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Archive 2015 · Lens Differences

  
 
MOJO-903
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p.1 #1 · p.1 #1 · Lens Differences


I apologize if this question is too obvious... I have a Canon 6D with the kit 24-105 f4. For various reasons I splurged recently on a 70-200 f2.8 IS II. My question is regarding the stunning difference between these two lenses.

I'm preparing to shoot photo booth style shots at a relative's wedding anniversary party against a medium/dark blue backdrop. I wanted to test things out at home using poor ambient light and a 430 flash w/ Omni-Bounce diffuser.

I started with the 70-200 and tested various camera settings and light scenarios. The pictures looked good so I switched to the 24-105. The pictures with the 24-105 were really dark & lifeless compared to the 70-200. I tried everything and couldn't get a good look. For example, shooting both lenses in Av mode at f7.1, 70mm focal length and auto-ISO, auto-WB, the 70-200 had good skin tones and hair color while the 24-105 looked pathetically dark. This was stunning since I've always been really happy with the 24-105 and have used it hand-held without flash in very dark situations.

Does this sound normal? I might expect the 70-200 to perform somewhat better but I never expected the 24-105 to look so bad. Is there an explanation regarding better light capture even though the focal length and aperture are the same?

Second question - when shooting a room in Av mode, shots without the flash results in better background lighting while shots with the flash make the background look darker. I expected this in Program mode but not in Av mode. Flawed expectations?

Thanks!
Joe
(first post on the forum...)



Nov 02, 2015 at 10:14 PM
Paul Mo
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p.1 #2 · p.1 #2 · Lens Differences


Welcome - when testing you have to be meticulous and methodical. Shoot manual. In terms of pure IQ the 70-200 will easily trounce the 24-105.


Nov 02, 2015 at 10:19 PM
melcat
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p.1 #3 · p.1 #3 · Lens Differences


MOJO-903 wrote:
Is there an explanation regarding better light capture even though the focal length and aperture are the same?


Although not often quoted for stills photography, lenses have a parameter called T-stop. This is like the aperture, but related to light transmission specifically, rather than depth of field. A lens with perfect light transmission would have T-stops the same as f-stops. Usually, it's a small difference. Even that matters for movies, which is why movie lenses are marked in T-stops rather than f-stops.

I have no idea what the situation is with your lens, but a Google search for "24-105 t-stop" (without the quotes) yielded this as the top hit:

http://www.dvxuser.com/V6/showthread.php?309352-canon-24-105-F4-not-an-F4&s=560d4c1858e907b22578f0c821a25667

It describes exactly what you're seeing. I don't know whether to believe it or not.

That said, the 24-105 also has a lot of vignetting, and who knows what the evaluative metering does with that.

Finally, Canon have a stupid "feature" for their fill flash in Av mode. It quietly adjusts the fill ratio you've set behind your back, by an amount that depends on the ambient EV level. I have no idea whether it's on in P mode as well.



Nov 03, 2015 at 02:08 AM
Ian.Dobinson
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p.1 #4 · p.1 #4 · Lens Differences


with regards the 24-105 being trounced by the 70-200 . yep I have/had the 24-105 and I have to say its a very underwhelming lens .

I got the 24-70/4 L and its a much better lens . much closer in quality to the best canon zooms . the 70-200 mk2 is probably THE best zoom out there (if you count the 200-400/4 its probably 2nd )



Nov 03, 2015 at 03:42 AM
hotdog12
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p.1 #5 · p.1 #5 · Lens Differences


The 24-105 is a very popular kit lens, but the 24-70 f/2.8L II blows it out of the water and has roughly similar functionality. The 70-200 f/2.8L IS II is an equally stunning lens, but it is rather difficult to use as a "go to" lens in standard party/gala venues.

But welcome to the wonderful world of pro "L" zooms. You'll never be satisfied with anything else.



Nov 03, 2015 at 07:45 AM
Zenon Char
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p.1 #6 · p.1 #6 · Lens Differences


I had the 24-105 and it did me well for 6 years but it is no comparison to my 70-200 II. I never liked it at 24mm. If you want to match it buy a 24-70 II. Costly but one of the best moves I ever did.

