Highlight tone priority vs. Burst

Not all of us look at all the icons in the viewfinder all of the time. Had me wondering. I know that my 40D and MK III are capable of some incredible max bursts but, it bogged down way too soon on me yesterday doing BIF. Seems HTP (highlight tone priority) does cut my max burst rate in half. I did not read this in the book. Haven't had time to read the white paper yet. Thought I'd pass the info along.

i don't remember HTP ever cutting my burst. let me ask you this though; do you have high ISO noise reduction turned on? because that one will kill your burst rate...

No, HTP alone cut the max burst in half.

there you go from the canon site:


"By expanding the range from the correct level (18% gray) to the maximum allowable highlight level, the gradation from the grays to the highlights becomes smoother and loss in highlight detail is minimized. This vital Custom Function lets photographers get even better detail in bright highlights, even in contrasty lighting conditions. It’s beneficial for nearly any form of professional work, where a user may encounter bright highlight areas where he or she wants to preserve details. Finally, there’s no impact on the camera’s shooting speed or burst rate when Highlight Tone Priority is engaged."

I just tried it again on my MK III. w/o HTP max burst says 68 jpg, w/ HTP 32.

well, i guess Canon is wrong i will also check it when i get back home...

Just looked at the chart on the book which says 110 jpg but I believe mine says 68 since I have jpg set at 10 (compression.) Like I said, I thought I could use HTP more often than not., Only downside was a bit more shadow noise but I was wrong I guess.

i just checked on my mkIII (i forgot that i have it here with me) and my burst does not change at all regardless of HTP. it does go down by about half when i turn on noise reduction but we already knew that...

Just to make a little semantic order here, please differentiate between burst rate - 6.5 or 10 f/s - and burst capacity. Blonde, the sentence you quoted says the rate is unchanged but says nothing about the maximum burst capacity.

It sounds like the OP meant buffer instead of burst.

With HTP on or off, my burst is 74 (large/fine jpg), with high ISO NR on, it goes down to 6.

Let me be clear. With HTP off the burst buffer (max) is 68 jpg, with it on the burst buffer (max) is 32 - with nothing else changed. No noise reduction involved. I am not talking about frame rate, just buffer size. I just got in from doing some more BIF and it does make a huge difference. Is there some other setting that I am using that makes HTP have this effect?

Could it have something to do with the write speed of your card?...Just a thought

Nothing to do with write speed at all. Camera changes buffer size (the number that appears in the viewfinder) when I engage/disengage HTP.

Things that change buffer size

HTP
High ISO NR
Long Exposure NR
ISO Safety Shift

I also know that if ISO Safety Shift is ON, the number of shots available on a card will NOT change when changing the ISO youre shooting at. If ISO Safety Shift is OFF, changing the ISO will change the number of available shots showing on the card.