1000d and sigma 150-500 autofocus

Hi,

I purchased a Sigma 150-500mm f/5-6.3 DG OS HSM APO Lens a couple of months ago to use with my 1000d.

I find it difficult to focus the lens consistently with wildlife using the autofocus.

The lens tends not to lock on to the subject and when it does the focus is not great. (see attached image) the centre af point is on the body/far wing.I set my camera using the centre spot auto focus.

I end up resorting to manual focus.

Look at this this tends to be the case in the f5.6-6.2 range in low light. Is it the lens?

I know that the dof is low at long distances at this aperture. However I tried using a higher iso and over 400 the images show considerable grain.

Would a better camera have a better autofocusing system and allow me to use a higher iso and therefore a smaller aperture to get a better dof?
Thanks in advance for any help,
Darren

image shot at 1/2000 f6.3 iso 400 at 500mm

dhitchen said:

Hi,

I purchased a Sigma 150-500mm f/5-6.3 DG OS HSM APO Lens a couple of months ago to use with my 1000d.

I find it difficult to focus the lens consistently with wildlife using the autofocus.

The lens tends not to lock on to the subject and when it does the focus is not great. (see attached image) the centre af point is on the body/far wing.I set my camera using the centre spot auto focus.

I end up resorting to manual focus.

Look at this this tends to be the case in the f5.6-6.2 range in low light. Is it the lens?

I know that the dof is low at long distances at this aperture. However I tried using a higher iso and over 400 the images show considerable grain.

Would a better camera have a better autofocusing system and allow me to use a higher iso and therefore a smaller aperture to get a better dof?
Thanks in advance for any help,

Click to expand...

In this particular case the background will confuse the AI servo prediction of motion. It'll switch from background to subject and back depending how large the subject is and how well it covers the AF point. Will a better body improve this? Definitely yes. A 50D or 7D would be better able to follow the subject. Especially the 7D, from what I've read can follow the subject even with difficult backgrounds reliably. Keeper rate would be better. However you can practice a lot with your current camera and improve keeper rate quite a bit. The subject should at least fill the AF area, preferably with good contrast from the background.

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

Thanks for the advice.

I had just kitted out my 1000d with a battery pack so didn't want to change my body just yet. The af point was set on the bird, so I was dissapointed to see such a bad photo. There is a big difference with af servo and shooting still photos.

Light is a big problem here as the lense is does not have fast glass I have to boost the iso to compensate hense the fuzzyness.
I keep practicing and know I have a lot to learn!!!
Thanks again

dhitchen said:

I end up resorting to manual focus.

Look at this this tends to be the case in the f5.6-6.2 range in low light. Is it the lens?

Click to expand...

Hey, I bet AF in 1000D doesn´t work with lenses slower than f/5.6 (except Live View) - it should be written in the manual, so check it out. If you want to use AF even in the range f/5.6 and higher, you have to buy a more advanced camera. So it´s not the lens, it has nothing to do with the background and practising won´t help either.

Best,
c.

I looked at the specifications

AF working range: -0.5 to 18 EV (at 23°C, ISO 100)

Therefore the shot shown I calculated at a EV of 14 , iso 400, F5.6, 1/2000

I can't seems to find information about what the minimum aperture of the centre point is ...........I looked at the 7d and the centre point af is 2.4
This problem has occured with other lenses in low light.
Any suggestions? E-mail Canon?
Thanks for the help

dhitchen said:

I looked at the specifications

AF working range: -0.5 to 18 EV (at 23°C, ISO 100)

Therefore the shot shown I calculated at a EV of 14 , iso 400, F5.6, 1/2000

I can't seems to find information about what the minimum aperture of the centre point is ...........I looked at the 7d and the centre point af is 2.4
This problem has occured with other lenses in low light.
Any suggestions? E-mail Canon?
Thanks for the help

Click to expand...

http://snpi.dell.com/sna/manuals/A1761803.pdf - page 162

You can also check this by using DOF button - set the aperture value to 5.6 or higher, press the button and the AF won´t work.

I've never heard anyone complain about not being able to AF at all with a sigma 50-500mm or the one the OP uses (both f/6.3 at 500mm). That the AF has trouble beyond f/5.6 in low light I can agree.

I can't believe after only owning a telelens for 2 months that one is at the top of the learning curve tracking BIFs. So there's plenty to practice and learn.

costojanku said:

dhitchen said:

I end up resorting to manual focus.

Look at this this tends to be the case in the f5.6-6.2 range in low light. Is it the lens?

Click to expand...

