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Author Topic: 24-70/2.8 or 24-105/4 on 5D MK2  (Read 7910 times)
atassy
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« on: January 26, 2009, 07:19:38 AM »
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i'm looking for a 'standard zoom' for the canon 5D MK2. after having done quite a bit of research, asking people and pondering i'm still somewhat undecided between the canon lenses 24-70/2.8 and 24-105/4. i can imagine that a lot of people are in the same situation so let's see...

i expect this to become the lens that i use most frequently on the camera so the price difference is not an issue. i would be using it for events and concerts (relatively dark venues, both flash and available light), documentary (mostly available light and daylight), also a fair bit of landscapes and of course as a general, walk-around lens around town and when travelling.
i do have other lenses (wider, longer, zoom, primes etc) for more specific purposes. this would be the one for when i want to be as quick and flexible as possible, carrying minimum gear. smaller and lighter (24-105 wins here) is better of course but there are other factors that could be more important.

my gut feeling guides me towards the 24-70 for it's slightly better optical quality (less distortion), more efficient lens hood and larger aperture. call me old school but i'm still a bit reluctant to consider a lens slower than f2.8 on a 35mm format slr particularly as i don't know how the 5D Mk2's autofocus will react to such a lens. i rely on the cross type sensor in the middle a lot and don't want it to lose it's accuracy due a slow lens.

on the other hand, the 24-105 seems hugely popular due to it's longer reach, image stabilisation and still pretty decent image quality. it seems to have convinced quite a few people who previously used the 24-70 of its qualities.
its longer reach would constitute a welcome benefit for portaits and longer shots but i'm not sure if its worth the trade-off in speed and image quality (and possibly in AF accuracy). image stabilisation on the other hand - it's a nice addition but i don't know if it would be crucial for me in this focal length range. i think for my handheld stuff i'd sooner have trouble with subjects moving than from camera shake.

as i've almost (almost!) answered my own question:
does anyone have any additional comments, or a direct comparison between these two, that may swing me towards the 24-105?
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francois
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« Reply #1 on: January 26, 2009, 08:11:02 AM »
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You've summed up all the positives and negatives of both lenses. I would only add that the 24-70 f/2.8 is really heavy compared to the 24-105 f/4 and if you carry your camera all day, your neck will feel the difference.

How about renting each of these lenses for an afternoon? I know that it's not always easy to rent equipment but it would certainly help to make your final decision.
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Francois
atassy
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« Reply #2 on: January 26, 2009, 10:22:37 AM »
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Quote from: francois
You've summed up all the positives and negatives of both lenses. I would only add that the 24-70 f/2.8 is really heavy compared to the 24-105 f/4 and if you carry your camera all day, your neck will feel the difference.

How about renting each of these lenses for an afternoon? I know that it's not always easy to rent equipment but it would certainly help to make your final decision.

you're right francois, i'll definitely compare their handling.
any comments on how the AF works with the 24-105/4? all my other lenses are f2.8 or wider which at least with other cameras is the limit for the more accurate cross type sensor. this for me is an important feature that i wouldn't want to lose.
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francois
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« Reply #3 on: January 26, 2009, 10:37:51 AM »
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Quote from: atassy
you're right francois, i'll definitely compare their handling.
any comments on how the AF works with the 24-105/4? all my other lenses are f2.8 or wider which at least with other cameras is the limit for the more accurate cross type sensor. this for me is an important feature that i wouldn't want to lose.
I don't have the 24-105 anymore but, if I remember correctly, the AF was a bit slower in low light. It was very similar to my 17-40 f/4 but I didn't test side-by-side.
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Francois
aaykay
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« Reply #4 on: January 26, 2009, 11:17:34 AM »
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Quote from: atassy
you're right francois, i'll definitely compare their handling.
any comments on how the AF works with the 24-105/4? all my other lenses are f2.8 or wider which at least with other cameras is the limit for the more accurate cross type sensor. this for me is an important feature that i wouldn't want to lose.

In the past when a Canon user (currently shooting with the Sony A900), I shot with both lenses.  In decent light, there was no difference between the 24-105 and the 24-70, when it came to AF performance.

Under low-light conditions, I found the 24-70 f/2.8 to be noticeably faster in AF performance, even dis-regarding the fact that one can shoot at a lower ISO when compared to the f/4 lens (assuming adequate DOF at f/2.Cool.  

