Shallow Review: Tamron 150-600 f/5-6.3 VC vs 300mm/2.8 II +2xTC III

[jrista]

DxO rates the Tammy better than the 100-400 in the range where they overlap:

For bird/wildlife photo, I would look at other criterias than dxomark when rating a lens.

100-400 is clearly sharper in center wide open at 400mm. And is able to give really quality sharpness (green)
Tamron is not. And it is quite soft at 600mm, even stopped down to f8. A deal breaker for me.

You have to weigh all these factors in the face of the 600mm lens' 2.25x greater magnification, though. Even if the Tammy isn't as sharp wide open at 600mm as the Canon is at 400mm, the difference is clearly NOT enough to overcome the increase in magnification. When your goal is to improve your reach, magnification is everything. Magnification accounts for the vast majority of the IQ increase, because it results in more pixels on subject.

The Tammy would have to be deep red in all of those maps in order for it to perform worse than the upscaled 400mm...but it isn't red...it's yellow-green in most cases, and and even orange in one case. The evenness of those maps indicate that the 600mm has a pretty flat field and a fairly normal response center to corner. That's actually a good trait...means you know the lens will perform roughly the same midframe or even towards the edge as it does in the center. It also means that applying sharpening in post (a super easy way to increase acutance) will affect most of the frame in the same way...with the Canon, the center will end up oversharpened while the midframe and edge get sharpened the way they need to (which, as it turns out, is generally the case...I used the 100-400 for years before I purchased the 600mm f/4 II.)

When it comes to differences in focal length, magnification is the primary difference. All other differences are secondary unless they are particularly severe. This is the danger that relying solely upon DXO-type lens tests and measurements to compare lenses poses. There is a LOT more to a lens than how they compare on DXO (or any artificial lens test for that matter...DPR's test results aren't any different...they would tell you the same thing, and it would be just as incorrect.)

 

[AlanF]

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III.

What?!!
Did you look at the image in full view? If you cant see the day/night difference between the 300mm +2xtc and 100-400 upscaled, then you really need some glasses or a new monitor....
But thats not what I want to show. My question is: is the upscaled 100-400 as good as a tammy can be at 600mm wide open?
I would never replace my 300mm+2x combo with tammy. But can the tammy replace my 100-400mm as a travel lighter/smaller package? For me, it looks like the tammy only gives better results than an upscaled 100-400mm if you shoot at f8. And thats a turn off for me.

You have deliberately edited my post to make it look as if was saying the opposite of what I did. Here is my full post:

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III. That is because you look at the thick black lines etc that dominate. But, look at the elements with fine detail. I have cropped the ACE sections from the image from the 300+2xTC and the (100-400)x1.5, which have fine detail on the black background. You can see that the fine detail is lost in the upscaled 100-400. (Download to see clearly).

Is that an honest thing to do?

 

[Albi86]

Pit, I am afraid you are confusing sharpness (in terms of subjective contrast perception), resolving power and acutance.

Acutance and contrast are the easiest to increase in post processing. Virtually not an issue at all, besides spending a bit more time in LR.

The resolving power is what you can't make up, and the reason why upscaling an image is pointless unless you're going to print it bigger than you should and you merely need the pixels. You want a lens that resolves detail so that then you can bring it out. The Tamron does that.

 

[Pit123]

For the same sensor used at the same distance to subject, longer focal lengths will always produce sharper results than upscaled shorter focal lengths. No way around that.

The above statement is not correct, and now I can see you are agree.

I do agree that the 100-400mm has to be very sharp @400 to outresolve the tamron which also has to be very soft @600mm
Now, DXO confirms this. 100-400 @400m wide open is very sharp in center. Tammy is very soft @600m wide open.
So the difference between an upsampled 400mm and 600mm dont need to be that big. I dont think the upscaled image would resolve more, but its not far behind, and maybe only visible at large crops.

You may be surprised but my 300mm+2xTCIII @F6.3 upscaled to 700mm outresolves my 500mm is mk1 + 1.4xIII. (Using my 7D)

I'd need to see evidence of that. Either your 500mm lens needs tuning to recenter a misaligned element, or your 1.4x TC does.

