# The fastest autofocus system I've tested so far...



## ajfotofilmagem (Jul 4, 2017)

The modest EF70-300mm F4-5.6 IS ii USM

https://www.youtube.com/watch?v=IHCjiqhhp_k


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## Mt Spokane Photography (Jul 4, 2017)

Trying to wade my way thru 4 or 5 commercials, I finally gave up. It starts out like a commercial, a lens loaned to be tested, It might be fast, but how accurate? I don't know because I gave up due to the commercials.


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## ajfotofilmagem (Jul 4, 2017)

Mt Spokane Photography said:


> Trying to wade my way thru 4 or 5 commercials, I finally gave up. It starts out like a commercial, a lens loaned to be tested, It might be fast, but how accurate? I don't know because I gave up due to the commercials.


I always watch Christopher Frost reviews here in Brazil, and I only see one ad at a time. Maybe your user profile is very interesting for Youtube, and they direct more advertisement to you?


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## Mt Spokane Photography (Jul 5, 2017)

I tried again, and just got one commercial before a few seconds of a short teaser for a 70-300mm II. There was no measurement, and no test data about other lenses that were tested, just someone showing the footage dial move as they apparently pressed the AF button. Canon does not make any claims as to this lens being the fastest, except that its a improvement over the really slow micromotor AF.

I've never seen anyone seriously attempt to measure autofocus speed, at not least anyone who understood the variables involved. I filed it under the same category as someone who says a lens is the sharpest one they've ever owned. Apparently he going to take some photos with it to use his calibrated eyeball to determine AF speed? Will it be a sunny day, cloudy, how cloudy, what time of year / day compared to his other tests?

I would be interested to see if there is a actual test setup and how AF speed is measured. AF speed can be affected by many variables, so a tester first needs to determine which ones he can control, and which others affect the AF speed measurement. Some of these are, the camera body selected, sensor size, battery and battery configuration, amount of light, aperture settings, light color, temperature, IS on or off, probably more that I did not think of can affect speed. Most professional testers have just said they cannot test AF speed because of the variables. Some set their lens to its closest focus distance and time the focus to infinity, but thats misleading, a lens that focuses to 2 ft compared to one that only focuses to 13 ft will be apples to oranges, if you compare 13 ft to infinity times, at least, that helps with one variable.


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## Chaitanya (Jul 5, 2017)

Mt Spokane Photography said:


> Trying to wade my way thru 4 or 5 commercials, I finally gave up. It starts out like a commercial, a lens loaned to be tested, It might be fast, but how accurate? I don't know because I gave up due to the commercials.


Read the review posted by Lenstip, here is link to AF part of the test:
http://www.lenstip.com/503.10-Lens_review-Canon_EF_70-300_mm_f_4-5.6_IS_II_USM_Autofocus.html


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## Mt Spokane Photography (Jul 5, 2017)

Chaitanya said:


> Mt Spokane Photography said:
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> > Trying to wade my way thru 4 or 5 commercials, I finally gave up. It starts out like a commercial, a lens loaned to be tested, It might be fast, but how accurate? I don't know because I gave up due to the commercials.
> ...



I guess that some would be impressed thinking this was a test. It definitely does not impressed me as any kind of a test with repeatable results because of all the variables, it meets all the requirements for a test done by someone clueless as in my original post.

"Running through the whole distance scale and confirming the focus at the shorter end of the focal lengths spectrum takes 0.1-0.2 of a second; for the longer focal lengths the process is by 0.1-0.2 of a second longer."


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## Chaitanya (Jul 6, 2017)

Mt Spokane Photography said:


> Chaitanya said:
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I wouldnt call Christopher Frost clueless, his reviews seem quite reasonable. To me that nano usm is quite impressive and would certainly like to see that AF motor in more lenses, especially in a short tele macro lens (EF 50mm needs a replacement and is already late).


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## Mt Spokane Photography (Jul 6, 2017)

Chaitanya said:


> Mt Spokane Photography said:
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> > Chaitanya said:
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I come from a scientific background, where I managed labs that ran tests for NASA as well as FAA and other agencies. We would get laughed out of business with a test like that.

I think its fair to say the AF speed is greatly improved on the lens, but its not what I'd call a valid test by any means, since the variables are apparently not even recognized.

Being a good photographer does not imply being able to run a good test of something that many testers, if not all cannot measure. My neighbor was a airline pilot, but he was not technical as to how things worked, he just knew how to drive it.


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## Chaitanya (Jul 8, 2017)

Mt Spokane Photography said:


> Chaitanya said:
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I understand what you mean in terms of repeatability of tests with regards to Christopher Frost videos. But lenstip seems to be doing it under much more controlled environment, but they are a polish website and while reading reviews in english seems like sometimes content is lost in translation.


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## ajfotofilmagem (Jul 8, 2017)

Today, the complete review is out there:

https://www.youtube.com/watch?v=Iws0RqitJUc


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## ahsanford (Jul 8, 2017)

As MSP has indicated, no one really tests AF speed in a manner that will address all usage considerations. You just have to try these lenses out (renting is gold for this) and see what weird quirks they have. For instance, we obsess about speed/accuracy/reliability, but Mr. Carnathan at TDP flagged some MF focusing speed quirks with this lens. (He was a happy camper otherwise.)

As my upcoming EF 50 f/nooneknows IS USM EF 50mm f/1.4 USM II will reportedly also have this nano USM focusing, any positive read re: its speed in use are welcomed. This reads well for my future 50 prime, even if it will be [throw up in my mouth face/noise :-[ ] focus by wire and internal focusing is not a certainty.

- A


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## ajfotofilmagem (Jul 13, 2017)

Now, is the Dustin review:

https://www.youtube.com/watch?v=_mTmcVMl-qY


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