Should I get an EF 100-400 for my EOS R7?

[jinto26]

Is it a Good choise to buy a seconde hand EF 100-400 is II usm.. Also a converter 1.4.

Now i'm using the rf 100-400.
I want better pic and faster working.

Also it is cheaper then bying the 100-500.

So the question is. Is the slim and Good solution

Thanks

[shadowsports]

Greetings, 

That's a hard question to answer. The EF 100-400 mkII is still sold new.  However,  I would probably buy used if I was going to invest in EF glass. So you buy a used lens, a used EF 1.4x TC and an EF to RF adapter.  How much savings is there between that bundle and a used RF 100 500...  About $150-400 dollars.

I might look more deeply at what I currently owned and my future goals.  Do you own other lenses that you're going to be able to use the TC and adapter with?  If not, it might be better to go with the native mount.  I would be happier with less length on the front of my camera.  That extra 100 mm of native focal length also means you're not going to lose any stops using a TC.   I also don't use any of the EF glass I have left.  There's always another perspective or different way to look at it.  Lowest possible price versus a future proof investment.

[deebatman316]

@jinto26 RF camera stick with RF lenses don't bother with adapting EF lenses unless there is NO RF Mount counterpart. 

[pzphotomama]

One thing you need to remember is when you use a converter 1.4 - you are loosing light - so if the lens is 4.5-5.6 you need to x that by 1.4 - so it would be 6.3-7.84 so you aren't gaining much at all by getting an older lens and then adapting. I have the EF 100-400 myself and its a beautiful lens however adapted, its not going to be as fast as RF would be. The RF 100-400 is 5.6-8 so you are gaining nothing by making this change other than spending money.