450d as teleconverter

I was looking at prices of new canon teleconverter...and I thought which would be the difference between a 1.4x teleconv and a used apc-s reflex...which is better and why?

Thanks

Those new tele-converters are designed to work especially well with the new telephoto lens that have and are being released now. So $500 when it's going with a $7000+ lens makes sense

The short answer is that neither is "better." There are only different applications. Many wildlife shooters (myself included) are at least pretty happy with APS-C cameras for making their long lenses longer, but not so happy that wide lenses become longer, and of course many of the cheap cameras are very iffy with their autofocus and other features.

450D loses a bit in resolution and features compared with the newer models, especially the 18MP ones. I think a 500D is pretty okay; not sure if I'd go to the older 450D, though it seems the only real difference is 12MP in the sensor and DIGIC III instead of 15 megapixels and DIGIC IV.

I have never been really happy with the T1i (500D's) metering; sometimes hand shake has caused the metering to apparently be focused on a different enough area of the photo that it decides to totally change its mind about the exposure. Autofocus isn't great either, especially at f/5.6 (i.e. a 120-300mm f/2.8 OS + 2X teleconverter = good quality but poor AF in some situations, and no bird tracking ability most of the time since it's too slow.)

That reminds me of another point - the new Canon TCs slow down the lens AF to improve accuracy. It's great for One-Shot and Servo mode - if you aren't crippled by that speed loss in acquiring the target and it doesn't move so quickly that the lens can't keep up with it at that slower speed. Many subjects won't have a problem with this, but some will.

The major benefit of using an APS-C camera is that you don't lose precious aperture and you get more (although smaller) pixels most of the time - however the full frame cameras do get more light onto the sensor ( = less noise, though only at the same aperture, obviously a teleconverter doesn't help this) and generally have better features, and many of them have pretty good pixel counts already so you can simply crop to your desired framing, which is essentially all a crop camera is doing. The smaller sensor cameras can put a higher percentage of "pixels on target" out of the total number in their sensor, but I would look at the noise characteristics of the camera at the ISOs you are likely to use (say in a DPReview review) compared to newer cameras, or (ideally, if DPR lets you) compared to the full frame camera you already have.

Personally, I would not buy a 450D as a replacement for a teleconverter unless I had the ability to try it out and see that the results were to my liking. It's hard to argue against the price and not losing aperture, however.

Josh13 wrote in post #13086499
Those new tele-converters are designed to work especially well with the new telephoto lens that have and are being released now. So $500 when it's going with a $7000+ lens makes sense

He hasn't said he's looking at a new teleconverter or that he is using a $7000+ lens, however. You're right though, the newest Canon TCs are both $500 and I am quite happy with the 2X.

I'd suggest the older 'MK II' versions of the Canon TC's or one of the high end 3rd party selections like the Kenko 'pro' line. These are all much more affordable and (at least for the 1.4X versions) good performers.

A smaller sensor all by itself does nothing to increase reach. Higher pixel density can give a bit, but only if the limits to resolution that you are seeing are due to pixel count and not due to lens performance (in terms of resolution). Keep in mind that the older 8MP 1.6X format bodies have -zero- reach advantage over a 5D Mark II or 1D Mark IV.

JeffreyG wrote in post #13086597
A smaller sensor all by itself does nothing to increase reach. Higher pixel density can give a bit, but only if the limits to resolution that you are seeing are due to pixel count and not due to lens performance (in terms of resolution). Keep in mind that the older 8MP 1.6X format bodies have -zero- reach advantage over a 5D Mark II or 1D Mark IV.

Truly stated, but the 450D is a 12MP camera.

I think the way to tell if a camera is going to be substantially worth getting is by comparing pixel pitch directly (or pixel densities if you can find it) - the problem with APS-C cameras is that they will have to have a significantly smaller pixel pitch but this may be a symptom of a sensor which performs markedly worse in low light situations.

Some of it depends on what body and lenses you currently have.

crn3371 wrote in post #13086690
Some of it depends on what body and lenses you currently have.

True this -- the OP left that out, which is relevant data!

To the OP, an APS-C sensor doesn't really "act like" a 1.4xTC (or a longer focal length on a full-frame sensor/body, although it gets a similar "image circle" with typically "more pixels on target".

But with is good lens you could get some mileage using a TC and an APS-C body!