# thinking about a upgrade



## amartin (Jan 24, 2013)

i have a canon t3i and was thinking about upgrading it to the new canon 6d. what i would like
 to know is will my lens from my t3i fit the 6d
thanks
art


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## o hey tyler (Jan 24, 2013)

amartin said:
			
		

> i have a canon t3i and was thinking about upgrading it to the new canon 6d. what i would like
> to know is will my lens from my t3i fit the 6d
> thanks
> art



Your primes and 70-300 will work, but you're going to want to get better glass before you upgrade IMO. Full frame sensors are quite demanding in terms of optical resolution.


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## CanonJim (Jan 25, 2013)

o hey tyler said:


> amartin said:
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I agree - most f/f cameras will really shine when paired with better glass, and in some cases they will make iffy glass a little better, but they won't reach their full potential without "decent" or better glass up front. Your EF-S lens(es) will NOT fit on the 6D or any other Canon F/F body. The 6D can 'fix' some CA and geometric distortion on SOME Canon lenses, but not all.  What I would do is market your EF-S glass on eBay or Craigslist, and put that money towards a new body/lens kit, like the current Amazon 6D/24-105L kit that I just jumped on, for $2499. Your EF lenses will fit the new body AND your Rebel as well.


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## o hey tyler (Jan 25, 2013)

CanonJim said:
			
		

> I agree - most f/f cameras will really shine when paired with better glass, and in some cases they will make iffy glass a little better, but they won't reach their full potential without "decent" or better glass up front. Your EF-S lens(es) will NOT fit on the 6D or any other Canon F/F body. The 6D can 'fix' some CA and geometric distortion on SOME Canon lenses, but not all.  What I would do is market your EF-S glass on eBay or Craigslist, and put that money towards a new body/lens kit, like the current Amazon 6D/24-105L kit that I just jumped on, for $2499. Your EF lenses will fit the new body AND your Rebel as well.



I'm going to have to disagree that a full frame camera will make "iffy glass" look better. That doesn't really make sense. Usually when a lens is if poor optical design, it will show most of its flaws around the edges near the outer reach of the image circle... Which is part of a full frame image. APS-C bodies will crop out these flaws on the edges due to the smaller sensor.


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## CanonJim (Jan 25, 2013)

o hey tyler said:


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I didn't mean to state that a full frame sensor will make ALL "iffy" glass better - I meant it to mean that, with regards to recent DSLR sensor & CPU design, "borderline" good glass, meaning that stuff above kit lens level, but lower than L level, is IMPROVED, somewhat.  I've seen this stated in several reviews of the 5D/3 and 6D. I'll find the actual sites, if necessary.  

The downside of course is that most f/f cameras will make junk look even worse...


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## TCampbell (Jan 25, 2013)

You cannot mount a Canon "EF-S" lens (note the "-S" suffix) lens on any Canon camera other than an APS-C crop-frame body.  The 6D, 5D series, and 1D series cannot accept EF-S lenses.  That's because the "-S" stands for "short backfocus" and the rearmost element protrudes far enough back from the rear of the lens that a full-frame mirror would crash into the lens element when it tried to swing up.  Consequently Canon engineered a bit of a ledge in the lens mount so that the lens wont even seat on the mounting flange (technically the bayonet mounting ring is the same... it's a ledge or step that they put on the body to prevent the lens from seating so that you can't even try to use an EF-S lens... it simply will not mate with the body.

You can use any EF lens as well as Canon's specialty lenses (MP-E macro and TS-E tilt-shift lenses.)

You can generally use an 3rd party "EOS" lens as long as you verify the lens is for "full frame" bodies.  If the lens says it's for "crop frame" then it wont work.

The only lenses in your profile that will work are the 50mm f/1.8, 35mm f/2, and the 75-300.  

If you switch to full frame, you really want to invest in good glass.  E.g. upgrade the 50mm f/1.8 to the 50mm f/1.4.  Upgrade the 75-300mm zoom to the 70-300mm zoom (or better yet... an L series lens.)


