"You need all the stops you can get."

[pto189]

I quote the subject line from Jan to open up a discussion about f/4

versus f/2.8. Many folks have been claiming that with today digital

cameras, one stop is no longer critical as before in the film era.

What do you think? Would the coming Canon EF-24-105 f/4L IS team

with the 17-40 f/4L and the 70-200 f/4L to form an ideal set for a

DSLR? How would they perform compare with the legendary 2.8L set 16-

35, 24-70 and 70-200 IS? Please ignore the weight and price as well

as third party lenses. Your constructive, friendly and professional

arguments will be greatly appreciated.

[mawz]

Digital tends to handle a little underexposure quite well.

 

That said, the 17-40 f/4L, 24-104 f/4L and 70-200 f/4L kit would not be my ideal choice for a DSLR (Well, unless the rumoured announcement for next week is really full-frame) as you lose the wide angles, and you're covering a lot of useful area twice (24-40mm and 70-105mm). The ideal kit would require a 10-22 f/4L rather than the 24-105.

[peter_nelson1]

<I>I quote the subject line from Jan to open up a discussion about f/4 versus f/2.8. Many folks have been claiming that with today digital cameras, one stop is no longer critical as before in the film era. What do you think?</I><P>

 

It's <B>MORE</B> critical to have wider aperture with DSLR's!

 

<P><B>1. </B> Most DSLR's have small, dark viewfinders. This is not just because of the small form factor; it's also because so much of the light is diverted (my 20D only sends 60% of the light from the lens through the viewfinder, according to the spec sheet). A faster lens gives you a brighter VF.

<P><B>2. </B> One of the biggest complaints about DSLR's is lack of DOF control. The solution to that is a wider aperture. A full-frame sensor still doesn't fix the problem completely - even a FF sensor with an f/2.8 lens may give too much DOF for many shots, which is why many photogs still use MF - but an f/1.4 lens will usually do the trick.

<P><B>3. </B> Many DSLR shooters use zooms. Even the best zooms still need to be stopped down a stop or two to give their best performance. So if you start with f/4 that means you're talking f/5.6 or f/8!<P>

 

I can't believe how SLOW lenses are today. When I was a kid in high school (c.a. 1970) I had 3 lenses - a 50mm f/1.4, a 200mm f/2 and a 35mm f/2. Nowadays most DSLR shooters don't have ANY lenses that fast. Next time you wonder why your viewfindwer is so dark remember that an f/1.4 lens transmits <B>4 times</B> as much light as an f/2.8 lens.

[KenPapai]

f/4 are the mid-range L lenses. If you want the best get the 2.8's. The 2.8 gives you more light -- all the better for focusing (esp. the 1.6 crop DSLRs) and viewing through the viewfinder. Of course 2.8 bokeh is better than f/4's. None of this is new. Also, the 2.8's are better for your biceps... LOL.

[brad_w]

Peter, your comments about stopping down and image quality from the f/4 L's are way off

the mark. They are fantastic optics wide open and easily the equal of my 70-200 and

16-35 2.8's at the same apertures.

 

That said, Philip - I started with the f/4's then upgraded; I use the faster glass for low light

and manual focussing. The f/4L's are great and their limitations are obvious, likewise the

2.8's - I'm not sure what there is to discuss here, really.

 

-b

[mark u]

It depends on the crop factor. With 1.6 crop, you lose 1 1/3 stops of depth of field control, since diffraction bites at ~f/10 rather than ~f/16. So rather than f/4 lenses, if you want to replicate full frame f/2.8 capability, you need f/1.8 lenses. You might think that this gives some real advantage in terms of freezing motion blur, but it's less than you might think - at the same MP rating, the crop sensor will be noisier at a given ISO, so you lose the shutter speed advantage to noise, more or less. This noise comparison is more difficult to substantiate, because you never see two cameras of different crop released with the same MP at the same time, and technology is always advancing. The closest comparison is between the 1D Mk II and the 20D, shown here:

 

http://www.dpreview.com/reviews/canoneos20d/page20.asp

 

The jury is still out so far as wide angles on full frame is concerned - the 17-40 seems to perform better than the 16-35, but both fall a long way short of lenses such as the Zeiss 21mm:

 

http://www.16-9.net/ultrawides/

[peter_nelson1]

I wrote . . .

<I>Next time you wonder why your viewfindwer is so dark remember that an f/1.4 lens transmits 4 times as much light as an f/2.8 lens.</I><P>

 

This is a point that's lost on the younger generation. They hear guys my age complaining about dark viewfinders and they think we're just a bunch of crochety, kvetching, old geezers.<P>

 

Well, we are, but I can shut them up REAL FAST by having them look through the viewfinders of my FM2s or my RB67 with fast primes! Newbies to photography have no idea what they're missing, so they imagine that the view through a 20D or D70 with an f/2.8 lens is reasonable.

[kin_lau]

I would consider 17-40L, 35/2, 50/1.8 and 70-200f/4L as a kit instead. You can even drop the 50/1.8, but it's so cheap and good. The middle lengths is where I find I need the speed. My 350D/XT + 35/2 is a very small and light package. Iso1600 + f2 is not enough either sometimes.

