Hard to believe - but 28mm f2.8 and 28mm f3.5 Nikon primes beaten by A7 kit lens

Started Mar 19, 2014 | Discussions thread
Tim Devine
Tim Devine Senior Member • Posts: 1,251
Re: Hard to believe - but 28mm f2.8 and 28mm f3.5 Nikon primes beaten by A7 kit lens

I've heard that registration distance issues impact lenses with floating elements more than those without.  I have no idea whether the 28mm has floating elements, and whether the other lenses don't.  Also the wide angle lenses can be more affected than normal or telephoto.

In terms of the 28mm shot.  It looks like a good portion of the foreground is in focus, is that lens known for having field curvature?  Next time you have a chance, focus on the corners....see if they ever get sharper more than what you see while focusing on the central subject.

I was surprised how sharp the Canon FD 24mm f/2.8 was....but I was shooting stopped down, not wide open.  Even at 28mm, wide open is going to have a narrowing of DoF.  IF there is field curvature, that would aggravate things.

The Tokina shot looks pretty good for that aperture.  But it's stopped down (from the f/2.8 lens) and it's much wider...so it's going to have more DoF.  (Although it's not focused at infinity...so theoretically the closer you focus the more DoF is compressed.)

But it could always come down to that maybe you never looked at the the photos shot with these lenses with a loupe.  It's so amazingly easy to look at photos at 100%....back in the days of film, unless you enlarged them dramatically or you looked at them through a high power loupe, you may really have never noticed the performance.


Mel Snyder wrote:

Tim Devine wrote:

My bet is that adapter registration distance is off.

Mel Snyder wrote:

When I had difficulty focusing my 35mm Summilux closer than 3 feet this morning, I decided to try two Nikon MF primes - a 28mm f2.8 Ai and a 28mm f3.5 Ai - both inherited from my late father, an photographer for Bethlehem Steel. Both focus very close - and a few years back, I'd shot the f2.8 on a Nikon FM, and it worked really well.

But when I tested both today on my A7, both were soft on the sides and corners - even at f5.6 and 8. They were very distortion free.But useless for landscapes

And so, for comparison, I shot the same scene with my kit zoom at 28mm f3.5. No comparison - the kit was sharp side to side, a tiny bit of corner softness. Even with LR 5.3, there was a quite a bit of vertical distortion beyond the lens correction profile. But the kit was sharper, more contrasty, more colorful. And a simple slider fixed it.

Anyone interested I can upload examples. But the first time some revered old primes tested so badly compared to a lowly kit zoom.

Could be - but it is perfect on my 85mm f2 Nikkor AiS and my 17mm f3.5 Tokina AT-X Pro, both wide open to exaggerate potential issues - that would cover registration issues with the lens with the smallest and longest helical travel close to infinity.

That's the only way I could think of a registration issue - one side should be out more than the other if the adapter wasn't straight in one plane or another - right? How else might I test it

I agree it is weird that both would be soft on the sides and sharp in the center. The 28mm f2.8 AiS gets a 100 score from http://www.photozone.de/active/survey/querylens.jsp so I assumed it would be great. But that score was on an APS-C camera, which doesn't see the edges.

I am more than ready to purchase a new adapter, if it's an adapter issue.

OOC image of the 85mm f2 at f2 - tree limbs sharp across frame

OOC image of the 28mm f2.8 at f2.8 - note the branches of tree at far left, evergreen at far right - worse on left = decentering?

Tokina 17mm f3.5 @ f4 - DOF here might cover ills, but so should long shot of 28mm above

Do you see anything?

 Tim Devine's gear list:Tim Devine's gear list
Sony Alpha a7R Sony FE 35mm F2.8 Sony FE 55mm F1.8 Sigma DP1 Merrill Ricoh GR II +23 more
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