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## rexbobcat (Jan 25, 2013)

TCampbell said:
			
		

> You cannot mount a Canon "EF-S" lens (note the "-S" suffix) lens on any Canon camera other than an APS-C crop-frame body.  The 6D, 5D series, and 1D series cannot accept EF-S lenses.  That's because the "-S" stands for "short backfocus" and the rearmost element protrudes far enough back from the rear of the lens that a full-frame mirror would crash into the lens element when it tried to swing up.  Consequently Canon engineered a bit of a ledge in the lens mount so that the lens wont even seat on the mounting flange (technically the bayonet mounting ring is the same... it's a ledge or step that they put on the body to prevent the lens from seating so that you can't even try to use an EF-S lens... it simply will not mate with the body.
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> You can use any EF lens as well as Canon's specialty lenses (MP-E macro and TS-E tilt-shift lenses.)
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The image circle on EF-S lenses is also just large enough to fill the angle of view of FF size sensors. If you mount it on a FF or APS-H camera you will have a large black circle around the image perimeter.

And don't knock the 50mm f/1.8. Its bokeh sucks, but it's supposedly sharper with less vignetting than the 50mm f/1.4.


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## Rick50 (Jan 25, 2013)

I disagree with the "You can't mount a ES-S lens on a FF camera." I have a 60D (APS-C Sensor) and a 5D (FF sensor). I can mount my EF-S lens on the 5D. The connector pins are the same for both lens. I can even auto focus. It's just that the image circle on an EF-S lens does not cover the Full frame sensor. You can also USE your EF-S lens on a full frame camera IF your willing to live with the crop you will need to do.
This is a Sigma 30mm, 1.4 lens for APS-C on a 5D camera.


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## o hey tyler (Jan 25, 2013)

Rick50 said:
			
		

> I disagree with the "You can't mount a ES-S lens on a FF camera." I have a 60D (APS-C Sensor) and a 5D (FF sensor). I can mount my EF-S lens on the 5D. The connector pins are the same for both lens. I can even auto focus. It's just that the image circle on an EF-S lens does not cover the Full frame sensor. You can also USE your EF-S lens on a full frame camera IF your willing to live with the crop you will need to do.
> This is a Sigma 30mm, 1.4 lens for APS-C on a 5D camera.
> <img src="http://www.thephotoforum.com/forum/attachment.php?attachmentid=33871"/>



Yes, you can probably safely use OFF BRAND lenses. But it's not recommended. You could potentially break something internally, which I'm guessing you didn't consider.


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## Rick50 (Jan 25, 2013)

o hey tyler said:


> Yes, you can probably safely use OFF BRAND lenses. But it's not recommended. You could potentially break something internally, which I'm guessing you didn't consider.



I've never heard about this. I've had no trouble with any lens. Any reference?


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## Derrel (Jan 25, 2013)

o hey tyler said:


> CanonJim said:
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I'm going to have to disagree that a FF camera requires better glass than an APS-C camera...I think that in reality, the opposite is true. Why? Well...in tests of identical lenses, on APS-C and on FF cameras, the FF cameras ALWAYS (as in every single time) produce higher resolution figures than the same lenses used on APS-C cameras. Why? Well--it's a total "system"...the lens and its performance, and the physical size of the sensor (in area), and the pixel count...the full-frame sensor is around 2.7 times larger in area than the APS-C sensor...so a 70-200 2.8 Canon lens for example when used on FF out-performs the same lens when used on an APS-C camera. The resolution tests done everywhere show that the larger-sensor cameras "do more" or "record MORE information" than do smaller sensors, when using the same lens.

So, basically, what we see is that FF cameras out-resolve APS-C cameras. Lenses perform BETTER on full-frame cameras than they do on APS-C cameras. With sensors that are approaching three times larger, that means that full-frame cameras really do not "require" good lenses to perform well. The entire "system" favors the larger sensor, to a huge degree. Even with only a moderately decent  lens on it, a moderate MP count, Canon 6D sensor, of only 20 Megapixels, out-performs (in multiple metrics of performance) a similar MP-coiunt APS-C sensor camera. This is the same with medium-format sensors, which are MUCH larger, and higher in MP count than APS-C or FF digital sensors, and have lenses with significantly LOWER resolving power than 35mm system lenses. Medium-format lenses, and large format lenses are NOT REALLY what one would call "ultra-high resolution lenses"--and they do not NEED to be because....wait for it, wait for it--because their capture area is so large!!!

Bigger capture areas mean that lenses with lower "performance" do quite well, thank you. It is *ultra-small capture formats* which require the BEST lenses to do well.


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## Rick50 (Jan 25, 2013)

Well, I did a little research myself and I found this on Wiki-pedia:

"Canon designers have taken steps to ensure it is physically impossible  to mount EF-S lenses on EF-only cameras. This is because the increased  proximity of the lens to the sensor means that on full-frame sensor or  35mm film EF cameras the lens itself would obstruct the mirror's  movement and cause damage to the lens and/or camera. While it is  possible to modify the lens such that the physical obstruction is  removed, allowing for mounting to EF mount cameras, the rear of the lens  would still obstruct the mirror."

