EF 300mm f4L IS + 2X TC or Nikkor 500mm f8 reflex

[mcgarity]

A week or two back I read about an adapter that is now available to

allow mounting manual focus Nikkor lenses on EOS bodies. For $28 I

didn't even try to resist temptation. I bought one even though I

currently do not own any Nikkor lenses.

 

One thing led to another while searching the unmentionable site for

Nikkor bargains. I came across several listings of Nikkor 500mm f8

reflex lenses. From what I have read 500mm mirror lenses are not

terribly well thought of. Out of focus highlights can have weird

doughnut shapes and they are supposedly prone to vignetting. I am

thinking that with the crop factor on a 300D or 20D vignetting might

not be an issue.

 

All of this led me to speculate about how the optical quality of a

mirror lens would stack up against an EF 300mm f4L IS with a 2X

teleconverter? I'm certain the 300mm on its own would blow the

mirror lens away. But with the degradation of a 2X TC it might be

another story.

 

I don't have the 2X TC yet but I do own the EF 300mm plus a 1.4 TC.

Thats one sweet combo and I have absolutely no doubt it would beat a

mirror lens hands down.

 

I suspect I would really be better off just buying a 2X TC to use

with my EF 300mm, than spending money for a Nikkor 500mm f8 mirror

lens. But you never know till you ask so I am asking. Is the mirror

lens worth giving any consideration to at all? And before someone

attempts to educate me, I know the focal lengths don't match up but

they are close enough.

[User_1172872]

Having used one each of the two versions of the Nikkor, as well as the 300 + 2X combination, I think these are equally poor choices. In my experience the 300 + 2X had to be closed down 1.5 stops to regain the sharpness of the 300. The older 500 Nikkor can be had used for about the price of the 2X alone; mine did show signficant fall-off in the corners but was very sharp in the center. On the other hand the true aperture [t-stop] seemed much closer to t/11 so in practical terms it's not that much faster than the 300+2X stopped down a bit. My advice: save your pennies until you can buy the canon 400mm. Mine works quite well with the 1.4x, a very usable 560mm f/8. On my EOS-3 autofocus is reasonably fast and accurate.

[bobatkins]

There's little or no point in going for a 500/8 if you have a 300/4 + 1.4x. You're only going from 420mm (with AF) to 500mm (without AF), plus you're dropping from f5.6 to f8 (at best, probably more like f9 or f10) and loosing a lot of quality.

[mcgarity]

Thanks for the answers guys. Thats what I wanted to know. Guess I will save my money.