My current lenses:
I'm interested in wild life photography and landscape photography. I want to pick up my first L lens soon, and I am debating the 70-300mm vs 100-400mm. The only thing that is erking me to not get the 400mm is the push and pull zoom and the non weather sealing, also the 70-300 have better optics. However, seeing how I already have the substandard non L 300mm lens, which one should I pick up?
If your interest is wildlife, as someone who photographs wildlife and birds myself and uses this very lens, the Canon EF 100-400mm f/4.5-5.6 L IS is the lens you want. From a price/performance standpoint, it packs a LOT into a relatively easy to handle package, offering the benefit of a zoom and the bulk of L-series quality (lacking only wide-open sharpness at the long end.) This is a fairly old lens design...over a decade, if I remember correctly. There are a lot of anecdotes on the net that are frequently regurgitated on forums by people who dislike the push/pull design, however most of them are unfounded and based on speculation.
The Wildlifers Lens
First off, the good stuff. The EF 100-400 is well-known as a key lens for wildlife shooters. It has an ideal amount of reach, especially when paired with an APS-C camera for extra reach (it effectively becomes a 162-648mm lens on say a 7D, 60D, 650D, etc.) It also doubles as a decent lens for bird photography, however its about the minimum you would really want to use for that type (a 500mm f/4 or 600mm f/4 L-series lens, preferably with a 1.4x TC, or a 300mm f/2.8 with a 2x TC, is far preferable for birds as you need all the reach you can get, but the 100-400 will definitely do if you can't afford to drop seven to ten grand on a lens. ;) At 400mm, you are pretty much at the sweet spot for a lot of wildlife types...including ungulates (elk, deer, etc.), canines (foxes, coyotes, even wolves if your brave), and a whole host of rodents and other smaller creatures.
The EF 100-400 has IS, or image stabilization, which is pretty much essential for wildlife and bird work. It is not a top of the line, modern IS system...those will get you about four additional stops of hand-holdability (but it costs!) The EF 100-400 will get you around two stops, which means you can shoot fairly sharp hand-held shot at a 1/100th second shutter speed. For wildlife in the evenings, thats extremely handy (although you might have to use an ISO setting a stop higher than you might prefer.)
Generally speaking, the 100-400 is a sharp lens. At less than 400mm, its pretty sharp up to 1/3rd of a stop down from wide open. At 100mm, f/4.5 is sharp enough. At 400mm, this lens is tack sharp at f/7.1. For most things, unless you are shooting in very low light (such as wildlife 15-20 minutes after sunset), you should be able to shoot at f/7.1 without issue. Wide open @ f/5.6 at 400mm, this lens does get a little soft, however it is still acceptably sharp enough that it can serve in a pinch. A bit of post-process sharpening can do a lot to improve results as well.
When it comes to functionality, personally I find this lens to be excellent. There are a lot of nay-sayers on the net who trash the push/pull zoom design with an often astonishing gusto and glee. I would venture that very few of those individuals have actually used this lens for long enough to actually realize the potential such a design has. Even if you are used to lenses that have dual rings for adjusting focus and zoom, it does not take long to get the hang of a push/pull design. There are several benefits to this design as well. For one, it allows for very quick adjustments in zoom, much faster than can generally be achieved with a ring-based design (you can zoom from 100mm to 400mm in less than a second if you really need to.) The design also makes it easy to adjust both zoom and focus simultaneously since the adjustments are decoupled and require very different actions to perform, something that is rather difficult to do on a dual-ring design. The USM focus with full-time manual focus works superbly by a focus ring. The ability to give focus a quick manual adjustment to get it within range of your subject on the rarer cases where AF does act up means you spend less time hunting and more time shooting. With the push/pull design, you can even make those manual focus adjustments while zooming...a rather unique capability of this lens.
The Potential Detractors
There are a lot of nay-sayers who greatly dislike this lens, and several anecdotes that are regularly repeated about why this lens should be avoided. I believe only one might actually matter.
For its price, which streets at around $1400 these days, the Canon EF 100-400mm f/4.5-5.6 L IS USM lens is hard to beat. You get a 4x zoom range, L-series build and optics, 2-3 stop IS (about 2 stops @ 400mm), a very sturdy build, and relatively low weight compared to Canon's other supertelephoto lenses.
Potential Alternatives
Ok, now that sales pitch for the 100-400 is over (sorry, have to put some facts strait when there is so much misinformation and nay-saying about that lens!). There are alternatives to this lens. Canon does offer the 300mm f/4 L IS and 400mm f/5.6 L. Both of those lenses weigh slightly less, however they have their own potential drawbacks. There are also third-party zoom lens options, however I do not believe any of them actually compare to the price/performance/features ratio of the Canon 100-400mm.