Edited on Nov 03, 2015 at 03:59 PM · View previous versions



Nov 03, 2015 at 07:55 AM
arbitrage
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p.1 #7 · p.1 #7 · Lens Differences


Sure the 70-200 is a phenomenal lens and the 24-105 is a good lens. However stopped down to 7.1 they really shouldn't be that different. I think the poster who brought up t-stop would be the only logical explanation for the difference in light levels you are seeing if you are shooting in M mode. However, you note you had Auto-ISO on and in AV so both ISO and SS are not under your control, so when you compare two pictures are the exposure values the same or different?

Here is a t-stop comparison between those two lenses, as you can see even at the same f-stop the 70-200 lets in more light although it isn't that big of a difference.







Nov 03, 2015 at 07:55 AM
Scott Stoness
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p.1 #8 · p.1 #8 · Lens Differences


You are comparing 70-2002.8 with 24-105 4.0. When you look though the viewfinder you are seing 70-200 at f2.8 (bright) and when you are looking through the viewfinder at 24-105 you are looking at f4 (less bright)

I don't think either the 70-200 2.8 or 24-70 2.8 blow anything out of the water.
24-70 cannot do IS or 70-105 and at f8 its permance is similar to the 24-105. The 70-200 is pretty good for a zoom but does not compare well to a primes in corners.


http://www.the-digital-picture.com/Reviews/MTF.aspx?Lens=787&FLI=2&API=0&LensComp=687&FLIComp=0&CT=AVG

There is a little bit of exxageration and simplification going on.

But I agree for weddings, go with a 2.8 lens. But for landscapes I prefer the 24-105 to the 24-70 for reach and IS.



Nov 03, 2015 at 02:27 PM
Robin Smith
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p.1 #9 · p.1 #9 · Lens Differences


The camera measures the incoming light intensity so T-stops are not the explanation. Probably connected with the shutter speed or auto ISO or flash function - did the flash recycle fully? Did you have the flash on zoom so it can cover the required field of view?


Nov 03, 2015 at 02:35 PM
Kisutch
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p.1 #10 · p.1 #10 · Lens Differences


Easy answer is that the 70-200 probably isn't gonna be great for a photobooth setup, no matter how sharp it is. You'll likely want a wider angle and more DOF if groups of drunk/festive people are piling in front of the lens. You'll be stopped down around f/8 - f/11 shooting at low ISO (unless you need power to bounce flash off distant wall/celing), letting flash light stuff. In those situations, any lens/body is gonna shine.


Nov 03, 2015 at 06:25 PM
MOJO-903
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p.1 #11 · p.1 #11 · Lens Differences


Thanks to all for the great responses. I got the 24-105 back out tonight and it seems to be doing better than last night. Maybe it's just because I didn't shoot the 70-200... but I don't think so.

Then I recalled I have a seldom used 50mm f1.8... It may work great for this.

In most cases other than the booth with the blue background I'm liking the shots without flash best - even stepping the flash down. The 6D has really good low-light capability. Wood looks more natural and objects look more warm. It seems like Canon is screwing with settings when the flash is on.

You've all now shamed me into trying to shoot full manual now too. I just need to remember to double check the settings!

Thanks to all!
Joe



Nov 04, 2015 at 12:34 AM
scalesusa
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p.1 #12 · p.1 #12 · Lens Differences


MOJO-903 wrote:
Thanks to all for the great responses. I got the 24-105 back out tonight and it seems to be doing better than last night. Maybe it's just because I didn't shoot the 70-200... but I don't think so.

Then I recalled I have a seldom used 50mm f1.8... It may work great for this.

In most cases other than the booth with the blue background I'm liking the shots without flash best - even stepping the flash down. The 6D has really good low-light capability. Wood looks more natural and objects look more warm. It seems like Canon is screwing with
...Show more

The color of the flash is much bluer than ordinary room light, which is very warm.

You can adjust the colors to what pleases you either way, but since warm room lights are deficient in blue, and blue tends to be a weak spot in digital cameras, its better to use the flash and adjust the images to be warmer.




Nov 04, 2015 at 12:47 AM





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