[Klaus]

Sigma BF - is Sigma doing Leica now?
https://www.sigma-global.com/en/cameras/bf/

300-600mm f/4 DN DG OS:
https://www.sigma-global.com/en/lenses/s025_300_600_4/

16-300mm f/3.5-6.7 OS:
https://www.sigma-global.com/en/lenses/c025_16_300_35_67/

[Rover]

The 16-300 and 300-600 look like a natural combination... lol

[MLonlooker]

The 300-600mm F4 sounds about the pinnacle of where birders want to be in focal length
all for a price of around $/€ 6,000 .... for most F4 lenses you are looking at double that ....

next question is will it be available for the Z mount?

[Rover]

The 300-600mm F4 sounds about the pinnacle of where birders want to be in focal length
all for a price of around $/€ 6,000 .... for most F4 lenses you are looking at double that ....

  next question is will it be available for the Z mount?

It already is (inasmuch the lens itself is available)... with the tiny sliver of an E-Z adapter.

Anyway, I think most birders would probably find 600mm too short. Therein lies the rub, as the issue of TCs in E mount is notorious.

[MLonlooker]

Oh right so there is an EZ adapter ..... but really I'm talking about a native Z mount version .....

E mount ... shmmeee mount .....
....... of course I'm interested in the Z mount ..... I shoot mostly with the 600mm F4E FL sans TC ...... but it does come in useful sometimes (TC14E III) to get to 840 X 1.5 = on a D500 APSc = 1260mm .....
An awful lot of birders are happy with 500mm on a FF (750mm APS) .. so anyone who is looking for an F4 @ 600mm will jump at the chance of having a 300-600mm zoom range into the bargain ..... for half the price of an OEM fixed .....
No doubt the lens will be tested with a tele-converter (Z version) and if the results are decent, I see it as game, set and match, without resorting to the 4th and 5th sets.

[Rover]

Huh, of course there are multiple E-Z adapters on the market. Didn't you know?
I wouldn't count on a native version though.

[MLonlooker]

Huh, of course there are multiple E-Z adapters on the market. Didn't you know?
I wouldn't count on a native version though.   

    I know not of such things hence my moniker .... I onlook but I don't tread the paths of obscure adapters, let alone their multiple variants ......

   I'm asking myself why Sigma would deprive themselves of sales of the lens by not bringing out the lens in the Z mount .... but then?

[Rover]

Because Nikon did not authorize it, and would attack them with (legal) force if they go ahead and do it without being allowed?
Same deal as with the Canon RF system: only a smattering of third-party lenses with autofocus have been released in earnest, all of them for APS-C. With Nikon it's more nebulous; there are a few Sigma primes for APS-C, and a few Tamron lenses for FF, but there doesn't seem to be any pattern to this.

[MLonlooker]

Well it's a damned shame! .... yes looking on Thom Hogans Nikon page Sigma only has three general FL Z mount APSc lenses while Tamron has only two suitable for birding,
which according to Thom is because of a past Tamron/Nikon relationship. (Sony owns a share in Sigma).
Maybe if I won the lotto I might even switch to Sony for birding and see how their 10 million dot EVF fares .......

(I don't do the Lotto .... )

[joachim]

After looking a few Sigma BF reviews, this reminds me on the Olympus E-P1 release. But it is now 2025 now and not 2009 any more.