Regarding the Canon EF 400mm f/5.6 L lens. This is frequently listed as an ideal option for wildlife and bird photography. It has a single, and in my opinion fatal, detractor: It lacks any form of IS (image stabilization). For birds, thats a total dealbreaker, and for most wildlife, its usually a dealbreaker as well. If you have extremely stable hands or are already a skilled hand-held, non-IS panner, this might actually be the lens for you. It might also be a good lens if you always intend to use it on a stable tripod with a gimbal-type tripod head and lens mount. Its slightly sharper than the 100-400 wide open, but usually still needs to be stopped down to f/6.3 or f/7.1 for maximum sharpness. I've met a fair number of Canon 7D users using the 400mm f/5.6 out in the field as well, and heard their surprise when they tried out my 7D+100-400mm setup with its image stabilization. The list price on this lens is $1799, which deters most people, however the street price (actual sale price in most cases) is closer to $1400 (I believe I picked mine up for around $1580 minus a refund deal from Bing Shopping a few years ago, so it ended up being around $1420 or so). Thats just in line with the 400/5.6 L, and the 100-400 does offer IS...making it a more attractive option for 400mm handheld wildlife/bird photography. To keep things simple, you really want image stabilization for wildlife!
The Canon EF 300mm f/4 L IS is another option. If you want a sharp prime, this is a great lens. Its quite sharp wide open at f/4, and about as sharp as it gets at f/5.6. The big improvement with this lens over the 100-400 would be corner sharpness...its one of Canon's best corner-sharp lenses for the price (the next best thing would be the 500mm or 600mm f/4 L, which are two of the sharpest lenses Canon offers...but they sell for around ten grand.) The key drawback with this lens is the focal length. The loss of 100mm is quite a big loss, and will mean you either have to get a fair bit closer to your subjects (which, in the case of wildlife, is difficult...you either scare it off or increase personal risk.) At 300mm, outside of using a bird blind and sitting and waiting for the birds to come to you, your probably going to be out of useful reach of most birds and BIF.
There is an option for this lens to improve its versatility, and still be a bit sharper than the 100-400. Slapping on a 1.4x teleconverter converts this lens into a 420mm f/5.6 lens. The benefit of this lens over the 400mm f/5.6 is that it has image stabilization! Even with a TC, at 420/5.6, this lens would make a great wildlife and birding prime. The drawback is you'll need to spend an additonal $300-$500 on either a Kenko DGX or Canon 1.4x teleconverter, which makes the total price around $2000. If you have the money and want the sharpness, I'd say this is the better choice over the 100-400. Even with a TC attached, the EF 300 f/4 L has a size advantage over the EF 400mm f/5.6.
The Canon EF 70-300mm f/4-5.6 L IS USM is a decent lens. It is one of Canon's newest lenses, so it is a more advanced design than the 100-400, 300/4, or 400/5.6. It has great optics, sharp to the corners wide open, and has superb IS. As a general purpose telephoto lens, its probably one of the best options out there. It could serve as a wildlife lens if you needed it to, as well as a portraiture lens. However it doesn't really have ideal characteristics for a wildlife lens. It maxes out at a 300mm focal length. That is generally not quite enough reach to really get good frame-filling wildlife shots (400-500mm is better). Its also f/5.6 at 300mm, so if you tried to use a 1.4x TC to get 98-420mm out of it, you'll be stuck at f/8 on the long end (and probably be unable to AF, although you might be able to with a Kenko DGX, like on the 100-400.) Its certainly an option, however being a newer lens its likely to sell closer to its list price of $1599.
There are also a bunch of third-party options. Sigma, Tokina, Tamron, etc. all make lenses for the EF mount. Most of these lack the optical, build, and functional capabilities of Canon lenses, and usually have tighter maximum apertures (f/6.3 in many cases.) They are usually cheaper, sometimes quite a bit cheaper. You might be able to pick up a Sigma "Bigma" 50-500mm lens for a decent price, however its going to be just a bit worse characteristically than the EF 100-400mm lens.
Top Choices
In conclusion, if I had to recommend two options, these would be them:
Both options weigh the same, and offer roughly the same reach. If you don't care about zooming and have the cash, I'd say go with the prime option. Better optics, 20mm extra focal length for more reach, and slightly better IS. The whole getup will probably run you around $2000, but its probably worth it.
