You've got no gear at all - Would you get a 5DMKIV or D850

Charlie wrote in post #18969747
I dont think canon was countering nikon, the 400 and 600 came out nearly the same time as the Sony 400 and 600 of the same respective aperture, and Canon even beat sony by a few grams for good measure! Sony had the worlds lightest 400 f2.8 for seconds

I am sure the newer Canon 400mm f2.8 and 600mm f4 are fantastic lenses, at $25,000 for the pair they better be, the Nikon 300 f4 PF and 500 f5.6 PF can be bought for $5600 for the pair, I wish Canon would make equivalent lenses for those us that own Canon cameras.

Canonuser123 wrote in post #18969786
I am sure the newer Canon 400mm f2.8 and 600mm f4 are fantastic lenses, at $25,000 for the pair they better be, the Nikon 300 f4 PF and 500 f5.6 PF can be bought for $5600 for the pair, I wish Canon would make equivalent lenses for those us that own Canon cameras.

I have the very old 600mm f5.6 nikon that I adapt, same. I'm hoping someone with out the box thinking can make it like Tamron or Sigma, they are willing to go unconventional, and for the first time ever, I sigma has started to make somewhat smaller lenses for L and E mount, smallest in class 14-24 and 24-70. Tamron has a 70-180 f2.8 that's as small as the 70-200 f4! a lightweight 600 f5.6 or even 800 f8 would interest me.

I must say the Nikkor 200-500mm is no slouch either, and the D850 allows for massive cropping.

Bee on Clover Flower

Taken with a Nikkor 200-500mm lens @ 500mm a very impressive lens these are for the price.

Tom Reichner wrote in post #18969735
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Jake, it seems that you are not understanding me here.

To me and the way I shoot, and what is important to me in an image, large maximum apertures have nothing to do with low light, and nothing to do with the exposure triangle, and everything to do with depth of field.

That's all that matters when it comes to aperture, is having the ability to blur things out a wee bit more. . And that has nothing to do with whether I am using an old body or a new body.

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Ah, I see. I wasn't trying to put words in your mouth, I just misunderstood your claimed need for the faster lens. I don't think the posts I responded to mentioned DOF. My mistake in making the assumption.

But this leads me to another point of debate!

As an F/4 super-telephoto wildlife shooter, I quickly learned that most often, (particular when light or ISO provides) we find that f/4 (or f/2.8) is too fast to get the detail we want in the entire subject. We also notice that with a long lens, and the distances we shoot, subject isolation is not requiring a super fast aperture. The same creamy background is possible @ f/5.6 and smaller apertures in many cases. More importantly, we want the eye and the wing tip within the DOF, or the eye and nose and ears on a large mammal etc,. so again, when I am shooting wildlife, and most others in the field I talk to, we aren't shooting at f/4, and are therefore paying for and carrying about 2X more than we need to get the job done.

This is why these PF lenses made by Nikon (and the 400mm f/5.6L 400mm f/4 DO by Canon) have such an appeal. The F/4 Super telephoto lens design dates back to the film are, where 1600 ISO was max, and looked like arse.

Sure there are times 500mm @ f/4 will make an image better than @ f/5.6, but it's rare. So rare in fact, I can't find a single example from your own POTN image gallery where you chose the faster speed. Back when i had the SIGMA 300-800mm f/5.6, I never found the smaller f/5.6 aperture a problem at all. I only found it's tremendous weight and lack of IS/OS a burden.

I'd suggest you give it a try and see for yourself, but there is no need, as you have already been doing this all along. I see few if any images in your gallery taken at these fast apertures. Your most prolific work is done with two lenses that are f/5.6 (SIGMONSTER and 100-400mm at the long end) and in most cases you are not wide open. Lot's of images taken with the heavy 400mm f/2.8, none that I can find @ f/2.8, in fact the vast majority are stopped down past f/5.6
Your avatar image was taken with a 13 pound lens @ 400mm f/8! No one would see the difference if it had been taken with a 2.5 lb f/5.6

Here you have one with wonderful subject isolation, but you wanted all the DOF for the detail, so it's f/13 (perhaps stopped down more than needed) but there is no issue with DOF. The only issue is again you used a 13 pound lens to get the same image a 2.5 pounder would offer in those conditions.

So even after your clarification that cleared up my own bad assumption, I remain confused by what preach here in this thread vs. what you appear to practice.

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Hey, Jake!

I appreciate the very detailed response.

Yeah, back when I shot with the 400 f2.8, I often wanted to shoot at maximum aperture, which was usually f4 because most of the time I had the 1.4 extender on it. . But I almost always stopped down because that version 1 400 f2.8 IS was simply not quite as sharp wide open as it was stopped down 2/3 of a stop. . So when I stopped down, it usually wasn't because I wanted more DOF, but because I didn't really trust the lens to be at its very sharpest wide open.

It is the same with my current big lens, the Sigma 300-800mm f5.6 . . I rarely shoot it at f5.6 because it isn't quite as sharp at f5.6 as it is at f7.1 or f8. . This really sucks, because in many situations I hate the DOF that stopping down produces, but I hate the slight softness that f5.6 gives me even more, and so I compromise.

The great thing about the very newest Canon supertelephotos - the ones that cost upwards of ten thousand dollars, is that they are super incredibly sharp wide open! . I would really love to shoot wide open at wide apertures in many situations, but the big lenses I've owned simply aren't capable of being pixel-peeping sharp wide open. . That's why many of the images in my gallery are stopped down - because they wouldn't be quite as sharp if I shot wide open. . It's not that I want to shoot stopped down - it is that I am forced to stop down because I am using inferior equipment that isn't as good as more current gear.

So ..... in the context of this thread's title, if I had no gear at all and cost were no object, and I could have either a Nikon D850 or a Canon 5D Mark 4, the first thing I would do would be to compare the lens lineup of the two manufacturers, with particular focus on their 600mm f4 offerings. . In my opinion and for the way I would like to shoot, Canon's 600mm f4 would be preferable to the Nikon 600mm f4 because it weights 1.7 pounds less.

Hence, I would choose a Canon 5D4 over a Nikon D850, simply because I like Canon's 600mm lens better than I like Nikon's 600mm lens. . That 1.7 pounds of weight savings is more important to me than whatever difference there is between the two bodies.

So, while some have said that they would choose the Nikon body because they like the light, small, affordable telephoto lenses that Nikon has recently released, I would choose the Canon body because I like their latest 600mm prime better.

I hope this explanation clears up any confusion or apparent contradictions in what I said in earlier posts.
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For the record, it should be noted that in terms of DOF and the actual size of the opening, f5.6 at 800mm is roughly equivalent to f4 at 600mm and f2.8 at 400mm. So for me to use f5.6 is not showing a preference for a smaller aperture, because f5.6 is not smaller at 800mm.