Sigma 500mm F4.5 + Canon EX 1.4 II + EOS 5D mk3 - focus problems

[kallipk]

Got myself recently a used Sigma 500mm F4.5 DG EX HSM to get some more reach, but i have some problems with extenders.

In earlier times it was often reported that this lens should only focus on 1D bodies using converters so i thought it should not have any problems with 5D mk3 that has same level AF system. But still it seems i have some problems locking down on AF spot.

So at the moment i have tried with canon II extenders both 1.4X and 2X with and without taping the pins. It seems that the camera really struggles to lock down on AF spot with any of the extenders mentioned above attached.

Without taping the pins on extender (1.4X) - the lens is reported to camera as 6.3 lens and it tries to focus, but at most of the cases it never reaches focus. It just hunts rapidly around near focus area, but does not lock down on spot. If i tape the pins the hunting is just a lot faster (I guess the extender software slows down the lens AF to help camera finding focus points), but still no AF lock.

With the 2X extender it does not focus without taping the pins (well that is obvious as it is F9 lens then) but with taping the pins same story - hunting around near focus but not hitting the focus spot.

Have anyone experienced similar thing? I have heard that Kenko Pro 300 series extenders should be okay with this lens, but i can't find any on my local dealers so for now i am stuck with my canon extenders.

I also started wondering if there could be some dust in extenders of in my camera, but when attached to EF 300 F4 IS, AF seems to work okay even with 2X extender (making the lens 600mm F8 effectively). So the camera and extenders should be okay in that sense.

But in a positive side - the 500F4.5 without extenders is already a real beast. IQ is far-far superior to EF 300 +1.4 EXII

 

[Tazz93]

Was there a firmware upgrade that enabled the f/8 AF?

 

[wetoldboot]

I use the same body but with canon 500f4 lens and canon 1.4x mk2 and 2x mk3 converters. The 2x combo is pretty poor and hunts about in all but the brightest light,, the 1.4 is lots better but even this combo has its moments and hunts about at times. Whenever I get that hunting scenario I manually focus by the ring so I can see the subject and then let AF lock on. I think it just a trait of the cam maybe with my setup.

 

[Tazz93]

Sorry to hear, I assumed the 5D3 and the 5DS were very similar in their AF function. My 5DS very seldom hunts with a 1.4x TC on my 400 F4 and the 2x TC is very usable on the 400 F4. I feel it works fast enough for BIF, at least down to the point where I find the shutter speeds are too slow.

If you camera doesn't have the updated firmware really give it a thought. Looking at a couple of comments they made it sound like a night and day difference.

Canon firmware for 5D Mark III allows uncompressed video and AF at F8

"...Wildlife and nature photographers will be pleased to know that the firmware enables cross-type autofocus when working with a maximum aperture of F8, as is possible in the EOS-1D X. Using an F4 telephoto 'L' lens coupled with a 2x extender, for instance, you can autofocus using the center AF point with cross-type sensitivity. In addition, the surrounding four AF points can be used as focus assist points."

Click through to download firmware v1.2.1 for Canon EOS 5D Mark III

 

[larry55279]

My 5D3 AF's really well with the old Canon 400 5.6 AND the new 100-400ii with either the Canon 1.4xii or the Canon 1.4xiii.

Your Sigma is the problem. Not sharp enough, not enough contrast, or both.

 

[kallipk]

Thanks for the fast response.

The firmware i have is updated. Also i have no problem with EF300 F4L IS +2X EXII, so the F8 focusing actually works with this setup.

The problem is with Sigma 500F4.5 + canon extenders. Yesterday i decided to order Kenko pro300 series 1.4 converter and try with that. If it works i have success. If not, well then i have one spare converter

As i understood from wetoldboot even the Canon 500F4 hunts with extenders so i think i was just maybe expecting a little too much.

Unfortunately i had sold my 1Dmk3 before getting this lens so i can't check with this one also anymore. I guess i have to go visit some friends and start experimenting with different bodies and converters.

 

[brightcolours]

Thanks for the fast response.

The firmware i have is updated. Also i have no problem with EF300 F4L IS +2X EXII, so the F8 focusing actually works with this setup.

The problem is with Sigma 500F4.5 + canon extenders. Yesterday i decided to order Kenko pro300 series 1.4 converter and try with that. If it works i have success. If not, well then i have one spare converter

As i understood from wetoldboot even the Canon 500F4 hunts with extenders so i think i was just maybe expecting a little too much.

