Home
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

total newbie needs guidance.
View previous topic :: View next topic  


PostPosted: Thu Feb 08, 2018 10:29 pm    Post subject: total newbie needs guidance. Reply with quote

after years of being a digital (AF only) nut, I find myself looking down at two komura manual focus lenses, (with another on the way. the first , a 135mm f2.8 model with a Nikon auto adapter , it has the original apature ring disabled and works like a nikon via a ing on the mount.
pretty rickety it needs a severe sorting out ,it moves and wobbles and there is obviousely something amiss, that said I took a few shots with it on the DF , and the bokeh is glorious ,although its not the sharpest lens around.
but enough about that one ,the object of this thread is the second lens , its a 200mm f3.5 with dual preset dials 16 blade etc. and a really nice lens , its clean and tight , a bit stiff to operate ,(reminds my of my old zenit and the helios lens) but smooth.the problem is ,that it has a different mount , I think the mount is an exacta from what I have seen around ,but it comes off and there is a thread of 49.85mm on the main body , can this be adapted for nikon via a simple adapter change or adding another mount, or am I looking to remove some metel from the lens , I am more than capable of doing that but need help with the measurments, presumably the face of the nikon flange will need to be a specific distance from the rear element to guarantee the full range (to infinity etc.) sorry to be jumping right in with my first thread by asking for help , a photo of the lens is below with the adapter detached . thanks.


PostPosted: Fri Feb 09, 2018 12:42 am    Post subject: Re: total newbie needs guidance. Reply with quote

griffon22 wrote:
after years of being a digital (AF only) nut, I find myself looking down at two komura manual focus lenses, (with another on the way. the first , a 135mm f2.8 model with a Nikon auto adapter , it has the original apature ring disabled and works like a nikon via a ing on the mount.
pretty rickety it needs a severe sorting out ,it moves and wobbles and there is obviousely something amiss, that said I took a few shots with it on the DF , and the bokeh is glorious ,although its not the sharpest lens around.
but enough about that one ,the object of this thread is the second lens , its a 200mm f3.5 with dual preset dials 16 blade etc. and a really nice lens , its clean and tight , a bit stiff to operate ,(reminds my of my old zenit and the helios lens) but smooth.the problem is ,that it has a different mount , I think the mount is an exacta from what I have seen around ,but it comes off and there is a thread of 49.85mm on the main body , can this be adapted for nikon via a simple adapter change or adding another mount, or am I looking to remove some metel from the lens , I am more than capable of doing that but need help with the measurments, presumably the face of the nikon flange will need to be a specific distance from the rear element to guarantee the full range (to infinity etc.) sorry to be jumping right in with my first thread by asking for help , a photo of the lens is below with the adapter detached . thanks.


First of all, welcome to MF Lenses. We hope you enjoy your stay here. I've quoted your message because, as a means of reducing spam, a new user's first message cannot contain any images. But now everyone else can see them.

Yours is a pretty clear pic. Somebody will know what that lens fits. And once you know, you can get an adapter for it, and use it on your digital. Which is what most folks here do -- that is, they use MF lenses on their digital cameras. I certainly do. But there are also a great many of us who are still hardcore film users, so if you still like film, you'll be welcome here as well.

Now on to specifics. So, the threads I see are 49.085mm? This is not a standard thread size. And it looks like the lens to camera mount won't unscrew from the bare aluminum adapter ring. Or does it? Be sure to check it real close at the camera mount. It might come apart there. If it doesn't, then my conclusion is that this is a proprietary design. I wasn't aware that Komura did this sort of thing. Komura probably offered adapter for various cameras, but you had to buy their adapter. That would be my guess. First time I've ever seen anything like this. If -- that is -- if it doesn't come apart at the camera mount.

Now, assuming it doesn't come apart at the mount, if you want to use this lens on a Nikon, and if you have machining skills, you can get it done. You will need to know what this lens fits and the registration distance for the camera it fits. With those two numbers you will then know where the film plane occurs with that lens. And knowing that number, you being handy with machine tools and all, you should be able to cut an adapter to fit Nikon. You'll need to know Nikon's registration distance, as well.

In fact, with a bit of back-calculations, knowing the Nikon number, you can work forward to determine a number for a T-mount adapter, and, providing you'll have a machine that can cut threads, then you can use that lens with any camera for which a T-mount was made -- which was just about all of them.

Let us know how things work out for you.


Last edited by cooltouch on Fri Feb 09, 2018 4:00 am; edited 1 time in total


PostPosted: Fri Feb 09, 2018 2:47 am    Post subject: Reply with quote

Looks like a T-mount lens. Just get T-mount adapter for your camera.


PostPosted: Fri Feb 09, 2018 4:02 am    Post subject: Reply with quote

Except with 49.85mm threads, it isn't a T-mount adapter. T-mount adapters have 42mm threads.


PostPosted: Fri Feb 09, 2018 8:04 am    Post subject: Reply with quote

thanks for the replies all, according to the information I have ,the lens has an "Exacta/topcon" mount, if that helps, at the moment it means nothing to me ,is the bayonet portion Exacta, and the threaded part Topcon, or is there an exacta/topcon (single mount).
I will see if the next portion will screw off , but if it does there will be an even bigger thread there i would think .
thanks again, Graham