If you don't have the cash, the EF 100-400 really is the best lens for what you want to do. Its relatively cheap, it only weighs 3 pounds, and at 400/7.1 its as sharp as any other Canon L-series lens. It'll serve you well.
You don't seem to mention which body you're using (or I have a very specific kind of blindness), although from your lenses I'd suspect a FF body.
You should try to rent them. No on-line opinion can match your own impressions: you could end up buying the wrong lens (for your usage) and trying to persuade yourself all is well, despite obvious "problems".
That being said, I rented the 100-400L, using a 7D, giving me an effective reach of 160-640mm in 35mm terms. While shooting people and family I mostly used the 160-350 part of my range (and often tried to pull closer than 160mm - the main reason I'd rather go the 70-300L way, on my crop body). But when shooting wildlife, I almost exclusively used 640mm, while wishing for more. You just can't get too close.
In the same setting, you'd be limited at 400mm, unless using a 1.4x or 2x converter (canon's converters don't work with the 70-300!). 400mm is, this is a harsh statement considering I rarely shoot wildlife - it's more of an opportunity thing, way too short for wildlife. Using converters could give you the needed reach ,to get close to your subjects, while at the same time slowing down your lens. If you can't push up the ISO high enough to counter the speed loss, that can be quite frustrating.
So it's back to you, see how serious you are about shooting wildlife, if you can afford a (quite expensive) lens dedicated to that.
Just one last bit: the push-pull is quite useful when shooting wild-life. You can scan around at 100mm, and when you see a subject quickly push to 400mm and snap that picture. It also helps if you happen to lose your subject (a quite easy thing to do at long focal lengths). Pull back, correct and push ! I also don't agree on the zoom creep: there's a special ring to adjust the tightness, and after a while you start to develop a way to tighten and loosen the lens unconsciously.
Another option to consider, ASSUMING that your 70-300mm f/4-5.6 is the base model and not the 70-300mm f/4-5.6 IS USM model: purchase the 70-200 f/4 L. The optics on this lens are dramatically better than the base 70-200, and marginally better than the IS USM model. The focus and build quality are far better than the other two lenses. Plus, you can purchase the 70-200 f4 L for around $600.
Beyond that, the 70-200 f/2.8 L (or far more expensive IS model) are as good as the f/4 L, but much brighter (and bigger).
Again, if you do NOT have the IS USM 70-200, this is a very good option, and while you lose 100mm vs the 70-300L you mention, you get constant aperture, and far lower price than the 70-300 f/4-5.6 L lens.
The optical different between the standard 70-300mm and the 70-300mm L is way too big. I have used the 100-400mm and its' a very big and heavy glass, not suitable for longer periods of use. At first it felt like 10 lbs but at the end of the day it grew into atleast 100 lbs! On the other hand, the 70-300mm L is very sharp, comparatively lightweight, can be used without a tripod/monopod. Also, the push/pull zoom of the 100-400mm did not impress me, the zoom ring is not tight and often drags off when faced downwards. You'll need to tighten another ring in order to prevent this to happen.
But, the 100-400mm is better in case of wildlife photography just because of its 100mm more reach. Within a few days, you'll get used to the push/pull zoom so thats' not a problem. So, if you're seriously into wildlife, the longer lens you have, the better. Therefore I'd pick the 100-400mm over the 70-300mm though the latter is slightly superior optically.
Avoid the 100-400L:
I see you said you're interested in wildlife and landscape (I assume wide vistas)*, I'd suggest you figure out which type of photography you'd like to use your first L lens for and get a lens suited to that specific type of photography. If you want to start with landscape look at some wide primes (24L 24L TS-E) or zooms (16-35L, 17-40L, 24-105L) and if wildlife is your goal I highly suggest you look at the 400L f5.6, its incredibly sharp and focuses super fast which is what you want for wildlife.
*I say 'wide vistas' because landscape can be whatever you want, I shoot a lot of 'landscape' photos with a 70-200mm or 135mm lens.
I faced a similar decision last year. In the end, I opted for the 70-300L due to its blazing fast autofocus. The image quality is absolutely superb, and the AF is only slightly slower than the 300/2.8. The improved IS is wonderful, too. I can reliably shoot at 1/30th at 300mm.
Do you need 400mm? Do you need it now? There are rumors of a newer 100-400 coming out. Then again, the new lens won't be anyplace close to the same price point. Maybe $500-1000 more.
If you're interested in birds such as sparrows and blue tits then 300mm will not have enough reach. Youll be better with the panasonic 100-400 on micro four thirds. Thats 200-800mm real world.
