T3i 3x Crop Zoom Comparison

[Taky Cheung]

Some screen caps with T3i with the Canon 17-55mm lens with and without the 3X crop zoom.

at 17mm


at 55mm


at 17mm 3x Zoom


at 55mm 3x Zoom


With this 3x crop zoom feature, it turns the 17-55mm lens into 17-165mm lens (neglecting the 1.6 APS-C crop factor). That's pretty sweet.

[Nigel Barker]

I just bought a 600D/T3i on Saturday but went cheap with the Tamron 17-50mm F/2.8 lens at less than half the price of the equivalent Canon lens. The 3X crop zoom is amazing as it effectively gives me an 80-200mm F/2.8 lens for free. I have been using 5DIIs for the last couple of years & this is the first APS-C Canon DSLR that I have owned & have been really pleased with it. I got the 600D as a cheap B-cam not expecting too much but it feels pretty similar to the 5DII in my hands & the fact that it is more oriented to video than the 5DII is very nice. The video I have shot so far looks indistinguishable from 5DII footage although I haven't shot in low light yet where I expect (hope?) that the strengths of the 5DII will be more apparent. I like the 1.6X crop factor making my long lenses even longer e.g. 135mm F/2L becomes 200m F/2L which would cost getting on for $6000 for that lens on my 5DII. With the 3X crop mode that lens becomes a 600mm F/2L! For really dark venues I can now use my 50mm F1.2L as a 240mm F1.2. Wow!

[Taky Cheung]

That's one of the reason I upgraded T2i to T3i. =)

Just curious how you get your number calculated. How you get 17-50mm to 80-200mm with the 3x zoom?

[Nigel Barker]

Originally Posted by Taky Cheung

That's one of the reason I upgraded T2i to T3i. =)

Just curious how you get your number calculated. How you get 17-50mm to 80-200mm with the 3x zoom?

Rounding error. I meant to write 80-240mm which makes my new free lens even better value:-).

[Taky Cheung]

17 x 3 = 51
50 x 3 = 150

Wouldn't the 3x zoom multiply the zoom range from 17-50 to 51-150mm ?

[Nigel Barker]

Originally Posted by Taky Cheung

17 x 3 = 51
50 x 3 = 150

Wouldn't the 3x zoom multiply the zoom range from 17-50 to 51-150mm ?

Plus the APS-C 1.6X crop factor which gives the following 35mm equivalent:

17x3x1.6=81.6
50x3x1.6=240
the normal non-zoom range for the lens is of course
17x1.6=27.2
50x1.6=80

I am used to the full frame 5DII so think in those terms. In round figures 28-80mm & 80-240mm all at a constant F/2.8 will cover 95% of what I need this camera for.

I am now beginning to regret being cheap & going with the Tamron 17-50mm F/2.8 over the Canon 17-55mm F/2.8 as from what I read the lens quality of the Canon is better (as expected) but the noisy OIS of the Tamron is going to be a problem. This was my first APS-C & EF-S purchase so I didn't want to spend too much in case it didn't work out but as it turns out it has exceeded my expectations & I think that this may end up being the camera that I use to shoot video the most unless there are those special situations like low light where the 5DII will be better. I think that I will probably take the Tamron back for a refund & get the Canon instead which will give me a little longer reach & (in round figures for 35mm equivalent) 28-88mm & 82-264mm.

[Bill Grant]

Crop factor does not zoom. The focal length doesn't change, it just takes 1.6x in the center of the frame. So your lens doesn't become a longer lens, it just has the "crop" tighter. it's just like zooming in post, you don't actually make your shot closer, you just pull it in and cut off the edges.
Bill

[Nigel Barker]

Originally Posted by Bill Grant

Crop factor does not zoom. The focal length doesn't change, it just takes 1.6x in the center of the frame. So your lens doesn't become a longer lens, it just has the "crop" tighter. it's just like zooming in post, you don't actually make your shot closer, you just pull it in and cut off the edges.
Bill

The lenses don't change focal length but the field of view does change depending on the size of the sensor & ignoring some differences with perspective the narrower field of view of the APS-C compared to a full frame sensor looks like you zoomed in. It's not the same as zooming in post as when you do that you are cropping down from 1920x1080 & ending up with less resolution because you are throwing away part of the image. Using the 1.6X multiplier for APS-C sensors is just a handy rule of thumb when comparing the field of view versus the same lens on a full frame camera. A 50mm lens on an APS-C camera has the same FoV as an 80mm lens on a full frame.

