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EOS 70D autofocus tracking???

Rising Star

Will the phase detect 19 point AF system in the 70D track subjects moving toward the camera at 100 miles per hour in AI Server mode? In other words, is the 70D usable for still photos of aircraft in flight, horse racing and automobile racing? Any references to articles on the 70D AF sustem that discuss its ability to track subjects moving toward the camera would be appreciated. Thanks.




If it's better than the 7D it won't be by much from what I've read but I haven't put any effort in that either. I have shot Radio Control events with a 7D with very good results & that's harder than full scale. I've also shot car racing with a 40D & had a pretty good keeper rate.


"A skill is developed through constant practice with a passion to improve, not bought."

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I do not understand your comments. I currently have a 60D and a 6D.”



I am sorry for the confusion. Being a 5D owner I can testify to it's unbelievable ability. IMHO, if I woke up in your shoes tomorrow and decided I needed a better camera, I would get the 5D and sell the 6D. I would forgo the apparent gain form the 1.6 crop sensor of a 7D or 70D. Now that is just my opinion but none of these are in it's (5D) class. My thinking was $2000 for a 6D and $1200 for the 70D is nearly what you would spend on a 5D Mk III. You could also buy a 1.4x tele adapter but that puts the price equalization out of wack unless you also sell the 60D.


However, now that my feeble brain has wrapped itself around your true question, I would, in your case, buy a 70D and not the 7D as I earlier suggested.

If you do not need the more robust build of a 7D, than a 70D will be great. The 70D shares almost the exact specs as the 7D except for the build. I have a friend that just loves hers.


PS. I would still give that 5D a long hard look before you pull the trigger. I have both and I shoot both side by side and have done comparisons in Photoshop. If the 7D beats the 5D when each is at the same enlargement it is in the pixel peeping range.

Is there really a 1.6 crop advantage? Yeah, there probably still is but it is slight.

Good luck with your decision,



EOS 1DX and 1D Mk IV and less lenses then before!

Thanks for the clarification EB. I did think long and hard about the 5D III before I bought the 6D. Everyone's needs and budget are a bit different and I think I made the right decision for myself. That said, I have a couple of friends that have the 5D III and they both love it. It is a great camera.



"Everyone's needs and budget are a bit different ..."


So true and exactly why Canon has so many choices. The biggest issue we all have is, learn to use what you have!

All the best to you and good luck with it.


EOS 1DX and 1D Mk IV and less lenses then before!

I realize that I'm late to this discussion but I am wrestling with the same questions.  I have a 6D and have been using it  for lots of different photographic situations, including, bird and aviation.  I recently photographed an air show (Blue Angels, etc.) with the 6D and the EF 70-300mm F/4.0-5.6 IS lens, mstly shooting at 300mm.  Results were disappointing.  I attributed this to a few factors.  Inexperience, shooting IS on "1", chromatic abberation of the lens (even with chromatic correction enabled), and  poor physical position relative to the action.  The next day I switched to my EF 300mm F/4.0 IS USM, switrched the IS to position "2" and got closer to the action with pretty amazng results.  One thing I found challenging was getting the focus I wanted.  I keep switching between center spot focus and all sensors on AI focus.  I still lost focus often when the subject was not over one of the selected sensors.  When this happened, the 6D went searching for focus and the imaged blurred.  After that happened it was almost impossible to obtain focus.  I had to point at the horizon to return the focus to near infinity then go hunting for the plane.  This happened about 10 to 20% of the time.  It happens a lot when I photograph birds.  this experience leaves me with the question, is there a better body for photographing planes and birds.


Enter the 'reach' issue.  I find the 300mm too short for birds and planes.  At best the subject fills only about 10% of the field and often as low as 3%.  After cropping, I find that I can only get a crisp print up to an 8" x 10".  After that things get soft.  This makes it pretty useless as I am interested in printing large.  So my question is: How can I improve my printing results without buying a Mark III and the 600mm lens? (Read "spend $10,000")  From various forums the low cost solution seems to be go to an APS-C sensor and add a 1.4x teleconverter.  According to my calculations this would increase the fraction of the field that the subject occupies from 3 to 10% up to 7 to 25%.  So it all boils down to this.  Can I get crisp 20"x30" prints with the following system:


Canon 70D body

EF Canon 300mm F/4.0 IS lens

canon 1.4x III teleconverter


According to calculations based on 200 dpi recommended print density,  20 megapixel file should provide the pixels for a 18" x 27" print at 200 dpi (no cropping).  Will the print be " tack sharp."  Can this expectation be met by the system described?


