Tamron 31A (200-500 5.6) vs Pentax 150-450 4.5-5.6

Started 3 months ago | Questions thread
xmeda
xmeda Senior Member • Posts: 1,759
Re: Tamron 31A (200-500 5.6) vs Pentax 150-450 4.5-5.6

gkreth wrote:

xmeda wrote:

gkreth wrote:

xmeda wrote:

Get Sigma 100-300/4 and be happy With K3 you have same reach as 150-450 on FF

Well, yes, a 300mm on a K3 has the reach of a 450mm on FF, but 450mm on a K3 has the reach of a 675mm!
Just looking for more reach, without dropping $1500....
Greg

You can always slap 1.5x TC or 2xTC on it and get 150-450/6.3 or 200-600/8

Wait, is that correct?

  • A 1.5X TC decreases the aperture by one full stop; so a f/5.6 would be f/8, not f/6.3.
  • A 2X TC decreases the aperture by two stops; ; so a f/5.6 would be f11, not f/8.

Am I missing something?
Greg

missing Sigma 100-300/4

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