[Taky Cheung]

Originally Posted by Bill Grant

Crop factor does not zoom. The focal length doesn't change, it just takes 1.6x in the center of the frame. So your lens doesn't become a longer lens, it just has the "crop" tighter. it's just like zooming in post, you don't actually make your shot closer, you just pull it in and cut off the edges.
Bill

Despite all the technical stuff, the way it works does make it feels like I have a longer lens. I think that's the most important that it gives me the extra flexibility in framing the shot, without moving or changing lens.

It is definitely NOT the same as zooming in post. Zooming in post is stretching pixels which cause loss in quality. The 3X crop zoom has no quality loss.

[Taky Cheung]

Originally Posted by Nigel Barker

Plus the APS-C 1.6X crop factor which gives the following 35mm equivalent:

17x3x1.6=81.6
50x3x1.6=240
the normal non-zoom range for the lens is of course
17x1.6=27.2
50x1.6=80

I am used to the full frame 5DII so think in those terms. In round figures 28-80mm & 80-240mm all at a constant F/2.8 will cover 95% of what I need this camera for.

I am now beginning to regret being cheap & going with the Tamron 17-50mm F/2.8 over the Canon 17-55mm F/2.8 as from what I read the lens quality of the Canon is better (as expected) but the noisy OIS of the Tamron is going to be a problem. This was my first APS-C & EF-S purchase so I didn't want to spend too much in case it didn't work out but as it turns out it has exceeded my expectations & I think that this may end up being the camera that I use to shoot video the most unless there are those special situations like low light where the 5DII will be better. I think that I will probably take the Tamron back for a refund & get the Canon instead which will give me a little longer reach & (in round figures for 35mm equivalent) 28-88mm & 82-264mm.

Thanks! Got it! I forgot about the 1.6 factor in it =)

I have Sigma 17-50mm F2.8 and Canon 17-55mm F2.8. The reason I bought the Sigma instead of Tamron was because Tamron has a different zoom ring and focus ring direction than the Canon. So I don't want to be all disoriented. =)

Another great feature of Canon over Sigma is, I can still manually adjust the focus ring while in AF mode. For the Sigma lens, when set to AF mode, the focus ring is very tight to be adjusted manually. I have to switch to manual focus before setting focus myself. So for the Canon, just set to AF mode and I can half-press shutter button to focus, or use the focus ring.

The Canon lens is noticeably faster in auto focus, and sharper. The sharpness can be tell just through the LCD screen.

[Nigel Barker]

I am definitely taking the Tamron back tomorrow & will pay the extra to get the Canon instead. The difficulty using manual focus when switched to AF & backward focus direction would drive me nuts when using the lens on a real paying gig. That combined with the noisy OIS, slow AF & lesser optical quality has made the decision for me.

[Keith Betters]

Thanks Taky for posting these results. I am already sold on the t3i, I'm just waiting for a few more weddings to go ahead pay for it. That combined with the no overheating, is a done deal. I don't even know why they still make the t2i, for only $100 less. I will have two t2i's to go with the t3i for magic lantern. But once they get magic lantern all tested and ready to go for the t3i, I will sell them both and upgrade those as well. The overheating is a big deal for me, especially here in Texas. Its 100 degrees outside and they reach overheating withing 30 min outsides..No Good!!!

Hey Taky let me ask you this, would you get the 28-70mm f2.8 or the 17-50mm f2.8. I want to be able to zoom to at least 250mm but if i have the 17-50mm that would mean I would be at 5x zoom. I don't mind doing that occasionally but not all the time! What are your thoughts on that?

[Taky Cheung]

Together with the articulating LCD screen and manual audio control, t3i beats 60D IMO. =)

The reason I bought the 17-55mm F2.8 instead of the 28-70mm F2.8 is the OIS. It's necessary to have OIS when shooting video. People keep saying Canon will release a new version of 28-70mm F2.8 with OIS.. Until that is available, 17-55mm F2.8 would be a better option.

[Bill Grant]

point was, beyond my flawed example is that the crop factor does not make the lens into anything, it just crops. This 3x feature on the T3i looks very interesting though because it does seem to zoom in... that means my 70-200 becomes a 210-600... yoikes! at 2.8 yoikes! with IS yoikes!
Bill

[James Donnelly]

Sometimes I feel like we need to shift away from discussions around focal length and start thinking in FOV. It would remove all the arguments around the crop factor etc. In the mean time 35mm equivalent will have to do.

Also, just thought it was worth mentioning in the x becomes y debate that the DOF is deeper when comparing the 3x effect with a lens which is really 3x longer but has the same maximum aperture.. Probably not such a bad thing, but worth remembering. Zoom to 3x, on a 50mm f/2.8, and yes it's a 240mm 35mm equivalent (awesome), but still has the DOF of the 50mm f/2.8, not a real 240mm f/2.8