Unfortunately i had sold my 1Dmk3 before getting this lens so i can't check with this one also anymore. I guess i have to go visit some friends and start experimenting with different bodies and converters.

The Sigma lens takes steps that overshoot focus with the extender attached, hence the hunting (the lens AF logic is kinda incompatible with your camera when using extenders). Try using a 3rd party extender that does not let itself be known to lens and/or body.

Also, you do not mention which focus points you use.. try with just the center AF point.

 

[kallipk]

Thanks for the fast response.

The firmware i have is updated. Also i have no problem with EF300 F4L IS +2X EXII, so the F8 focusing actually works with this setup.

The problem is with Sigma 500F4.5 + canon extenders. Yesterday i decided to order Kenko pro300 series 1.4 converter and try with that. If it works i have success. If not, well then i have one spare converter

As i understood from wetoldboot even the Canon 500F4 hunts with extenders so i think i was just maybe expecting a little too much.

Unfortunately i had sold my 1Dmk3 before getting this lens so i can't check with this one also anymore. I guess i have to go visit some friends and start experimenting with different bodies and converters.

The Sigma lens takes steps that overshoot focus with the extender attached, hence the hunting (the lens AF logic is kinda incompatible with your camera when using extenders). Try using a 3rd party extender that does not let itself be known to lens and/or body.

Also, you do not mention which focus points you use.. try with just the center AF point.

I also had similar impression that the lens always tries to go too far on both ends. I have so far tried with taping the pins on extender with no luck, but as soon as i get the kenko converter i will try with that. in the mean time i will try to check the AF micro-adjustment of the lens itself - maybe it is a tad off.

Normally i try with center AF point. Just to be sure the camera gives all it's got.

 

[Tazz93]

Did you get a chance to check for lens compatibility?

Also, to help aid in the AF acquisition, consider slowing the AF tracking settings. Granted, this will only be helpful if you're using a fast setting. I found this really helped on my 1DIIN. By slowing down the speed, it appeared to lock more accurately and moved on and off the target much less.

 

[kallipk]

So i managed to test with Sigma 1.4 newest teleconverter (visited local store and they had it in) - no luck. Same story as with Canon extenders - hunts a lot. Unfortunately it was already a bit dark also when i tried so this also contributed probably.

I tried with taping the pins and without with canon 1.4 and 2 II extenders - without taping it is actually better - it's slower and tries to lock - and if there is a really lot of contrast it even locks down (that is with 1.4 EX of course - with 2X without taping there is no AF).

I also tried EF300 F4L IS with those taped extenders and it also had trouble of locking the AF. So now i know that extenders somehow use software or sth. to slow down AF motors inside lens to focus more slowly, helping the camera to lock down on the spot.

The kenko teleconverter is still not here - most probably it will take some time to reach (ordered from ebay) so then i can tell whether i need to send the lens for software upgrade or just be happy what i have.

One thing i tried more - micro adjustments of the lens with 1.4 EX II attached - and that might actually made the difference between now seldom locking down AF and before not locking at all.

With the converter attached the lens seemed to focus a bit in front so i adjusted it slightly back and it might have helped. Good thing is that 5DMk3 saves lens and lens + converter as different lens combos so i don't need to worry about losing focus when extender is not attached.

Oh and the AF speed - yes i slowed it down as much as possible when using extenders - most probably it again helps.

So the verdict at the moment. In very high contrast situations i can lock down AF with 500 + 1.4 EX II combo but i would not dare to shoot any BIF like that - not even birds at ground to be honest. So for the extenders attached at the moment manual focusing it is.

But in any case, I spent whole day yesterday hiking outdoors with the lens, so now it is time to heal my left hand muscles - after a while it gets heavy But i am really happy with the results - without converter the pictures are pretty neat and AF is completely in Canons range (speed, tracking ability and accuracy).

 

[Tazz93]

Good to hear you like the lens, but sorry to hear the TC performance is still not quite as good as you'd like. Hopefully the Kenko will aid this, but its possible the optical design is simply a little too dark. Often lens makers market a lens at an significantly lower sensitivity than it is actually able to achieve. If this is the case, its optical design could be robbing precious light needed for the AF system.

 

[brightcolours]

Good to hear you like the lens, but sorry to hear the TC performance is still not quite as good as you'd like. Hopefully the Kenko will aid this, but its possible the optical design is simply a little too dark. Often lens makers market a lens at an significantly lower sensitivity than it is actually able to achieve. If this is the case, its optical design could be robbing precious light needed for the AF system.

t is about aperture size, not about transmitance (I guess you meant that with "lower sensitivity").

