMH AAs (pushing 3000mAh each these days) into a booster grip is the best way to get power into a camera. Don't know if that works to run the hotshoe, though.

    Caveat: I don't have money for a shiny dSLR, so this is all academic to me. You might try firing the battery questions off to; he seems to keep current on battery technology, although a quick search for "2CR5" comes up empty.

    • shandrew says:

      My favorite web-1.0 NY battery shop has them for $2 in quantities of 10,

      If you aren't too attached to Canon, you might want to consider the Nikon D700, which indeed has a built in focus assist light and has better low-light performance (better looking high ISO quality and better focus performance) than the 5D and 5D2.

  8. rafasgj says:

    On Canon cameras, the focusing screen imposes you a "brightness" of around f/2.5, that means that any lens that is faster than that won't make the viewfinder brighter and that the depth of field you'll see will be GREATER than the real one, and unless if you are using a focusing screen designed for manual focus, it is pretty hard to get critical focus with lenses that are f/2 or faster.

    I often use this same lens, but on a Canon 400D/XTi. If you think it is hard to focus on the 5D, you don't know half of the history. The diminutive viewfinder of the 400D makes it nearly impossible to know where the focus is on.

    That said, I don't know of any decent alternative, but you might want to check out how people who does astrophotography with Canon cameras handle the focus issue.

    BTW, a focusing aid device, cheaper, smaller and lighter than an ST-E2, and powered by AA or AAA batteries is something I'd buy as soon as it is announced.

    • semiclever says:

      I don't know what you mean by the focusing screen imposing a brightness, but at the very least your comment about the depth of field being greater cannot be correct. Depth of field is a property of the aperture of the lens and has nothing to do with the focusing screen or the brightness of the finder. It may be hard to judge narrow depths of field in a small finder however. The screen itself is a ground glass plate and does absorb some amount of the light passing through it. A more matte screen allows for more accurate focusing but absorbs more light, appearing darker.

      It might be possible to manually focus in low light with a split-prism focusing screen, but I'm not sure you could get adequate focusing accuracy, as I've never used one with a lens faster than f/2.8.

      I presume people who do astrophotography set focus at infinity, as even the moon is well beyond any lens's hyperfocal distance.

      As to jwz's original problem, the best idea I can come up with is to buy the smallest/cheapest 3rd party flash available and then bust the thing open and rip off the flash head. Keep in mind there are some juicy capacitors in a camera flash as the bulbs operate at high voltage.

      • rafasgj says:

        Take a Canon camera with a faster than f/2.5 lens. After focus it, use the depth of field button. Until f/2.5 you won't find any change to both the brightness and the depth of field.

        Split-prism are great to focusing on dimmer light. I've used them with f/2 and f/1.4 lenses. Although, they are only useful for manual focusing, which is not the problem at hand.

        • semiclever says:

          Just tested this with a Canon 350D (Digital Rebel XT) and a 30mm f/1.4 lens. I agree the finder does not appear darker until f/2.5. Curious. I didn't note any appreciable change in depth of field until f/3.5. (I used targets set at 1 foot intervals from 3 feet away) You can hear the aperture close when you press the DoF preview button. I don't think these phenomena are related. I think it's just that the finder's too small to resolve the difference.

  9. otsdr says:

    Since the problem seems to be the casing of the rechargeable batteries, you could swap out the innards of a used disposable battery with the ones from a rechargeable one.

  10. legolas says:

    Have you tried to use one disposable and one rechargeable battery (even if it's just to try and locate the connection problem)?

    • tkil says:

      The reason it's called a 2CR5 is that it's two CR5s that are physically connected. (With the tabs on the "bottom" of both of them, if you will.)

      It might be possible to fill the battery compartment with some frankenbattery, but not sure that's the best thing to do to a 300$ component...

  11. cryllius says:

    Sadly, the way I resolved this was putting down the money for a case of 2CR5s online and make-believing that the problem doesn't exist any more.

    Not the solution I wanted but it's the only one I could find. I'm hoping my cache of batteries will last me until someone wakes up and realizes there is a market for the exact device you described.

  12. fieldsnyc says:

    The 270EX flash is pretty compact, and does an AF assist beam, though I'm not sure if it will work with the 5D. I've found it to be a very nice alternative to the larger flash units.