A Vintage Lens Mount and Lens manufacturer you probably have never heard of…

Hello Readers!

This week I’m taking a look at some history and looking at vintage lenses again.

Recently I’ve been busy trying to recover some footage I shot for a recent Anamorphic Video that i will be putting out soon however today I wanted to look at a vintage lens mount that not many people I know talk about.

That mount is the Exakta lens mount or EXA for short.

A little about Exakta and the Topcon Company

The Exakta mount comes from Germany and was developed sometime in the early 1930s. The company that created it was original formed in 1912 is Dresden, Germany. (source Wikipedia)

Topcon was a Japanese Camera and optic company and founded in 1932.

Now there were several Exakta mount version in existence over the years. The first Topcon Exakta mount camera of interest started in 1957 with subsequent improvements throughout the years.

I am assuming here that during World War 2 the Germans shared optical and technical information with the Japanese and that there may be been more fixed style lenses during that time period. Most other lenses used the screw type mounts like Leica’s M42 M39 etc. as well as the later on C-mounts.

The Exakta mount is a bayonet mount. According to documentation I found it was the first bayonet mount (way before Canon Rangefinder or FD, Nikon or Pentax K even existed or had one in production that was a commercial success).

The Germans are and were known for their optical and technical prowess in the field of cameras and optical experience for a quite a long time.

Topcon entered the SLR game with its first Exakta mount in 1957. (source Hugo Ruys – topcon history). I should point out as well that Topcon went out of business (or at least the camera division did) in the early 70s.. there most successful camera was the Topcon RE Super (the predecessor to the RE-2) so don’t expect any kind of newer lenses or cameras from them any time soon.

Over the course of the following years Topcon created up to 7 different style of Bayonet mounts with the name Exakta. Not all were the same and is a confusion point even now to collectors.

The most modern version of Exakta (for Topcon) being the RE-AUTO Topcor style that allowed internal through the lens metering and had the spring-loaded clip on the side of the lens mount. This resulted in a much sturdier support.

Why Should i care about Exakta now?

If you are a collector or vintage lens videographer like I am and love vintage glass, its worth taking a look at some of these lenses.

I recently picked up this Topcon RE-2 REAUTO-Topcor 58mm f1.8 Exakta (shown with the Viltrox speedbooster and Exakta adapter mounted) from a local antique store. The lens was in amazing shape. According to online reviews the 58mm f1.4 version is also a great lens (however a lot more expensive now).

There are about 4 different versions of the Topcor 58mm f1.8 that were made. The one i purchased is the 3rd version (according to serial number – see below).

I recently found a description in a forum post regarding a book (thats now out of print) on the Topcor company itself and it had this excerpt:

Topcor RE-AUTO – F1.8 Serial numbers

There’s four generations of 58/1.8. First is 62xxxx. Second is 99xxxx, optically different (same number of elements, one more group). Third is 1160xxxx, no optical change. Fourth is 1161xxxx and up, another optical change. (Per Atonetto’s book.)

I have no idea what optical change may have been in the fourth version of this lens. It could be that the 4th version had coatings and that they took out the radioactive elements in the lens or that they added an extra lens element or better.. they added an aspherical element however i am just speculating here as there isn’t much information on the subject on the internet.

Looking online at allphotolenses.com website, its revealed that other users rated this lens fairly high on the optical and mechanical side.

My initial thoughts and reasons for wanting to try this lens

I was thinking that this lens may be adapted in order to be useful again. Shooting vintage lenses on the GH5 has been a recent hobby of mine and seeking great quality is always tough to find.

Considering that this Topcon RE-AUTO Topcor lens may in fact be using German glass or a similar glass formula so I decided to pick it up and experiment.

For manual video shooting having the added bonus of manual focusing and de-clicked aperture on this lens was a real bonus. The lens rotates quite smoothly and focus throw is large. Perfect for video recording.

But what about adapters?

Luckily one of my favorite adapter companies, Fotodiox, currently makes a Pro adapter with correction optics that works fantastic for this lens.

