Kase creates a 200mm F5.6 Catadioptric for RF mount

[Canon Rumors Guy]

Outside of a few internet resources I can find little about this from actually Kase. I’m going to assume this isn’t generally available but was soft-announced during CP+ 2024, as Kase is there. Kase, who makes some pretty nice filters and sets seems to be setting their sights on lenses (like just about every other

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[Mistral75]

Additional specifications:

• angle of view (24x36): 23.6°
• Length: 95 mm (Canon EF) / 114,7 mm (Canon RF)
• Weight: 384 g (Canon EF) / 430 g (Canon RF)

Source: https://weibo.com/ttarticle/p/show?id=2309405004304690839855

 

[Del Paso]

Additional specifications:

• angle of view (24x36): 23.6°
• Length: 95 mm (Canon EF) / 114,7 mm (Canon RF)
• Weight: 384 g (Canon EF) / 430 g (Canon RF)

Source: https://weibo.com/ttarticle/p/show?id=2309405004304690839855

Reminds me of the Minolta catadioptric, 250mm, F5,6. It was, when they discontinued it, dirt cheap (about Euro200 equivalent). Nowadays, you can find used ones for Euro1500...
Zut, j'aurais pu repondre en francais...

 

[John Wilde]

Someone should make "de-donuting" software for catadioptric lenses. With all the AI things going on, that should be technically doable.

 

[mb66energy]

The FDnew 4 200 was 121 mm long compared to the 95 mm of this lens for the EF-Mount.
26mm longer for one stop more, diaphragm, ball bokeh instead of donuts ...
It should be possible a f/4 200mm lens in the same size of this mirror lens if you use modern glass types and maybe an aspherical element.
Such an RF mount lens with 1:4 close-up and AF would be very interesting for me.

 

[AlanF]

The FDnew 4 200 was 121 mm long compared to the 95 mm of this lens for the EF-Mount.
26mm longer for one stop more, diaphragm, ball bokeh instead of donuts ...
It should be possible a f/4 200mm lens in the same size of this mirror lens if you use modern glass types and maybe an aspherical element.
Such an RF mount lens with 1:4 close-up and AF would be very interesting for me.

And, an f/5.6 mirror lens lets in only about as much light as an f/8 refractive lens.

 

[Richard CR]

And, an f/5.6 mirror lens lets in only about as much light as an f/8 refractive lens.

yes but far more compact especially for telescope focals - but 200mm is basically what I would call a wide field telescope really, versus the 1500 to 25000mm normal schmidt cassegrains. My most portable telescope way back when was a Williams optics 80mm FL telescope. I miss that thing. It was still a beast of a lens though. That being said, at 200mm you can get away with a cheaper mount too.

 

[Dragon]

yes but far more compact especially for telescope focals - but 200mm is basically what I would call a wide field telescope really, versus the 1500 to 25000mm normal schmidt cassegrains. My most portable telescope way back when was a Williams optics 80mm FL telescope. I miss that thing. It was still a beast of a lens though. That being said, at 200mm you can get away with a cheaper mount too.

The challenge for cats in everyday work is the vanishingly thin DOF. They can be decently sharp (in theory even sharper than a refractor) at the exact point of focus, but the lack of central illumination causes a more rapid loss of sharpness as you move away from perfect focus. That feature makes them more challenging to find focus with as well. They also have a pretty severe loss of MTF at medium frequencies (that gets worse at lower f numbers) and that causes loss of contrast that has to be fixed in post. I have 10 different cats and love to experiment with them, but they are not suitable for everyday picture taking other than, as you suggest, possibly Astro, where mid frequencies are not of interest when looking at points of light and there truly is only one point of focus, infinity.