I found the high desnity sensor on 7d are able to pull out more details from the 300mm combo than the 500mm combo. I did the same test with my 1d4, but got the opposite results. Because it has a lesser demanding sensor (lower pixel density), hence the 500mm combo resolved better.

I give you two examples: one from short distance (10meters), the other 948 meters from subject (according Google maps). Download and show in full size 1920x1080.
Short distance:

 

[Pit123]

Long distance:

 

[Pit123]

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III.

What?!!
Did you look at the image in full view? If you cant see the day/night difference between the 300mm +2xtc and 100-400 upscaled, then you really need some glasses or a new monitor....
But thats not what I want to show. My question is: is the upscaled 100-400 as good as a tammy can be at 600mm wide open?
I would never replace my 300mm+2x combo with tammy. But can the tammy replace my 100-400mm as a travel lighter/smaller package? For me, it looks like the tammy only gives better results than an upscaled 100-400mm if you shoot at f8. And thats a turn off for me.

You have deliberately edited my post to make it look as if was saying the opposite of what I did. Here is my full post:

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III. That is because you look at the thick black lines etc that dominate. But, look at the elements with fine detail. I have cropped the ACE sections from the image from the 300+2xTC and the (100-400)x1.5, which have fine detail on the black background. You can see that the fine detail is lost in the upscaled 100-400. (Download to see clearly).

Is that an honest thing to do?

Sorry if I offend you.
Your first comment (the one I quoted) was so amazing that I didnt really read the rest, or didnt see your point
And I never intend to claim an upscaled 400mm to be comparable to the canon 300mm +2x. If you looked at the image in full screen you should immediately see the BIIG difference. But you obviously did not, hence my comment.

 

[AlanF]

Alan, as you move beyond the test charts and such, I'd be interested to hear your thoughts on the more subjective comparisons between the Tamron & Canon combo - things like AF speed, color, contrast, bokeh, and general handling of the lenses.

Also, I just realized that the Canon has a huge advantage in polarizer use. I'm sure you can find a big one for the Tamron, but you certainly can't adjust it like you can with the drop in CPL on the Canon.

Mac
The 300mm f/2.8 II is generally considered to be one of, if not the, finest lenses available. It is optically as good as you can get and built like a lightweight tank with phenomenal AF. It is going to remain the main lens for me when I travel in the UK for bird photography. It is so good that something 80% as good will be good enough to give stunning results. And that is where the a tamron stands. The Tamron is easier to handle being 1 to 1.5 lb lighter, depending on TCs, and very nicely balanced. It is also smaller and fits into a smaller bag, as well as being more versatile. So, it will be my travel lens, and it will give great results and bring much pleasure to many.

I hope soon to use it in real action rather than charts.

 

[AlanF]

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III.

What?!!
Did you look at the image in full view? If you cant see the day/night difference between the 300mm +2xtc and 100-400 upscaled, then you really need some glasses or a new monitor....
But thats not what I want to show. My question is: is the upscaled 100-400 as good as a tammy can be at 600mm wide open?
I would never replace my 300mm+2x combo with tammy. But can the tammy replace my 100-400mm as a travel lighter/smaller package? For me, it looks like the tammy only gives better results than an upscaled 100-400mm if you shoot at f8. And thats a turn off for me.

You have deliberately edited my post to make it look as if was saying the opposite of what I did. Here is my full post:

Superficially, your upscaled credit card from the 100-400 (x1.5) looks as good as the image from the 300 f/2.8 II plus 2xTC III. That is because you look at the thick black lines etc that dominate. But, look at the elements with fine detail. I have cropped the ACE sections from the image from the 300+2xTC and the (100-400)x1.5, which have fine detail on the black background. You can see that the fine detail is lost in the upscaled 100-400. (Download to see clearly).

Is that an honest thing to do?

