Sony E 18-105 vs Sony FE 24-105

[JohnNEX]

The release of the FE 24-105mm f/4 lens has got me thinking.

The 18-105mm f/4 lens is 110mm long and weighs 427 grams.

The 24-105 f/4 lens is 113mm long (retracted) and weighs 663 grams. Its around 140mm extended.

So the 18-105 has a longer focal range but is significantly shorter and weighs significantly less.

I have made the point many times that lenses made for APS-C are no different in size to lenses made for full frame, all else being equal. I don't mean the equivalent lens (e.g. FF 35mm vs APS-C 24mm) but the same lens (50mm f/1.8 for FF vs 50/1.8 for APS-C). There are lots of examples which show that there is no significant difference in size, except perhaps for wide angle lenses.

So, why is the APS-C 18-105 f/4 so much smaller than the FE 24-105 f/4 ?

The 18-105 is the odd one out. Most 24-105 lenses are similar in size to the FE version.

For APS-C lenses, the 18-105 is usually smaller because the lens is only f/5.6 at the long end (Fuji's 18-135 is also f/5.6 at the long end). The Sony E-mount manages to retail the f/4 at the long end.

I think the answer is in the lens design, where Sony has cleverly fit the lens into a smaller package, but the cost is the massive distortion. Squeezing all that zoom into a small space means the optics are compromised. Sony has relied on software corrections - which are pretty good - to enable an engineering work-around in order to achieve a much small size. Whether this is worth it will vary from person to person.

Its also an insight into Sony's view on APS-C lenses, where they prioritise size over almost everything else. That is, Sony believes, and has said publicly, that APS-C is focused on small size, which explains the trade-off between size and distortion, and I think that explains why they don't prioritise a f/2.8 zoom - its just too big (in their view).

I don't own the 18-105 f/4, but I now appreciate it more now. A lot of folks refer to its size as a negative, but it really could be a lot larger, or be f/5.6 at the long end. Its a cleverly designed small lens, but you need to understand the trade-offs.

 

[blue_skies]

The release of the FE 24-105mm f/4 lens has got me thinking.

The 18-105mm f/4 lens is 110mm long and weighs 427 grams.

The 24-105 f/4 lens is 113mm long (retracted) and weighs 663 grams. Its around 140mm extended.

So the 18-105 has a longer focal range but is significantly shorter and weighs significantly less.

I have made the point many times that lenses made for APS-C are no different in size to lenses made for full frame, all else being equal. I don't mean the equivalent lens (e.g. FF 35mm vs APS-C 24mm) but the same lens (50mm f/1.8 for FF vs 50/1.8 for APS-C). There are lots of examples which show that there is no significant difference in size, except perhaps for wide angle lenses.

So, why is the APS-C 18-105 f/4 so much smaller than the FE 24-105 f/4 ?

The 18-105 is the odd one out. Most 24-105 lenses are similar in size to the FE version.

For APS-C lenses, the 18-105 is usually smaller because the lens is only f/5.6 at the long end (Fuji's 18-135 is also f/5.6 at the long end). The Sony E-mount manages to retail the f/4 at the long end.

I think the answer is in the lens design, where Sony has cleverly fit the lens into a smaller package, but the cost is the massive distortion. Squeezing all that zoom into a small space means the optics are compromised. Sony has relied on software corrections - which are pretty good - to enable an engineering work-around in order to achieve a much small size. Whether this is worth it will vary from person to person.

Its also an insight into Sony's view on APS-C lenses, where they prioritise size over almost everything else. That is, Sony believes, and has said publicly, that APS-C is focused on small size, which explains the trade-off between size and distortion, and I think that explains why they don't prioritise a f/2.8 zoom - its just too big (in their view).

I don't own the 18-105 f/4, but I now appreciate it more now. A lot of folks refer to its size as a negative, but it really could be a lot larger, or be f/5.6 at the long end. Its a cleverly designed small lens, but you need to understand the trade-offs.

 

[sgkoala]

I think you are right about the compromise on distortion allowing a smaller lens. Sigma has also said that their Contemporary lenses are smaller than they otherwise would be if they had to keep distortion at a minimum.

Note also that the 24-105 has been designed to have strong corner sharpness even at 24mm on full frame.

If the 18-105 had been a 16-105 with strong corner sharpness, I'm sure it would have had to be much bigger than it is.

 

[Sympa]

Distortion is a lens aberration that can be corrected very well if you have sensor pixels to spare (and I think we do). So it makes sense to have smaller size, lighter weight, larger aperture, but also sharper corners, less coma, less CA, etc, if that causes distortion to go up.

Vignetting is another one that can be corrected, but we do not have SNR to spare (and if we did, we could make the lens less bright, making everything easier). And vignetting is related to cat-eye bokeh, with bokeh being the other reason to look for large aperture.

Note that people regard for example the RX100 series highly - and these lenses are also distortion corrected in software. For some reason it doesn't matter there?

 

[QuietOC]

At least one review has stated the 24-105G has a lot of distortion too.

A 105 mm lens only needs to be 105 mm from the sensor at infinity.

Having used several x-105mm lenses they vary in size alot. The Sigma 28-105mm F2.8-4 is much smaller than than their current 24-105mm F4 Art. The Minolta/Sony 24-105mm F3.5-4.5 is very compact. The Sony DT 16-105mm F3.5-5.6 is larger despite being a slower lens for a smaller sensor.

The 18-105G was designed to be camcorder lens, and it fits that role well. It is an odd choice for the A6x00 cameras except when they are being pushed into camcorder duty.

I like my Sony DT 18-135 F3.5-5.6 SAM, and would probably opt for the similar zooms in other systems. It is definitely not a camcorder lens. It is light, fast focusing, sharp in center at all focal lengths, direct manual zoom, clutched direct manual focus. It extends quite a bit at 135mm, but that doesn't bother me at all.

The 16-70mm F4 sounds very attractive for the A6x00 cameras. It should be the kit lens. Leave the 16-50PZ to only be the kit for the A5x00 bodies and QX1.

 

[val1]

Yep.. I may jump to an a7r2 for the 24-105g. The a6000 is great with primes but none of the zooms do it for me. The 18-105g is passable and flexible enough to earn a bag spot for now.