Originally posted by normhead My Tamron 300 2.8 with the 1.4 gives me 420 ƒ4. Sigma also make 300 2.8., and I believe they have a 2x for theirs.
The Tammy with the 1.7 gives me 510 4.5... an A*300 2.8 with the F 1.7x AF Adapter also gives you 510 with limited AF. On the K-3 thats almost an 800mm FoV and still not 5.6. There are just to many cheaper ways to get there.
Had to read that a few times; do it fast and out loud and people will start to stare...
I do think I would benefit from a 300mm f2.8 and a 1.7/1.4 tc...
Though, it would be nearly impossible to get rid of my DA*300. I just love that lens.
Unless there was a DA*400 - I know it's unrealistic, but I can dream a bit.
I wish someone lived near me that had the setup you talk about and I could test it out first hand.
I'm putting money away towards a purchase. It may be a while.
I would love to get a Sigma 500mm f4.5, but that's not gonna happen anytime soon... if ever according to my wife
---------- Post added 12-15-16 at 02:34 PM ----------
Originally posted by biz-engineer Pentax already covers 300 f4 to 560 f5.6 for static shots. The only thing they don't cover is 300 f2.8 or 400 f2.8 for when freezing motion is a must (fast shutter speed + medium ISO) but they would also need a kick ass AF to go with the 300/400 f2.8.
Shooting along with Canikon 400 f4 to 600 f4, for static shots they don't have much advantage over the f5.6 lenses of Pentax.
That's fair.
I know I wouldn't be able to afford a new production 400mm f2.8. That lens would likely be very large and very expensive.
---------- Post added 12-15-16 at 02:36 PM ----------
Multiple people are telling me, "If you ever want to take wildlife photography seriously, you'll have to give up Pentax"
I'm trying to find a way to prove them wrong.
Reality - If I ever want to take my wildlife photography 'seriously' - not that I don't already... - I'll likely need to sell a few organs...