Even my 450D with 70-200mm f4 lens and 1.7x TC did manage to focus, so the AF of the 5D mk III with center point should be OK with the Sigma and 1.4x TC. The issue here is the lens and its AF system.

 

[Tazz93]

Brightcolours, you might have made a mistake there or I'm misunderstanding your comment, the effective light lost through the optical design is what the "T-stop" represents. The F-stop doesn't account for light loss, it just references the size of the opening in relation to the focal length.

"A T-stop (for transmission stops, by convention written with capital letter T) is an f-number adjusted to account for light transmission efficiency (transmittance). A lens with a T-stop of N projects an image of the same brightness as an ideal lens with 100% transmittance and an f-number of N. A particular lens' T-stop, T, is given by dividing the f-number by the square root of the transmittance of that lens:"

For the OP, http://frankandersonphotography.blogspot.com/p/sigma-500mm-f45-ex-dg-hsm.html, this review suggests the TC slowed down the AF (as expected), but was still resaonable with both a 30D and 1DIII, the 1DIII was better as expected.

Out of curiosity, I know most AF systems are sensitive to battery output, is it possible your battery is a little run down or defective?

 

[kallipk]

Good to hear you like the lens, but sorry to hear the TC performance is still not quite as good as you'd like. Hopefully the Kenko will aid this, but its possible the optical design is simply a little too dark. Often lens makers market a lens at an significantly lower sensitivity than it is actually able to achieve. If this is the case, its optical design could be robbing precious light needed for the AF system.

Well there are some reviews in internet of people having decent AF with Kenko extender so i am still fingers crossed. Due to the Easter holidays and some bad weather in the region my shipment got stuck somewhere. But now the tracking shows that i can wait for it any day now

Yesterday i was out shooting some woodpeckers. Tried with canon extenders again and in some cases 1.4 did lock down AF, but i had AF-stop button under my thumb all the times to correct manually if needed. So I would say Canon extenders is a not really a way to go.

Just for a fun I stacked two extenders on top of each other making it 500+1.4x+2x= 1400mm on FF - well it's not what one would probably want to handhold for a long time, and the image quality took some hit there, but when in need totally usable in my understanding. Of course not for large prints, but for screen view good enough if the alternative would be no photo at all.

 

[kallipk]

And we have the answer.

With Kenko pro 300 1.4 converter the AF works. I don't know what magic they put into this converter, but AF works like a charm no matter how much speed i put (af focusing speed from cameras menu). I did not check yet but i am pretty sure BIF at some distance should not be a problem. And the best thing, the aperture is also reported by the converter (camera knows that the maximum is 6.3) so there is no messing around or false metadata.

But at the same time i am not limited to center AF point - I could use all the AF point settings i normally use (zone AF - Af point with surrounding assist etc. )

Regarding the image quality - well i must see about that, the first impression was that it is good enough for converter.

So as a conclusion AF works with the following setup like a charm - Sigma 500 F4.5 + kenko pro 300 1.4X + EOS 5D mk3

Thank you all for suggestions and good toughs!

Sharp images to everyone!

 

[brightcolours]

And we have the answer.

With Kenko pro 300 1.4 converter the AF works. I don't know what magic they put into this converter, but AF works like a charm no matter how much speed i put

Canon (and I think also Nikon?) slows down the AF speed the moment it sees an 1.4x TC (to about half speed), the AF algorithms change. The slow down is even bigger with 2x TC.

Why do they do that? To increase AF accuracy with large aperture lenses when are designed to perform optimally speed wise and accuracy wise with the designed aperture. With a TC the resulting "combined" aperture ratio gets smaller.

So, you found out that this Sigma lens does not play well with the 5D mk III in the different AF mode the camera goes when it sees a TC. Kenko TC's circumvent how the camera reacts to a TC. That is why you see your Sigma not having the same hiccups.

Glad you got it resolved and working!

(af focusing speed from cameras menu). I did not check yet but i am pretty sure BIF at some distance should not be a problem. And the best thing, the aperture is also reported by the converter (camera knows that the maximum is 6.3) so there is no messing around or false metadata.

But at the same time i am not limited to center AF point - I could use all the AF point settings i normally use (zone AF - Af point with surrounding assist etc. )

Regarding the image quality - well i must see about that, the first impression was that it is good enough for converter.

So as a conclusion AF works with the following setup like a charm - Sigma 500 F4.5 + kenko pro 300 1.4X + EOS 5D mk3

Thank you all for suggestions and good toughs!

Sharp images to everyone!