ST-E2 and rebel xt and 17-55/2.8

[s_hassan]

I am confused. I would like some help. I recently purchased an st-e2

transmitter and when it is on the hot shoe and is turned on the camera changes

the shutter speed. Remember the camera is in AV Mode(aperture priority) and as

far as I know whether flash is on or not the shutter speed does not change in

the aperture priority mode whether flash is on or off. So for example just now

i took a picture with ste2 off and I had 2.8 with 1/60 and when i turn it on

the seeting gets changed to 2.8 and 1/125. and it underexposes the picture.

The camera seetings exposure and flash compensation are 0.

 

I will appreciate the help. Is it a fault in the camera or the st-e2. should i

return it.

hassan

[steve_parrott]

As far as I know, you are correct, the shutter should not change regardless if the ST E2 is

on or off... or a flash mouted to the hot shoe should also not affect it... as long as you are

in AV priority mode, which you said you are. I use my ST E2 on my 1DS to remote fire my

580 EX, and it certainly does not change any of my settings when I have it on or off. Maybe

someone else knows why yours is doing this, but I definitely think it is NOT supposed to.

[mark u]

Read this:

 

http://photonotes.org/articles/eos-flash/index2.html#confusion

 

and this

 

http://www.eosdoc.com/manuals?q=NEVEC

 

and note that with flash in Av mode, evaluative ambient metering supposedly places more emphasis on the background (and by implication less emphasis on the subject). Turning on or off an ST-E2 will cause the camera to believe that flash will or won't be used. From what you describe, perhaps you were trying to photograph a Black Labrador in a room with white walls? Maybe you should be using partial metering and exposure compensation.

[PuppyDigs]

I'm afraid Steve is wrong here. The reduction of amient exposure during fill flash in low

light is a long standing "feature" of Canon EOS bodies with E-TTL. TTL bodies didn't do

this as well as the first generation of E-TTL (Elan IIE and EOS IX). Both my 1999 EOS 3 did

it and my Elan 7E. All my DSLRs are the same.

 

There's even a name for this feature:NEVEC

 

You can read all about it at:

 

http://eosdoc.com/manuals/?q=NEVEC

 

And, yes, when you place the ST-E2 on your hotshoe you camera "thinks" you'll be using a

flash. If you merely want to use it as AF assist, you need to disable the flash/enable AF

assist via CF and thus defeat NEVEC. Not sure if a Rebel has this CF but my Elan 7, 10D,

20D, 5D and 40D all did. Your ST-E2 is working correctly.

 

Incidentally, NEVEC still bothers me after all these years and I add EC to offset when

appropriate...

[PuppyDigs]

Incidentally S, you might be able to disable NEVEC by using PARTIAL or CENTER-WEIGHTED

metering mode. Works on some bodies but not all.

[s_hassan]

I think I should clarify my question a little bit. I noticed this problem when I started using the ste2 but now even when I am not using the ST-E2 and still use the camera in Av mode the shutter speed doubles when I open the camera's own built in flash and slows down when I push the flash down. This is surprising behavior by the camera. I just went to best buy and tried a 40D and an XT and XTi and in all of them the shutter speed stays constant whether flash is open or not, but in my camera shutter speed is different when flash is on and when it is closed.

Any thoughts are welcome.

 

ps. this behavior became apparent after I just bought and started using 17-55/2.8IS and bought ste2 with two 580exII(Kit from Adorama). I dont know if the new lens or the new STE2 caused a problem in the camera.by the way adorama's kit says it is USA warranty but the ste2 box has manual in japanese only and no english manual, and its warranty card says international warranty. the flashes have usa warranties though. you can check the link http://www.adorama.com/CA580EX2UK.html?searchinfo=st-e2&item_no=2

[mark u]

Are you sure the shutter speed doesn't change to 1/200th rather than say 1/125th? Have you checked the setting of CF 3 (see page 148 in your manual)?

[s_hassan]

yes the custom function 3 is set to '0' (Auto) and the speed changes to double of whatever it is when the flash is off. say if it was 1/60 it will become 1/125, and one more thing i noticed just now is that it only happens in Av mode when the metering is set to evaluative and this phenomenon disappears if I set the metering to partial of center weighted. I never noticed it before. to me it looks like a new behavior. i dont know if anyone else can check it on their camera. I will rush to best buy again before the close tonight and check it to see if the display cameras have this behavior when the metering mode is changed in AV mode.

[wandern]

Puppy Face's two posts contain the answer to your query, and also the solution to it: NEVEC, and your metering mode (which you in fact refer to in your last post). Please read the documentation he links to and you will understand.