Is the canon 24-70 mm 2.8l ii a worthwhile investment for the 70d?

[Ma49ers1]

70d

[TCampbell · Accepted solution]

The high-end version of a standard zoom with low focal ratio for the 70D is the Canon EF-S 17-55mm f/2.8.  That's basically the same focal length range as the typical kit lens (18-55) but it can provide an f/2.8 focal ratio at any focal length rather than varying the focal ratio as the kit lenses tend to do.

[cale_kat]

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@TCampbell wrote:
Such is the nature of f/2.8 zooms. In order to lower the focal ratio but maintain the same focal length the physical diameter of the lens has to be increased. Then all the glass elements inside get a larger physical diameter, which also makes them thicker. That may result on stronger dispersion requiring even more corrective elements in the lens. By the time all that happens the lens weights noticeably more.

My solution is to use a more comfortable camera strap. I use a sling type strap (Black Rapid) rather than a traditional neck strap.

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Ha ha, but a neck strap doesn't made the 17-50mm f/2.8 EF-S weigh any less.

[ebiggs1]

Bob in Boston,

The f-stop is the focal length divided by the diameter of the lens. One example, a 200mm f/4 lens will be 50mm wide. 200mm/50mm = f/4.   The light-gathering ability of a lens is determined by its area, and f-stops are determined by diameter. 

Now in a zoom lens things are more complicated and corrector lenses are needed.  So zooms get heavier as their f ratio goes down (number gets smaller) and very much more costly.

This is a fixed physical condition and it is the reason the lens does not and can not change anything when used on a different body.  Be it a FF, medium, or Rebel crop.

[cale_kat]

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@ebiggs1 wrote:

Bob in Boston,

The f-stop is the focal length divided by the diameter of the lens. One example, a 200mm f/4 lens will be 50mm wide. 200mm/50mm = f/4.   The light-gathering ability of a lens is determined by its area, and f-stops are determined by diameter. 

Now in a zoom lens things are more complicated and corrector lenses are needed.  So zooms get heavier as their f ratio goes down (number gets smaller) and very much more costly.

This is a fixed physical condition and it is the reason the lens does not and can not change anything when used on a different body.  Be it a FF, medium, or Rebel crop.

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ebiggs1 writes, "The light-gathering ability of a lens is determined by its area.." 

Though a EF lens is unchanged, regardless to the body (duh, there won't be a magic show) it will never be able to fully capitalize on the coverage when mounted on a Crop-sensor body. Imagine a Corvette engine in a Cobalt body which is never able to use much of its capacity. (BTW, I do not mean to suggest that the 70D is anything less than a extremely good camera.)

[ebiggs1]

"The lens's only real drawback is that it's a lot bigger and heavier ..."

I could probably think of a few more but whose counting?    It is a great lens for 75% of the folks.

[cale_kat]

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@ebiggs1 wrote:

It is a great lens for 75% of the folks.

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Whoa there Canon dude. 75% of anyone with a camera. 75% of the people that casually use their DSLR? Which 75%?

Making stuff up is fun, don't you think Bob?

[RobertTheFat]

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@cale_kat wrote:

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@ebiggs1 wrote:

It is a great lens for 75% of the folks.

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Whoa there Canon dude. 75% of anyone with a camera. 75% of the people that casually use their DSLR? Which 75%?

The 75% of Canon users who haven't gone FF?

Making stuff up is fun, don't you think Bob?

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<chuckle!>

BTW, going FF isn't necessarily a reason not to continue to use one's 17-55 f/2.8. If I'm doing an event and the 70-200 is on my 5D3, my second camera will be a 7D with the 17-55.

[cale_kat]

Ma49ers1, I wouldn't buy the 70-200 f/2.8 unless you are "working your way" towards a FF body. The lens was optimized for FF shooting and with the crop-sensor 70D, you'll be "wasting" a substantial portion of that lens. Imagine buying a car and only using it within 60% of its capabilities. That's like buying a minivan and never once using the third row seats.

I second, third, or whatever, the 17-55 f/2.8 EF-S as a great option. If you want a faster lens with reach, I'd recommend choosing a prime lens from among the Canon choices of 60mm f/2.8 EF-S macro, 85mm f/1.8 and 100mm f/2 EF lenses. Buying used is also a great way to test lenses without the pressure of a pending sale. Good lenses hold their value and you can generally recoup much of what you spend.

[ScottyP]

I'll fifth for 17-55. Mine is great, though I don't use it now that I have a FF body. I may get the new 7d2 when it appears (or 6 months thereafter to catch it on a sale, and maybe miss any 1st run manufacturing defects), in which case it will be used again. I would NOT use a 24-??? Lens on a crop camera like 70d because you would be limited on the wide end to the equivalent of 38mm.

I will also agree with Tim wholeheartedly on replacing the neck strap (awkward sternum-smashers that they are) for a shoulder sling strap.

Black rapid is the biggest name but I didn't like the way the camera twirls around, hanging from just 1 attachment point. I really like my Cinch Strap from Luma Labs. Not only does it attach at 2 points (top and bottom) so the camera can't twirl, but it also shortens up snug for walking around, and lengthens out for shooting, and it attaches on one end with an Arca plate so the camera can mount straight onto a tripod without removing the strap.

http://luma-labs.com/pages/cinch