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x 2 or 1.4 converter


mikehit 10 8.0k 13 United Kingdom
8 Apr 2015 9:06AM
Any tc will do but my view would be why buy a lens like the 500mm f4 and then skimp on the cost of a tc so buy a Canon tc and accept any limitations it gives on autofocus.
Teleconverters are so simple in construction that I would have no hesitation in buying one second hand.

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cheddar-caveman 16 1.1k England
8 Apr 2015 9:12AM
Absolutely, I would never attach anything but a Canon to a Canon. In the 500mm f4 (wish I could afford one) one has probably the best telephoto on the market at that length, in fact all Canon "L" series are market beaters.
tomcat 14 6.4k 15 United Kingdom
8 Apr 2015 10:56AM
There seems to be a mismatch of terminology in the thread

A converter is something that extends the focal length of the lens i.e a 1.4 x on a 400mm lens takes it to 560mm

An extension tube depending on what size enables the lens to focus closer in one instance

i.e a 12mm extension tube on a Canon 400mm 5.6 allows the minimum focus distance to be shortened from 3.5M to about 2.8M
Overread 11 4.1k 19 England
8 Apr 2015 2:28PM
Tomcat - I think the confusion comes because Canon officially calls their teleconverters "extenders".

Rather like how Nikon calls its macro lenses "micro" lenses.

cheddar-caveman 16 1.1k England
8 Apr 2015 4:25PM
Correct Overread! Being a Canon man I have been using their terminology, "extender", never mentioned extension tubes which are completely different.
LenShepherd 11 4.1k United Kingdom
9 Apr 2015 8:27AM

Quote:
If it is a 7D (crop, not full frame) then your AF won't work with the 2X extender as it will only work up to f5.6 but the 1.4X will be brilliant, taking you out to 700mm with full AF.


One of the reasons I chose Nikon over Canon in 1999 was top pros were pointing out that AF worked at f8 effective with any Nikon AF point and any lens even though Nikon said not slower than f5.6.
It is broadly true AF works with any f5.6 Nikon body at f8 well enough for accurate static subjects in reasonable light though focus tracking may be no more than walking pace speed. Most advanced Nikon bodies now have some "official" f8 AF capability.
With Nikon Mk 1, Mk II and Mk III converters it does not affect lens compatibility providing there is enough space at the rear of the lens (as with Canon) to accept the manufactures protruding front element converters. If there is no space generally the Kenko Nikon fit work nearly as well at about half the Nikon price.
Overread 11 4.1k 19 England
9 Apr 2015 11:26AM
The 7D will af at f8 - actually far as I know most Canon DSLRs will do that now - but only in live-view mode (as it uses a totally different set of AF sensors).

Viewfinder wise I think some are now adding the feature (I think the 7DMII and 5DMIII can af at f8 but double check as I'm going by memory on that and don't own either).

In general though on cameras that don't af after f8 you can "tape the pins" which basically means the camera doesn't "see" the teleconverter which thus retains the AF; however many report that when done AF is slower and more prone to missing (though its decent enough on some prime lenses).
mikehit 10 8.0k 13 United Kingdom
9 Apr 2015 11:56AM

Quote:The 7D will af at f8 - actually far as I know most Canon DSLRs will do that now - but only in live-view mode (as it uses a totally different set of AF sensors).

My 7D focusses quite happily at f8 (100-400L plus 1.4xtc) in 'normal (non-Live Viuew) mode. It was a pleasant surprise given all the talk about this, but I guess this was helped by having decent light. I was using a Kenko teleconverter which seems to support your comments about taping the pins on the Canon tc because of the way lens-tc-camera communicate .
strawman 16 22.1k 16 United Kingdom
9 Apr 2015 11:25PM

Quote:One of the reasons I chose Nikon over Canon in 1999 was top pros were pointing out that AF worked at f8 effective with any Nikon AF point and any lens even though Nikon said not slower than f5.6.
As Nikon themselves knew and pointed out there was a technical reason why the AF performance fell off as you went past f5.6. It is all due to how phase detection works and the problems you encounter as you operate slower lenses. Later cameras have had improved AF sensors that have coped with slower lenses.

