Why did a 50 1.8 slow down my frames per second?

Its the lens. The 50/1.8II is a slower AF motor, loud too.

The 50/1.4 USM is faster than the 1.8II by a bunch. But its nowhere near the speed of the 70-200's. The ring USM drives are the motors that won't slow down AI Servo.

One thing you can try instead of MF which works for me, especially when I use a 2X TC. Is switch from AI SERVO to ONE SHOT focus, while using High Speed Continuous. That way the AF system only locks focus for the first shot, and then doesn't move the focus as long as you keep firing... all the way thru the buffer (17 shots on my 40D).

Of all my lenses, the EF70-200 f/4L IS USM is the only lens that can keep up to full framerate while in AI SERVO (have yet to test the 100mm f/2.8 Macro USM, in this respect so that one might be able to as well).

-Alan

nureality wrote in post #7177773
Is this an attempt at sarcasm? or do you believe the 50/1.8II has a fast AF motor?

This motor is a slow slow sloth.

I'm pretty sure he meant it as sarcasim. That's why he put it in quotes.

Alan, thanks for your informative reply. I'll try some different things to see what works best (fastest).

JeffreyG wrote in post #7174255
Strange, because only the 1D bodies have a custom function that will give focus priority in servo mode. So far as I know all other bodies will happily snap away totally OOF images in servo mode while maintaining the set speed.

Not the 20D,
AF priority or not it has to find focus before it starts its motions.
It does not ever reach 5FPS with AF on almost any lens. It gets close.
The wider the lens the slower the AF rate is.

tkbslc wrote in post #7177684
Yeah, the 50mm 1.4 and 85mm 1.8 have USM focus motors like your 70-200. Should be quite a bit faster for what you are trying to shoot.

Not exactly. The 50 has micro-motor USM, not ring.

There is interesting effect with all older Canon AFD lenses. It might also apply to the 50mm 1.8 II. Here is my question and his answer:

THE DIGITAL JOURNALIST
Tech Tips
June 2008
by Chuck Westfall


http://digitaljournali​st.org …tips.html#comme​nt-2234509