15-85 f3.5-5.6 or 17-55 f2.8?

Started Jan 22, 2013 | Discussions thread
MAC Forum Pro • Posts: 13,742
Re: 15-85 f3.5-5.6 or 17-55 f2.8?

qianp2k wrote:

MAC wrote:

qianp2k wrote:

Sovern wrote:

Yup 5.6 is faster than 2.8 and the difference between 15mm and 17mm is large a long with the fact that max aperture speed of a lens does not equate to AF speed :D.

You guys can have at it with the nonsense, I'm done reading and responding to posts that are ignorant on here.

I don't want to get involved into the debates between your two.

Nevertheless one thing you're right that many confused max aperture to actual AF speed that are not related to each other. Such as 85L is a fast-aperture lens but a pretty slow AF lens, 400L/5.6 is a slow-aperture lens but a hell fast AF lens. One is aperture fast and another is AF fast (strong and fast AF motor inside together with body function such as 1DX is able to drive some lenses if not all AF lenses faster).

Hope it makes clearer.

well said Peter.

and I'll say again as others have said

on crop camera F2.8 is FF equivalent of F4.5. an effective F4.5 and only 50mm or 55 mm ain't going to give very much shallow dof. You need fast primes for that on crop. fast means f1.2 - f2.2

One thing I agree that 17-5X/2.8 zoom are not best choice for portraiture.

agree, primes rule except for my group shots

whereas on a FF body - f2.8 is F2.8 and F2.8 can give more shallow dof possibilities

F2.8 is still the F2.8 no matter on which crop format from light exposure perspective. You're talking about DoF.

yep we're talking "equivalence" though between the formats where f2.8 dof = f4.5 dof

so my point, as others have said also - is and has been - why bother with F2.8 17-50/55 zooms on crop. I chose instead a combo prime and variable zoom approach - and with a zoom with arguably the best IS of the bunch that has been shown by the digital picture site to be able to shoot down to ss of 1 second.

Among those three popular walk-around zoom with 'IS' for Canon APS-C, each has its pro and con. You choose 15-85 for its best IS (agreed) and widest range while other choose F2.8 zoom for its faster-aperture in low light that depends on your priority, none of them is absolutely better than others. I chose Sigma because it's f2.8 and $400 cheaper and on par with Canon F2.8. 'IS' is not that important in shooting any moving subject including wedding most times (people are moving and you likely will use strobe flash many times).

I use 15-85 for group shots and with bounce and off camera flash and radio triggers. otherwise primes rule without flash

The 5d3 has arguably a 2 stop better hi iso performance than our 60d's

I'd say only about 1.5 stops.

interesting - you own both, I'll take your word for it

if the new sigma 30 f1.4 art lens just announced is as sharp at f1.4 as the new sigma 35 f1.4 art lens, then:

On APS-C crop as we have seen between EF and EF-S lenses, 35/1.4 may not has significant or any noticeable advantage over 301.4. However on FF camera combo, then 35/1.4 will win easily over 30/1.4 on APS-C, former can be used on both FF and APS-C and latter Sigma only can be used on APS-C. FF combo is still noticeably sharper due to 1.6x times more crop penalty in APS-C.

They are different in FoV - 35mm vs 48mm FF eq, and DoF F1.4 vs F2.5 FF eq.

yeah, I'll probably get the siggy 35 to fit both my FF and crop

my 60d or my T4i with the new 30 F1.4 sigma art lens would only be 1 stop of high iso noise away from the 5d3 + the new canon 35 F2 IS.

How about compare to 5D3+Sigma 35/1.4? I thought you don't like Sigma and emphasize 'IS', so a bit of surprise you don't consider Canon 35/2.0 IS on your APS-C that you seem rave about these days? So it's only one-stop of apeture difference vs 'IS' that I thought you usually prefer 'IS'.

it is balancing new 4 stop IS and plastic casing - I love my 100L, and light weight of overall setup and ability to stop motion in low light and reduce noise - the below changed my mind


Therefore, in my opinion, for a lighter setup, with the great 4 stop IS system, and low light high iso, where you don't need ultimate outer point AF, then I think the 60d/T4i plus 15-85 4 stop IS with new siggy 30 F1.4 art lens is the powerful combo I want to carry all day long -- 2 cameras, 2 lenses - around $2500 if you shop.

Sure you have legitimate reasons to choose lighter/cheaper setup, just as many chose mFT setup.

yeah my t4i is my light mFT

if the new siggy 30 f1.4 art works out as I expect, per the above, it could get me to consider selling my beloved 5dc

However your 5Dc still can deliver IQ in certain scenarios that none of your APS-C can really match such as shallow DoF, sharpness and creamy look.

agree - so it likely will be: the 15-85 IS with off camera flash system on the 60d.  The 5dc gets the new sigma 35 f1.4 art and the 100 L; and the T4i gets the 60 f2.8 and toki 10-17 FE.

I think of my T4i as a light lens

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