Sony A7 / A7r - Sigma 20mm f/1.8 tests - My FE lens 'solutions'

Images above (top to bottom) A7r Sigma 35mm, A7r Minolta 24-105mm, A7 Minolta 35-70mm.

A Soundimageplus reader very kindly shot me some test images and sent me the raw files from the Sony Zeiss 24-70mm f/4 as I was thinking of getting it. Note the word was. The samples were plagued with vignetting, distortion and soft corners, some of the wider angle shots being quite bad. Also not as sharp as I expected. So it seems that 3 out of 4 of the first FE lens releases are not that great. The 55mm f/1.8 does seem to be a decent lens, but then if you can't make a decent lens at that focal length and that widest aperture, there's no hope really. This used to be the standard lens sold with all 35mm lens cameras after all.

Add in the fact that there is probably going to be the usual Sony tortoise speed lens rollout and the fact that these FE lenses they are putting out are very expensive for what they are, it's obvious that if I want to keep on using the A7 and A7r, which I most definitely do, then I have to come up with other solutions. Fortunately amidst this somewhat ordinary batch of optics Sony have released a gem in the shape of the LA-EA4 a-mount to e-mount adapter. Taking advantage of that I have bought some old Minolta lenses at knockdown prices. (And I have to say I think my £18 35-70mm zoom is every bit as good as the 24-70 within it's range) Plus I have the extremely wonderful Sigma 35mm f/1.4 ART lens and now the Sigma 20mm f/1.8. So it's a-mount lenses from here on in. And I'm going to go with these and my Nikon primes for manual focus when I want to do that. And I'm pleased with the AF from the adapter and I'm pretty impressed with the image quality I'm getting as well.

So what of the Sigma 20mm? 

DISTORTION


As you can see barrel distortion is very well controlled and the lens profile makes very minimal changes. If you have a look at the top of the TV screen on the left you'll see what's being corrected.

SHARPNESS

 f/1.8

 f/4

 f/5.6

As you can see f/1.8 is probably emergency use only, but by f/4 things are looking really good. Lovely crisp detailed images that show just what these sensors can do. Maybe Sony should ask Sigma to make their lenses for them!!

VIGNETTING


f/1.8

f/4
f/5.6
Non-existent even wide open. Corner sharpness is also very good. It's even reasonable wide open.

So why can't / won't Sony make lenses like this? They don't even seem to be able to better or even equal 20+ year old Minolta 35mm lenses. I have no answer to this and we can all speculate as to why that might be. However there is an excellent alternative. And I should mention a substantially cheaper one as well. This 20mm is absolutely mint, hardly used and cost me £250. And this shows up the Zeiss badging / designer label myth once again. The 24-70mm samples were sent to me privately so I won't publish them with permission, but the 24mm end wasn't even close to what I'm getting from this Sigma. You can imagine just how much better the Sigma 35mm f/1.4 is. And Sony want over £1000 for this 24-70mm. Makes you wonder just how much Zeiss charge to put their name on it.

So what of the 24-70mm for people who have bought it or pre-ordered it? Well Sony are normally very good at providing lens profiles and one should appear in Photoshop soon, which should fix a lot of the problems. And to a large extent I don't have an issue with lens correction as such. If it keeps lenses smaller, lighter and cheaper then I don't see it as a bad thing. However, the 24-70mm isn't cheap. In fact it's VERY expensive and surely if you pay that much for a lens then you have the right to expect premium quality. Also it's worth bearing in mind that lenses that need a lot of correction, as it seems the 24-70mm does, then there is the question of why does it need that much correction? What standard of materials are being used here and how will it impact on other aspects of a lenses performance?

When you consider also that the 35mm f/2.8 FE lens is currently £750 in the UK and that lens has issues too and the Sigma 35mm f/1.4 a-mount, which is a superior lens is £100 cheaper, I wonder if there is an element of profiteering on Sony's part here. Certainly I can see no justification for the prices Sony are charging for these FE lenses. As well as the 24-70mm and 35mm lenses The 28-70mm, which is a pretty ordinary kit lens is £450 and the 55mm f/1.8 is again close to £1000. Are these lenses worth that much? Well not to me. In fact in the case of the 28-70mm which I have I know it's not. And in the end won't this backfire on Sony? I've already written their e-mount lenses off for my A7 and A7r. I am keeping the 28-70mm but pretty much as a video lens only. I'm really hoping that Sigma will see an opportunity here and come up with some decent zooms and primes. If they do I suspect they will make a killing.

Finally there is I think an interesting point to be made about lenses and the A7 and A7r. For some reason when they were first announced they were seen as some kind of Leica alternatives. It never seemed that way to me, but they were talked up as such on many forums. However it seems that Leica and m-mount lenses and Zeiss lenses (m-mount, SLR and mirrorless) have some of the worst performing lenses on the Sonys. And some of the best are Nikon, Canon and Sigma SLR lenses, including many that are pretty old in digital photography terms and many that were designed for film camera. Perhaps this will further encourage the demolition of lens brand worship, myths and legends and we may be in for a serious reappraisal of what constitutes a quality lens and who is and who is not a quality lens maker. 

I was amused to see a while ago  a Leica lens owner squealing on a forum about how his ultra-expensive wide-angles vignetted and had colour casts. He did of course blame Sony for this saying that they had 'cut corners' on the sensor. The implication being how on earth could Leica or Zeiss ever do anything wrong, they are just SO expensive? Interesting perspective. But then when my second-hand Minoltas perform as well as and often better than hyped-up designer label lenses then MY take on the Sony sensors in these cameras is that they have got it just right. And since I believe the A7r sensor to be the best I've ever seen on a digital camera it does show that Sony do a lot of things right. However, it seems that for now lens making isn't one of them.


 
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