Yoshizen's Blog

Sony lens Mystery ? ? ? (Focus moves without power)

Sony FE lens for E-mount has 18mm frangeback and Nikon-Z camera was designed to have the distance from the mount to image sensor 16mm = in the traditional sence, this 2mm gap can easily be overcome by the focus adjustment (infinity may come with a bit of rotation) by extend the focus 2mm more.   Yet, I do know the Sony lens was fixed to the minimum F-aperture and there is no manual focus ( = so-called focus by wire) when it was not connected to the Sony camera. = no point for attempt to use the lens anywhere else.

Though, as I made a lens mount adapter NEX (Sony E) to Nik-Z, I needed to find where the exact top point of the ring, before the Nik-Z mount ring and the bayonet part of the Sony lens cap was fixed.   Then I discovered very strange phenomenon of the Sony lens’ behavior.  

(The shape of internal shade appeared on the image = it never happen when the lens was used on the Sony body — in any distance, in any F-aperture = seemingly it is only to destruct the experiment.    The truth was that this lens SEL30M35  was for APS-C cropped size = not for the full frame = black frame shows the size of APS-C image and the image on the A7R finder was in fact digitally enlarged 50mm equivalent image. )

At first sight, the lens seems to be frozen at the closest focus position  —– In that case, I should click the camera (Nik-Z) to close-up test, then utterly unexpectedly, the focus of the lens jumped to infinity !   I couldn’t believe my eyes.  On the repeated test, the lens behaved like this again.  

(Note, only the Sony Macro 30mm showed this strange phenomenon, not with other lenses such as 12~24mm Zoom or Zeiss 55mm F1.8)

Since the lens was not mounted to the Sony body, its mean no connection to the power supply, how the focus motor can move ? ? ? —– (Is Sony lens got internal power back-up inside of the lens barrel, such as a super capacitor ?) —– The most peculiar things was, how the lens did know if the lens was mounted on the camera (even though it was not on Sony camera) and aimed at a close subject or not ? ? ?    In other words, when the Nik-Z and the Lens was left alone or lens alone, it doesn’t move at all, as if the lens got its own self-awareness !   Otherwise, who is activating this phenomenon ? (Further test found that the lens alone ( without being mounted to any camera (Sony or Nikon which ever)) moves = both F-Aperture and Focus moves = the lens got internal power back-up —– When the lens was aimed to dark object = Focus moves to far,  and if it was aimed to bright subject (such as the Sky) the focus moves to the closest.)   (Microchip may operate with little power though, the motor driving the lens for AF needs a certain amount of power = even a super capacitor can not operate long.)   The another question is, is it only to annoy the people ? ( —– to whom ? —– How many people in the world would experiment like this, other than me ! ? ) otherwise what is it for ?  = It’s nothing but a mystery is it  ! ? ? ?

Sony’s camera division was created by the former Minolta people who developed the world first Auto Focus SLR, Alpha 7000.  Once I was invited to visit Minolta’s Osaka HQ as a camera critics and met Mr.Kobori who lead the creation of A7000 system.   However, why Minolta couldn’t keep the position of top runner was, that they gone too far on the system design. = Try to fulfill all the possibility of the photography, then trespassed the secret of the individual creativity.   So that, despised by the top photographer (Even if they do use the same technique, they don’t want it given by the camera.)  —– while looking back, I’m not sure whether the bad habit or paranoia of the Minolta people still hanging around Sony’s floor ? ? ?   😀   (Isn’t this a paranormal, or horror story ?    This is a camera equivalent of a severed head speaks ! — If not a poltergeist )   😀


To see if it was a joke or accident, I tested them again.

Nik-Z-E mount-(B2)-001

The Sony 30mm Macro was mounted on Nikon-Z via homemade NEX to Nik-Z adapter, when the Nikon-Z was switched on, the image appeared then with a bit of noise the black frame appeared (photo left) as the lens focus seemed to be close up, I aimed the camera out of window (photo right)

Nik-Z-E mount(B1)-001

And, I put an object for close up —– then spontaneously the focus was moved to infinity, seemingly to destruct the close up image !  (Strange ! — Image sensor is Nikon-Z side which was not connected to the Sony lens —– How the lens did know it was a close-up image ? ? ?)    (I wonder, if the devices started to communicate each other with a common code by NFC, Near Field Communication kind = rather futuristic horror story isn’t it  ?) 

All those were happened while the lens 30mm Macro was on the NEX to Nik-Z adapter, its mean, the lens was having no power supply or feed back from the camera body.

(Yet still, as I said few lines before, if the devices started to communicate, and using RFID like system, lens may able to receive the Info’ even a power from the camera body ! —– and near future, the camera may starts to beep beep you “The girl sitting over there is a well-known model, would you like to take her picture ? ” )   😀

Still, the question is the same = What makes the lens focus move without power without intelligence of the image.    What was that for ?    (I need to ask SONY —– I gave an inquiry of which the Case number was  18 ****8 —– Who answer me ? ? ? —– In fact, I wonder how many technician in Sony ever got knowledge of this  ?)


After I discovered that the lens keeps moving whether it was mounted on the Nikon (using homemade NEX to NikZ adaptor) or left alone.   So, they were the photographic evidences of Sony (or Minolta) zombie state.