Note that these cameras have high-speed/high-accuracy f/2.8 sensitive AF points, which kick in when a lens that is f/2.8 (or faster) is mounted.  These AF sensors work, even when such an f/2.8 (or faster) lens is stopped down to f/5.6 or f/8 or whatever.   Obviously, these high-speed/high-accuracy AF sensors are non-functional, when an f/4 (or slower) lens is mounted.

Hope this helps.
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marcmccalmont
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« Reply #5 on: January 26, 2009, 04:15:05 PM »
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If more than 50% of your shots are handheld buy the 24-105 IS
I sold my 24-70 2.8 and replaced it with a 24-105 IS
Marc
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Marc McCalmont
Gary Ferguson
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« Reply #6 on: January 27, 2009, 10:13:46 AM »
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Easy.

For general hand-held photography IS is absolutely the best thing since sliced bread. For extreme available light photography, or for tripod photography, a few primes would serve you better. But in the unlikely event that you really are a war photographer then I suppose a case could be made for the 24-70.
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Gary Ferguson
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« Reply #7 on: January 27, 2009, 10:16:17 AM »
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Quote from: aaykay
Obviously, these high-speed/high-accuracy AF sensors are non-functional, when an f/4 (or slower) lens is mounted.

Why is that obvious? Why would any camera deliberately down-grade focusing accuracy?
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francois
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« Reply #8 on: January 27, 2009, 10:34:07 AM »
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Quote from: Gary Ferguson
Why is that obvious? Why would any camera deliberately down-grade focusing accuracy?
I'm sot sure how AF sensitivity works on different models but for the 1d3/1Ds3 (from user guide):


Lens’ Maximum Aperture and AF Sensitivity

The EOS-1Ds Mark III can execute high-precision AF with lenses whose maximum aperture is f/2.8 or larger.

With f/2.8 and faster lenses*

With the 19 AF points indicated by , high-precision, cross-type AF (both horizontal- and vertical-line sensitive) is possible. With cross-type AF, vertical-line detection is about 2 times as sensitive as horizontal-line detection. The remaining 26 Assist AF points are horizontal-line sensitive only.
* Excluding the EF24mm f/2.8 and EF28mm f/2.8 Assist AF points Cross-type points

With lenses whose maximum aperture is f/4 or larger
If the maximum aperture of the lens or Extender and lens combination is faster than f/4, the center AF point will work as a high-precision, cross-type point sensitive to both horizontal and vertical lines. The remaining 18 AF points and the 26 Assist AF points work as horizontal-line sensitive AF points.

With lenses whose maximum aperture is f/5.6 or larger
With lenses whose maximum aperture is larger than f/5.6, all the AF points, including the Assist AF points, will be horizontal-line sensitive only.

With lenses whose maximum aperture is f/8 or larger
With lenses whose maximum aperture is larger than f/8, AF will be possible with the center AF point which will be horizontal-line sensitive. AF will not work with the other AF points.
« Last Edit: January 27, 2009, 10:36:56 AM by francois » Logged

Francois
atassy
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« Reply #9 on: January 27, 2009, 12:22:35 PM »
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for a comparison, here's what the 5D Mk2's manual says (p.83):
[blockquote]
Lens’ Maximum Aperture and AF Sensitivity


With lenses whose maximum aperture is larger than f/5.6

With the center AF point, cross-type AF (sensitive to both vertical and horizontal lines) is possible. The remaining AF points are horizontal-line sensitive or vertical-line sensitive.

With lenses whose maximum aperture is larger than f/2.8
With the center AF point, high-precision, cross-type AF sensitive to both vertical and horizontal lines is possible. The center AF point's sensitivity to vertical and horizontal lines is about twice as sensitive as the other AF points. The remaining eight AF points are horizontal-line sensitive or vertical-line sensitive.[/blockquote]

the manual of the 1Ds Mark III in francois' quote sounds pretty clear to me. this is also how i undestood the AF points worked.

the 5D Mk2's manual on the other hand, doesn't make sense to me. if you read the differentiation between f/2.8 and f/5.6 carefully it seems like they only added 'high-precision' in the second paragraph, and removed the brackets. apart from these phrasing games, the capability of the centre AF point would be the same at f/2.8 and f/5.6 (and indeed any lens wider than f/5.6) if you believe the wording in the manual.
this, however, is different from what i know from other canon bodies (see also francois' quote). i'm not sure if i'm not missing something here but if this is true, then either the 5D Mk2's manual is wrong or they improved the cross-type sensor without pointing it out to anyone (missed marketing opportunity?).

