70D Dual-Pixel Sensor makes a 2nd appearance

Started Nov 6, 2013 | Discussions thread
Ember42 Contributing Member • Posts: 679
Re: 70D Dual-Pixel Sensor makes a 2nd appearance

Lawrencew wrote:

Ember42 wrote:

Primes past about 50mm (maybe a little longer for a macro) will probably not be any smaller than an ef-s version. If you look into the back of an EF lens and the back element is not right at the back, the shorter flange length likely wont benefit the lens, as the 43mm flange length of EF is not the limitation on the optical formula.

The main difference would be in not needing the EF adaptor which adds size and weight - effectively doubling the depth of the body before a lens is added.

Look at the size of the EF 40mm F2.8 pancake. The EF adaptor effectively doubles the size of that lens on the M. Make it available in a native EF-M mount and you instantly reduce the size by half.

For some that will be important, for others irrelevant...

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That's the point - if the back element already needs to be more than 43 mm from the sensor, a native ef-m version would effectively have the adapter built into the lens.  The most basic lens formula - see 50 to 85 mm lens diagrams have their elements centred at about their focal length from the image plane.  A typical 50mm lens will have something like 40mm of clearance between the last element and the sensor.

The a 40 mm version would benefit from native - probably could do an f2.0 version that is effectively a scaled up ef-m 22 mm.

 Ember42's gear list:Ember42's gear list
Canon EOS M Canon EOS 7D Mark II Canon EF-M 22mm f/2 STM Canon EF-M 11-22mm f/4-5.6 IS STM Fujifilm X-T1 +13 more
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