Focus assist light

[ejwebb]

I just purchased a G3 and notice that the focus assist light is within the center focus box only when the camera is a few feet from the subject. As the subject distance increases beyond 2-3 feet the focus assist light quickly falls out of the focus box in the viewfinder.

I realize that this is a necessity but shouldn't the focus assist light be centered in the focus box at a more common shooting distance - like 5 to 10 feet? When taking pictures as these distances the focus assist is useless.

Mainly, I just want to see if this is a design issue with all G-3's or just with this one - I am still within the refund period and can return it if it is faulty. Thanks.

[jyrgen]

I'm afraid it's a design issue with all G3-s. At least I have it too. I don't find this light of any assistance anyway, even if it falls into the focus box. Trying to learn focusing manually or using hyperfocal in such situations.

[jannez]

I have this issue also. In low light conditions I move the white frame in LCD to match with illumination point and solve the problem that way.

[ejwebb]

Thanks - just as I suspected... Have not yet had time to fiddle with the camera much but will try your suggestions. Thanks.

[12345Michael54321]

FWIW, focus accuracy is far more critical at short distances (2-3 feet, or less), than it is at, say, 8 feet.

An error in focus of just a couple of inches can ruin a shot taken at 2 feet. A similar error on an 8 foot subject will often not even be visible, especially at moderate apertures.

I guess what I'm saying is that if the focus assist light has to be optimized for some distance, it makes perfect sense to optimize it for short distances.

[nomel]

I noticed that sometimes I can get the camera to accurately focus in low light by aiming it slightly above the subject (or maybe it's below...).

Maybe someone could make an autofocus assist lamp that uses the existing lamp to trigger a large array of LED's attached where the hotshoe is! hrmm!? hrmmm!? Is that something you guy's might be interested in? I could draw up a schematic.

Anyone know any details about how the autofocus works, like which color of light might work best? I'm guessing it would be green. Yeah! more experiments to do this weekend!

[ejwebb]

Why couldn't Canon just allow the external flash assist to work - I have a 420EX and the ST E2 but their autofocus does not work. Oh, well... can't have everything!

[nomel]

What do you mean? is there an autofocus assist light on the flash? How is this controlled normally? Does the camera tell it to turn on the lamp? Or, does the autofocus assist lamp on the camera not function when there is a flash attached?

[PacAce]

nomel wrote:
What do you mean? is there an autofocus assist light on the flash?

Yes, on the EX series flashes. THat's what's behind that red plastic in the front and under the flash.

nomel wrote:
How is this controlled normally?

By camera's internal brain.

nomel wrote:
Does the camera tell it to turn on the lamp?

Yup.

nomel wrote:
Or, does the autofocus assist lamp on the camera not function when there is a flash attached?
Yes, if the flash is an EX series flash.

BTW, this is only true for the EOS cameras. Not the Powershot G series camera and hence the gripe of many G series owners.

[nomel]

sorry...a little slow today :)

BTW, this is only true for the EOS cameras. Not the Powershot G series camera and hence the gripe of many G series owners.

Which part, that the in camera flash assist lamp doesn't work, or everything?

So, from what I understand...when you have an EX flash on, the flash assist in the camera doesn't work, and the flash assist on the flash doesn't work.

Do these flashes actually communicate with the camera, or is it just making contact on two of the contacts, causing the flash to flash (or something equaly simple). Do you know how the camera knows it's an EX flash? Again, is it communication (like data), or is it just the contacts?

[PacAce]

nomel wrote:
sorry...a little slow today :)

BTW, this is only true for the EOS cameras. Not the Powershot G series camera and hence the gripe of many G series owners.

Which part, that the in camera flash assist lamp doesn't work, or everything?

So, from what I understand...when you have an EX flash on, the flash assist in the camera doesn't work, and the flash assist on the flash doesn't work.

Do these flashes actually communicate with the camera, or is it just making contact on two of the contacts, causing the flash to flash (or something equaly simple). Do you know how the camera knows it's an EX flash? Again, is it communication (like data), or is it just the contacts?

The focus assist lamp on the EX series flashes does not work with the G3. If you have a flash mounted on the G3 and turned on, the G3 will NOT make use of the focus assist lamp on the flash. However, the focus assist light on the G3 will still be used.

The G3 actually actually communicates with the EX series flashes via contacts other than the normal two used to fire the flash. AAMOF, the flash is used in E-TTL mode with the G3 although with the 550 EX flash, this could probably be overridden by shooting in manual mode. Although I don't know the specifics, the G3 does know that the flash that's mounted is an EX flash.

BTW, Canon isn't the only maker of flashes that work with the G3. Sigma and some others also make flash units that are compatible with the G3 and work similarly to the EX series flashes.

[nomel]

That's great!

Do you have any idea how the EX flash knows to turn on the focus assist lamp usually? How is the communitacion is actually done?

[flowe]

Hi all

Go to http://www.rkornberger.de/speedlite/

This site deals in German and English with the hardware modification of the 420EX to use the focus assist light with the G3 and some other features such as controlling the focal adjustment of the reflector.

I didn't dare to do it yet, but sooner or later...

[OmeRobbie]

I have a 420ex and a STE-2.

Has anyone tried these modifications yet? And does anybody know if the modifications also work for the STE-2? It would be nice if I could use the STE-2 instead of the 420ex as AF-assist permanently.

[Bean]

ejwebb wrote:
Why couldn't Canon just allow the external flash assist to work - I have a 420EX and the ST E2 but their autofocus does not work. Oh, well... can't have everything!

Because of the differences in the Focus types between the cameras, the Red autofocus sensor will not work with the G series, which uses a cheaper contrast type system.

[Bruce]

Focus assist light is not aligned with focus frame by design, AFAIK. The G3's passive autofocus system tries to guess focus by finding the lens position that maximizes contrast on a HORIZONTAL array of pixels. Having the assist light misaligned leads causes a vertical oriented contrast change that helps camera AF system to work effectively.
This means that subjects with horizontal lines only (landscapes, sea, horizon) can be difficult to focus on. In this situations rotating camera by 90 degrees just to take focus can help.

[Deckyon]

Instead of modifying flashes and worrying about slow focus, here is a tip that, for $10 you can solve all low-light focus issues.

Check out the following article. I am not stealing from this guy, but his tip worked so well for me, I have to pass it on. It will eventually make it to an article on my site.

The Use Of A Laser Pointer To Focus In Dim Light
(http://www.outdooreyes.com/photo76.php3)

I know of the Sony Mavica MVC-CD400, and up (maybe all CD models of the Mavica) use a laser matrix for low light focusing. I have used one and it works great. I tried out the method mentioned in the article and got the same great results.

[phili1]

Brad according to the article it is only good for short range, the problem I am having is at around 30 to 40 feet. Have you teseted it for long range.

[Deckyon]

I have and have had success. I bought one of the laser kits with like 40 tips with different patterns. It cost me $15. The more of a pattern the laser makes, the further away you can focus. Just play with it...

[phili1]

Brad which pointere did you buy and where.

[Deckyon]

phili1 wrote:
Brad which pointere did you buy and where.

I got mine at a novelty store "Spencer's Gifts" I do not remember brand. It has 42 different patterns.