if the latter is true then my above concern, that with an f/4 lens i would lose focusing accuracy in certain situations, would be unfounded. but before i believe this one line in the manual i'd need a bit more evidence especially considering that it's stated pretty much everywhere that the 5D Mk2's AF system is the same as the previous version's    
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k bennett
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« Reply #10 on: January 27, 2009, 01:33:00 PM »
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If I understand it correctly, the 5D and 5D2 autofocus system has a cross-type sensor only on the center AF point. That makes the center point much more sensitive and quicker to focus under many common focusing conditions. It means that "focus and recompose" is often the order of the day.

Getting back to the lens question, I would agree that IS is a *huge* addition for hand held walk-around photography. I own the 24-70/2.8, and would trade it for a 24-105/4IS almost any day of the week. When I need larger-aperture lenses, I can use my fast primes, which cover pretty much the whole range and then some. (As an aside, I just picked up a 17-55/2.8 IS lens for my 40D, which solves the problem of choosing between the two.)

The only time I might miss the f/2.8 zoom is when I do indoor event coverage, and have to drag the shutter to get the background to balance. The extra stop is well worth it in that situation. And I wouldn't choose the 40D for that type of photography, because in my experience the AF system isn't anywhere near as good as the 1D-2 AF in near-darkness.

Perhaps the correct answer is that you need both....
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aaykay
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« Reply #11 on: January 27, 2009, 02:09:40 PM »
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Quote from: Gary Ferguson
Why is that obvious? Why would any camera deliberately down-grade focusing accuracy?

It is "obvious" because it is not an "f/2.8 or faster" max aperture lens.  Did you think f/4 = f/2.8 ?  

Bottomline, f/2.8 provides TWICE as much light as an f/4.  AF is most efficient if it has an adequate amount of light to work with, and is done at the max aperture of the lens, even when the lens is stopped down.  In lower light conditions, AF performance deteriorates and the f/2.8, which lets in DOUBLE the light as the f/4 version, obviously provides enough juice for the AF sensors to do their job well.  The specific f/2.8 sensitive sensors are purpose built to take advantage of the extra light an f/2.8 lens lets through, over that let in by an f/4 lens.

Does the "obviousness" of the statement now make sense ?
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Gary Ferguson
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« Reply #12 on: January 28, 2009, 01:12:45 AM »
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Quote from: aaykay
It is "obvious" because it is not an "f/2.8 or faster" max aperture lens.  Did you think f/4 = f/2.8 ?  

Bottomline, f/2.8 provides TWICE as much light as an f/4.  AF is most efficient if it has an adequate amount of light to work with, and is done at the max aperture of the lens, even when the lens is stopped down.  In lower light conditions, AF performance deteriorates and the f/2.8, which lets in DOUBLE the light as the f/4 version, obviously provides enough juice for the AF sensors to do their job well.  The specific f/2.8 sensitive sensors are purpose built to take advantage of the extra light an f/2.8 lens lets through, over that let in by an f/4 lens.

Does the "obviousness" of the statement now make sense ?

'Fraid not.

Your theory of how AF works is that the high precision cross-type AF sensors need plenty of light, and an f2.8 lens can deliver this, but an f5.6 lens can't.

But think about it. An f5.6 lens in bright conditions is delivering far more light to the AF sensors than an f2.8 lens in overcast conditions.

If your explanation was correct the Canon guide books would talk about the high precision cross-type sensors only being operative in bright sunlight. But that's absolutely not what they say. High precision AF, according to the Canon guide books, has nothing to do with ambient light or light reaching the AF sensor, and everything to do with the lens's maximum aperture.

So, I stand by my original point. You haven't yet explained AF and there's certainly nothing "obvious" about it.
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aaykay
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« Reply #13 on: January 28, 2009, 02:10:39 PM »
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Quote from: Gary Ferguson
'Fraid not.

Just to test this theory out, carry a lens and try to AF in good light.  Now take that very same lens and try to do it in really dim conditions.  Does the AF struggle at all in dim conditions ?  If so, then why ?  The reason is that very little light is reaching the AF sensors, so that they can go about the task of auto-focusing.  