When the lens detects the light, its focus moved to closest (photo left)  When the lens detect no light (ie; dark) focus was fixed to far — Then suddenly take the lens cap off and aimed to the outside, the focus move back to closest = So, this picture was just before the focus moves (photo right)   (I have no idea what sort of the game Sony heated up ? ? ?  —– But, the game against to whom ? —– It seems all those strange activities were to make this APS-C lens work on a full-frame A7R body = automatically adjust the 30mm image zoom-up to 50mm equivalent image. )   😀



Sony NEX to Nikon Z homemade Mount adaptor

To use Nikon-Z camera with my system, I needed to make a mount adaptor to attach Sony NEX optics on Nikon-Z which is not available on the market.  —– If it is not there, why not to make one myself (is my motto).  Since I made so many lenses etc to use on Sony A7R, to remake them for Nikon-Z mount is too much work. 

And to have a lens comparison kind of work, there are so many mount adaptor to EOS but very few to Nikon, its mean, since I got EOS to NEX adaptor, such as Rollei to EOS, Contax to EOS, etc, and EOS to NEX, Leica to NEX then NEX to N-Z, all those lenses could be summarized on Nikon-Z . (in theory but may not be in practice. 😀 )  (So far, it seems that the N-Z7 camera can easily deal with even a dark pinhole while showing very little noise, they seems to be pretty usable and in comparison, in camera VR seems to be very effective.   (However, intentionally set M mode, 1/2 second for the test, still the result was not shaky picture —– It’s too good to be true though, it was discovered that it was not because of the VR but the shatter makes very little vibration and the lens I used (Canon 100mm macro F2.8 with proxer) happen to be very solid and steady even for handheld shooting.)

But the hidden cost of N-Z was, —– that the XQD memory card is hugely expensive and we need to buy Sony XQD card reader for a whopping cost of £40 ! —– I thought, card reader should be about £5 though, in close look both of them were rare Made in Japan, not from China or Korea but by Sony themselves ! —– then there was a second thought, wait a moment, has Sony got memory factory ? = the XQD Memory chip might come from Toshiba Yokkaichi Factory. )   😀

There is only 2 mm gap between those 2 mount. (Nikon Z got 16mm and Sony NEX is 18mm)   2 mm is so small to fill —– you may think, though it is a quite troublesome 2 mm.    Unlike M42 (Pentax screw mount), bayonet mount needs to fill many requirements.  Bayonet claws needed to have slick enough but not wobbling, tight enough spring to hold the male craw, and as it can slip off, it needs to have a secure stopper pin. etc etc.  Use Nikon F lens on Canon EOS case, the EOS mount was large enough to accommodate Nikon bayonet therefore 2.5mm gap was enough to make an adaptor. (so, we can easily get them cheap about £5 from China)   

The another trouble between NEX and N-Z is, Sony lens wouldn’t work on anywhere else, other than a Sony camera.   There is no manual focus ring, neither manual F stop control.  Attempt to use Sony lens on N-Z would be useless = forget it. —– Yet still, as all of my homemade lenses are utterly bare minimum = nothing automatic, there wouldn’t be any problem of those functions.  = as long as my optics stays there securely, I can take picture, and that is all what I need.

Base material I got for mount adaptor was a 58mm reverse adaptor for Nikon-Z from China. = This adaptor goes to Nikon side.  And to receive the bottom of Sony side was, simply a rear lens cap for Sony lens.  

Then the work starts.  They are all very very simple work = scrape off the 58mm screw part on the ring.  And to cut out the bayonet part from the lens cap.  —– Still it took nearly half day. (don’t get short-tempered = it would spoil all the effort done within a short second = Be a good Buddhist ! —– remember, even a rain drop would carve the rock)  😀    (If you got a good milling machine, even a bench drill with milling bit, such kind of work would be a matter of few minutes though the machine wouldn’t make you enlightened)   😀


(by the way,  the surface of the adaptor photo left, was finished with oil-stone)

Then, insert the bayonet ring of the lens cap into the N-Z adaptor ring and fix it.  (The lens on the adaptor would be as secure as how the lens cap stays on the lens = don’t expect too much —– anyhow, the cost of this adaptor was only about £6 or so) —— (and get enlightened was an option   😀  )

Voila, NEX to N-Z lens mount adaptor (though, it has no stopper pin, the heavy lens could fallen off, yet still, it works perfect with my homemade — such as 110 Pentax lens, Vest Pocket camera lens etc etc.  

Thanks goodness, I did very good job ! 


Over a year, after Nikon Z came to the world, now the adaptor NEX lens to N-Z camera appeared on the market. The product which I got from China was well made and only about £10 = it convinced me that it would be cheaper to buy this than to make one out of Nikon-Z 58 mm reverse ring, which I did in this post.


A cool customer like me who need to use the adaptor only for the homemade NEX mount lens, this adaptor works perfect, but if anybody who wants to use a genuine Sony lens on Nikon-Z would be utterly disappointed. The Sony lens was not designed to work manual on any camera body other than Sony. So, never attempt to do it, or to buy this adaptor.


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