Tokina RMC 17mm at Lens Turbo v1

calvin83 · Joined: 12 Apr 2009 Posts: 7584 Location: Hong Kong

I need an ultra wide to for practicing before I buy my first FF. Since I have already owns two ultra-wides(the Tokina 17mm and Topcon 20mm), I decide to pair them up with a lens turbo to get an ultra-wide my Nex 5N. As my Topcon need some modification to use on my EOS version lens turbo, I can only use the Tokina 17mm for testing.

My initial test shows that the will add a bit more field curve to a lens and it works best with flat field lenses. The adapter also has the 'blue spot' issue when there is a strong light source in the field. The lens(Tokina 17mm) shows visible field curve on my camera without the lens turbo.

Here are some photos taken with the setup. I use F8 or F11 on all the photos. No distortion/CA correction is made.

Click the photo to enlarge:

#1

#2

#3

#4

#5

#6

#7

#8

iangreenhalgh1 · Expire: 2014-01-07

Looks like it performs like the one I tried - centre is acceptable but edges are poor with smearing and strong lateral CA.

Lloydy · Expire: 2022-01-01

I'm not sure I agree with you Ian, I don't think the difference between centre and edge is enough to warrant 'criticism' of this lens - which I know is a lens that you rate highly. I don't think a lens of this 'width' is ever likely to be consistently sharp across its full width, I think there has to be an acceptance of some fall off. I think the Tokina is a remarkable lens of its time, which still holds its own today.

calvin83 · Joined: 12 Apr 2009 Posts: 7584 Location: Hong Kong

I think will be less CA and field curve on a real FF camera than a crop camera with the lens turbo. Take a look at #4, the left and the right window are in focus and the middle part of the image are not.

iangreenhalgh1 · Expire: 2014-01-07

Well, on my a850 FF, the Tokina 17mm has much better corners than Tokina 17mm + Lens Turbo didon myNEX-3 when I tried it. On the a850, you only need to close the aperture 2 stops and the corners are great, but with the Lens Turbo + NEX, even at f11, the corners were poor. If you look at the top right corner of #1 and the top left corner of =6 you will see colour fringing caused by lateral CA, that has been introduced by the Lens Turbo. Or rather, I think it has magnified the CA present to make it visible. The Tokina 17 has, I think, less than 1px width CA in the corners, but the Lens Turbo is magnifying this so it's more like 3px

It's the Lens Turbo that is to blame, the Tokina 17 has good corners, especially stopped down.

So I think it's nice to practice with the UW perspective, but you won't get an impression of how the lens really performs on FF.

I think they intended the Lens Turbo to be used with fast 'normal' lenses such as a 1.4/50, to gain extra speed, and it just isn't very good with wider lenses.

calvin83 · Joined: 12 Apr 2009 Posts: 7584 Location: Hong Kong

None of my 50mm works great with the lens turbo but my Tomioka Yashinon 60mm does work pretty well with it. The best lens I tested is my Tamron 350 mirror which has good corners when focus at far distance. Wink

Lloydy · Expire: 2022-01-01

Yes, pic's 1 and 6 are showing degradation exactly as Ian says, which I have to say I didn't see until he pointed it out. But that would be a struggle for any lens, especially pic' 6.
It would be interesting to test the same lens, for the same picture, on two cameras - FF and Turbo'd - to see the difference.

iangreenhalgh1 · Expire: 2014-01-07

Interesting that longer lenses work better.

Sadly I don't have a Lens Turbo anymore otherwise I'd give that a try.

Certainly, the high contrast edges I pointed out are challenging and most lenses would show some CA in such circumstances, I just think the Lens Turbo makes it worse.

kds315* · Expire: 2021-03-09

Looks pretty good to me. I like that lens a lot (have two or three), but never used of FF or Turbo.

Lloydy · Expire: 2022-01-01

I borrowed Phil's Minolta lens turbo for a short while, and I must have tried the Tokina 17 on it. I remember being impressed with it, but I wasn't pixel peeping. I shall try and find some pic's taken with the combo.