Question Sir/ Madam.

[surapon]

Just one question to my dear teachers and dear friends.
Why canon Company not just Do EF 24 MM F/ 2.8 STM Pancake for Canon Full Frame Cameras( Similar to EF 40 mm F/ 2.8 STM, Pancake)---BUT why they just do EF-S 24 MM and sell us now ?
No, It not make sense to me, EF Lens can use all Canon EOS Camera bodies and Canon can sell more of this EF Lenses, BUT Only EF-S can use with Small Sensor EOS Cameras only.
Yes, I will buy EF-S 24 mm Pancake Lens and use with Canon extention tube with my 1DS, and 5D MK II.
Thanks you, Sir/Surapon

 

[Loswr]

Why? Physics. 24mm on an EF mount would need to be a retrofocal design, meaning more complex, more elements, and thus bigger than a 'pancake'.

 

[Besisika]

Why? Physics. 24mm on an EF mount would need to be a retrofocal design, meaning more complex, more elements, and thus bigger than a 'pancake'.

That's unfortunate. I would like one.

 

[Jane]

What Neuro said. It's physics! So sorry Mr Surapon.

 

[Eclectik]

On the other hand, why not an EF-S 24mm F2.0 pancake, rather than F2.8 ? More interesting, for those (like me) who still have APS-C format.

 

[Rocky]

On the other hand, why not an EF-S 24mm F2.0 pancake, rather than F2.8 ? More interesting, for those (like me) who still have APS-C format.

The lens flange distance for both EF and EF-S mount are 44mm. When you look at any EF lens. The lense mount sticks out 5mm into the flange. Therefore only 39mm is allowed between the sensor and the distance of the last optical element. Therefore the 40 f2.8 EF is already semi -retrofocus design. And Cannon has done a good job in making it into a pancake by keeping it at f2.8.
For EF-S, with a smaller mirror, the last optical element gets another 3.5 mm into the camera body. That make it 35.5 mm between the last optical elemnt and the sensor. Canon has alread done an excellent job to make the EF-S 24/2.8 into a pancake. Anything faster than that will not be a pancake.
As to answer Surapon's question, 24mm EF lens must be a retrofocus design. therefore it is hard to be a pancake. As a foot note, Voigtlander makes a 20/3.5 that is almost a pancake. The design diagram shows that it is retrofocus design. they have done a super job to keep it small. One of their trick is to keep it at 3.5 instead of 2.8 or faster.

 

[surapon]

Why? Physics. 24mm on an EF mount would need to be a retrofocal design, meaning more complex, more elements, and thus bigger than a 'pancake'.

Thank you, Sir , Dear Teacher Mr. neuroanatomist .
Yes, Sir- That are a great Tech. and Logic answer= Bigger and Cost More. Alot more than $ 150 US Dollars
Have a great night, Sir.
Surapon

 

[surapon]

Thanks you, Sir/ Madam, to all of my friends.
Yes, After Read the Answer of your, and Mr. neuroanatomist = That real clear that Canon take the easy way out, to do the good & Cheap Lens to sell more canon Fan.
Have a Great Night, Sir/ Madam.
Surapon