# True reach of 100-400 L II



## Aichbus (Feb 27, 2015)

Hi, I just compared my f/5.6 400 L to the new 100-400 L II.

Image quality difference that I perceived is more or less like displayed at "the digital picture". In short: In the center, the 100-400 L outperforms the 400 L by just a bit, in the corners, the 400 L is better and also, the distortion of the 100-400 L is more pronounced.

But that's nothing new. However, there is another striking difference: The reach at "400 mm". I have no means of testing the absolute focal length of both, but assuming that the focal length of the 400 L is exactly 400 mm, then the longest focal length of the 100-400 II is only 363 mm. If found that by measuring lengths in images of testcharts, taken with both lenses from the same spot. Distance to the test chart was 6 m.

I already knew, that the indications of focal lengths of zooms are often rounded up quite a bit. For instance, my 200 L II + 1.4 extender (= 280 mm) gives practically the same reach as the long end of my 70-300 L.

But in the case of the 100-400, I find the rounding a bit over the top. I didn't examine the wide end, but let's assume that the 100 mm are correct, the we are talking about a 100 - 363 mm lens. 

And anyone wants to add reach with a 1.4 x extender must know that he doesn't get 560 mm (which could maybe still be described as "almost 600 mm") but in reality, he gets 509 mm, which of course is something very different. 

Again, my calculations assume that the 400 L is 400 mm. If its real focal length were 440 mm, then the long end of the 100-400 would really be 400 mm, but I heavily doubt that. 

Does anyone have measured the real focal lengths? Also, I know that the focal lengths sometimes change with distance. I could do the same test with targets at infinity ... but maybe someone of you has already done that?


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## mackguyver (Feb 27, 2015)

Read this post by Arthur Morris / Chuck Westfall:
Is the 100-400 II Really 400mm at the Long End?


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## Aichbus (Feb 27, 2015)

mackguyver said:


> Read this post by Arthur Morris / Chuck Westfall:
> Is the 100-400 II Really 400mm at the Long End?


Thanks, this link is really interesting and explains my findings!


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## e_honda (Feb 27, 2015)

This is a bit disappointing (especially since I have one on order), but not entirely surprising. 

Focal lengths are routinely rounded up (and often times down on wide angles). The 70-300L is noticeably shorter at the long end than the 300L F4 prime. It's quite obvious. 

It's disappointing but, I suppose as long as the 100-400 II is 100mm longer than the 70-300L, then that makes it worthwhile.


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## AlanF (Feb 27, 2015)

e_honda said:


> This is a bit disappointing (especially since I have one on order), but not entirely surprising.
> 
> Focal lengths are routinely rounded up (and often times down on wide angles). The 70-300L is noticeably shorter at the long end than the 300L F4 prime. It's quite obvious.
> 
> It's disappointing but, I suppose as long as the 100-400 II is 100mm longer than the 70-300L, then that makes it worthwhile.



This is terrible, perhaps I should send mine back. It's clearly dreadful that the lens shortens its focal length as it focusses from infinity down to less than a metre, just to obey the lensmaker's equation and keep the length of the lens constant. You would have thought that the Canon engineers could have the the lens gradually lengthening by about 500 mm as you focussed down to keep the focal length at a constant 400mm. Perhaps the Mk III will do that.

Seriously, in order for the lens to focus down to 0.98 m and have a magnification of 0.31, the focal length drops to 304mm. It's a small price to pay.


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## RGF (Feb 27, 2015)

Maybe we should get the folks who think every image should be labeled as to the degree that the animal is captive, habituated, or free on this thread. 

We could then claim the lens is 100-380 at infinity, 95-370 at 3 meters, ...


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## Act444 (Feb 28, 2015)

To me, as long as it puts out ~100mm more reach compared to the 70-300, I'm good with that. That's what I bought it for - 100mm extra reach. Regardless of whether it's a true 400 or not - I definitely know the 70-300 wasn't a true 300 at the long end, especially near MFD.


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## weixing (Feb 28, 2015)

Hi,
IMHO, 6m is a bit too short to test the 400mm focal length... may be you can compare the FoV of the 400mm F5.6L with it at longer distance?

Have a nice day.


