# 400 F4 for ASP-C?



## AprilForever (Dec 6, 2010)

I wish Canon would make one of these: a 400 F4 IS, not DO, designed for ASP-C. Hopefully it would be inexpensive (comparitively; I wouldn't mind 1,500-1,900). Though EF-S would probably make it incompatible with TC's, so hopefully they could make it ASP-C but not EF-S? 

Is this a crazy idea? Or would others buy this too?


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## kubelik (Dec 6, 2010)

while I like the idea of a new 400 IS lens, making it incompatible with teleconverters and incompatible with full-frame cameras are two reasons this lens will never happen.

I'm not following what you mean by "APS-C but not EF-S" ... if it's APS-C only, it's going to be an EF-S mount ... why make something that could mount to a full-frame but not project a full image circle? you lose any of the size benefits while simultaneously losing a large chunk of your potential market.

even updating the 400 f/5.6 L with the addition of current IS would be fantastic ... that I would buy


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## lol (Dec 6, 2010)

Many things to consider here. The high cost of these lenses is due to the huge lumps of glass on the front, which would be largely common regardless if the image circle covered APS-C or FF. The possible saving from making the smaller elements in the back even smaller would not be significant for the loss in sales and need to have multiple lenses.

Also, the key point of EF-S mount is it allows a rear protrusion into the mirror area which the smaller APS-C mirror accepts but would interfere with FF ones. A long tele lens doesn't need to use that protrusion, so in theory you can create crop sensor lenses with EF style mount. I think most 3rd party crop sensor lenses would happily work on FF bodies. As weird as it may sound, I used the Tamron 18-270 on a 5D for a while when I had the wrong stuff with me on a trip out before.


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## neuroanatomist (Dec 7, 2010)

AprilForever said:


> I wish Canon would make one of these: a 400 F4 IS, not DO, designed for ASP-C.



The advantages of EF-S lenses with their short back focus are applicable to wide angle lenses, not to telephoto lenses. An EF-S 400mm f/4 lens would be only marginally cheaper to produce than an EF 400mm f/4 lens because the elements would need to be nearly as large. Given the more restricted market for such a lens, I really don't see Canon doing that.

I'm with kubelik, though - I'd definitely be interested in a 400mm f/5.6L IS prime!


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