Sorry if I offend you.
Your first comment (the one I quoted) was so amazing that I didnt really read the rest, or didnt see your point
And I never intend to claim an upscaled 400mm to be comparable to the canon 300mm +2x. If you looked at the image in full screen you should immediately see the BIIG difference. But you obviously did not, hence my comment.

Of course I saw the full image - I posted some crops from it and surely it must be obvious to anyone that to crop you have to download the JPEG, open it in PS or LR etc.

 

[Lightmaster]

the 300mm f2.8 is yours for 6000-6500 euro.

people should be happy that they can get the quality the tamron offers for 1100 euro.
i don´t get why some people in some forums try to bash the tamron.

all reviews says the tamron is as good as the 100-400mm.

but of course some people who never touched the tamron can tell that this is not true.
maybe 100-400mm owners who can´t stand the facts?

as always i believe people with first hand experience not some pixelpeeper on forums.

 

[Lightmaster]

You have to weigh all these factors in the face of the 600mm lens' 2.25x greater magnification, though. Even if the Tammy isn't as sharp wide open at 600mm as the Canon is at 400mm, the difference is clearly NOT enough to overcome the increase in magnification. When your goal is to improve your reach, magnification is everything. Magnification accounts for the vast majority of the IQ increase, because it results in more pixels on subject.

suprisingly that´s hard to understand for some photogs.

i too know a few who think upsampling creates more DETAILS.
must be CSI and all this crap who makes them believe that.

 

[jrista]

For the same sensor used at the same distance to subject, longer focal lengths will always produce sharper results than upscaled shorter focal lengths. No way around that.

The above statement is not correct, and now I can see you are agree.

I do agree that the 100-400mm has to be very sharp @400 to outresolve the tamron which also has to be very soft @600mm
Now, DXO confirms this. 100-400 @400m wide open is very sharp in center. Tammy is very soft @600m wide open.
So the difference between an upsampled 400mm and 600mm dont need to be that big. I dont think the upscaled image would resolve more, but its not far behind, and maybe only visible at large crops.

You may be surprised but my 300mm+2xTCIII @F6.3 upscaled to 700mm outresolves my 500mm is mk1 + 1.4xIII. (Using my 7D)

I'd need to see evidence of that. Either your 500mm lens needs tuning to recenter a misaligned element, or your 1.4x TC does.

I found the high desnity sensor on 7d are able to pull out more details from the 300mm combo than the 500mm combo. I did the same test with my 1d4, but got the opposite results. Because it has a lesser demanding sensor (lower pixel density), hence the 500mm combo resolved better.

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.

I give you two examples: one from short distance (10meters), the other 948 meters from subject (according Google maps). Download and show in full size 1920x1080.
Short distance:

I'm not really sure what your saying about the distances. Were they at the exact same distance, or was the 600mm combo closer? If you normalized framing, then the comparison is invalidated, as the 600mm combo would effectively be putting the same number of pixels on subject...when the 600mm combo used at the same distance should be putting fewer pixels on subject. Either way, your own example shows the 500mm+1.4x is sharper than 300mm+2x. The 700mm combo is pretty crisp, you can clearly see the effect of the 2x TC on the 600mm combo.

 

[jrista]

You have to weigh all these factors in the face of the 600mm lens' 2.25x greater magnification, though. Even if the Tammy isn't as sharp wide open at 600mm as the Canon is at 400mm, the difference is clearly NOT enough to overcome the increase in magnification. When your goal is to improve your reach, magnification is everything. Magnification accounts for the vast majority of the IQ increase, because it results in more pixels on subject.

suprisingly that´s hard to understand for some photogs.

i too know a few who think upsampling creates more DETAILS.
must be CSI and all this crap who makes them believe that.

Yeah...LOL, damnable CSI and all their magical video zooming and resolution fabrication crap. It's like that device from Blade Runner that allowed him to extrapolate content from within that one room by extracting detail out of tiny reflections and what not...the Infinite Resolution Device. Oh, but were it true!

 

[AlanF]

The series III Canon extenders will not physically fit onto the Tammy - not that I would really want to use a TC on it. You will have to use a 3rd party TC.

 

[Pit123]

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.