Hey, I bet AF in 1000D doesn´t work with lenses slower than f/5.6 (except Live View) - it should be written in the manual, so check it out. If you want to use AF even in the range f/5.6 and higher, you have to buy a more advanced camera. So it´s not the lens, it has nothing to do with the background and practising won´t help either.

Best,
c.

Click to expand...

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

The 1000D (and all Canon cameras except for the 1 series) will not autofocus with any lens that has a maximum aperture that does not open up to f/5.6.

Therefore, your lens, at f/6.3 maximum aperture, will not autofocus properly (if at all) on your 1000D.

The 1 series cameras have a center AF point that is sensitive down to f/8, while pretty much all other Canon DSLRs are only sensitive to f/5.6.

imqqmi said:

I've never heard anyone complain about not being able to AF at all with a sigma 50-500mm or the one the OP uses (both f/6.3 at 500mm). That the AF has trouble beyond f/5.6 in low light I can agree.

I can't believe after only owning a telelens for 2 months that one is at the top of the learning curve tracking BIFs. So there's plenty to practice and learn.

Click to expand...

I do not have the Sigma lens (yet) but I´m following the manual + the DOF button test I proposed. Could you please explain to me how practising can make AF work beyond the f-values it is not designed for? Thank you a lot.

Many thanks for your help........thank you for pointing me in the right direction.

I spent a week in the south of spain shooting vultures with little success using the autofocus. I resorted to manual focus... . I did get some good shots in the end.

It looks as if I have outgrown my camera. I have read that throwing money at the hobby will not make things better, however it looks as if I bought the wrong lens for the camera!!!

costojanku said:

imqqmi said:

I've never heard anyone complain about not being able to AF at all with a sigma 50-500mm or the one the OP uses (both f/6.3 at 500mm). That the AF has trouble beyond f/5.6 in low light I can agree.

I can't believe after only owning a telelens for 2 months that one is at the top of the learning curve tracking BIFs. So there's plenty to practice and learn.

Click to expand...

I do not have the Sigma lens (yet) but I´m following the manual + the DOF button test I proposed. Could you please explain to me how practising can make AF work beyond the f-values it is not designed for? Thank you a lot.

Click to expand...

In this post someone claims to have no problem using the lens at 500mm and focuses just fine. He suggests the lens may report the lens as being a 5.6 to the system while reporting 6.3 in the exif info. How this is done I don't know but it seems to work which is all that matters.

http://www.wildaboutbritain.co.uk/forums/photography-critique-and-advice/23100-new-sigma-150-500mm-f5-6-3-dg-os.html

The OP had difficulty getting consistent results, so AF does work but not reliably. You are suggesting that there's a cut off point beyond which AF doesn't work. That does not seem to be the case or there seem to be workarounds (luckily )

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

Ok, then. If this is so, I wouldn´t mind for sure.

Best,
c.

Q: Will the 170-500mm APO zoom lens autofocus with my AF camera?

A: The Sigma 170-500 f/5-6.3 APO zoom lens will autofocus with today’s autofocus cameras, in spite of the fact that its maximum aperture ranges from f/5 at 170mm to f/6.3 at 500mm.

from:

http://www.sigmaphoto.com/faq/faq.asp?navigator=3

If the 170-500mm can AF, then the 150-500 should too.

--
Kind regards
Imqqmi



http://www.pbase.com/imqqmi

Ok, fine, thanks. This is good even for me because I´m thinking about purchasing Bigma and I thought I would have to focus manually towards the longer end because of its limited max. aperture.

This is simply not true. I've used the Sigma 150-500 on my XSi and had no issues focusing at at 500mm using F8.0. Poor lighting may slow the AF process resulting in the AF missing (focus at a point the bird used to be at) or hunting long enough that you miss the shot. It may just be too slow in low light for moving objects. Technique may also come into play. Keep trying. I only got to use the lens for a couple of hours but had very few shots that weren't in focus. Here's and example at 500mm using F8.0. I'm planning to purchase this lens in the future for use with my XSi.



-Bill

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http://www.flickr.com/photos/billsphotos/

BillsLIPhotos said:

This is simply not true. I've used the Sigma 150-500 on my XSi and had no issues focusing at at 500mm using F8.0. Poor lighting may slow the AF process resulting in the AF missing (focus at a point the bird used to be at) or hunting long enough that you miss the shot. It may just be too slow in low light for moving objects. Technique may also come into play. Keep trying. I only got to use the lens for a couple of hours but had very few shots that weren't in focus. Here's and example at 500mm using F8.0. I'm planning to purchase this lens in the future for use with my XSi.

