Buy and then sell a 24-70?

wallybud wrote in post #5872225
NO IT WONT HAH OMG!! The 24-70s FOV at 24mm ON A CROP BODY is 38MM!!
Im going to hang myself!

Yes, but a on a 17-50 APS-C set to 24mm will have the 35mm equivalent of 38mm.

I think you have a misunderstanding of APS-C specific lenses. The Tamron 17-50mm or Canon EF-S 17-55 lens for the matter is not stated in "35mm equivalence" Those are the actual focal lengths. It is "27-80mm equivalent"

Wally, sorry but you're still wrong.

I repeat - The Tamron set to 24mm will have the SAME FOV of the 24-70 set to 24mm when both are mounted on a APS-C camera

Can someone back me up here?

wallybud wrote in post #5872225
NO IT WONT HAH OMG!! The 24-70s FOV at 24mm ON A CROP BODY is 38MM!!

... and so is 24mm on the Tamron.

Clarification: The focal length of a lens is just that, focal length of a lens. FOV depends on the sensor size the lens is being used with. So a 24mm lens is a 24mm lens no matter what camera you attach it to. On a 1.6x crop camera a 24mm lens will provide a FOV similar to that of a 38mm lens on a full frame. On a 1.3x crop the FOV is similar to a 31mm lens on a full frame.

Further clarification: The Tamron is meant for 1.6x crop cameras. This means, (since it comes in an EF mount) if you were to mount the lens on a 1.3x or full frame camera, it will vignette horribly. The image circle of acceptable quality for this lens is not much bigger than a 1.6x sensor.

DAMNIT! I go so jazzed up and now I feel like an ass haha! maybe this belt will in fact fit around my neck...

sorry guys, walk of shame

wallybud wrote in post #5872188
what is everyone talking about jeez! anything you have on the 24-70 that you put on a crop body will be multiplied by 1.6 ?!
The TAMRON is build for a 1.6x sensor so 50mm on the tamron is 50mm

If you put a 24-70 on a 5D and set the focal length to 50, then you put the Tamron lens on a 40D and set the focal length to 50, the image through the viewfinders will be different.

At 50mm on a 40D, the Tamron lens will look roughly equivalent to an 80mm lens on the 5D.

wallybud wrote in post #5872283
DAMNIT! I go so jazzed up and now I feel like an ass haha! maybe this belt will in fact fit around my neck...

sorry guys, walk of shame

It happens to the best of us!

yep, still the same 24mm=24mm. It doesn't matter if the lens is built for APS-C or 35mm (full frame), it is still the same focal lenght. Field of view changes from APS-C to 35mm because of the 1.6 crop, but that doesn't change the focal length. I think where the confusion has set in is where it is believed that a lens built for a crop sensor has a true field of view at the given focal length when in actuality you still need to multiply the focal length times the crop factor to get the field of view.

All focal lengths for each lens are based on the 35mm equivalent, therefore it won't matter if the lens is a crop lens or a 35mm lens, they focal length printed on it based on the 35mm format since it is the standard for measuring focal lengths. Since some lenses are built for an APS-C size frame, then that means that have a narrower field of view which would cause vignetting on a 35mm (full frame) format.

Again, the OP would get a wider field of view using the 17-50 lens vs the 24-70. He would be missing the 7mm on the wide end if he uses the 24-70, but the OP also stated that he would rather gain the extra 20mm on the long end. I have the 24-70 and I love it. I am sure there are limitations for some being that it isn't a true 24mm FOV on the wide end, but it suits me just fine.

EDIT: Sorry, it seems there were other posts while I was writing this to clarify the issue.

Not sure what you're trying to say, but the focal length is an absolute property of the LENS and has nothing to do with the "35mm format". Now whether a particular lens has an image circle large enough to cover a particular format is another issue.

But the 35mm format is NOT the standard for measuring focal lengths. I believe the millimeter is the standard

jdharris wrote in post #5872338
All focal lengths for each lens are based on the 35mm equivalent, therefore it won't matter if the lens is a crop lens or a 35mm lens, they focal length printed on it based on the 35mm format since it is the standard for measuring focal lengths..

wallybud wrote in post #5872188
what is everyone talking about jeez! anything you have on the 24-70 that you put on a crop body will be multiplied by 1.6 ?!
The TAMRON is build for a 1.6x sensor so 50mm on the tamron is 50mm

wallybud wrote in post #5872225
NO IT WONT HAH OMG!! The 24-70s FOV at 24mm ON A CROP BODY is 38MM!!
Im going to hang myself!

egordon99 wrote in post #5872207
OK, The Tamron set to 24mm will have the SAME FOV of the 24-70 set to 24mm when both are mounted on a APS-C camera (ie Rebel series/40D/etc....)

egordon99 wrote in post #5872266
Wally, sorry but you're still wrong.

I repeat - The Tamron set to 24mm will have the SAME FOV of the 24-70 set to 24mm when both are mounted on a APS-C camera

Can someone back me up here?

I'll back you up! (better late than never!!!!)

wallybud wrote in post #5872283
DAMNIT! I go so jazzed up and now I feel like an ass haha! maybe this belt will in fact fit around my neck...

sorry guys, walk of shame

shutterfiend wrote in post #5872280
... and so is 24mm on the Tamron.

Clarification: The focal length of a lens is just that, focal length of a lens. FOV depends on the sensor size the lens is being used with. So a 24mm lens is a 24mm lens no matter what camera you attach it to. On a 1.6x crop camera a 24mm lens will provide a FOV similar to that of a 38mm lens on a full frame. On a 1.3x crop the FOV is similar to a 31mm lens on a full frame.

Further clarification: The Tamron is meant for 1.6x crop cameras. This means, (since it comes in an EF mount) if you were to mount the lens on a 1.3x or full frame camera, it will vignette horribly. The image circle of acceptable quality for this lens is not much bigger than a 1.6x sensor.

egordon99 wrote in post #5872371
Not sure what you're trying to say, but the focal length is an absolute property of the LENS and has nothing to do with the "35mm format". Now whether a particular lens has an image circle large enough to cover a particular format is another issue.

But the 35mm format is NOT the standard for measuring focal lengths. I believe the millimeter is the standard

Oh, I'm glad that got cleared up...

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I didn't see where anyone mentioned the Tamron 28-75 f2.8 as a possible alternative to the Canon 24-70. It's the same aperture, smaller in size and lighter in weight (a consideration fror travel) and less expensive to purchase ( about $550 to $600 less.)

michaelgreen78 wrote in post #5873135
I'll back you up! (better late than never!!!!)

Oh, I'm glad that got cleared up...

hahah I love it, it like you popped in to make sure everything was ok

that was an interesting thread...from help to yelling and screaming to agreement...haha

JWright wrote in post #5873231
I didn't see where anyone mentioned the Tamron 28-75 f2.8 as a possible alternative to the Canon 24-70. It's the same aperture, smaller in size and lighter in weight (a consideration fror travel) and less expensive to purchase ( about $550 to $600 less.)

I don't think OP was looking for an alternative, besides, 24 is at least wider than 28.

Here are my quick thoughts. I have recently switched from the Tamron 17-50 to the Canon 24-70. While there is a very small difference in image quality, the only reason that I switched to the Canon was because there was not a third party lens available that offered USM. I do a lot of action photography and the Tamron simply would not focus fast enough for that. There are may times when I miss the extra on the wide end. If you are doing much landscape I think that you would miss the extra width even more. This is just my two cents worth on the topic.