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

Started 9 months ago | Discussions thread
bigley Ling
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Re: Hard to believe - but 28mm f2.8 and 28mm f3.5 Nikon primes beaten by A7 kit lens
In reply to Mel Snyder, 9 months ago

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?

It is possible that the design of the old nikkors are not suited for the A7 or A7r. The old AIS lens was designed for film, whereas the kit lens for your a7 is designed for digital. Also I suspect the A7 has built in correction data to remmedy alot of issues like CA bignetting etc.

I have used my 28mm f2.8 MF nikkor on speed booster on my Nex 5r and and found the sharpness to be adequate in the corners wide open.

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