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## AlanF (Feb 28, 2015)

If you have a simple lens of focal length 400mm, then it would have to be 428mm from the sensor to focus a subject 6m away. If you have a simple lens a fixed 400mm from the sensor, then it would need a focal length of 375mm to focus an image 6m away. The lens designers do a fantastic job overcoming simple optics, and it is truly amazing to have a lens like the Mk II that has constant exterior length and focuses down to a quoted 980mm, and in practice 900mm, with minimal CA, distortion etc. Well done Canon lens designers!


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## Aichbus (Feb 28, 2015)

weixing said:


> Hi,
> IMHO, 6m is a bit too short to test the 400mm focal length... may be you can compare the FoV of the 400mm F5.6L with it at longer distance?


Yes, 6m is indeed short _for this kind of_ test. Real world tests at infinity are not good for testing sharpness, contrast or colour, because of the air between the lens and the object at long distances. But for the sake of comparing focal lengths I redid my test, using a church spire as the test target which was a bit more than 200 m away. That's not infinity, but for any practical purpose it can be regarded as such.

Again, I assumed that the focal length of my 400 L is exactly 400 mm. On this assumption, the focal length of the 100-400 L II and some of my other lenses are the following:

400 L + 1.4xIII: 560.7
400 L + 2xIII: 799.8
100-400 wide: 103.9
100-400 tele: 394.3
100-400 + 1.4xIII: 553.5
100-400 + 2xIII: 790.4
70-300L wide: 73.5
70-300L tele: 295.3
135 L 135.8
200 L II 198.4
200 L II + 1.4xIII: 278.9
200 L II + 2xIII: 397.7
600LII: 598.0
600LII + 1.4xIII: 835.7

Well, it is not hard to see that the primes are a bit more accurate than the zooms, but at this distance, I am completely satisfied with the findings.

I am also amazed how accurately the extenders extend the focal length.

There was one poster who considered cancelling his order because of the shorter focal length of the 100-400 II at short distances. To this poster I'd like to say: Don't! The 100-400 L II is truely amazing. Its IQ in the center is even a bit better than that of the 400 L. The 400 L is a bit better in the corners and has less distortion, but that's it. With the 100-400 II you get a very, very, very good IS, which is worth a lot. Plus you get the focal lengths from 100 to 399  103 to 394, which is worth even more. I think the difference in price between the two is very reasonable.


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## privatebydesign (Feb 28, 2015)

It is kind of funny the way this knowledge slips out, seemingly everybody talks about it then it goes away for a while, then it is reignited and the debate starts again.

Anyway, the worst 'not the actual focal length on the label' I know of is the Nikon 70-200 f2.8 VR, their top of the line 70-200, at portrait distances the 200 becomes a 130mm! Now that os something to complain about, thinking you have a 200mm lens and not getting the focal length of your 135mm lens. But again, at infinity it is pretty close to the 200, so what can you do..........


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## Plainsman (Feb 28, 2015)

Aichbus said:


> Hi, I just compared my f/5.6 400 L to the new 100-400 L II.
> 
> Image quality difference that I perceived is more or less like displayed at "the digital picture". In short: In the center, the 100-400 L outperforms the 400 L by just a bit, in the corners, the 400 L is better and also, the distortion of the 100-400 L is more pronounced.
> 
> ...




When Canon states that a focal length is 400mm - whether that's a zoom or prime - it WILL BE 400mm at infinity.

In practice "infinity" may typically be as close as a couple of hundred metres but at 6m there will be a big focal length loss probably more so with zooms than primes i.e. some parabolic type relationship where image size changes more rapidly at close quarters

At app 200m I compared the image size of the 400/5.6 and the 100-400 and found they were almost 
exactly the same i.e. @200m if the prime was actually 400mm the zoom was also the same.


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## Mt Spokane Photography (Feb 28, 2015)

privatebydesign said:


> It is kind of funny the way this knowledge slips out, seemingly everybody talks about it then it goes away for a while, then it is reignited and the debate starts again.
> 
> Anyway, the worst 'not the actual focal length on the label' I know of is the Nikon 70-200 f2.8 VR, their top of the line 70-200, at portrait distances the 200 becomes a 130mm! Now that os something to complain about, thinking you have a 200mm lens and not getting the focal length of your 135mm lens. But again, at infinity it is pretty close to the 200, so what can you do..........



