EF-S (or Digital Only) Long Tele-Zooms - why don't they exist?

Hey everyone,

A thought just dawned on me. Why doesn't anyone make a long tele-zoom, or even non-zoom for crop bodies only?

Here's my thought, it could be smaller and lighter or it could be the same size but bigger aperture.

For instance, we have the Sigma 17-70. Wouldn't it be nice to complement that with a 70-300 that was f2.8?

I know what you are thinking, "the manufacturers have made the equivalent lenses though. We have th 18-50 and 50-135/150 for crop bodies which equates to 24-70 and 70-200 on normal bodies". But my point is, wouldn't it be possible for them to create crop lenses that go to 300mm or beyond at f2.8 cheaper than those for full frame?

Imagine a 300mm f2.8 lens for $1k instead of $2600 for the Sigma. I suppose you could buy the Canon 300mm f4L IS for $1200 but still...

Because its more difficult to get wider on a crop body with existing lenses. So to make wide available for crop bodies they produce lenses to accommadate the need to go wider. As for tele there isn't a need because crop body by itself is lik having a TC permanately attached.

It always looked like to me they should be able to make an adapter that took an ef lens and turned it into an efs lens, making it either wider or faster, or maybe both, since there is all that glass that is not being used when it's on a crop body camera.

sWampy wrote in post #3376970
It always looked like to me they should be able to make an adapter that took an ef lens and turned it into an efs lens, making it either wider or faster, or maybe both, since there is all that glass that is not being used when it's on a crop body camera.

How would they make it faster???
The aperature would still be the same regardless of the adapter.

lostdoggy - you are missing the point. I know that WIDE is a problem on crop and long is not, but cheaper/lighter/faster tele lenses I think would be advantageous. Yes my 300mm lens is bloody long on my crop body, but I can't afford the 300mm f2.8's on the market. I would think that a crop version of this lens could be made more cost effectively because less glass would be needed.

sWampy wrote in post #3376970
It always looked like to me they should be able to make an adapter that took an ef lens and turned it into an efs lens, making it either wider or faster, or maybe both, since there is all that glass that is not being used when it's on a crop body camera.

It also shoots electromagnetic bullets and is responsible for the fall of the USSR.

Layston wrote in post #3377031
lostdoggy - you are missing the point. I know that WIDE is a problem on crop and long is not, but cheaper/lighter/faster tele lenses I think would be advantageous. Yes my 300mm lens is bloody long on my crop body, but I can't afford the 300mm f2.8's on the market. I would think that a crop version of this lens could be made more cost effectively because less glass would be needed.

No, the same amount of glass would be needed to accomodate an f 2.8 aperture. The only glass you may reduce in size would be at the rear of the lens because the EFS mount has a smaller exit pupil. All 300mm f 2.8 lenses would require a front element that measures 107mm in diameter. Making smaller lenses near the exit pupil would not necessarily save much weight on a lens like this. Overall length would remain the same, too.

oldsquawk wrote in post #3377137
No, the same amount of glass would be needed to accomodate an f 2.8 aperture. The only glass you may reduce in size would be at the rear of the lens because the EFS mount has a smaller exit pupil. All 300mm f 2.8 lenses would require a front element that measures 107mm in diameter. Making smaller lenses near the exit pupil would not necessarily save much weight on a lens like this. Overall length would remain the same, too.

Sigma's 120-300 is 105mm?

oldsquawk wrote in post #3377137
No, the same amount of glass would be needed to accomodate an f 2.8 aperture. The only glass you may reduce in size would be at the rear of the lens because the EFS mount has a smaller exit pupil. All 300mm f 2.8 lenses would require a front element that measures 107mm in diameter. Making smaller lenses near the exit pupil would not necessarily save much weight on a lens like this. Overall length would remain the same, too.

That's not true, not even remotely true.

They don't do it because they know that you are going to buy L series for long glass. It is not worth their while.

I do not own any EF-S lenses anymore, I don't see the point of them (although I am looking at a siggy 17-70 I admit)

Sigma 50-150 2.8 is effectively an EF-S lens that offers speed and lighter weight in the sense you are speaking of (versus 70-200 2.8's). My suspicion is that there are optical reasons why you need a closer rear element for wide angle (which I think is main reason EF-S won't mount on EF camera) that doesn't apply to tele.

sWampy wrote in post #3377217
That's not true, not even remotely true.

Would you care to elaborate? By definition f/2.8 means that the entry pupil is 1/2.8 the focal length (f/2.8) Plug in 300 mm f.l. and I get an entry pupil of 107.14 mm. So light approaching the lens from the front has to see a 107 mm diameter opening if the lens is f/2.8. Front elements may be larger than the entry pupil (see especially ultrawide angle lenses), but it's going to be hard to make one smaller than this.

The economies in designing EF-S lenses are economies of design, more than economies of production. Telephoto lenses use a diverging lens or group in the optical path to "fold" the light path, letting a telephoto lens be shorter than its focal length. However, since even with this you can easily have the rear-most lens element well away from the lens mount, there's no particular need to design a "short mount" like the EF-S. Wide angle lenses, OTOH, have to put a "spacer" element or group, since a basic 18 mm lens would be well inside the mirror box. So they're essentially a "reverse-telephoto" or retrofocus design. With the reduced clearance that Canon's designed into EF-S cameras, they don't have to have quite as much of this built in to the lenses. So they don't need quite as much correction of the retrofocus component as more extreme designs do. However, when comparing costs of EF-S lenses to EF lenses you really should note that just because the AoV is the same doesn't mean the same design can be used; especially at wide angles, the shorter the focal length, irrespective of the crop factor, the greater effort will need to go into correcting the lens' inherent aberrations. So a 17-85 EF-S IS isn't necessarily going to be cheaper than a 28-135 EF IS. It will be cheaper than an 17-85 EF IS, but only because the image circle that corrections need to be made over is smaller.

Well... if I recall correctly Olympus made a 35-100 f/2 lens for their four thirds system which is the equivalent of a FF 70-200 F/2... now if Canon could come up with something like that...

angryhampster wrote in post #3377189
Sigma's 120-300 is 105mm?

Close enough. That's filter size, not necessarily the same size of the diaphragm opening inside the lens.

sWampy wrote in post #3377217
That's not true, not even remotely true.

Really? So what is the truth, the "remotely true", sWampy? I believe Jon covered the topic pretty well.