Click to expand...

nice pic, I'm also considering the Sigma 150-500

BenMorrissey said:

The 1000D (and all Canon cameras except for the 1 series) will not autofocus with any lens that has a maximum aperture that does not open up to f/5.6.

Therefore, your lens, at f/6.3 maximum aperture, will not autofocus properly (if at all) on your 1000D.

The 1 series cameras have a center AF point that is sensitive down to f/8, while pretty much all other Canon DSLRs are only sensitive to f/5.6.

Click to expand...

I'm pretty new to my sigma 150-500 os, had it about a month now. But i am more than happy with the lens on my 500d, I generally shoot at f7/f8 and upto iso 1600 with shutter speeds down to as low as 1/60 at 500mm. I can't say i've really noticed this will not focus problem. Currently in UK the light is very low at this time of the year but even so the lens has perfomed well. BIF and wildlife are a new hobby to me but the lens works fine for the job ... maybe the poster has a bad copy.

heavily cropped, 500mm @ f7.1, iso 400, 1/800



500mm, iso1600, f8, 1/80

BenMorrissey said:

The 1000D (and all Canon cameras except for the 1 series) will not autofocus with any lens that has a maximum aperture that does not open up to f/5.6.

Therefore, your lens, at f/6.3 maximum aperture, will not autofocus properly (if at all) on your 1000D.

Click to expand...

AFAIK it's not quite that simple. The camera will refuse to AF with a lens which reports that its maximum aperture is narrower than f/5.6. People get around this in various ways (e.g. by programming the lens to report an f/5.6 max.), and you can AF with those lenses, but not as well as with a genuine f/5.6 or better lens.

BenMorrissey said:

The 1 series cameras have a center AF point that is sensitive down to f/8, while pretty much all other Canon DSLRs are only sensitive to f/5.6.

Click to expand...

I believe this is not primarily about how much light reaches the AF sensor (although obviously more light is better), but about the virtual rangefinder that is the heart of a phase detection AF system. What I think is really happening is that a narrow aperture lens will not provide rays with a wide enough angle between them for the rangefinder to work well. IOW, a narrow aperture lens projects an image with too narrow a "base" for the rangefinder ( http://en.wikipedia.org/wiki/Autofocus#Phase_detection ).

All this information is getting too many conflicting points for my little brain to resolve ......but thanks anyway.

With the 1000d my sigma does autofocus at f/6.3 at 500 mm. I guess that Sigma have programmed the lense so that it autofocuses fooling the camera into it being f/5.6

With regard to the minimum aperture stated for af, the manual only states an ev range which is -0.5-18ev... f5.6 @ 1/2000 iso 400 at 500mm is in this range.

Canon also state that "If an Extender (sold separately) is attached and the maximum aperture of the lens is f/5.6 or smaller (larger f/number), AF will not be possible (except Live mode AF)" They have stated this because the end result is changed by one or two stops ?

With regard to a DOF autofocus test on the canon... I held down the DOF preview at f/5.6 and f/6.2 and nothing. So I tried this with other my other lenses and in summary it doesn't work... not the AF, the test...it will not allow a shot to be taken with the AF down..

If we return to my initial BIF photo. At f/6.3 on the 1000d the camera did autofocus,whether sigma programmed the lens to fool the camera or not, the camera locked on and focused. The end result well... is ok if I wanted to compress the image...

How do we know that the Canon 1000d will not focus above f/5.6? I don't mean to insult anyone , I am a scientist so need facts by nature.

What I want to be is sure.... because if this lens will not AF correctly on this camera it will mean for me a new camera! Hence more moola (money).....

Thank you all for your contributions..... Everyone has been helpful and polite !

I HAVE FOUND MY PROBLEM WITH THE AUTOFOCUS/SHARPNESS..........

HAVING A LENS COAT ON MY LENS I PULLED IT OFF TODAY TO FIND THE SERIAL NUMBER.... 101... I BOUGHT THIS A FEW MONTHS AGO EXPECTING THAT I WOULDN'T GET ONE OF THE FIRST FEW BATCHES.

I NOW NEED INFORMATION ABOUT THE SIGMA 150-500 WITH SERIAL NUMBER 100/101 BEING SOFT.. WHICH IT IS....

THIS LENS, AND THE COMPANY IN THE UK I BOUGHT IT FROM IS/WAS A STRESSFUL EXPERIENCE. I CAN NAME AND SHAME WHEN I HAVE THIS SITUATION SORTED.... BOUGHT THROUGH AMAZON MARKETPLACE.