The Nikon lens MAY ( probably is ) be sharper than the Tamron 150-600, especially when the Tamron is at full zoom 600mm.
But the Nikon f4 300 with a 2x TC will give you a 600mm f8.0 lens. The Tamron lens at 600mm is f6.3 so it will be a bit brighter and MIGHT AF a tiny bit faster.
I would suggest stopping down either of these choices at least 1 -> 1.5 stops less than wide open, for a bit more sharpness. As you can see, either lens at 600mm is not going to be very bright in low light.
Which is sharper at 600mm may depend on individual lens variation. I am inclined to favor the Nikon lens, but with a 2x TC on the Nikon, they may be pretty close.
Either choice will require a good tripod and long lens technique to best utilize what they offer.
I own the Tanron 150-600 and a 300 prime, so I don't strongly favor one over the other.
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But the Nikon f4 300 with a 2x TC will give you a 600mm f8.0 lens. The Tamron lens at 600mm is f6.3 so it will be a bit brighter and MIGHT AF a tiny bit faster.
I would suggest stopping down either of these choices at least 1 -> 1.5 stops less than wide open, for a bit more sharpness. As you can see, either lens at 600mm is not going to be very bright in low light.
Which is sharper at 600mm may depend on individual lens variation. I am inclined to favor the Nikon lens, but with a 2x TC on the Nikon, they may be pretty close.
Either choice will require a good tripod and long lens technique to best utilize what they offer.
I own the Tanron 150-600 and a 300 prime, so I don't strongly favor one over the other.
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