300 F2.8 & 2X teleconverter or 600

The 300 + 2XTC is as good as the 500 or 600 + 1.4XTC.

The real question between 300 2.8 and 600 f4 is do you want 300, 420 and 600mm (with the 300 2.8)

Or do you want 600mm, 840mm and 1200mm (with the 600)

1200 mm on the 600 needs a 1 series for AF.

Here is the 600 with 2XTC for 1200mm.
http://www.hikingplane​t.com/pics/IMG_8026.JP​G

If you expect to always need a longer focal length - go with a longer lens. I don't see any sense in buying equipment of this caliber and then always degrade image quality with a 2x TC.

The 1.4x is fine but the 2x visibly lowers image quality to a degree I don't accept. As a last resort if you can't get close enough, sure, but not for every shot.

I do not agree that a 300+2x is as good as a 500+1.4. I do own both lenses and TCs and I leave my 2x at home these days. Just about the only lens I think the 2x works reasonably well with is the 300/2.8 so I still keep it on the off chance I'll have limited space and will carry the 300 plus both converters instead of the 500/4. Hasn't happened yet though.

Have you seen this thread?
https://photography-on-the.net/forum/showthre​ad.php?t=227242

The MTF charts with the 300mm/2.8 + EF 2X show very respectible performance, athough obviously not on par with the 600mm.

Also checkout the photozone test which also has results with the EF 2X on APS-C.

canonshooter4life wrote in post #2257846
...why would AF be the biggest problem my 400 f5.6 focuses just fine at 5.6 wouldnt the 2.8 and a 2X TC be essentially f5.6?
Brandon

That's an interesting question that goes right across the line-up, for example the 300/4 + 1.4X AF is slower than the 400/5.6 and the 200/2.8 + 1.4X is slower than the 300/4 or 200/2.8+2X slower than 300/4+1.4X although all the max f-stops pair up.

I can only assume this is something to do with control loop gain, but I don't see why Canon can't fix that in software.

If you cover the TC pins with tape the AF then tends to be underdamped and thus inaccurate or hunt, a clear sign of the control loop gain and bandwidth not being right.

So my assumption is Canon turn the control loop gain down to make the loop criticly damped, but why they can't do this in a way which preserves AF speed at the new max fstop I don't understand.

Of course, it could just be a marketing decission to ensure we all pay for more lenses....

Oops,
my mistake. I'm so used to working with the f4's, I completely overlooked something very obvious. Yes, Billingthekeys is completely correct. The 2.8 aperture of the 300 will allow you to use the TC's as stated.

Thanks guys you really helped me out i think ill go with the 500 but if i cant then the 300 it is...

Thanks

Brandon

try look around at B&S forum (here, fredmiranda) or ebay. Sometimes good deal may appear