Canon xTi won't power up

Make sure both the lens and the camera are switched to af (auto focus). If that doesn't work remove the lens and replace it to make sure it is mounted properly. You can also check the camera with a different lens to make sure it isn't a problem with the settings on the camera. If all of that fails take it to a camera or electronics store that does service work to make sure it hasn't been damaged.

Hiyou might have a problem of either main pcb or power control pcd (dc/dc convertor). it is common but it cost. It cause usually come from loosen screw going around inside and short. If it is lucky, then your unit would just a fuse brown. If not, it has to change main pcb and all of computer adjustment is involved. Your local repair shop would charge you around $65 to 235.

http://www.usa.canon.com/cusa/support/consumer/eos_slr_camera_systems/eos_digital_slr_cameras/eos_digital_rebel_xti_ef_s_18_55_kit#DriversAndSoftware

Rebel XTi Digital Camera with 18-55mm lens drivers at above link.

Make sure the 420EX is set to E-TTL and set the camera to "P". If is need of more light, increase flash exposure to +1 or 1.5.

If you are new to photography in general and especially SLR photography I would suggest holding off on buying any lenses besides the 18-55mm.

The reason I suggest not buying extra lenses just yet is coz you need to get to know your camera and if you are new to SLR photography then you need to get your fundamentals right. Sure the 400D will let you shoot in full auto mode but you will really not learn much doing that and certainly not be making the most of your camera in that process and that will extend to your new lenses too.

Get used the the control, the 18-55 is a great little cheap lens with the pop up flash it will work great for most family pics. The 55-200mm is a new "cheap" lens, its been marketed as letting you go beyond 55mm thats why it starts at 55mm goes to 200mm.

Hope this helps you...

Having same issue as above - I thought it was my cable so I ordered a new one. The camera attempts to 'speak' to the pc - and then the Windows box pops up not recognising the USB installed device....I also uninstalled and reloaded the Canon software (had camera for 18 months and only started this rubbish a month back) - was about to re-laod my entire PC - thankfully I saw it was not only me.

Will send mine in for a Firmware update / service.

Make sure that the switch on the lens is set to AF. If that doesn't work, you may have a faulty lens. The EFS 18-55 is not a high quality lens.

If you're on a budget, the 50mm f/1.8 II is a great deal, $100ish, f/1.8 is great for low light.

If you have a bit more cash, the 50mm f/1.4 has better build quality (the 1.8 is all plastic) and much better autofocusing (its USM so its fast and quiet, as well as more reliable) and its also slightly sharper.

If you want a zoom, from canon theres the 17-55 f/2.8, which has image stabilizer and USM focusing.
Also, the 24-70mm f/2.8L, which has USM, and since its an L lens, fantastic optical quality. However, it will run you over a thousand most likely.

From sigma, theres several zoom options, the 28-70mm F2.8 EX DG, 24-70mm F2.8 EX DG MACRO, and 24-60mm F2.8 EX DG. All under $800 or so.

appears to be a defect and not user serviceable.
sorry for the news.
good luck.
mark.

same issue here, but with 18-200mm. worked for 18 months fine.