Hi, I have a sigma 28-300mm for canon af, manual focus at all focal lengths works fine but not auto focus. when in auto focus mode and looking through the viewfinder i hear a whirring mechanical noise like it's trying to focus but just can't. is there anything i can do? thanks
Your Sigma 28-300mm doesn't have a HSM-motor as far as i know. When you switch it from MF to AF, you also have to disengage the manual focusing ring by pulling it towards the camera, or pushing it away from the camera. Using the AF without unlocking the manual focusing ring may damage the AF motor.
I hope this helps,
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Could be, because most camera's only can auto focus till f/1:5.6. And if 5.6 is reached at the focal length of 200 mm, the camera stops it from going to a part it can't be focused.
Perhaps you try the lens in manual focus, and manual zoom.
You haven't stated which body you have but the AF will not work with the extender if the effective lens aperture is too low (remember that a 2x extender doubles the focal length but halves the effective aperture).
Canon's own website states: "Autofocusing does not operate if the effective maximum aperture is
greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3)."
It will default to manual through the viewing screen. It will only work on automatic, using the viewfinder. Make sure you also set the focal length (lens to shutter distance). You might also have a mf / af switch on the lens. This also only works through the viewfinder.
Hi - I own this lens and it manually focuses at all focal lengths (hard to see at 18mm unless your subject is extremly close). You may need to get the lens checked. BTW - Mine was set as follows when I checked for you:
Did it ever work on this camera?
I have seen some Sigma lenses that are auto focus on canon film cameras but then when put on the digital they dont work right. If you have used it on this camera then make sure the lens is clean.sometimes dirt on the front wil make it try focusing on the dirt. Next try focusing in manual focus to make sure the focus is working. Then take the lens off and then put it back on and make sure it clicks into place.
Let me know if none of those things work. also make sure to try focus on something close and somthing far away.
(From Sigma lens literature) Capable of macro photography, this
lens has a 1:2 maximum close-up magnification at the 300 mm focal
length. It's the ideal high performance lens for portraits, sports
photography, nature photography, and other types of photography that
frequently use the telephoto range. It also has a switch for changeover
to macro photography at focal lengths between 200mm and 300mm with a
maximum close-up magnification from 1:2.9 to 1:2. The minimum focusing
distance is 1.5m / 59 in. at all zoom settings.