Note: At first I purchased a simple cheap metal adapter version from EBAY as I read that the flange distance on this lens is 44.7mm for Exakta (versus Canon EOS EF len’s 44mm) however I soon found out that most of the Exakta metal adapter versions do not fit the Topcor RE-Auto version of Exakta mount properly. The Fotodiox Pro adapter does and has corrective optics for a really clear picture.

Explanation: The flange distance is the distance from the sensor (or film plate) to the back of the first lens element.

Pro tip: Canon EF mount is an excellent mounting system to adapt other lenses to due to its short flange distance. Most modern mirrorless cameras have extremely small flange distance. Adapting lenses to them makes sense from a universal point of view. For more info on this topic please google “flange focal distance wiki”.

One thing to consider is that using one of these adapters will add a 1.4X crop to your image. In my opinion it’s still worth it but you need to consider what type of shots you need to get.


How to get the most of the image quality?

On the GH5 I’m using the Viltrox EF-M2 EOS to MFT speedbooster. Recently the firmware was updated in order to allow Manual lenses to be attached with a warning. This means you can make use of the speedboosters optical properties for a manual lens (obviously all electrical information isn’t carried through however).

This makes the GH5 one of the best cameras to adapt this lens to!

So what type of field of view will we get?

Our formula for calculating that is as follows (in Full frame Equivalency):

Lens Field of view (as per written on lens)    X      Sensor crop size     X     Adapter Crop      X      Speedbooster Crop reduction amount  =  New Equivalent Field of view


58mm  X  GH5’s 2x crop  X  1.4X (Fotodiox EXA to EOS Adapter)  X   0.71 (Viltrox’s EF-M2 Crop) = 115mm   Full frame Field of view Equiv.

On the GH5 you can also use the Telescopic function to get even more reach if needed. shooting in 4K modes turn that on and you get 2X @ 230mm equivalent

For wider shots you will have some issues unless you use a wide-angle converter on the end however this may result in less optical quality unless you use a fairly good quality one.

Buyer Beware: A Word about Radiation in old lenses

RADIATION: Some of these older lenses due contain traces of radioactive thorium elements that were used in the process of making the glass elements which helped with Chromatic Abberation and other optical properties. You can usually tell an older lens with radiation as the lens will turn yellowish in color. in the 1950s and 60s the thought was that these elements increased the resolution of the glass at a cheaper cost then using other techniques. That is true, a lot of these lenses were sharp.

Debates online suggest different amounts of exposure when directly touching these elements for long periods of time can cause issues however the radiation and exposure is generally distance related. I was unable to verify from documents that this lens is in fact radiated however i did do a very simple geiger test using a cellphone geiger meter i bought on Ebay for $40. The lens does register as having 3 times higher radiation levels than standard background radiation. To put this in perspective, with limited proximity (and only to one lens) your getting 3 times your exposure in the course of a year to background radiation.

Radiation in general is harmful when exposure over time combined with the amount is excessive and its cumulative however.. most articles on radiation i have read suggest the amount your would be exposed to at the distances and time scales when using a lense like this are very minimal and the risks are not that great to you.

That being said.. as these lenses age they start to emit gamma radiation as they decay and gamma radiation is the most harmful to humans. Alpha and beta radiation are more dependent on distances whereas gamma will go through anything.

I'm not trying to scare anyone here only to inform you of the choices you make and considerations when buying some of these older items.

Radiation is a huge topic of discussion and concern as there are varying opinions online but there are facts to support exposure levels

Here is link to the radiation chart to give you more of a sense of the danger or exposure levels.

Link to chart: https://bit.ly/2N0C3Jy


Image quality on this lens is fantastic. There are really some gems in the world of vintage lenses out there. I got a bargain deal on this well-built and very usable lens that i can adapt to my GH5. Coming soon on my Youtube channel I will be posting a video showcasing quality tests for vintage lenses on my anamorphic setup. Stay tuned for that!


If you can’t get to an Antique, flea market or pawn shop.. consider check out ebay for vintage lenses. Typically these are higher on ebay but you can find deals occasionally.

Here’s a link to a Topcor 58mm F1.4 from Japan to get you started on your search online (opens a new window for you)!

Click Here for Ebay

If you want to buy the Exakta Fotodiox Pro adapter check out my Affiliate links below:


Site Owner and Administrator of www.karrgalaxy.com

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