The difference in magnification between 600mm and 700mm is 1.16x.
So I have to upsample the image by 1.16x to give the same image. The same effect as putting a 1.16x TC on it. How you translate this to 2.78x more magnification is just simple stupid.
How much magnification gives a 1.4x tc?
How much more magnification gives a 18mp 1.6 crop camera vs a 18mp FF.
And how can you claim the magnification between 400 and 600 to be more than 2x?.
It is 1.5x. Nothing more, nothing less.
I just ask since you don’t seem to understand what we talk about here.

I give you two examples: one from short distance (10meters), the other 948 meters from subject (according Google maps). Download and show in full size 1920x1080.
Short distance:

I'm not really sure what your saying about the distances. Were they at the exact same distance, or was the 600mm combo closer? If you normalized framing, then the comparison is invalidated, as the 600mm combo would effectively be putting the same number of pixels on subject...when the 600mm combo used at the same distance should be putting fewer pixels on subject. Either way, your own example shows the 500mm+1.4x is sharper than 300mm+2x. The 700mm combo is pretty crisp, you can clearly see the effect of the 2x TC on the 600mm combo.

Read again. The first example image was taken from approx 10 meters, The other example was taken from 943 meter (about 3000 feet). Would it make sense to change the distance depending on lens used if I try to demonstrate the effect of upscaling a very sharp lens vs a lens with more FL? No, Of course not. I said I can upscale the 300mm+2x combo to show similar (or even better details than the 500mm+1.4x combo).
I guess you had to ask because you cant believe your own eyes here.

Did I say that the upscaling will add details compared to original image? Of course not.
But its much easier to compare lenses with different lens mm when the one is upsampled to the other lens mm. Or you can downsample the other. But downsampling will loose details. Upscaling will remain the details already there.

How can you clearly see the effect of the 2x? Explain? What you can see is the effect of the upscaling.
But even after upscaling, the 300mm+2x, shows at least similar details, especially in the long range image.
But also on the hair detail in the short range.

I have both lenses, and have compared them a lot.

And now back original question: Is it possible that a sharp 100-400mm centercrop upscaled by 1.5x can match a confirmed soft Tamron @ 600mmf63. Im quite sure its a closer match than many people here seems to believe.
If anyone read this as bashing the Tamron, then they have a problem I think.

 

[Loswr]

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.

The difference in magnification between 600mm and 700mm is 1.16x.
So I have to upsample the image by 1.16x to give the same image. The same effect as putting a 1.16x TC on it. How you translate this to 2.78x more magnification is just simple stupid.

You should follow your own advice about reading again… : I bolded the relevant part to make it a little easier for you.

The 2.78x mag in context was comparing 500mm vs. 300mm. (500mm ÷ 300mm)2 = 2.78x magnification. The linear magnification (1.67x) is squared - maybe your still images have only one dimension, most people's have two.

It's like that device from Blade Runner that allowed him to extrapolate content from within that one room by extracting detail out of tiny reflections...

That sounds a lot like the MIT camera that can take pictures around corners by recording the reflections of light off surfaces that normally aren't considered reflective.

 

[Pit123]

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.

The difference in magnification between 600mm and 700mm is 1.16x.
So I have to upsample the image by 1.16x to give the same image. The same effect as putting a 1.16x TC on it. How you translate this to 2.78x more magnification is just simple stupid.

You should follow your own advice about reading again… : I bolded the relevant part to make it a little easier for you.

The 2.78x mag in context was comparing 500mm vs. 300mm. (500mm ÷ 300mm)2 = 2.78x magnification. The linear magnification (1.67x) is squared - maybe your still images have only one dimension, most people's have two.

Why are you introducing the 300mm vs 500mm? I talked about 600mm vs 700mm?
Why introduce lens mm I didnt show and then talk about the "magnification" between these.

And regarding magnification:
Why do I have to upscale the 600mm by only 1.16x (16%) to get the same "reach" from the 600 as the 700mm?
With your theory, I would have to upscale by 1.36x, and that is just confused rubbish.
There is no point to think magnification as number of pixels in this scenario.

