70-300 L or 100-400 L?

Here are my thoughts having used both of these lenses.

[U]70-300[U]

Pros:
Weather sealing
Smaller size/easier handling
Slightly sharper
Slightly less CA
The most flare resistant lens I've used
Really nice minimum focusing distance ( same as 300 f/4)
Faster autofocus
Excellent IS

Cons:
Does not include a tripod collar
Does not come with the zipper case. It has the soft one instead
It's not as good if you need more reach

100-400

Pros:
Longer reach
Includes tripod collar
Comes with a better case

Cons:
Slightly less sharp
Not as resistant to flare
Minimum focus not quite as good
Operations are less refined in my opinion( strange location for the tension ring for push/pull that makes it hard to manually focus
Heavier and larger
Slower focusing
IS is noticeably worse

My overall opinion is that if you are going to be shooting at 300mm (or more) at least 80% of the time than the 100-400 is the better choice. The IQ is similar in the 100-300 range and it would be hard to convince me that using a tc on the 70-300 is a wiser choice. You would probably lose iq and would be forced to be @ f/8.

If you prefer the shorter range of 300mm or less, the 70-300 is the better lens in my opinion.

KayakPhotos wrote in post #14656042
Here are my thoughts having used both of these lenses.

[U]70-300[U]

Pros:
Weather sealing
Smaller size/easier handling
Slightly sharper
Slightly less CA
The most flare resistant lens I've used
Really nice minimum focusing distance ( same as 300 f/4)
Faster autofocus
Excellent IS

Cons:
Does not include a tripod collar
Does not come with the zipper case. It has the soft one instead
It's not as good if you need more reach

100-400

Pros:
Longer reach
Includes tripod collar
Comes with a better case

Cons:
Slightly less sharp
Not as resistant to flare
Minimum focus not quite as good
Operations are less refined in my opinion( strange location for the tension ring for push/pull that makes it hard to manually focus
Heavier and larger
Slower focusing
IS is noticeably worse

My overall opinion is that if you are going to be shooting at 300mm (or more) at least 80% of the time than the 100-400 is the better choice. The IQ is similar in the 100-300 range and it would be hard to convince me that using a tc on the 70-300 is a wiser choice. You would probably lose iq and would be forced to be @ f/8.

If you prefer the shorter range of 300mm or less, the 70-300 is the better lens in my opinion.

according to Canon the TC won't work on the 70-300L.

Kenko will.

I have the dust pump 100-400L and consider it a decent lens. Its definitely a "good light only" lens and is acceptably sharp. Once the light fall I find this lens unacceptable. Out of all of the lenses I own I find the image quality is "ok" and far from stellar. Its sharp enough for furry/feather friends and objects like cars/buidings but for human subjects its OK.

Personally I've considered a 70-300L due to physical size but I find for most applications I prefer constant aperture zooms instead of variable. Also for hobbyist that doesn't do BIF photos I'm considering a $900 physically small 75-300 (equiv to 150-600mm) for my M43 system. Many images I've seen puts my 100-400L to severe shame.

In the canon realm the 100-400L is a compromise lens. Its "ok" sharp but the only zoom with that sort of focal length. To get serious FL you must spend large for long primes. IMO many use the 100-400L strictly for versatility of a zoom (good example is an airshow or budget birder).

If your expecting image quality like the 70-200 f/4 IS you'll be severely dissapointed. I accepted the IQ of the 100-400L and knew it from the start. I had a hard time deciding between the 70-300L and dust pump 100-400L. The 70-300L IQ is more like the 70-200 f/2.8IS MK1 so thats excellent in my book. My thoughts are cropping more with my 70-200 f/2.8IS mk2 instead of spending more money on a variable aperture 70-300L that is variable aperture lens.

If your concerned about overall versatility I'd go for the 70-300L for substantially better IQ and workable FL if you dont need 400mm often.

AlanU wrote in post #14656491
In the canon realm the 100-400L is a compromise lens. Its "ok" sharp but the only zoom with that sort of focal length. To get serious FL you must spend large for long primes. IMO many use the 100-400L strictly for versatility of a zoom (good example is an airshow or budget birder).

If your concerned about overall versatility I'd go for the 70-300L for substantially better IQ and workable FL if you dont need 400mm often.

I have had the 100-400L for about 3 months. This gentleman's assessment of that lens is one that I can very much agree with. Although I must add that perspective is everything. I came to this lens from the 70-300 IS USM (non-L), and the 100-400 is a huge improvement in IQ. It is also very large and heavy compared to that lens. I bought the 100-400L for two main reasons:
1.) Best IQ at 400mm for any zoom I looked at.
2.) Best IQ at 400mm for any zoom I could afford.
One comment about the IS on the 100-400L. It isn't really helpful. I have gotten some shots (at 400mm) down around 1/250, which is a stop-and-a-half on a cropper. Go faster than 1/640 and you pretty much don't need it. And the lens seems to focus faster with IS shut off. Also, in my opinion, the push-pull zoom is the way it should be.

The 100-400L IS a compromise. All lenses are. Want zoom, give up some IQ. Want aperture, carry the weight. Want IQ, go prime and lose some versatility. Want a 10X+ zoom, give up everything else for convenience.

My next lens will be a compromise, too. I want the 70-200 f/2.8L. I will give up IS, because for my intended use, bright light and fast action, I can live without it. It is just not worth $1,000 to me. Each user must decide which compromise is right for him(her)self.

Great points on this page and like others have already mentioned if you value compact size the 70-300L is a great option.

I bought the lens 100-400 today
and I will decide which of them will leave my bag for ever

i bought the 100-400 for one reason only
because i sold my EF 400mm f/5.6L USM

moltengold wrote in post #14657131
i bought the 100-400 for one reason only
because i sold my EF 400mm f/5.6L USM

I used to own the 400 prime as well. I've found the 100-400 to be a better all around lens but I sometimes miss the faster AF. It always impressed me, especially for an f/5.6 lens

sambarino wrote in post #14656679
One comment about the IS on the 100-400L. It isn't really helpful. I have gotten some shots (at 400mm) down around 1/250, which is a stop-and-a-half on a cropper. Go faster than 1/640 and you pretty much don't need it.

The IS is less effective than newer models. I have also found with my 7d that I really need to have my technique down to avoid motion blur.

[QUOTE=KayakPhotos;146​57182][QUOTE=sambarino​;14656679]
One comment about the IS on the 100-400L. It isn't really helpful. I have gotten some shots (at 400mm) down around 1/250, which is a stop-and-a-half on a cropper. Go faster than 1/640 and you pretty much don't need it. [QUOTE]

I have gotten sharp photos at 1/10 to 1/15 at 300 mm on the 70-300L.

moltengold wrote in post #14657037
I bought the lens 100-400 today
and I will decide which of them will leave my bag for ever

moltengold wrote in post #14657131
i bought the 100-400 for one reason only
because i sold my EF 400mm f/5.6L USM

dude, just hours ago you said you sold the 100-400 because it was "old and slow and soft"
Now you are buying the 100-400 ... again !

Does the 70-300 have a zoom lock, or is it tight enough as an L lens that it doesn't creep? I ask because my Cinch will position the lens pointing straight down and they all tend to creep without a lock it seems.

It has a lock.

Nevermind, just read the manual. Are there any other brands that have lenses that compare to these two?