# Focal Reducer



## johnhenry (Jul 8, 2013)

This topic comes up from time to time and I think it would be a great way to do a number of things.

The utility of using EF lenses AND getting the full frame effect they were meant to give is more than just a passing nod to these optical treasures.

Focal reducers have been used in astronomy for more than 50 years. All the do is they make the resulting light cone steeper, the result is that exposure time is reduced, and giving a wider field of view.

For my 8" f/10 Intes Maksutov, it changes the optic from a 2000mm f/10 to a 1360mm f/6.3. This particular one works both with CCD cameras AND visually. There are some that will change this to a 1100mm f/5.5 or to 550mm f/3.3 but these are for CCD use only.


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## Mt Spokane Photography (Jul 8, 2013)

Unfortunately, to use a focal reducer on a FF camera requires a medium format lens. The focal reducers that exist adapt a FF lens to a smaller sensor. 

I don't think there is one yet to adapt EF lenses to a EOS-M body, but its likely coming. There is one to adapt a EF lens to a Sony NEX.

http://www.metabones.com/info/105-info/154-speed-booster


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## tnargs (Jul 9, 2013)

Is there a speed booster that brings an EF lens (not EF-S) back to full circle on a canon crop body? I might be interested in such an item if optics are good.


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## Mt Spokane Photography (Jul 9, 2013)

tnargs said:


> Is there a speed booster that brings an EF lens (not EF-S) back to full circle on a canon crop body? I might be interested in such an item if optics are good.


 
Not currently.


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## adhocphotographer (Jul 9, 2013)

johnhenry said:


> For my 8" f/10 Intes Maksutov, it changes the optic from a 2000mm f/10 to a 1360mm f/6.3. This particular one works both with CCD cameras AND visually. There are some that will change this to a 1100mm f/5.5 or to 550mm f/3.3 but these are for CCD use only.



Thanks for the clarification.


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## pharp (Jul 9, 2013)

http://www.canonrumors.com/forum/index.php?topic=14857.0

I'm sure one is coming - the million dollar question; who makes it to market first, Metabones or Canon (or some no name Chinese outfit of which I've seen several on e-bay). The Metabones one looks to be very good quality, not certain Canon can do better or beat them on price. We'll have to wait and see.


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## epsiloneri (Jul 9, 2013)

Unfortunately, a focal reducer for fast lenses at maintained IQ will remain a dream. An EF to EF-S reducer would be wonderful: it would effectively make your APS-C camera equivalent to a FF camera.


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