Help with Sigma lens compatibility for EOS 2000D

[Griff1968]

Hi, could anyone tell me if the sigma 18-35 f1.8 art lens is compatable for my camera which is a canon eos 2000d, and if this lens would be ok to shoot small gigs in poor light in pubs and clubs. Iwoul be purchasing this lens second hand to keep the cost down.

Thanks in advance.

[deebatman316]

Where exactly are you buying this lens second hand from. Get it from a reputable shop/ seller. Since this is a 3rd Party lens it is available in MANY different lens mounts. Make sure it has the Canon EF Mount or it won't work. 

[Griff1968]

Ive not sourced it yet, but will make sure of that, is the lens suitable for the job i require?

[deebatman316]

The fast F/1.8 aperture will help. Is the camera not locking focus on low light. That is a weakness of the 9 point AF system. My old EOS 40D uses that same AF system. It too struggles in low light. Even with an F/2.8 zoom lens. 

[Griff1968]

No think the Af will be ok, but i only have a kit lens at the moment f3.5 its not good enough for the lighting conditions i need to use it in, i was going to get a nifty fifty lens, but think the sigma may be a little more versatile for me.

[deebatman316]

Actually your kit lens is variable aperture so it is F/3.5-5.6 so F/3.5 can't be used at all focal lengths. At 18mm wide open is F/3.5 and at 55mm wide open is F/5.6 so low light and contrast will cause focus locking problems. I don't know what your budget is. But Canon does make the EF-S 17-55mm F/2.8 IS USM lens its a very good lens. It performs very well in low light conditions too and focuses fast with its Ring Type USM AF motor. You'll be able to use a lower ISO instead of a higher one which causes noisy pictures. It also has IS which reduces camera shake. I am very familiar with the 9 Point AF system and my challenge was the camera not locking focus. If the camera can't lock focus it won't take a picture. The camera will keep trying to find focus if the camera is set to do so. Or in Full Automatic Mode (Green Square) the built in flash will pulse rapidly to assist the camera's AF system. This is called an AF Assist Beam. Canon has used several kinds of AF Assist Beams. Intermittent Flash Firing is utilized by the built in flash and some speedlites. It makes audible buzzing sounds. Some speedlites utilize and "IR"/ Infrared beam (not really infrared) red grid pattern. To assist the camera's AF system. This is the fastest method for the camera to lock focus. It also doesn't have any noises associated with it. 

IR/ Red Grid AF Assist Beam

[Griff1968]

Deebatman316 , thanks for your help with this, so much to learn😁.

[deebatman316]

So just because a lens has a wide aperture. That doesn't mean it will focus fast. That's up to the camera's AF system. 

[Griff1968]

Ah! so is that down to the motor that drives the shutter or the camera body telling the lens to focus, or both?

[deebatman316]

No it's up to the AF sensors in the camera. The lens doesn't know if it's in focus or not. Every lens for Canon has motor in it. Canon has NEVER used a motor in the camera body for AF. All the lens motor does is follow commands that the camera sends it. Some of Canon's lenses use fast AF motors such as Ring Type USM or Nano USM. Or some use very old and slow Micro Motor or AFD (Arc Form Drive).