[peter_nelson1]

<I>Peter, your comments about stopping down and image quality from the f/4 L's are way off the mark. They are fantastic optics wide open and easily the equal of my 70-200 and 16-35 2.8's at the same apertures.</I><P>

That may not say much for the latter two lenses. Check out the edge MTF's of the f/4 "L" zooms and compare them to f/5.6.

[jbq]

A stop remains a stop. It still gives you the ability to shoot in half as much light, it still gives you a brighter viewfinder and more precise focusing, it still gives you 30% less DoF when shooting wide open.

 

Yes, for most normally lit situations, most DSLRs' ability to shoot at ISO 400 with veyr little visible loss certainly allows to walk around with slow lenses. At night or indoors, where DSLRs can shoot in conditions that people wouldn't otherwise consider, fast lenses remain a must-have.

[vatovec]

There is no a fast enough lens!

[ben_rubinstein___mancheste]

Used to shoot with a 17-40L and a 50 1.8 on a 10D, nuff said, the difference in viewfinder brightness was incredible.

 

I have the 70-200 f4L but the trade off in aperture for the size and weight compared to its big brother was worth it, so was the difference in price, I don't use it much.

 

I was thinking about it for a day or so when I heard about the new lens, would my heavy 24-70L lose to the extra reach and IS of the 24-105L? A few things decided it for me. My 1Ds is now up for sale anticipating the 5D (I'm out of photography for 3 months from September due to an operation). With the less able AF I could do with the extra stop, the difference may be in hundredths of a second but it is a difference. Secondly on full frame my 17-40L although exemplary on the 10D, is not a patch on the 24-70L (the 70-200 f4L is at least as good though)at full frame. For landscape work where I'm shooting at f22, due to the diffraction I need every bit of quality I can get from a zoom ditto for wide open portraiture.

 

If I was to drop my 24-70L for the 24-105L I would go back to primes for landscape and shoot weddings and portraiture with the 85 1.8 alongside. I bought FF and the 24-70L so I would have an event/portrait one lens solution, I'd prefer not to step backwards.

[byronlawrence]

I have to agree with Peter and the others here. I have a few old cameras with bigger lenses (like an old canon f-1) and an rb67. I only wish my 20d was that nice to focus and view through. if 2.8 is the biggest zoom they have then that is probably what one should aim for. no need to cut corners with f/4. I think the 1dsMkII with one of those older f/1 L lenses would be awesome, but I have to wait till that much money is 'extra'.

[thomas_sullivan]

I think the zooms at f/4 are good for the daytime hours...plenty of light. But even the 2.8's dont do justice with night and dark indoors.....you need those f/2 or better primes for that. At least that is how i purchase lenses. All my zooms are the f/4 (or at least bracket that stop....3.5-4.5, etc), and they are great for daytime and dusk.....or with flash. But true "unavailable light" shooting they suck, and having used the less expensive primes at 2.8 max f-stop on manual cams, they suck too. You need a prime at f/2 or faster to shoot in the dark........even with a 20D at 1600.....at least I do.

[ozone42]

I've only been into photography for a few years, and I got my first dSLR this year. Here's the way I see it: There is no substitute for another stop of light.

 

I can understand Canon's marketing, and it's success with the f4L lenses. It makes sense. They're cheaper, they're lighter, they're good! In some ways a few are even equal or superior to their faster cousins. They're a different animal, though. To me they just seem like "pro-sumer" lenses. There's nothing wrong with them at all, they're all excellent lenses.

 

Given the choice? I'd go f2.8 every single time. The reasons have already been listed: Better viewfinder visibility, better low light performance, they're superior at f2.8 :)

 

The flexibility of low noise, easy iso switching does make the f4 lenses much more viable, but it doesn't solve the inherent problems. Even with IS fixing camera shake you have to deal with motion blur of subjects with low shutter speed. Even with less noisy high ISO helping you get the right exposure there's still noise to be dealt with. My camera can see much better than I can, it can take pictures darker than I can focus them so every stop of light to help ME is welcomed.

[jim_larson1]

I too fail to understand the way the question is framed.

 

Considering aperture only while ignoring weight and price is like comparing two cars based upon engine, but ignoring price and number of doors!

 

Without question. . .2.8 zooms are better than 4.0 zooms. That is obvious. BUT . . .because the COST DIFFERENCE is 50%. . .I buy the 4.0 zooms.

 

Would the 17-40/4L, 24-105/4L-IS, 70-200/4L be an ideal kit? NO. Clearly not. There is too much overlap in the middle. The 24-105 should be a 25-75 (ie, not more than a 3x zoom so as to retain quality). The 70-200 needs IS. The 17-40 should be a 10-25.

 

In other words. . .the 4L kit you want is 10-24/4.0L; 24-85/4.0L (maybe 24-85/4.0L-IS) and 70-200/4L-IS.