Then I retried my lens. My sigma lens work on the 5D. My Tamron mounts but does not communicate. All my canon lens are full frame (EF).

So I  should withdraw my statement that you can use APS-C lens. Not sure why you would want to anyway....


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## amartin (Jan 26, 2013)

thanks for all your help. so i take it no EF-S will not fit the 6D. THE 2 main lens i have are the EF 70-200mm F/4L USM. and the EF 17-40mm F/4L USM. and they will fit the 6D?? if they fit i will do the upgrade
thanks again for all your help
art


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## Justman1020 (Jan 26, 2013)

Yea

The L lens fits on full frame. We didn't know you had those because they are not in your sig.


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## TCampbell (Jan 27, 2013)

Rick50 said:


> o hey tyler said:
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> > Yes, you can probably safely use OFF BRAND lenses. But it's not recommended. You could potentially break something internally, which I'm guessing you didn't consider.
> ...



The issue is that on a "Canon" EF-S lens, the rear-most element actually protrudes beyond the mounting flange.  That means it extends slightly into the camera body.   This is a problem for the mirror.

On an APS-C crop-frame body, the sensor is smaller, so the image circle is smaller, the reflex mirror is smaller and the pentaprism is smaller.  But it's the smaller mirror which is key to why it all works.  The mirror is small enough that when it swings upward, it has no problem clearing the rear lens element on the lens.

On a full-frame body, the reflex mirror (and everything else... but we're mostly concerned with the mirror size) is physically much larger.  If the rear-most element on the lens were allowed to protrude into the camera body, then the reflex mirror would actually strike it while swinging up.



Notice in these images that the 5D II body has a series of steps near the bottom (I've circled them).  But on the 60D (actually it's a 60Da for astrophotography but the body mount is the same as for any Canon APS-C body) you can see that those steps have been removed... it's hollowed out.

That hollowed out area is what the rear-most element fits into on an APS-C crop frame body, and the lack of that area being hollowed out is what prevents an EF-S lens from being allowed to properly "seat" onto the lens mounting flange.

You can also see how much larger the mirror is on the 5D II (full frame) body.


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## TCampbell (Jan 27, 2013)

Derrel said:


> o hey tyler said:
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The basis of the idea is that when you look at the MTF graphs for various lenses, you can see the pattern that the "sweet spot" of almost any lens is usually the center axis.  As the distance from the center increases, the resolving power of the lens degrades.  In any APS-C lens, you only need to control resolving power out to about 13-14mm from center.  On a full-frame lens I think the distance is closer to about 22-23mm from center axis.  

I think the fear is that a budget quality full-frame lens might skimp and allow the optical quality to degrade horrendously as you get toward the edges and corners.

But this is a generalization.  Canon publishes the MTF graphs for their lenses so it's easy to look up the expected performance of any specific model rather than rely on the generalization.

People tend to believe that all "L" series glass is better than all non-L glass.  But there are some non-L lenses with amazing optics.  I tell people that when you buy an L lens there are usually a lot of other attributes that Canon improves aside from just the optics.  They may have a metal body.  They may (and usually are) weather-sealed.  Often they'll have more aperture blades for more rounded aperture and better quality in the out-of-focus areas (bokeh).  Usually L lenses offer constant focal ratios throughout the zoom range (but not all of them.)  The list goes on... so it's not necessarily true that the "L" lens is better because it's optics are better.


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## Rick50 (Jan 27, 2013)

I think I opened a can of worms here. Out of curiosity I looked at my 5D Mk III and it's different than the photo Tim posted for the 5D Mk II. 
I think I understand why the Sigma lens work now.

Here's a photo of my 60D and 5d III. The ribs are gone from the 5D Mk II.



Sigma 30mm 1.4 lens (EF-S)


Tamron 10-24mm (EF-S)



Canon 16-35mm L (EF) Lens. Mounts on 60D and 5D.


I don't see any difference so has Canon changed it's mind on mounting EF-S lens mounting?
I know I will still NOT use the EF-S lens on the 5D.


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## CanonJim (Jan 28, 2013)

Rick50 said:


> I think I opened a can of worms here.


If your can is an EF-S mount, it will only fit on your 60D..


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## SJphoto (Feb 4, 2013)

Yeah, it would be best not to mount EF-S on EF. Check the specs for any Canon camera you buy before taking any advice from here.


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