My camera is a Canon Digital Rebel XT.

How do I take pictures of shiny objects like coins and videogame
arcade machines in environments where it's impractical to set up my
own lights?

Right now, I either take the picture at an angle or I turn off the
flash and bump up the exposure time. Taking it at an angle doesn't
really give me the picture I want and bumping up the exposure can
result in a picture that's redder than it should be. The latter can
also require a tripod if I need to bump it up too high.

It'd be nice if there was a way to make the flash diffuse so that I
could take a picture straight on without having a little white star in
the middle of the image.

I know that there's a circular flash that goes on the end of the
lense, but that would only work for small objects right?

I've tried using a polarized filter, but I can't see any difference in
the test pictures I've taken no matter which way I rotate the filter.

HI mxnmatch!! 


What you need to do is to make the flash light "diffuse"; there are
specific devices made for the dedicated flashes (like the 420EX -
http://www.dpreview.com/news/0508/05082206canon430ex.asp -).
See for example:
"Sto-Fen Omni Bounce":
http://www.stofen.com

and
"LumiQuest":
http://www.lumiquest.com


The above solutions are the indicated for the dedicated flashes 430EX
and 550EX because they compensate the reduction of the amount of light
that your flash unit produces:
"6) I?ve put a diffuser or reflector on my flash. Do I have to
compensate for this somehow?
Diffusers of any kind obviously reduce the amount of light that your
flash unit produces. You?ll find a similar effect if you bounce the
light from your flash unit off a wall or into a photographic umbrella.
However, so long as you?re using automated (TTL, A-TTL or E-TTL)
metering then the camera will compensate automatically. There is no
need to adjust anything.
You?ll have decreased range, but you shouldn?t have any exposure
problems unless you?re too far away from the subject and the decreased
range now means you?re out of range. Diffusers can easily cost you at
least half your flash range, depending on the type."
From "Flash Photography with Canon EOS Cameras - Part I.":
http://photonotes.org/articles/eos-flash/


Regarding the diffusers see the following chapter at the "Flash
Photography with Canon EOS Cameras" article, you will find some
interesting notes about LumiQuest and StfoFen devices and the
following regarding a "cheap homemade diffuser":
"Finally, don?t think you have to spend the money on these
accessories. You can always just slap together a homemade flash
diffuser out of a white translucent milk jug or tracing paper or thin
fabric or whatever else you have lying around. A common trick is to
angle the flash unit vertically, then use an elastic band to wrap an
index card around the back of the flash head. This provides some
forward light in addition to the light bouncing off the ceiling. The
expensive accessories are mainly just more convenient and
professional-looking."
http://photonotes.org/articles/eos-flash/index3.html#diffusers


Here are the links to the 3 parts of the "Flash Photography with Canon
EOS Cameras" article:
Part 1: http://photonotes.org/articles/eos-flash/
Part 2: http://photonotes.org/articles/eos-flash/index2.html
Part 3: http://photonotes.org/articles/eos-flash/index3.html


More articles about homemade diffusers and related topics:
"eBay.co.uk Guides - Using Flash Photography - Direct and Diffused Light":
http://reviews.ebay.co.uk/Using-Flash-Photography-Direct-and-Diffused-Light_W0QQugidZ10000000000777711?ssPageName=BUYGD:CAT:-1:LISTINGS:1

"DigiHack - Digital Photography projects: Macro Light Box":
http://www.dennisonbertram.com/hackmaster/2005/02/macro-light-box.htm

"Flash diffusion": (You must need to pay to become a member and gain
access to the article)
http://www.photographytips.com/page.cfm/281



Search strategy:
flash photo "shiny objects"
flash photo "shiny objects" canon rebel


I hope this helps you. Please do not consider this answer ended, feel
free to use the clarification feature if you find this answer unclear
or incomplete before rate it.


Regards,
livioflores-ga

Good stuff. Thanks!