Active autofocus unit?

[asmodai]

So. I do a lot of low-light shooting. I'm a night person. Between my 5dII and my 80mm f/1.2, I'm getting really close to being able to shoot as I've always dreamed of: able to capture the night just as I see it. Tripods: sometimes. Flashes: seldom.





But here's my issue. Even when there's sufficient light to be shooting wide open @ iso6400 in terms of exposure, autofocus is wont to disappoint me me. Often, it will fail entirely, and with so little light manual focus can be roulette. I've got a speedlite--the 430ex-- and I often find myself attaching it just to use the AF assist beam, no flash. I've gotten some amazing shots that way.





But often, portability is a concern for me. It seems silly to lug around a flash for the assist beam. Here's what I want to know:


Is there a dedicated, small active AF device which attaches to the hot-shoe? I've looked all over to no avail.





If not, could one hack one together? Is the communication language between unit and camera proprietary, in need of advanced reverse engineering? Or is it simple enough?





Whatta you folks know? And is there a reason this isn't on the market? Some flaw I don't see? With the amazing low-light capacity of cameras today I can't imagine I am alone in my focus-woes.

[Fred Doane]

Asmodai,





The Canon Speedlite Transmitter ST-E2 will do what your looking for. According to Brian's review of the transmitter HERE...





"The Canon Speedlite Transmitter ST-E2 support 45 focus point bodies. The ST-E2 focus assist effective distance ranges from 30' in the center to 16.5' in the periphery. EF lenses 28mm and up are supported, AI Servo mode is not supported"





It will also come in handy to wirelessly control all compatible canon (580ex, 580EXII, 430 EX, etc) flashes without losing E-TTL capability. Of course others will argue there are cheaper ways to accomplish that those options won't provide you with the Autofocus assist. It isn't a cheap piece of equipment. It is selling on B&H's website HERE for $220.





Fred~

[asmodai]

Well, shoot. I feel the horse's ass. You know, I poked around SO much, read (I thought) the flash reviews on this site, probably even saw this device at some point, and just dismissed it because I thought it's only function was as a controller. I imagine I was using the wrong search terms for it to smack me in the face. Really, I've been looking for something like this for the better part of a year.





I'm really shocked at my web-fu failure. =>








Anyway, thanks. Everybody else: Nothing to see here. Move along, move along.

[peety3]

For the sake of simplicity, and because I don't know what you shoot, would a flashlight work? Maybe a laser sight for a gun ($15-20 at Walmart), or just a cheap laser pointer (laser is probably too small to illuminate a contrasty spot and actually get both "sides" of the contrast, but the beam won't spread like a flashlight).

[asmodai]

The flishlight is the stand-by, but since I don't want that light in the photo it winds up being hard to illuminate, focus, drop/shut off the light, and maintain focus. Also, when my subject is a person, they seem to react poorly to having bright lights shown in their eyes-- don't ask me why. =]

[Daniel Browning]

It would be nice if there was an inexpensive alternative to the ST-E2, that only has the autofocus assist light (cheap) and and not the wireless flash control (expensive). I've been looking for one for years, and haven't found it yet.

[asmodai]

Mmhm. And I'd wager it would go from 'small' to 'diminiutive', or even 'neglegable'.





Perhaps one day, after every dSLR has 45 cross-type AF points which are all selectable by eye.

[Chuck Lee]

It would be nice if there was an inexpensive alternative to the ST-E2, that only has the autofocus assist light (cheap) and and not the wireless flash control (expensive). I've been looking for one for years, and haven't found it yet.

Somebody send an e-mail to gadgetinfinity.com...they'll have one in a few days. LOL..[] Serious!!

[luck101]

or u could get a 50mm 1.0, lol





j/k i think the transmitter idea looks like a good alternative

[wickerprints]

My understanding is that below a certain EV, no aperture will be sufficient for a passive AF to operate. F-number tells us how much light gathering capability there is, but if there is little to no light entering the lens, there's nothing for the AF system to detect.


The crazy thing about some of these dSLRs is that the ISO capabilities combined with some ultra-fast lenses (f/1.8 and wider) are such that one can have enough light to record a usable image, but not enough light for AF to perform unassisted.


As for a flashlight I have found that it sometimes doesn't work as well as an AF assist beam. I'm not sure why--maybe someone can explain?