Just think at the image as one simple rectangel. Increase the size ( or diagonal) by 16%, and then you have the difference between 600 and 700mm. Exactly the magnification as putting a 1.16x TC on.

 

[jrista]

I'm sorry, but that's completely illogical. Resolving power is resolving power. A 500mm lens resolves more detail than a 300mm lens, because it's resolving it at a higher magnification, plain and simple. It magnifies your subject 2.78x more. That is even more than the difference between a 400mm and 600mm lens. Additionally, the 2x TC introduces more of it's own optical aberrations than the 1.4x TC. There is no way that the 300mm + 2x will ever outresolve the 500mm + 1.4x. Just plain aint going to happen.

The difference in magnification between 600mm and 700mm is 1.16x.
So I have to upsample the image by 1.16x to give the same image. The same effect as putting a 1.16x TC on it. How you translate this to 2.78x more magnification is just simple stupid.
How much magnification gives a 1.4x tc?
How much more magnification gives a 18mp 1.6 crop camera vs a 18mp FF.
And how can you claim the magnification between 400 and 600 to be more than 2x?.
It is 1.5x. Nothing more, nothing less.
I just ask since you don’t seem to understand what we talk about here.

LOL! I know EXACTLY what I'm talking about! There is a very simple mathematical formula that proves it.

Sorry, but 1.5x is the ratio of focal lengths. The ratio of magnification is the ratio of focal lengths SQUARED!!!! You have to SQUARE the ratio of focal lengths, because lenses resolve in two dimensions!

(600mm/400mm)^2 = 1.5^2 = 2.25

The FoV is 1.5x smaller in both the horizontal and vertical...meaning 600mm FoV covers 2.25x less total area than the 400mm lens, but that 2.25x less total area is enlarged to fill the same sensor area....it has 2.25x GREATER MAGNIFICATION!

As for 2.78x, that was the ratio of area between 500mm and 300mm:

[code](500mm/300mm)^2 = 1.67^2 = 2.7889

So a 500mm lens magnifies it's subjects about 2.8x more than a 300mm lens! That's a pretty significant difference.

BTW, MAGNIFICATION is the factor we want here, rather than the simple ratio of focal lengths, because the number of pixels on subject is relevant in those same two dimensions. You enlarge the subject both horizontally and vertically relative to the sensor frame. That means you put more pixels on any given area of subject detail in both the horizontal and vertical.

I give you two examples: one from short distance (10meters), the other 948 meters from subject (according Google maps). Download and show in full size 1920x1080.
Short distance:

I'm not really sure what your saying about the distances. Were they at the exact same distance, or was the 600mm combo closer? If you normalized framing, then the comparison is invalidated, as the 600mm combo would effectively be putting the same number of pixels on subject...when the 600mm combo used at the same distance should be putting fewer pixels on subject. Either way, your own example shows the 500mm+1.4x is sharper than 300mm+2x. The 700mm combo is pretty crisp, you can clearly see the effect of the 2x TC on the 600mm combo.

Read again. The first example image was taken from approx 10 meters, The other example was taken from 943 meter (about 3000 feet). Would it make sense to change the distance depending on lens used if I try to demonstrate the effect of upscaling a very sharp lens vs a lens with more FL? No, Of course not. I said I can upscale the 300mm+2x combo to show similar (or even better details than the 500mm+1.4x combo).
I guess you had to ask because you cant believe your own eyes here.

Sorry, but there is absolutely NO way that either one of those sample credit card photos was taken from 3000 feet away. That is the better part of a mile. Neither of those lenses has that kind of resolving power. Not even REMOTELY close to that kind of resolving power. LOL I don't know what your smoking, but you need to double check your facts. Like you need to double-check your understanding of what magnification is and why it matters.

Three thousand feet...and it somehow resolved just as good as something photographed from about 33 feet away? HAH! Bullsh*t!! Bull. Sh*t.

Did I say that the upscaling will add details compared to original image? Of course not.
But its much easier to compare lenses with different lens mm when the one is upsampled to the other lens mm. Or you can downsample the other. But downsampling will loose details. Upscaling will remain the details already there.