A fast lens will always hold an edge over a slower lens, under identical conditions (not fast lens in dim conditions vs slow lens in well-lit conditions) and the more light the sensors have, to work with, the better will the AF performance be.  No rocket-science there.  

An f/4 is a relatively slow lens.  For a Zoom lens, there is none faster than an f/2.8, which lets in twice the light of the f/4 version.  The AF performance will be proportionately better/worser.

On top of the above, there are some VERY SPECIFIC f/2.8 sensitive AF sensors in these cameras.  Those will ONLY function if an "f/2.8 or faster" lens is mounted.  Those VERY SPECIFIC f/2.8 sensitive AF sensors lose their ability for high-accuracy and high-speed, if you mount an f/4 or slower lens.  Is this clear enough ?  
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Geoff Wittig
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« Reply #14 on: January 28, 2009, 06:40:58 PM »
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Quote from: atassy
i'm looking for a 'standard zoom' for the canon 5D MK2. after having done quite a bit of research, asking people and pondering i'm still somewhat undecided between the canon lenses 24-70/2.8 and 24-105/4. i can imagine that a lot of people are in the same situation so let's see...
does anyone have any additional comments, or a direct comparison between these two, that may swing me towards the 24-105?

Looks like this thread got diverted into navel-gazing about autofocus, but I can offer an opinion, as I own and regularly use both of these lenses on Eos-1Ds II and III cameras.

The 24-70 f:2.8 is a little bit sharper, enough that you'll notice a slight improvement in very large prints, presuming the usual caveats—solid tripod, careful focus, mirror lock, low ISO etc. The wider aperture is useful in terms of a brighter viewfinder, but I mostly shoot landscapes so it's not otherwise very relevant to me. Its biggest practical shortcoming is that I always find myself wishing for a little more reach on the long end, especially if I'm photographing people. The 24-105 is no question a more useful focal length range, hence it's much nicer when you're walking around with just one camera and the lens mounted on it. That's generally what I use it for. However, the 24-105 has an achilles heel in the form of vignetting. To my eye it has very obvious vignetting on full-frame cameras that is not gone even at f:8. If the image includes lots of blue sky, this can make creating stitched panoramics a major pain in the behind. You can remove most of the vignetting in ACR, but it's never exactly even.

So I generally use the slightly sharper, non-vignetting but less convenient 24-70 f:2.8 when I'm working on a tripod out of a Trekker backpack, where I can swap to the 70-200 f:2.8 anytime I need more reach. I use the 24-105 instead when I'm walking around with just the one camera & lens, or sometimes for people photos where the extra reach is great.
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atassy
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« Reply #15 on: January 29, 2009, 05:02:07 AM »
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hoping to round off the 'navel-gazing about autofocus', here's the answer i got from a very helpful, technical person at canon when i posed them this question:

[blockquote]There are two answers the offical one and the other one:-)

Offically the centre AF point works with apertures up to f/5.6. But this is really just a general rule, in fact AF is possible at small apertures but this will depend on how much light there is.

[...]

My point is that more light could be transmitted to the AF system in brighter light irrelevant of the aperture than in darker conditions at a fast aperture. The f/5.6 is a kind of minimum perform guarantee.

AF sensors have an EV range in which they can operate and is quoted in the specifications i.e. -0.5 EV to 20EV. The Cross type sensor should be able to operate with a f/5.6 lens as long as the subject has enough contrast for the system to detect.  If the EV is 0.5 or 20 and there is no contrast (e.g. plain white subject) the AF system can not operate at any aperture or brightness.

So in brighter light a smaller aperture could in affect be used and still allow enough light to be transmitted for the AF system to focus. There is a point where this no longer applies but this is to technical for me and can be for example temperture dependent.

This is part of the reason why no cameras have cross type sensors (and in fact AF points ) at the edges of the frame, due to the amount of fall off of the light transmission at the edges. To over come this would require a much larger mirror and mirror box and thus a much bigger camera.[/blockquote]

bottom line: the wording in the manual is indeed a simplification of the matter, and can be misleading. performance of the cross-type AF point is not directly dependent on max. aperture of the lens but rather on absolute light input (apart from having a detectable focusing target).

sorry if it looks like a diversion from my original post. this question was important to me as this would potentially be the first lens slower than f/2.8 that i own.
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francois
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« Reply #16 on: January 29, 2009, 05:14:11 AM »
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Quote from: Geoff Wittig
Looks like this thread got diverted into navel-gazing about autofocus, but I can offer an opinion, as I own and regularly use both of these lenses on Eos-1Ds II and III cameras.

