Michael Reichmann's take on smaller full frame Sony FE mount lenses

Started Dec 18, 2013 | Discussions thread
EarthQuake Senior Member • Posts: 2,500
Re: False
1

Anders W wrote:

rhlpetrus wrote:

EarthQuake wrote:

rhlpetrus wrote:

Lab D wrote:

FrankS009 wrote:

"A lens has to be of a certain size to cover full frame. That size is now smaller than it used to be, because FE mount lenses don't have to have the large rear register distance that ones designed for DSLRs did. "

This is not true for lenses over 40mm. A 200mm needs some way to be 200mm. (There are a couple exceptions like lenses with reflectors and the Canon DO lenses, but they cause other issues). So a FF 200mm lens will need to be 200mm and have a much larger diameter than say an M43 150mm lens which will have more reach.

This may be why Sony so far only has lenses up to 70mm. To compare, my 90mm EFL M43 lens is not only longer than anything that FF has, but is tiny in comparison to even those much shorter lenses (especially diameter which is 2 out of the 3 dimensions).

btw, the longer registration distance allows you to make longer pancake lenses. This is why the Canon FF pancake lens is so small.

I have a Nikkor 70-300mm zoom and it's not even close to 30cm long. Actually, it's about 150mm long zoomed in and about 200mm zoomed out.

That distance, plus the flange distance is the total distance of the optical design. So add 46mm for the Nikon F flange. So your lens at 300mm is about 250mm, not far off of what was stated above.

This is important, because with telephotos, when you shrink the flange distance to make the camera smaller, you need to make the lens longer. There is no free lunch here.

The point was that the poster assumed that FL implies a lower limit to the lens length that would be, included FD, at least the FL. Not the case, just pointing that out, and there are many other examples around. Actually the issue is not FL and length, but aperture and bulkiness.

It doesn't matter the sensor size, a 300mm f/2.8 will use a huge front element and also a large midsection. Using equivalence for example, mFT and FF:

200mm f/2

400mm f/4

Both will need at least a 100mm front element. The 200mm f/2 will be shorter, certainly, but it'll be bulky and won't balance well, much like the 400 f/4 on an FF body.

So, in the end, the talk about size/bulk will tend to be less relevant as FF moves to ML.

It will become less relevant only if FF lenses are starting to be made as small and slow (in equivalence terms) as MFT lenses. Consider, for example, the new Sony Zeiss 55/1.8. It's hardly particularly small and light for a moderately fast normal prime, is it?

Your example above presumes that MFT users want to match fast FF lenses in equivalence terms. I certainly don't want to do that. Rather, I am ready to sacrifice some speed (in equivalence terms) to have smaller and lighter lenses since this in turn makes it far more likely that I actually have them with me when I need them.

Right, I think its silly to assume M43rds users want "equivalent" lenses in terms of not only FL but also DOF and light gathering. Most people who use the system understand the tradeoff, you get less DOF control, worse noise performance, at a much smaller size and weight.

Sony can offer the same thing, but they have to make slower lenses to do it, so you lose the DOF and light gathering advantage.... So, what is the point exactly?

If Sony can make a Compact 50/1.4 the size of the 25/1.4 or an 85/1.8 the size of the 45/1.8 I would be first in line to buy one, but they can't because its physically impossible to do so.

There are a few lenses that will come close, the 55/1.8 isn't actually that much bigger than the 25/1.4, but when you go through the entire system of lenses, Sony just can not compete on size/weight, again especially in the telephoto range, when considering equivalent focal length.

Nobody needs or cares about a 150/1.4 in M43rds land. With lenses this long, DOF control is not an issue (too little DOF is usually more of a problem), so all you're left with is noise performance. Again, most M43rds users are perfectly happy with the very good noise performance of the current gen sensors. Sure, FF sensors are better, but again, its a trade off.

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