Yep but they are 30% more expensive than the Sony ones sold in the US! So maybe they would bring over if Sony stopped selling theirs.

I agree completely about buying a D500 (I have two) but just to note, a top of the line SDXC card, the Sandisk 128 GB Extreme Pro UHS-II is $199, about the same as the the Sony 120GB XQD card and the Sony card is faster. And a Sandisk 128 GB Extreme Pro CFast card (which is used in the top of the line Canon cameras) is $299! Obviously one can buy much cheaper SDXC cards, however most are slower and/or of lower quality. I was fortunate to buy a Lexar 128GB XQD card for $159 in 2016 (before they stopped making them) so prefer using a card in each slot, backing up my photos. But as you note, the beauty of the D500 is that is up to you.

Yep with a number of manufacturers lining up to make them as well as potential much higher read and write rates, they do look to be the future. However, I would be surprised if high quality CFExpress cards are much different in price than the current XQD cards since these companies will be trying to recoup their investments and they know the price of the other cards they are replacing. Questions do remain of whether Nikon will follow through and role out the software patches for all the XQD using cameras they have manufactured. Also does anyone know if one installs such software on a camera, will the camera be able to use either a XQD or CFExpress card?

Life is short! A camera's life is even shorter. And the XQD card's life is long. I usually find that I replace my cards because I want bigger ones, not because they have failed. I have two D500s and two XQD cards, one Sony (a 64GB) and one Lexar (a 128 GB). Both cards have worked flawlessly for thousands of photos and several years. It seems IMO crazy to have a camera with two slots and not use both slots, in case of emergency, etc. I have been thinking of getting one more XQD card (maybe even the 256 GB) and don't worry about it, just enjoy my D500s.

FYI: When I try to photograph owls, I often shoot when there is low light. This is a photo with my D500 at ISO 32,000 (usually the highest I go)

Thanks! Enjoy your and your wife's retirement! I reached this stage a number of years ago and my wife also joined me. However she keeps very busy with the grandkids, leaving me to my photography.

Any at the upper limit of your ISO at a distance?

Can you post a photo taken at 12,800 at 420mm? Thanks!

It definitely is nice to have a camera with better "low light sensitivity" (ie. being able to use higher ISO) and frankly, had never looked at the Pentax KP. So what sort of ISO do you go up to? I often shoot at plus 5000ISO with my D500. My problem is that I mostly shoot wildlife so the other main criteria I have for a camera system are the lenses, I want sharp, light long lenses. And at least at a quick look, Pentax doesn't have them. Their 560mm f/5.6 lens is 6.7 pounds?
But kudos to you for shooting Pentax.

Wow I had no idea that my D500 could photograph at ISO 819200! Are these photos JPGs from the camera? Is high noise suppression turned on in the D500?

Is this picture cropped? What were your settings? (shutter speed, f, ISO

Not sure if it is me, but don't see the newer BIF shot you mention? But the amount of light available for focusing makes a huge difference. My 300mm f/2.8 lens still smokes any of my other lenses in acquiring focus, especially in low light. So a 300mm pf f/4 lens will be better than any version of the 70-300mm zooms because of this, again especially in low light. However the D500 is better a focussing in low light than a D7200.

I think question 3 might be the first that the OP needs to answer. They have already indicated to some extent their budget by saying they were contemplating buying either a D500 (new $1,500) or a 300mm PF lens (new $2,000), but not both. The latter lens is only slightly heavier than the 70-300mm and more importantly, is a f/5.6 at 300mm versus the f/4 of the PF lens. Allowing twice as much light in will alone increase the speed of acquisition of focus.

Glad you added a picture to show what you meant (as well as the info on shooting). Can one assume these photos are not cropped? After reading the comments, you are probably very confused! The simple answer is that all 3 things suggested could increase the chances of getting a better BIF shot; improve your technique, get the D500 and/or get the 300mm f/4 lens. As someone who has the D7200 as well as the D500 and the 300mm pf lens, I would say that if you can get these used, maybe you could stretch your budget to get both? Baring that, I would say to get the 300mm PF lens. I used the D7100 and D7200 with better lenses than the one you have and have gotten decent BIF shots (see the one below with the D7100), so your lens could be the problem (I have never had that lens). The 300mm PF lens focusses quickly and is a very sharp lens.

Unless I have missed it, there really are only two choices currently. Sony and Delkin are the two currently manufacturing and selling the XQD cards, with the Delkin being slightly more expensive. Lexar used to make them (I have one and it has been fine) but closed this division and sold it to another manufacturer (presumably because they didn't make enough money from them). The main problem is so few cameras require an XQD card, hence little interest in companies manufacturing. Lexar as mentioned previously sold this division to another company who then couldn't get a license to manufacture them, so as far as I know, there are no knew Lexar XQD cards being manufactured (when they were closing this out, there were some real sales on these cards). If you see a Lexar XQD card for sale, it is either used or an old one. As to the cost of an XQD card, they are about the same price as a high quality SDXC card. For example, the SanDisk 128GB Extreme PRO UHS-II SDXC is about $200, the same price as the Sony 128 gb XQD card and the Sony card is faster. Of course if you have a D500, you have an option to only use cheaper SDXC cards in the SD card slot. However I am happy to have a backup and use the XQD card slot as my primary.