Was that not the time period just before professionals started to abandon Nikon?

For some reason Canon decided it was best not to offer unreliable AF if the Camera knew it was an F8 or slower lens. I think it a daft decision but there you go. If the camera is used with a 3rd party converter it will usually focus fine with an f5.6 long focal length lens on a teleconverter. Even my old 300D with its fairly basic AF would work fine in good light with an f5.6 lens on a 2x converter. So there was a fair chance it may make have made a reasonable job of focusing an f8 lens. Not to the standards any of the manufacturers would be happy with, but probably acceptable to most of us.

If I go back to when I started photography on my Minolta SRT100 I could happily focus with an F8 mirror lens, but a friend with a more advanced OM10 had half a blacked out split focusing screen. Stick an f1.8 lens on the Olympus and that focusing screen was much better than the Minolta plain ground glass screen Smile
LenShepherd 11 4.1k United Kingdom
10 Apr 2015 8:47PM

Quote: As Nikon themselves knew and pointed out there was a technical reason why the AF performance fell off as you went past f5.6. It is all due to how phase detection works and the problems you encounter as you operate slower lenses. Later cameras have had improved AF sensors that have coped with slower lenses.


You have your facts part "not right".
"Nikon official f5.6" AF is unlikely to have fast enough focus for Nikon's minimum focus tracking ability, though to the best of my knowledge Nikon have not said what their minimum standard is. I said all Nikon slr and DSLR f5.6 AF points usually work well enough for good AF in reasonable light at effective f8. They do Smile
Many Canon bodies disable AF with many combinations slower than f5.6, while Nikon allow the photographer to keep shooting to f8 and to get good AF with most static subjects.
5 Jun 2015 8:08PM
Pretty sure I read that the 7D mkii will retain AF at f8. I'm thinking of adding the 1.4 extender mkiii to my 100-400 mkii. Anyone using this combination? Would appreciate comments as I was thinking sigma 150-600 sport but the extender is a much cheaper option.
mikehit 10 8.0k 13 United Kingdom
5 Jun 2015 8:29PM
Yes, the 7D2 will focus with an f8 lens but only using the centre focus point. I use the 1.4x tc on my 100- 400. I have also looked at the 150-600 but the added bulk puts me off.
5 Jun 2015 8:36PM
Is AF with the centre point pretty fast and reliable? Must admit I've heard the sigma 150-600 is heavy to hand hold, and the sport version almost impossible. I'd be happy with just the centre point as long as AI servo on the 7D mkii stays on track with birds in flight and fast moving mammals.
mikehit 10 8.0k 13 United Kingdom
5 Jun 2015 9:48PM
I found it pretty fast even with the original 100-400 - maybe not fast enough to track fast birds in flight but i have some pretty good shots of wagtails doing aerobaics to catch flies. Apparently the 100-400 MKII (although the IQ is not significantly better) works much quicker with tcs (I have one on order).
5 Jun 2015 10:30PM
Thanks for that. Might take the plunge or maybe hire the extender and see how it goes. Must say I am delighted with the 100-400 mkii. It's quite heavy but easy to hand hold for short periods and images seem very good. Focus is fast and the IS seems pretty good too. Only complaint is the lens hood which is okay, but doesn't seem very substantial. Not sure I will ever put a circular polariser on it so the little door is unlikely to be useful. Really think a metal hood would be better. As I say IQ seems great at all focal lengths. Best lens I have in my collection. Unfortunately it will probably lead me to want to upgrade a few others. My Sigma 105 macro has no OS and think I'd like a good L series wide angle prime too. Wonder if I could convince my dear family to put them on my Christmas list.


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