Stoop, it's the age old question
- how to get more reach, better, for less :eek!:
I will leave FF vs APS-C deliberations to you, as you would have a good handle on that, and let you know of my solution, since I am in a similar sort of boat.
I use the Nikon D7100 and Tamron 150-600mm f6.3 with a Black Rapid Sling as an all purpose rig with lots of walking around (never tripod). I can highly recommend the setup (within its limitations) and especially the sling - walking around is what gives me great joy o
I always shoot in 1.3x in-camera crop mode (it gives 1 extra fps, and much needed reach).
You can check out some results in my user gallery. I have many more shots to post after I wade through the processing, as I've only just passed the 10,000 shot learning curve. All things considered, it's probably a genuine 1150mm 35mm equivalent at full stretch and mostly it stays there, though in maybe 10% of conditions a raptor will co-operate and I can zoom back in, and there's maybe another 10% where good lighting and distance planets align where I can zoom back in to 500mm (~950mm eq), or less.
I will leave you to research the Tammy vs Siggy Contemporary question, and just give you what I have found with the Tammy.
1. The closer the distance, the better the result.
2. There will be unit to unit variation, mine seems pretty average.
3. According to the test sites, stopping down from f6.3 to f8 at 600mm helps. I try and do this at longer distances, but for small birds close in will open up, unless the background and light allows me to stay stopped down.
4. Likewise the last 50mm at the limits of the tele end seem softer, so where possible I throttle back to 500mm.
5. I seem to have settled on single point focusing as the way to go in all but the brightest of light and zoomed back, where the 3-D tracking mostly keeps up.
6. With the D7100, AF is great for the first 4 frames in a burst, and then the limited buffer kicks in and the rig audibly chugs away making staying on the bird a bit harder. It helps not to get too excited and refrain until the distance and aspect (for exposure/lighting) of the bird is optimal before unleashing a continual burst.
7. I have always liked zoom setups as a framing and composition tool, and this rig is really handy and lots of fun to shoot.
8. The VR gives some ridiculously good results sometimes, but a bit of experimentation around your preferred shutter speed is worthwhile to see where the best results lie with your own particular frequency of shaking.
I have a mate who shoots Canon 7DMarkII with a 300mm f2.8 and 2x TC. You wouldn't think that extra 1/2 stop of light would make that much difference, but combined with the quality of that glass, and better, more experienced technique (and often a tripod) the difference can be slightly depressing at times, producing sharpness that I'm very jelly of. At other times I've got the gems, but generally it runs 80-20 his way. His missus shoots a 400mm f5.6, and generally I have the wood on her, but it can be closer to 50-50 close in, with techniques and tripods making bigger differences.
Sadly, and oddly, Nikon has not deemed fit to send its 300mm f2.8 on a diet yet??? If you don't mind the extra 600grams (over what it could be - Canon weight) it might be an option. Or use a Tammy or Siggy until they do lighten it up -- surely that can't be far away? - all the rest of the range has been to 1800Jenny ! :-O
Hope this helps, Chosun :gh: