I have an Exa Ia that I'm shooting with a Carl Zeiss Jena Flektogon 4/25, a Meritar 2.8/50 and a Carl Zeiss Jena Biometar 2.8/120
So the Prakiflex was only 3 years after the Kine Exacta, after WWII it evolved, to became the Praktina in 1952 and as a camera system was superior to the Exactas, the first full 35mm SLR camera system with a motor drive. They are rather collectible cameras people building up complete systems.
The Communists stole the company & put Noble & his son in Buchenwald after WWII, the son being sent on later to a Soviet labour camp, John was only released in 1955 after the US Presidents intervention with Stalin. KW later merged with East German Contax becoming Praktika, then taking over Exacta a few years later.
After the collapse of the Berlin wall John Noble was given back one his fathers factories, and began making Noblex panoramic cameras, the company went bankrupt and was bought by the employees.
I like my Eaxcta Varex IIb though, possibly the best of the Exacta's and need to get my Exa 1a fixed.
I haven't had an Exakta for some time. When I did it was a VX 500 with a 50/2 Zeiss Pancolar zebra lens. The lens was reasonably sharp. I think it was one of the better standard lenses in Exakta mount at the time it was made. One of the problems for me was that there was always a little play in the mount when the lens was attached. I ever got the feeling that the mount was as tight as that of a Canon FD or Minolta SLR camera. I still have one lens which is in an Exakta type mount. It's a 105/4 Noflexar bellows lens in Topcon mount. I used it mostly with an adapter on a third party bellows in Konica AR mount. The camera was an FT-1 with a Nikon E screen (grid type) installed. If I did not already have so many other macro lenses in Canon mount I might try using adapters to use the Noflexar on a Canon bellows.
Back to the original question, from what I have seen most of the Exakta mount lenses fit most Exakta cameras. Whether you are happy with the exact fit is anlther question.
The Pancolar is supposed to be a fantastic lens. Though I haven't got or used one, not being a 50mm fan....
Anyway, a loose Exakta camera mount can be tightened if necessary by (very carefully) using a small screwdriver to slighly expand the mount flange (easier seen in reality than trying to describe it....)
I initially solved the lens question this way:
First a few 50mm's that came with my bodies, old and newer. Like I have 2 RTL 1000 bodies, one of which work, but both delivered 50mm's....
Then I started searching for lenses and quickly settled for the easy solution: I got a range of Soligor T2 / T4 lenses and found Exakta T2 / T4 adapters, just a few adapters will do, but you can buy the whole catalog of lenses.....
That settled, just start taking pictures, and as you eventually find more *original* lenses (what is THAT for an Exakta??), CZ J and Meyer for instance, just shift the Soligors over to other camera bodies via more adapters.
I have adapters for most of my SLR bodies, so choosing a lens sometimes takes a long time!
Many will berate old Soligor lenses, I have found that that is just more drivel than fact. They are even quite reliable as far as QC goes, I have 3 135mm f:3,5 lenses, all spitting image and all deliver quality results, impossible to see any difference.
I'm not saying there ain't better lenses under the sun, but for handheld photography outside of a lab......
Also I find it slightly perverse, putting on a fairy modern zoom lens on a 60 year old camera body and snapping away, I recommed 3.rd party lenses as an adventure and a way to discover more thoroughly how photography WAS, back in the day, for instance getting to know how to manipulate and make pictures in a hurry with pre-set lenses, using a handheld exposure meter, and so on, is an eye-opener for anyone that grew up with autofocus, auto everything cameras and lenses!
The Firstflex had a leaf shutter, my Plusflex has a EXA I-type shutter, i.e. the mirror itself is the shutter, with all of 3 shutter speeds, B 60 and 125, an ADVANCED construction! :D:D:D
I offered it for a swap-deal to the australian that has a site that mentions them BTW, its an orphan in my house, and a dead end, but no response yet......
So, I've been poking around the lenses on that evil auction site, and I note some are for an Exakta RTL? The bayonet flange looks the same. What's the difference?
It's a Praktika body with Exacta bayonet, I think there's an aperture pin inside the lens mount. so while it accepts older lenses with the aperture lever over the shutter release the lenses for it will only be Manula aperture control on older Exacta's.
It's not such a nice funky, enigmatic camera as the Varex models (VX in the US)
You can use all Exakta lenses on a RTL 1000, but not vice versa, unless you are prepared to put up with a few difficulties - which is more or less the POINT of using one in the first place! :-) I've put film through mine, I would say it was a nice camera to work with, at least when it was new, but of course it was dated even back then compared to the Canon F1 I was using back in the early 1970's.......