As with many other posts, we seem to get repeats of the same information over and over. We have a lot of new members joining all the time, and its going to happen as they journey thru the process of learning about cameras, lenses, and how they work. 

Fortunately, you and a lot of other knowledgeable and experienced photographers on the forum take the time to teach the same thing over and over. 

That's a good thing, so thanks for helping.


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## RGF (Feb 28, 2015)

Mt Spokane Photography said:


> privatebydesign said:
> 
> 
> > It is kind of funny the way this knowledge slips out, seemingly everybody talks about it then it goes away for a while, then it is reignited and the debate starts again.
> ...



I agree. I learn a lot by reading this forms and having my inaccurate information corrected. Only at times I wish it was done to teach rather than to berate.


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## nc0b (Feb 28, 2015)

I will stay with my 400mm f/5.6 and 300mm f/4 IS for raptors and wildlife. For BIF it would be a rare case I would want less than a 400mm focal length with my 6D, which does better than any of my other bodies with this task. 

Yesterday afternoon I went out my front door to check on a ham radio antenna problem. First I scared a large jack rabbit which ran off to the back yard. When I got to the back yard a hawk was not 30 feet from me and about 15 feet in the air. It was chasing the jack rabbit which may have out weighed the hawk. The chase went on for less than 30 seconds before the hawk gave up and landed on one of my 70 foot towers. 

Did I have a camera I my hands to capture any of this? No camera, no prime lens, no zoom, but it was a stunning sight !


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## 9VIII (Mar 1, 2015)

http://www.the-digital-picture.com/Reviews/Canon-EF-100-400mm-f-4.5-5.6-L-IS-II-USM-Lens.aspx

Brian at TDP measured the focal length of the 100-400ISMkII from 42 feet as being 383mm, that being the case it doesn't look like you have to go too far away before you get very near the specified focal length.

I'm betting they had to make some concessions to get the incredible Maximum Magnification that they do, but as someone who takes pictures of small things as often as large the trade off is definitely be worth it for me.

It's funny how the 400f5.6 is still (still still still, lens after lens none of them are solidly better, I feel like I'm going to be saying this for the rest of my life) the best lens of its type on the market. If you don't need the zoom and want to save a grand definitely get one of those.


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## TheJock (Mar 1, 2015)

How is the 400L f5.6 plus the 1.4x and 2x convertors compared to the 100-400L II also using them?
I'm confused with the amount of reviews on this subject :-\
Is it worth selling a 100-400 mark I for the II?
Thanks in advance.


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## Aichbus (Mar 3, 2015)

TheJock said:


> How is the 400L f5.6 plus the 1.4x and 2x convertors compared to the 100-400L II also using them?
> I'm confused with the amount of reviews on this subject :-\


Both lenses take the 1.4xIII very well and even the 2xIII gives quite good results. The corners are a bit better with the 400L and both extenders, but the 100-400 LII is more contrasty and sharper in the center, so I found the 100-400L II to be generally better with extenders. You will have to manually focus both lenses when you use them with the 2x (and on most bodies also with the 1.4x). But this is pretty easy with the 100-400 L II, thanks to its very efficient image stabiliser. Manually focussing the 400 L with the 2x extender however is next to impossible due to the enormous shake of the viewfinder image at 800 mm! So for using the 2x, the 100-400 L II is clearly better.

Keep in mind that at 800 mm and longer distances (around 50 m and more) depending on the atmospheric conditions image quality might be degraded more by the moving air between the camera and the subject than by the extenders. 



TheJock said:


> Is it worth selling a 100-400 mark I for the II?



If you have a good copy of the mark I and you have to watch every penny, I'd say stick to the mark I. Otherwise go for the mark II!


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## Aichbus (Mar 3, 2015)

Here is a 100% crop at 800 mm (100-400 L II + 2xIII) wide open from the center of the image (6D, sharpening in DPP4: 2)


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## TheJock (Mar 3, 2015)

Thanks for this Aichbus, I think I need to AFMA my copy of the 100-400L as I'm not always 100% sure that it's giving the IQ that others achieve, I bought it 2nd hand, but this is probably 90% user error!!!!!!! 
1.4XIII will be on it's way shortly!!!


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