Shooting air shows takes a bit of panning skill & I have no experience with the 70D but did shoot R/C with a 7D and it did fine (R/C is harder than full scale). The most common air show lens is the 100-400 L IS but that may change if the new Tamron 150-600 can focus fast enough. Adding a TC to most lenses slows the AF & makes things more difficult. Anything bigger is too hard to hand hold which is a problem so do some careful homework before buying. As for settings my comments here might help.


or this article here but keep in mind the shutter speeds are for R/C.


As for printing I've made several large prints after cropping but I'd have to find the original files before cropping to see just how deep I went (which I'll try to do tonight) BUT you need a very sharp image to start with or the flaws will grow as you crop.

"A skill is developed through constant practice with a passion to improve, not bought."

As you regulars here already know, I don't like 3rd party lenses.  But the Tamron 150-600mm has a lot of appeal.  It's price being the single most atractive.  I can not find one for sale at my preffered outlets and maybe to the good. Smiley Frustrated

There are lots of reports of problems with focus on the Canon 7D.  

At any rate it is at the limit of f ratio for good focus speed at best.   Maybe the lack of availability, is a fix being made by Tamron.


It just might be a lens that is too good to be true.

EOS 1DX and 1D Mk IV and less lenses then before!

Thanks for your response.  I too was attracted to the Tamron 150-600mm F/5-6.3 VR Zoom.  but I just watched a video by Tony Northrup who gave it bad performance reviews.  The conclusion of the video was:


The Canon 400mm F/5.6 (cropped down to 600mm frame size) gives better resuts than the Tamron 150-600mm F/5-6.3 VR at 400mm, 500mm and 600mm.


Here's the link:



Can that equipment provide a sharp print?  Yes, it can.  Will it be as sharp as you want?  Who knows!

You will just have to try and practice.  Shoot a lot.  Learn the best way to use it.


Secondly, it is not the paper size, 8 x 10, that is critical but the subject size is.  It depends on how much of a percentage you enlarge, blow up, your image.  You can have an 8 x 10 that has no enlargement done and you can have one that has a 100% enlargement.  Which will be sharper?


I shoot all three sensor sizes, 1.6, 1.3 and FF.  With everything being absolutely equal except sensor size, I doubt there is any benefit from the crop factor.  If there is it is very slight.  To this end I doubt Canon will ever make another 1.3 body.

Some rumors suggest the 1.6 may be on the short list, also.


Budget allowing the EOS 5D Mk III is as good as it gets right now.  Crop or not.

EOS 1DX and 1D Mk IV and less lenses then before!

Thanks.  So you're saying that I shouldn't go to the 70D just for crop factor / increased reach.  Should I do it for improved focusing capability?


How about teleconverters to increase reach?  I heard that the 1.4x is the way to go.  Bu I also heard that the 2.0x III is quite good.  


I just can't justify the $3,300 for a Mark III plus the  $13,000 for the EF 600mm F/4.0.  


How can I best extend my reach on a budget?

2 different problems with using teleconverters. Firstly they slow down the AF & secondly they cut the light, To use a 2X TC & retain AF you need either an f2.8 lens or a 5D3 or 1 series body because none of the other bodies can AF at f8.0. &d or 70D can't AF if you add a 2X TC to an f4.0 or smaller aperture lens & I doubt you'd want to shoot air show type stuff manually even though it can be done that way. Now to compare the difference between shooting a FF body against a 1.6 cropper you need to understand the sensor ratios. The artificial reach from the crop body can be huge if deep crops are needed because the crop bodies full frame is roughly 40% of the full frame image. In other words (hopefully easier to understand) IF the full frame camera had 20 Megapixels ONLY 8 Megapixels would be left when cropped to the same field of view the crop body saw (and captured)


FF sensor area = 864 sq mm

70D sensor area = 337.5 sq mm


Ratio of one to the other = .3906 or 40%


Therefore IF you want to shoot FF and get crop body pixel count you'll need a full frame body with roughly 50 megapixels. .

"A skill is developed through constant practice with a passion to improve, not bought."