Question Regarding the New TS-E 17 f/4...

Hey everybody..


I have heard a lot of discussion regarding the new TS-E 17mm f/4 L. It looks like a great lens.



However, many have commented on the inability to use filters (specifically polarizing filters with landscape photography) due to the very large and convex front element.


I do not have a very in-depth knowledge of optics - Maybe you can help me a bit...


Is the front element this convex due to the large image circle this lens has to provide? I would assume the image circle would have to be significantly larger to provide effective shift mechanisms.


Is this correct? Daniel Browning - Bring on the technical information! [:)]


- Alex

I have also wondered this--it seems strange that the front element looks more like a 14mm. The 16-35/2.8L and the 17-40/4L certainly have smaller front elements...

I would assume that it has something to do with the tilt/shift mechanism requiring more angle of view to operate, but I really have no idea, just a guess. My assumption is based on things like zoom lenses requiring a lot more glass to achieve a given aperture diameter. It just seems like the variability requires more room to move around, optically. But, again, I have no idea.

One of the marketing points for the two new TS-E's, was a larger projection circle. This is needed since the lens will be moving around a bit, and you don't want light drop off near the edges of the extremes. So I imagine you'd need a much larger front element to achieve that.

This is what I was expecting. I have noticed obvious light falloff when using view cameras to maximum shift.