Wednesday, January 16, 2008

Pop-up Bounce Flash

I think its well known that the pop-up flashes on most DSLRs produce less than flattering results. The direct blast of flash usually robs the shot of color from the environment and is usually harsh. For flash photography, people usually look for soft, diffuse lighting. One way to do this is to use 'bounce flash' where the flash is directed at a surface in the scene which then reflects it around over the entire scene. On most DSLRs however the pop-up flash faces only one direction, right at the target, making it difficult to use bounce flash. At least thats what I thought until earlier this week. With a 5 cent tool and about 10 seconds of time, one can easily convert the Rebel XTi's (and the Rebel XT's) pop up flash to use a bounce card.

The job is simple:
  • Find a plain white business card
  • Pop-up the camera's flash and look for the two metal rods that hold up the flash
  • Line up the business card so its centered over the rods and make a mark
  • Use a pair of scissors and make about 1/2" cut where you marked
  • Now slide the business card so that is snug with the rods sticking into the business card
You can control the angle of the bounce card just by rotating it up and down. The results using this simple method are surprisingly good. In the top picture, the left was taken with direct flash and the right with the 'business card' installed. Same settings the only difference was the one on the left had flash exposure compensation set at +2EV. Since the camera sets the flash power for direct flash, you'll need to compensate for the light loss caused by diffusely spreading the everywhere by dialing up the flash exposure compensation.

This trick works well for longer focal lengths but really doesn't work well for shorter ones, so it'll be good for a portrait but not good for photographing something like an entire room. I also just checked to see if you can do the same thing with the 40D and sadly you can't, the flash's pop-up mechanism is slightly different on the 40D.

I learned about this from a photography website, sadly I don't remember which site it was. Despite its limitations I think it'll come in handy in a pinch, and hey all it requires is putting a business card in your camera bag.

Technical Specs (only for top picture): Canon Rebel XTi, 17-85@61, f/5.6, 1/80s, ISO 1600.


Michael said...

Nice! That's a really cool simple solution, and definitely easy to have in your camera bag at all times just in case you need it!

One question though: I thought the camera still uses the E-TTL II preflash with the pop-up flash to determine the flash power to use when exposing the scene. So in that case why would the flash compensation need to be adjusted? Shouldn't the fact that the preflash is bounced as well cause the camera to naturally boost the flash to compensate?

Aravind Krishnaswamy said...

You are indeed correct. I completely forgot about the preflash. So yes, there shouldn't be a need for exposure compensation. I'll have to investigate further tonight.

Tiffany said...

I know this post is a few years old, but I just found it and tried it out! This will definitely help out when I need to use flash. Thanks! :)