The 24-70 f:2.8 is a little bit sharper, enough that you'll notice a slight improvement in very large prints, presuming the usual caveats—solid tripod, careful focus, mirror lock, low ISO etc. The wider aperture is useful in terms of a brighter viewfinder, but I mostly shoot landscapes so it's not otherwise very relevant to me. Its biggest practical shortcoming is that I always find myself wishing for a little more reach on the long end, especially if I'm photographing people. The 24-105 is no question a more useful focal length range, hence it's much nicer when you're walking around with just one camera and the lens mounted on it. That's generally what I use it for. However, the 24-105 has an achilles heel in the form of vignetting. To my eye it has very obvious vignetting on full-frame cameras that is not gone even at f:8. If the image includes lots of blue sky, this can make creating stitched panoramics a major pain in the behind. You can remove most of the vignetting in ACR, but it's never exactly even.

So I generally use the slightly sharper, non-vignetting but less convenient 24-70 f:2.8 when I'm working on a tripod out of a Trekker backpack, where I can swap to the 70-200 f:2.8 anytime I need more reach. I use the 24-105 instead when I'm walking around with just the one camera & lens, or sometimes for people photos where the extra reach is great.
Geoff,
This is a very good summary! If I only had one lens I would choose the 24-105 but having many fixed and zoom L lenses I kept the 24-70.
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Francois
atassy
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« Reply #17 on: January 29, 2009, 06:45:55 AM »
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Quote from: francois
Geoff,
This is a very good summary! If I only had one lens I would choose the 24-105 but having many fixed and zoom L lenses I kept the 24-70.

i agree, very helpful indeed. thanks for the useful info, geoff!

this thread succeeded in changing my mind: i'll get the 24-105 and see how i get on with it. on jobs i will keep a bunch of primes in my bag as a back up in case i run into problems. i'm sure in general 'walk around' situations it will be fine, and for slow/critical work i can use other lenses anyway.
if i then find that i still need the specs of the 24-70 i might have to get both as suggested above.

thanks everyone for the good input. i'll report back in a while to let you know what you talked me into  
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lovell
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« Reply #18 on: January 29, 2009, 10:54:23 AM »
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My Canon 24-70L is a tad sharper, and at all overlapping focal lengths, and f-stops, then my Canon 24-105L.

In addition, focus is more accurate with the F2.8 lens, especially in challanging light.  This is true for all Canon DSLR models, regardless if they are able to AF at F5.6 too.  F2.8 provides brighter light, and brighter means more accurate, eventhough the series 1 does great at F5.6.  AF is about brightness and contrast.  More light = more accurate AF.

The f2.8 provides more bokah possabilities too.

Zoom lenses with longer focal ranges tend to have more compromises then those that have shorter focal ranges.

The only time I reach for my F4 is when I travel abroad and went to bring the least amount of lenses.  Otherwise I reach for the better F2.8 and make up the difference in focal range with my two good legs.

However the IS of the F4 is great, and can't be ignored, but on balance, I still prefer the F2.8.
« Last Edit: January 29, 2009, 11:01:38 AM by lovell » Logged

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Anthony R
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« Reply #19 on: January 29, 2009, 12:06:33 PM »
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Quote from: lovell
My Canon 24-70L is a tad sharper, and at all overlapping focal lengths, and f-stops, then my Canon 24-105L.

In addition, focus is more accurate with the F2.8 lens, especially in challanging light.  This is true for all Canon DSLR models, regardless if they are able to AF at F5.6 too.  F2.8 provides brighter light, and brighter means more accurate, eventhough the series 1 does great at F5.6.  AF is about brightness and contrast.  More light = more accurate AF.

The f2.8 provides more bokah possabilities too.

Zoom lenses with longer focal ranges tend to have more compromises then those that have shorter focal ranges.

The only time I reach for my F4 is when I travel abroad and went to bring the least amount of lenses.  Otherwise I reach for the better F2.8 and make up the difference in focal range with my two good legs.

However the IS of the F4 is great, and can't be ignored, but on balance, I still prefer the F2.8.

I concur.
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