How can you clearly see the effect of the 2x? Explain? What you can see is the effect of the upscaling.
But even after upscaling, the 300mm+2x, shows at least similar details, especially in the long range image.
But also on the hair detail in the short range.

I have both lenses, and have compared them a lot.

You are comparing different results taken under entirely different circumstances. Scientifically, that is invalid. You can only compare results taken under the same circumstances. You trying to compare your credit card samples to AlanF's chart samples is invalid. You can't make any kind of reasonable comparison between those two disparate data sets.

You can only legitimately compare YOUR OWN two samples, or Alan's TWO samples, but you cannot cross-compare them. Using only your two samples, you yourself have proved that the Tamron is markedly sharper than the upsampled Canon 100-400mm. MARKEDLY. I mean, plain as day, I could probably cut my fingers on the razor-sharp text in the Tamron sample, and sooth my bleeding fingers on the Canon sample, kind of difference here. If you can't see that, then you might want to get your eyes checked, because you are either exceptionally nearsighted, or particularly farsighted.

If you want to compare the Tamron with the 300/2.8 + 2x, then you need to do that test yourself with the exact same credit card, under the same lighting conditions, with the card at the same angle, imaging the same region of the card, so the results can all be DIRECTLY compared. Since you have not done that, then we really can't know what the relative difference between all three lenses is. We don't have a single complete data set that covers all three lenses tested under identical circumstances.

And now back original question: Is it possible that a sharp 100-400mm centercrop upscaled by 1.5x can match a confirmed soft Tamron @ 600mmf63. Im quite sure its a closer match than many people here seems to believe.
If anyone read this as bashing the Tamron, then they have a problem I think.

First fact your getting wrong: The Tamron is NOT "confirmed soft". It is tested (not sure why, I need to check with Alan about those results) "softer than" a 300mm f/2.8 L II PRIME. But that does not mean it is confirmed soft in general. Relative vs. absolute. Important distinction there. RELATIVELY SPEAKING, the Tamron is softer than the 300/2.8. RELATIVELY SPEAKING, according to your own results (!!!) the Tamron is sharper than the 100-400. Your own samples of the credit card PROVE that the Tamron is relatively sharper than the Canon.

Oh, and it's still a magnification ratio, i.e. a resolving power difference, of 2.25x. Your missing a VERY fundamental optical concept here that conforms to a very simple mathematical formula:

(LongerFL/ShorterFL)^2 = MagRatio

 

[AlanF]

Tamron soft Pit123? That is unfounded, unsubstantiated drivel. Here are the acutance tests done by DxO. The first is the Tamron at 400mm f/5.6 vs the 100-400 at 400 f/5.6. The Tamron is just as sharp in the centre of the field and its sharpness extends more to the edges. This is not just a one-off result, lensrental measurements are in exact agreement.

The second (bottom) is the Tamron at 600mm f/8 vs the 100-400 at 400 f/5.6. The Tamron is as sharp at 600mm as the Canon is at 400 at the centre, and it is much better at the edges.

 

[jrista]

Tamron soft Pit123? That is unfounded, unsubstantiated drivel. Here are the acutance tests done by DxO. The first is the Tamron at 400mm f/5.6 vs the 100-400 at 400 f/5.6. The Tamron is just as sharp in the centre of the field and its sharpness extends more to the edges. This is not just a one-off result, lensrental measurements are in exact agreement.

The second (bottom) is the Tamron at 600mm f/8 vs the 100-400 at 400 f/5.6. The Tamron is as sharp at 600mm as the Canon is at 400 at the centre, and it is much better at the edges.

This makes so much more sense. Which beggs the question, where in the world did he get the previous DxO measurement diagrams that showed the Tamron was so bad? Something really smells like rotten fish here...

 

[mackguyver]

This makes so much more sense. Which beggs the question, where in the world did he get the previous DxO measurement diagrams that showed the Tamron was so bad? Something really smells like rotten fish here...

Those were for the 7D, these are the 5DIII.