Conclusion or "why have lenses become so big?"

When I compared lenses, you may have noticed that I regularly made comments about size and weight. In particular, when comparing the Tamron 28-75 to its Carl Zeiss equivalent.

You will understand if you look at this picture (it's not the 24-70 but the similarly-sized 16-35):

On top of it, the Tamron is almost half the weight. I can insure you that you will notice when carrying the A900 with one lens or the other.

Maybe the Tamron is not the best example. After all, even if it can give very good pictures, I have had AF problems with it regularly.

I also commented about the 24-105 being an "ideal travel lens". Let us look at the difference:

Now, that is a lot of difference, and the lens has much bigger range as well. Of course, it is not as fast. In particular, if you want best results you should use f/8 (f/11 at 24mm). But for a day trek in the mountains, which one is the best choice?

Of course, you can even go smaller and lighter if you use a prime, here the 50mm:

Or look at the difference between the old 135mm f/2.8 prime and the huge 70-200 f/2.8 G zoom:

(and the prime has even a built-in hood... why don't they do that any more?)


Bottom line: there is more to a lens than test pictures. The lens with the worst picture quality is the one you left at home...


And it seem that every manufacturer is building their 35mm lenses bigger and heavier nowadays.

135mm, 3 lenses, 2 primes, 1 zoom, corner.

I am finally reaching the end of these comparison here (I won't do 200mm on this subject, it is not far enough). Corner performance of the:

Sony 70-200 f/2.8 G
Minolta 135mm f/2.8 (another 20 years old lens)
Sony 135mm T4.5 STF.

(Even if two lenses are called "Sony", all three are actually Minolta designs).

f-stop	Minolta 135mm f/2.8	Sony 70-200 f/2.8 G	Sony 135mm STF
f/2.8-T4.5
f/4-T5.6
f/5.6
f/8
f/11

Interestingly, the best corner performance comes from the tiny 135mm f/2.8 prime (look at the writing on the newspaper). The STF does not quite live to its reputation, since is the least sharp of the three. In all fairness however, I should point out that all three lenses are close to perfection at full aperture and that the differences are inconsequential.

135mm, 3 lenses, 2 primes, 1 zoom, center.

At 135mm, the lenses compared will be:

Sony 70-200 f/2.8 G
Minolta 135mm f/2.8 (another 20 years old lens)
Sony 135mm T4.5 STF.

The STF will be compared at its geometric apertures, that is f/2.8 and f/4.0. These two apertures are darker than for the other lenses (this is why they are called T4.5 and T5.6), but the depth of field is the same than for the other lenses at f/2.8 and f/4.0.

I did not use smaller apertures for the STF, they do not really make sense with that lens. Neither does it make much sense to use the lens as infinity, as is almost the case here, this is just for comparison purposes.

f-stop	Minolta 135mm f/2.8	Sony 70-200 f/2.8 G	Sony 135mm STF
f/2.8-T4.5
f/4-T5.6
f/5.6
f/8
f/11

All 3 lenses are already almost perfect at full aperture. The pleasant surprise comes from the small and light 135mm f/2.8 here... it really is a pity that Minolta or Sony discontinued making these small primes.

100mm, 4 lenses, 2 primes, 2 zooms, corner.

Here the corner sharpness for the following lenses:

Minolta 100mm macro f/2.8 (a 20 years old copy...)
Minolta 100mm f/2.8 soft focus
Minolta 24-105 f/3.5-4.5
Sony 70-200mm f/2.8 G

f-stop	100 Macro	100 Soft	24-105	70-200G
f/2.8
f/4 (4.5)
f/5.6
f/8
f/11

The primes are best, followed by the 70-200G. The 24-105 never reaches the same level, even at f/11.

100mm, 4 lenses, 2 primes, 2 zooms, center.

At 100mm, we will examine not less than 4 lenses:

Minolta 100mm macro f/2.8 (a 20 years old copy...)
Minolta 100mm f/2.8 soft focus
Minolta 24-105 f/3.5-4.5
Sony 70-200mm f/2.8 G (actually another Minolta design)

The 100mm soft focus is a specialty lens, where spherical aberration can be adjusted for a soft and "glow" effect. Here is is used without any "soft focus" effect, of course.

Because there are 4 lenses in the table, I needed to make the thumbnails even smaller. Do not forget that you can click them and they will open in their own tab for a comparison at the pixel level.

f-stop	100 Macro	100 Soft	24-105	70-200G
f/2.8
f/4 (4.5)
f/5.6
f/8
f/11

It seems that the main difference in sharpness come from different focus, and all 4 lenses are very, very close at f/8. The 24-105 has a little bit less contrast, the 70-200G a little bit more contrast, but the difference is unlikely to be obvious unless by direct comparison as we are doing here.