Canon RF 150-600mm f/5.6L IS USM added to the Super Telephoto Zoom Mystery

I really don't see the point of having a TC on a zoom. Just build the extra focal length into the zoom range. The current RF 200-800mm is very, very sharp at at 600mm f/8, and a quick twist of the zoom gives an f/9 800m. 1.4xTCs lower MTFs by 10% or more.
 
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Hmm I think Canon needs hardly to hurry up in tele lenses!

I will wait until end of year I think to see what Canon will have done in the tele area!
Otherwise I will switch to Nikon for this!
You can use three mounts on the Z mount! I can still use my fantastic 300 2.8 etc etc… and also could buy the nice 300-600 4.0 with adapter also with TCS.. or/and the great, lightweight and WAY cheaper 800mm! (Canon think 20k€ is ok for their f5.6 ‍♂️)
 
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I really don't see the point of having a TC on a zoom. Just build the extra focal length into the zoom range. The current RF 200-800mm is very, very sharp at at 600mm f/8, and a quick twist of the zoom gives an f/9 800m. 1.4xTCs lower MTFs by 10% or more.
I had been wondering about this and the idea of a 0- 2x zoomable TC
 
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I really don't see the point of having a TC on a zoom. Just build the extra focal length into the zoom range. The current RF 200-800mm is very, very sharp at at 600mm f/8, and a quick twist of the zoom gives an f/9 800m. 1.4xTCs lower MTFs by 10% or more.
I think it's a real different thing. I'm not a specialist, but aren't TCs like "croping in optics", whereas extra focal length impose a real modification of the optical design ? And I mean, when you know it's a TCs, you know you loose on image quality. It's a compromise. On a "pur" zoom, you don't want that... So it also has to be more expensive to compensate the extra development... Right ?
 
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Not if it is an integral part of the (optimised) optical design. Standalone TC's are, to an extend, a compromise because a) they need to work with many diggerent lenses and b) they always are forcibly stuck at the end of the lens (as opposed to the optimised and integrated 'drop in' type)
 
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Not if it is an integral part of the (optimised) optical design. Standalone TC's are, to an extend, a compromise because a) they need to work with many diggerent lenses and b) they always are forcibly stuck at the end of the lens (as opposed to the optimised and integrated 'drop in' type)
I'm sorry but it is a fact that even with optimised optical design TCs lower the MTFs of even the most expensive big white primes as well as making them even more expensive. The RF 1200mm is the RF 600mm with an optimised optical 2xTC bolted on, and MTF 30 lp/mm drops from 0.9 to 0.79. Similarly, the RF 800mm which is the RF 400mm with its optimised integral 2xTC gives a drop from 0.91 to 0.82. Here are the MTF charts, with the 30 line, which is a measure of sharpness, in blue.

1200_spec-mtf.png600_spec-mtf.png800_spec-mtf.png400_spec-mtf.png
 
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I think it's a real different thing. I'm not a specialist, but aren't TCs like "croping in optics", whereas extra focal length impose a real modification of the optical design ? And I mean, when you know it's a TCs, you know you loose on image quality. It's a compromise. On a "pur" zoom, you don't want that... So it also has to be more expensive to compensate the extra development... Right ?
Like many who use a telephoto zoom for birding, I use the longest focal length most of all, the mid range for birds in flight, and the shortest focal length very rarely. So, I would far prefer a 140-700mm that was optimised over that range than a 100-500mm that has a built in TC. When I go out birding, I grab my RF 200-800mm rather than my RF 100-500mm. Though when travelling and compromised for hand luggage, the RF 100-500mm is my choice plus a 2xTC - I find the 2x more useful than the 1.4x.
 
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I'm sorry but it is a fact that even with optimised optical design TCs lower the MTFs of even the most expensive big white primes as well as making them even more expensive. The RF 1200mm is the RF 600mm with an optimised optical 2xTC bolted on, and MTF 30 lp/mm drops from 0.9 to 0.79. Similarly, the RF 800mm which is the RF 400mm with its optimised integral 2xTC gives a drop from 0.91 to 0.82. Here are the MTF charts, with the 30 line, which is a measure of sharpness, in blue.

View attachment 223971View attachment 223972View attachment 223973View attachment 223974
Well, you can't have it all (1.2m of bulk in a 60cm package). Something's gotta give. I was just pointing out that standalone TCs, while not bad, they're worse than built-in ones. And that is exactly what you've shown: 600 to 1200 w/external TC gives worse results than a built-in 400->800 jump. And yes, with built-in, the combo isn't perfect either. But then again, the 600 is not as perfect as the 400 and neither of the two have a TCs applied. It's complicated and always a tradeoff (size, weight, cost).
 
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An advantage of having a built-in extender for, say a 150-600 f/5.6 ± 1.4xTC vs 210-840 optimised is f/5.6 vs f/8, ie a 1 stop advantage at 600mm and shorter. It would be nice if they could design a 210-840mm that was f/8 at the long end but would progressively widen as it gets shorter so that it would be f/5.6 at 600mm and f/4 at 420mm etc. But, they haven't done so yet as far as I know. The 200-800mm widens to only f/8 at 500mm. Also, if it was f/8 at the long end, the usual trolls would moan that it is only an f/8 lens, whereas psychologically f/5.6 at 600mm with TC in the out position sounds better.
 
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Well, you can't have it all (1.2m of bulk in a 60cm package). Something's gotta give. I was just pointing out that standalone TCs, while not bad, they're worse than built-in ones. And that is exactly what you've shown: 600 to 1200 w/external TC gives worse results than a built-in 400->800 jump. And yes, with built-in, the combo isn't perfect either. But then again, the 600 is not as perfect as the 400 and neither of the two have a TCs applied. It's complicated and always a tradeoff (size, weight, cost).
The-digital-picture did a careful review of the EF 200-400mm with built-in 1.4xTC. You can see from his image comparison that the internal 1.4x TC does reduce the sharpness of the lens and that it is no better than an external 1.4x. In Bryan Carnathan's own words:

“Compare the image quality of the 200-400mm L lens's built in 1.4x extender to the external Canon 1.4x III Extender. The first difference I notice is that the internal extender appears to add pincushion distortion while the external extender adds a touch of barrel distortion. This difference is what would account for the difference in test chart detail sizes. Otherwise, I don't think you will see a difference in image quality between these two extenders used on this lens.”


 
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Canon has previous form for a 150-600mm f/5.6L which dates back to the 1980s with exactly that lens in FD mount, of course. At the time it was one of its most expensive lenses (other than special order ones). It’s big and heavy, with a grab handle on top. I’m fortunate to own one, and its front element is similar in diameter to the FD 300mm f/2.8L, and length more than double that of the 300mm. Optically, it is superb. It was often converted for cine use for wildlife documentaries. It is an unusual zoom mechanism whereby the focus knob slides up and down a rail, making it an internal zoom.

I would love to see something like that in RF mount, albeit with IS and 40 years of advancement of materials and optical design. I expect it could now shift a fair amount of the weight.
 
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This would have the same front entrance pupil as the 100-300mm f/2.8 and if it's L lens quality similar size and price and an orphan just like the rumoured 300-600mm f/5.6.
Personally if it is a similar price I'd choose the 100-300mm f/2.8 and use my extenders for when I want more focal length or just switch to my 200-800

I don't think a constant aperture is an advantage though: 150mm f/5.6 is pretty slow so why not have a variable aperture starting at f/4 or brighter if that's feasible ?
 
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