K & F Concepts Sony camera to Nikon lens adapter - help

[Brad Richardson]

I own a Sony A6400 and I wanted to adapt some Nikon mount lenses. I purchased the K & F Concepts KF06.436 adapter. I have the AF Nikkor 50mm 1.8 D which works with the adapter - manual focus and manual aperture adjustment on the lens. So far, so good. I have the Sigma EX 30mm 1.4 D DC HSM and the Tamron SP 17-50mm F2.8 VC Di 072 B005 (both Nikon mount for Nikon D300) and these lenses will mount but I have no aperture control - I presume because I bought the wrong adapter thanks to the K & F website email bot that couldn't recognise that I was using a couple of non-aperture control via the lens lenses. But I have to take responsibility for this and I should have done more research - are the last two lenses (the Sigma and the Tamron) G mount? Anyway - all is not lost I hope - can someone tell me - when I use this adapter and mount the Sigma or the Tamron - are they at maximum aperture and can't be changed? Also - why is the adapter marked "pro" - the adapter I should have bought with aperture control was cheaper - I just don't follow.

[rodeo_joe1]

" - are the last two lenses (the Sigma and the Tamron) G mount?" 

Yes. 

The 'G' lens adapter, with aperture control ring, is the one you need. Even then, the aperture control is fairly crude. The adapter's control ring has a short throw and very lightly detented 'click' stops. But because G lenses vary in their minimum aperture, the click stops don't necessarily give you one f-stop variation between clicks. 

It's a lot better than no aperture control at all though.

On 10/13/2024 at 9:00 AM, Brad Richardson said:

can someone tell me - when I use this adapter and mount the Sigma or the Tamron - are they at maximum aperture and can't be changed?

G lenses default to their minimum aperture - i. e. smallest opening and highest aperture number. This severely limits their usefulness unless there's a mechanism to push against the control lever on the back of the lens to open the iris up. 

On 10/13/2024 at 9:00 AM, Brad Richardson said:

Also - why is the adapter marked "pro" - the adapter I should have bought with aperture control was cheaper - I just don't follow.

Can't answer that. Marketing bods probably have to abandon any logic or contact with reality to do their jobs! 

My advice would be to just return the incorrect adapter as unsuitable and plead for a refund or credit note towards the G-lens version. 

[Brad Richardson]

Thanks so much, R_J1 - One of the reasons I own the Tamron  (f2.8) and the Sigma lens (F1.4) is to use them at their minimum aperture - even if I buy the "correct" adapter - am I sure the adapter will open these lenses at their minimum - I really think K & F could do a better job.

[rodeo_joe1]

On 10/16/2024 at 1:30 AM, Brad Richardson said:

even if I buy the "correct" adapter - am I sure the adapter will open these lenses at their minimum - I really think K & F could do a better job.

I have the K+F Nikon(G)-to-Sony adapter with aperture control. It works well - within the limitations I pointed out.

However, I think we're at cross purposes over the meaning of 'minimum aperture', since I find it difficult to believe you want to use your lenses fully stopped down all the time. The correct definition of minimum aperture is the smallest 'hole' size that the lens is capable of. I.e. at the highest f-number - f/16, f/22 etc. and, just to make it clear, showing the darkest image. Maximum aperture, OTOH, means the biggest hole size, smallest f-number and gives the brightest image. 

K+F's aperture control adapter for Nikon G-lenses has a lever that pushes against the aperture control on the back of the lens, allowing the lens to be used at maximum aperture when the control ring is turned fully clockwise - as seen from behind the camera. The ring also allows for the lens to be stopped down to its mimimum aperture through 6 click-detented positions. Unfortunately the clicks don't necessarily align with one-stop changes in aperture, but the arrangement is entirely usable.

Edited October 17 by rodeo_joe1

[Brad Richardson]

Thank you appreciate your help - I have now purchased the correct adapter. Yes I mean that I want to use the lenses at f2.4 and f1.4.