Blured zoom shots due to low light

Something is bad with the lens or it needs to have an upgraded circuit put it to make it compatible (if it is older). Usual cause of lens failure is the aperture unit. Almost impossible to get Sigma parts these days.

Sigma makes lenses with a variety of camera mounts. A lens with a Pentax mount, for example, will not fit onto a Canon camera. Assuming you get the lens with the Canon mount, then it will work on the EOS 350D with full functionality.

Hi I am SAGHA camera repairer from mumbai,I think your sigma 18-125 dc lens is having electronically operated aperture unit in which one Film PCB runs from mount contacts to aperture unit.Due to multifolds of that film inside the barrel the film gets cracked at one fold location So either you have to get that film changed or the whole aperture unit replaced from an expert.give me feedback for this tip Vote me if you found it useful,ALL THE BEST.

For daytime, make sure the ISO is kept low, say 100, or 200 if a little dull. For nighttime or indoor, you may need to increase the ISO up to the max of 1600.
Check also the AV+/- setting isn't set too high - are the shots brighter than normal? If so, hold the AV+/- button and use the scroll wheel to bring the setting back down.
One other thing to check is your CF card - have you changed cards recently? I have two 2Gb UltraII cards from Sandisk - one is really fast, about 1-2 pictures per second, the other is really slow, about 3-4 seconds per picture. They should be the same but are not.
Also try shooting in AV mode to keep the lens wide open and get the fastest shot possible.
Hope this helps!

Are you sure you bought a lens with Canon AF mount? To me it sounds like you got one with a mount for a different camera.
Does the mount on the lens look like this?


If it doesn't, you got the wrong version of the lens. If it does look like the mount in the picture, your just mounting it incorrectly.
If you hold the camera with the lens mount facing you, the red marker on the lens should be in the 12 o'clock position, lining up with the red marker on the lens mount on the camera. The turn the lens clock wise, about an 8'th of a full turn, and the lens should click into place.
I hope this help you!
/Chris

Simga makes lenses to fit several different makes of camera bodies including Canon and Nikon. I'm assuming your Sigma lens has a Nikon mount, if so there are some adapters, but they may not work like you want - not all functions may work properly thru the adapter. For best results you should return or sell the lens and get one with the Canon mount.

In low light you need a high ISO setting, probably 1600.
You also could do with a lens with a low F number to let in lots of light. You can get a fixed focal length F1.8 cheap but might find the lack of zoom a problem.
A decent zoom with a low F number is going to be expensive.
The EF-S 17-55mm F2.8 IS for instance has a list price of around £800 / $1200 !!
You can get a non-Canon one which would be more affordable and you also won't need the IS at short focal lengths (although it always helps). Have a look at Sigma and Tamron in the F2.8 to F4.0 range but check the online reviews to make sure they are of reasonable quality.

It will not focus on anything closer than 5 feet.

(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.

The standard canon 75-300 lens is not considered a "fast" lens. Because of this, when zooming in on objects you are actually reducing the amount of light hitting the image sensor. Fast lenses cost $$$$. Just google "Canon L Glass" and you will see what I'm talking about. Try opening the field of view (zooming out) to allow more light to be absorbed bu the image senor. Crop your subject later in whatever software you use. You can also use one of the manual modes and up your f-stop to make the camera more sensitive to low-light conditions (higher f-stop means higher film speed.. higher film speed is how fast the "film"... aka image sensor absorbs the light. for action photos, faster film speed is key!!). have fun experimenting.

low light means the shutter stays open longer to capture the image.   Try changing exposure settings.