[mark u]

Viewfinders: There are a lot of misconceptions about viewfinders! The reality is that a 1.6 crop at a given aperture and angle of view is only receiving 40% of the light that a full frame finder has available, assuming equal reflectance of the reflex mirror. This is a stop and a third of loss - much more than the loss from having a 60/40 partially refecting reflex mirror to feed the AF system (3/4stop). Ways of compensating for it are to have a brighter focussing screen (usually a much more important factor than the oft quoted difference between a pentaprism and a pentamirror which is probably worth no more than 1/3rd stop), and to limit the magnification of the viewfinder image - which has the side benefit from the manufacturer's point of view that focus screen positioning is less critical. The disbenefit from the user point of view is that judging manual focus becomes much more difficult, and the tiny image size makes it hard to discern details of the composition.

 

However, as the 5D reminds us, DSLR is not an acronym for Dismal Slow Lens Recorder.

[peter_nelson1]

<I>The reality is that a 1.6 crop at a given aperture and angle of view is only receiving 40% of the light that a full frame finder has available, assuming equal reflectance of the reflex mirror. This is a stop and a third of loss - much more than the loss from having a 60/40 partially refecting reflex mirror to feed the AF system (3/4stop). </I><P>

 

Yes, but on most cameras the VF image is also smaller, so that smaller amount of light is spread across a smaller area (different camera makeras have taken different approaches to this). The usual complaint about DSLR's is that they are both dark AND small.<P>

 

One think I've noticed on my D100 is that when I put a fast (f/1.4) it's dramatically brighter than with the f/2.8 lenses that many of today's shooters think of as "fast". Unfortunately the fastest lens I have for my 20D is only f/2.8 so I can't do the same test with that body.

[jon_austin]

"In other words. . .the 4L kit you want is 10-24/4.0L; 24-85/4.0L (maybe 24-85/4.0L-IS) and 70-200/4L-IS."

 

Come on, Jim, let's stick with the 3x or less rule of thumb you stated (and with which I agree) for the f/4L line:

 

10-30, 25-75 (w/ or w/out IS), 70-210 IS!

 

Oh, yes, and all EF, no EF-S.

 

If I were an active professional, I'd buy the f/2.8L zooms without hesitation. But I'd also own 1D-series bodies!

 

As an amateur, the price performance equation makes the f/4L zooms the clear winners for me, all the optical compromises notwithstanding. As stated by others above, even f/2.8 falls well short of optimal in many situations. Which is why I own a couple of fast primes!

 

You can buy an f/4L zoom and two excellent, fast (non-L) primes in each FL range for less than the price of the f/2.8 zoom. I have 50- and 85mm primes, and will be buying 28- and 135mm primes before the end of the year. (Unless the 24-105 becomes real and gets good ratings; in which case, it will supplant my 24-85...)

[andrew robertson]

The 24-105 IS lens is appealing. f/4 is slow, though. One of the reasons I sold off the

70-200 f/4L is because it was almost too slow.

[terry_smith2]

You almost can't get enough overlap. It has something to do with the number of times you need to change lenses and the amount of time (and images) lost while doing this. I use a 17-35/2.8 L, a Tamron 28-105/2.8, and a 70-200/2.8 L plus a 14/2.8 L , 50/1.4, and an 85/1.2 L. I also have a 400/4.5-2 in R/FL/FD mount that I can use on EOS cameras with an adapter.

[ron c sunshine coast,qld,a]

Frankly i find that the difference one stop makes to my overall shooting is completely trivial.

<BR>Naturally it gives no benifit to me at all anytime i can use a tripod

<BR>It only adds about 20 min to the time i can continue to shoot handheld near sundown.

<BR>One stop is not enough to make a difference when shooting indoors.<BR>And one stop is NOWHERE NEAR enough to make any kind of difference when trying to shoot night sports.For that i NEED an f1.8'ish lens,ISO 1600 and even then i get tons of dud shots

[mark u]

One other point worth mentioning is that Canon implements high precision focus only for f/2.8 and faster lenses. Another reason not to be stuck at f/4 maximum aperture.

[ho_ho]

The following copy from PUTS (http://www.imx.nl/photosite/comments/c011.html):

"We are all familiar with the fact that the sensor area in most D-SLR's is smaller than the traditional 35mm negative. This fact explains the correction factor for focal length (a reduction of angle of view would be a better description). But what is not often discussed is the fact that the reduction of the angle of view has the same effect as stopping down the aperture of the lens). In both cases the marginal rays are cut off and are no longer part of the image forming process. The net effect is this: if we have a lens with a maximum aperture of 2.8 and reduce the angle of view, we get in fact the image quality of a lens stopped down to 4 or 5.6!"

 

By the way, I sold the 80~200L for 70~200/4 considered with size and weight, and feel comfortable with D30's ISO400 performance (now 10D). However, I miss the AF performance, even it's the ancient EOS1+80~200L/20~35L. It's the reason for me not to trade the 10D for 20D: I have to get the f/2.8s again, and cost too much!

 

Would 1D/mKII with f/4s be a waste?

[jbq]

"Would 1D/mKII with f/4s be a waste?"

 

You wouldn't waste everything. You'd certainly lose the f/2.8 AF, and as with all cameras one stop in the viewfinder (the viewfinder in the 1D is quite bright, though).