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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 20 Feb 2011 (Sunday) 21:08
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Canon T2i & Promaster 7500edf flash - exposure issues - any suggestions?

 
forevermephotography
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Feb 20, 2011 21:08 |  #1

Camera: T2i

Flash: Promaster 7500edf (ttl enabled)

I am still having a problem with the exposure when using this flash. :(

Canon has an exposure bar on the display screen that shows when you have a perfect exposure. It looks like this: -2...-1...0...+1...+2

Without an external flash, it works perfectly. When I attach my external flash (either ON the camera or off the camera), the camera doesn't seem to take into consideration the light it will throw when determining exposure.

For example, let's say I'm indoors. I have my shutter speed at 1/200, my aperature at 5.6, and my ISO at 400. My exposure, using these settings, is showing low, with the line at -1 on the exposure bar. However, when I use the flash, the end result may be blown (way overexposed).

Is there a way to get the 2 of them to talk to each other so that the camera can see what the flash will do to the exposure and display it on my screen? Anyone know? This is driving me nuts! LOL


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ThePwnyExpress
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Feb 20, 2011 21:11 |  #2

Do you have the flash set in TTL mode? That flash is designed to work with that camera so it should meter properly considering flash output. However if you have the flash in manual mode then you will be forced to shoot in manual mode on the camera and compensate your shutter speed / aperture settings to your flash output for proper exposure.


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forevermephotography
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Feb 20, 2011 21:13 |  #3

Yes, I have it in TTL mode.


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Feb 20, 2011 21:19 |  #4

Not sure if any answers may be answered here: http://photonotes.org/​articles/eos-flash/ (external link)


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lannes
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Feb 20, 2011 21:21 |  #5

Promaster's compatibility sheet says it's not compatible with the T2i, best check with them directly.

http://www.promaster.c​om …ducts.asp?produ​ct=7500EDF (external link)


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ThePwnyExpress
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Feb 20, 2011 21:28 |  #6

I would make sure the firmware is up to date as well. I have sold many of those flashes and I am certain a few of them to people with T2i's and haven't had one come back for incompatibility reasons. I believe that compatibility sheet on their homepage is old.

Edit: Yeah, the document is labeled 1/1/2010 which is a few months before the T2i was released.


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forevermephotography
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Feb 20, 2011 21:35 |  #7

I bought the flash at the camera store and was told it is compatible. It works fine - I've used it a lot (mostly as a slave for studio type of work). I don't think the compatibility is an issue.


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forevermephotography
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Feb 20, 2011 21:41 |  #8

Okay...so I read the info you posted, ThePwnyExpress. From what I understand, when shooting in manual mode (which is all I ever shoot in usually), you can set your settings however you want. The camera then talks to the flash and together, they determine (based on those settings) how much ambient light is available and how strongly the flash should go off. The flash then adjusts itself to give me a correct exposure.

I tested this out - the first shot came out correctly exposed. I then set my settings unbelievably dark (shutter speed 1/200...aperature 20....iso 100) in a not-so-lit room. The exposure, though able to see it, still came out dark. This might be a case of the flash just not having enough power to light it under those extreme settings.

I get all of this. What I don't get is this...

When I set it and got a good exposure, on the display it STILL says it is a "-2" on the exposure meter, even though it came out perfectly exposed. I still can't figure out how to get the camera and flash to talk to the degree that I can look at that bar, BEFORE firing the photo off, and tell if it will be properly exposed. IF I could do that, I would have been able to tell the other would be too dark, and adjust my settings accordingly.

Grrrr! LOL


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dedsen
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Feb 20, 2011 21:54 |  #9

You cannot rely on the exposure meter on the camera when using flash. The meter in the camera is a reflective meter. It measures the light reflecting off your subject and back in to the lens. It cannot measure light that has not been produced by the flash yet. You control the flash exposure with the aperture, the flash power setting and the ISO. If you are shooting in eTTL mode you can use the Flash Exposure Compensation (FEL) to turn the flash power up or down. The camera tries to decide how much power is needed from the flash by firing a pre-flash just before the actual exposure. This pre-flash is measured as it hits the subject and the camera trys to set the flash power. It can be fooled by dark or reflective surfaces. This is when your use + or - FEC to get the exposure you are looking for.
Shooting with flash is a whole new situation. There is no magic bullet to make it work. You need to read and learn as much as you can about it to understand how to get the best out of your flash.



  
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bryank930
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Feb 21, 2011 00:48 |  #10

I'm having similar problems with the same flash on my 60D. I just can't get a proper exposure. No matter what shutter speed, ISO, and aperture I select, all shots with this flash are underexposed. I just bought it a couple days ago, so it'll be getting returned.


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Shooting
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Apr 12, 2011 20:26 |  #11

What kind of batteries are you using? When I bought that flash I was told to use 2700 mah or higher..anything lower will give exactly what is produced here, inaccurate readings due to the low power not sending the right signals back and forth from camera to flash. At least that is what promaster told me and they were right as far as mine goes. Been using 2700 ever since and I get just as cconsistent results as my 580ex II.




  
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Shooting
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Apr 24, 2011 16:55 as a reply to  @ Shooting's post |  #12

Well, I take back my last statement. Today while shooting some easter shots I was using my 50D in manual mode and Promaster 7500edf in ttl mode..worked fine until the standby mode kicked in on the flash..when I depressed the camera's shutter button wake the flash up, every shot after that was underexposed and I noticed the ttl light did not come on after waking it up. Had to take the flash off, put it back on the camera and then it worked fine until after being woke up again from standby mode. I guess if I could get it from going into standby it would work fine, I dunno. I had the same problem with the 7500dx..all shots would be underexposed after flash woke up from standby mode AND after switching camera from auto to manual back to auto..had to take the flash off, put it back on and it would all work fine for about 10 shots before screwing up again. So far the 7500EDF only screws up after being woke up from standby mode. But I use mine on the Canon 50D




  
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Canon T2i & Promaster 7500edf flash - exposure issues - any suggestions?
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