Canon EOS lens adapter with aperture included.

[Jonas]

I'm almost 100% positive that it will not work with any lens (...)
One cannot just stick an iris in front or in back of a lens and expect it to work like one that's internal.

I guess this goes to show that someone can be a "terrific videographer" and not know #$%@ about optics.

Bif, I'm sure you are right, basically, about where a proper aperture should be. But is that the point?

I'm pretty sure it works with the focal lengths of my interest; the fast 50 to 100mm range. I base this on no theory at all, I know nothing about optics except from what I've learned by experience. I'm confident though that somebody intelligent well versed expert on this forum can explain everything, or at least give us a link to a ton of Zeiss white papers, lol.

I mentioned many have tried to make baffles for their fast 50mm lenses. The only effect that has been seen from all this work has been images that effectively have been looking as the lens has been stopped down.

I don't recall when I last stopped down beyond f/4 or so. Now, if this adapter allows a reasonable result from these fast lenses between say f/1.2 to f/4 matching what these lenses would do if they were internally stopped down, then there is definitely a use for this adapter. No more Zeiss sawtooth bokeh! No more ugly hexa, or octo-, gonals.

OTOH, it may be that Kipon never tried their idea before manufacturing and starting to sell the adapters. Then the incredible video guy is bought buy them and promotes the useless stuff along with a couple of those having commented the product at his site. Nothing is impossible.

EDIT: I didn't see your reply, Diane, before starting to type this. The next generation adapter Phil mentions is the electronic one working as a full flange interface between the Panasonic cameras and the EF lenses. That is cool, but expensive and probably worth it for the hard core video maniacs only. I woul dthink a fully manual lens will be the best one in most of the cases... with a stepless aperture....

 

[kwalsh]

For an iris diaphragm to affect DOF and/or Spherical Aberration (SA) is must be located in the light path between the entrance pupil and the exit pupil. I think it has to be in "nodal space" between the "frontal principal node place" and the "rear principal node plane".

I think you are confusing a number of terms here. First off, there are many optical systems in which there isn't any space between the entrance and exit pupils. In fact in many systems the exit pupil lies in front of the entrance pupil. This seems counter intuitive, but it is very common. The entrance/exit pupils are typically the virtual images of the iris and for refractive systems often lie outside the optics and often opposite of what you'd expect (exit pupil lies to the object side of the optics, entrance to the camera side of the optics).

Similarly, nodal points/planes (which are entirely different from the entrance and exit pupils) are often not physically inside the lens. This is in fact the entire point to telephoto and wide angle (aka reversed telephoto) designs - creating lenses that are either more compact than you'd imagine based on their focal length (telephoto) or shorter in focal length than would see possible based on the flange distance (wide angle).

All that said, your larger point that the iris probably needs to be within a relatively narrow range of positions (and most likely within the physical optics of the lens) is in all likely hood quite correct. An adapter like this will actually in all likely hood act much like an aperture stop but it will be sub-optimal - many aberrations won't be as corrected as you'd expect when stopping down and the image circle could be adversely affected (vignetting, but since these are FF lenses not likely to be a big deal).

Ken

 

[agoglanian]

Of course, I could be wrong - this is interesting

http://forum.getdpi.com/forum/showthread.php?t=22008

Keith

I commented in that thread because the guy is complaining that it won't work with the Tokina 11-16mm lens which is meant for Canon EF-S bodies. The Kipon people said SPECIFICALLY that the adapter will not work with EF-S lenses.

.... Just a thought.

 

[slau]

I wish people will stop making big statement without any reasonable knowledge or experience about a product. May be this video will help us to see some of the good and bad of the new Kipon adapter. The shooter used 7 different lenses on the adapter, from Zeiss, Olympus and Canon lenses, and they all seem to be working with the adapter:
http://vimeo.com/groups/gh1/videos/17821964

One thing that you cannot tell from the video is how much does the aperture affect the image quality of stills. In theory, the image quality should not have suffer too much if any. But, I will wait for someone's comment after he/she posts some still images taken with the new adapter. Talk is cheap and seeing is believing.

 

[Tesselator]

K. Walsh,
Thanks for the clarifications! Very helpful and informative!

slau,
Cool video. Nice find. For most of the tests it works about like I thought... not very well to say the least. Some of the tests were pretty surprising tho and I'd have to say that "it worked" for those.

Interesting!