Where are all the small lenses?

[JoeySnaps]

One of the supposed benefits of mirrorless cameras, resulting from dispensing with the mirror box, was going to be new designs of lenses, including compact wide-angle and standard lenses, since the rear element could now be positioned closer to the sensor, making complex retrofocus designs un-necessary.

So why is it that almost all the new lenses appearing for the R series cameras are notably big and heavy? This:

... is the old FD 50mm f/1.4 lens, which those of us with long beards may remember was very well thought-of in its day. And it's tiny! Comparing it with modern 50mm f/1.4 lenses (there isn't one for the RF mount, but the f/1.2 gives an idea, and there are f/1.4 lenses for other systems) they are all enormous - and heavy.

I would dearly love to have a pancake lens in RF mount, so the camera could be carried in a (capacious) coat pocket complete with lens. Please, Canon?

[rs-eos · Accepted solution]

Yea, I was a bit bummed by this as well.  When I move to mirrorless (prob in another 3 years or so), It will be the R5 Mark II or equivalent.  The savings in size and weight compared to an EOS 5D IV will be dwarfed by the increase in size and weight by the RF 50mm f/1.2 (vs EF 50mm f/1.2).

The 50mm is my most used lens and this will lead to around a 30% heavier camera/lens combo.

I am though looking foward the much better quality and sharpness one can achieve with the RF version.   So at least there will be much benefits to gain to make up for the extra weight.

[rs-eos · Accepted solution]

Yea, I was a bit bummed by this as well.  When I move to mirrorless (prob in another 3 years or so), It will be the R5 Mark II or equivalent.  The savings in size and weight compared to an EOS 5D IV will be dwarfed by the increase in size and weight by the RF 50mm f/1.2 (vs EF 50mm f/1.2).

The 50mm is my most used lens and this will lead to around a 30% heavier camera/lens combo.

I am though looking foward the much better quality and sharpness one can achieve with the RF version.   So at least there will be much benefits to gain to make up for the extra weight.

[JoeySnaps]

FD 50mm f/1.4 235g

EF 50mm f/1.2 580g

RF 50mm f/1.2 950g

Yes, I see your point! It's true that image quality has improved over the generations in leaps and bounds. The old FD lens can't hold a candle to the newest designs and maybe to achieve these stellar results requires a big heavy lens. But I suspect that the advances made in lens design could be applied to a more compact, lightweight design and still achieve adequate image quality. And they would have at least one customer for the lens!

[ebiggs1]

There are laws that limit what can be physically produced. A f1.2 lens has to have a large element. No way around that. Focal length is a ratio and another law that can't be broken. 50mm is generally considered the focal length that most closely approximates the human field of view or FL if you will. However, it doesn't define aperture and there in is the problem. Mechanics needed to create a camera lens.

The size of the sensor requires a certain amount of coverage. Think of your iphone which has an approx. 35mm equivalent lens and a pinky finger sized sensor compared to a normal 35mm lens for a FF camera like the Canon R5.

If you really want a small camera you need to buy a small camera. That will be a lot more successful than thinking a full size DSLR or Mirrorless will ever be pocketable with a 50nn f1.4 lens on it.

[JoeySnaps]

Yes indeed. I'm still interested, though, in the difference in size and weight between an FD 50mm f/1.4 lens and an EF 50mm f/1.4 or RF 50mm f/1.2 lens.

The laws that you refer to state that the optical centre of a 50 mm lens will be 50mm from the focal plane. And the objective element of the f/1.4 lens will have a diameter of 50/1.4 or about 35.7mm. But modern 50mm f/1.4 or f/1.2 lenses are MUCH bigger than this. Whereas my old FD 50 matches these figures pretty much exactly.

Modern lens designers are doing clever stuff, presumably to optimise image quality, which increases the size, complexity and weight of the lens significantly. I think it's a pity that we're not given the choice - I for one might easily buy a compact 40 or 50mm lens, and another bigger one for when the ultimate image quality is more important than size and weight.

[ebiggs1]

It is not possible to produce a simple 50mm piece of glass and use it for a camera lens. The reason is not all light focuses to the same point. Thus corrector lenses have to be added to the package that eventually becomes a camera lens. There is, again as I mentioned, an aperture. That has to be in there too. If you would be satisfied with a 50mm FL piece of glass and didn't care too much about aberration, distortion or IQ you could have a tiny lens. I bet you wouldn't like it!

[JoeySnaps]

Reviewing this thread, I realise I'm bleating about wanting a wide aperture standard lens as compact as the old FD lens, and of course there is a ready solution:

[Stephen · Accepted solution]

Have you met the RF50mm F1.8 STM? It might be what you're looking for. Check it out: https://canon.us/3SofDjg 

[JoeySnaps]

Thanks for the suggestion, Stephen and yes that will probably do the trick. I think I read somewhere that the 50mm STM lens is optically the same as the old EF 'nifty fifty' and quite an old design. Not necessarily a bad thing, of course, the old lens was very well thought of. Do you have any experience with it? What do you think of it?

[Stephen]

I have the newest EF version (with STM), and the one just before that (without STM). I will tell you that the one with STM is both an optically superior lens and having the STM focusing motor is a complete game changer. When I got the STM lens, initially, I was disappointed because the front element was so much smaller, but real-world use blew me away. 

I'm by no means a pro, but the 50mm (STM), my 40mm (STM), and even my EF-S 24mm (STM) are my go-to walk-around lenses. (All of which will work perfectly on your R6 Mark II - EF-S lenses will put it in crop mode.)
Canon Canon EOS Rebel T7i w/EF 50mm f/1.8 STM ƒ/1.8 1/80 50mm ISO4000

Camera: Canon EOS Rebel T7i

Lens: EF 50mm f/1.8 STM
AV:ƒ/1.8
TV: 1/80
FL: 50mm 
ISO: 4000