Hi all! I have a 5D3, and I just bought the new 100-400L IS II lens.

[LisaQ]

Hi all!  I have a 5D Mark III, and I just bought the new 100-400L IS II lens.  I have an EF 2x III Extender, and I can't get the lens to auto focus when using the extender.  Can someone help me with this?

[Skirball · Accepted solution]

Using a 2X extender doubles your minimum aperture.  The aperture of the 100-400 is 4.5 - 5.6, so if you double that it's 9 - 11.  The maximum the 5d3 can autofocus is f/8, and I believe that is only the center point (and with the firmware?  I don't remember). 

Long story short, no AF with the 2X.   With 1.4x the center point should work.

[Skirball · Accepted solution]

Wise choice.  In general, most find that the 2x diminishes image quality too much for their liking.  1.4x is usually better regarded.  From what I've read, it's gotten good results on the 100-400 II with the 5d3.

[ebiggs1 · Accepted solution]

LisaQ,

I am going a little further and say even the 1.4x extender is going to be problematic.  You are transforming the lens into basiclly an f8 560mm.  The camera will still struggle but it will do it.

Most people use their zoom lenses at the long end is why I say this.  Because why would you put an extender on a lens that already has most of the focal lengths without it? (100mm to 400mm vs 140mm to 560mm?)

Another concern is 560mm at f8 is going to be a trick to hold and get sharp photos.  Yes, it can be done but you will need practice in hand holding.  Or, better yet, get a tripod.

As a general statement I don't recommend folks buy or use tele extenders at all.  But if you must, only on lenses that are f2.8 or faster.  Another suggestion, if I needed a 400mm lens that could get me 560mm cheaply, I would prefer the EF 400mm f5.6 L prime lens with the 1.4x II extender.  It offers several advantages.  One being it is much lighter.

Good luck.

[ebiggs1 · Accepted solution]

LisaQ,

Also another point most, if not all, don't realize is when you put a 1.4x (or 2x) extender on any lens you multiply everything.

Yes, the focal length and that is nice but you also magnify all the bad, too.  So it becomes 1.4x (or 2x) times harder to use since you have to become 1.4x (or 2x) times better.  Shake, blur, accurate focus, etc, everything.

[Skirball · Accepted solution]

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@LisaQ wrote:

Thank you for your input.  You make a great point.   Much to think about!

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I recommend not spending too much time thinking.  Pick up the 1.4x, and give it a try, it's peanuts compared to a 100-400II and 5d3.  Yes, there are limitations and hurdles to extenders, but plenty of people use them with great results.  There's only one way to find out if it works for you.

[ebiggs1]

" The-Digital-Picture.com tested and reported ..."

Mabe so but the fact remains, in photography there is no free lunch.  You give to get.  The question becomes, is it worth it?

Not trying to discourage anybody from trying whatever they want.  But they need to know everything, which rarely gets reported.

[LisaQ]

we shall see how it goes!  

[ebiggs1]

You must post some photos for us.  I love to shoot hawks and egales.  I have a couple 600mm lenses and a couple 500mm lenses.  Go fo it and post back.  🙂

[ebiggs1]

Remember there are other very interesting birds, too.

[RobertTheFat]

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@ebiggs1 wrote:

Remember there are other very interesting birds, too.

Nice. I particularly like that one of the duck landing. 

[LisaQ]

wow these are great shots!!!

[LisaQ]

that excites me.  yay!!  I picked it up today, so we shall see tomorrow how it goes!

[LisaQ]

I bought it last week, and I'm having no problems with it.  It's been lots of fun!  Thanks for taking the time to post.  I even used it at my daughter's band concert last night.  Now I can sit up in the balcony (crowds make me crazy) and still get great shots!

[ebiggs1]

OM, I shoot lots of school events and lots of music concerts.  Get on my Facebook page if you like, there are some thousands of photos of the school band.  I usually get in the sound both both at the back of the auditorium.

What instrument does your daughter play?  I teach trombone and have played since I was in grade school.  

[LisaQ]

She plays clarinet for concert band, and tenor sax for jazz band.  She wants to be a music teacher someday, so I may be taking lots more pictures of her in concerts.  Stage lighting sure is tough though...some spots totally underexposed, and others completely blown out.