I have three versions of the f/3.5 lens, an f/4 and an f/4.5. The f/3.5s are an Auto Rokkor, an MC Rokkor (2nd version-aperture ring at the rear of the lens) and an MC Rokkor-X. My f/4.5 is an MC Rokkor and the f/4 is an MD. I have done very little witrh the Auto Rokkor. The MC Rokkor is excellent and the MC Rokkor-X is also excellent and better coated. The f/4.5 is a decent lens if you are shooting in bright light. The f/4 follows the trend of other manufacturers. Konica made a 200/3.5 and later replaced is with a smaller f/4. Asahi did this years earlier. There was a 200/3.5 pre-set Takumar and later the 200/4 Super Takumar. If I remember my weights the 200/4 is actually lighter than the older 200/4.5. The 200/4 is a good lens and my 200/4 MC and MD Celtic lenses seem to be identical to it. My favorite is the 200/3.5 MC Rokkor-X and I think it's the sharpest of the bunch. The 200/4 would be next and the 200/4.5 not far behind. There was at least one Celtic version of the f/4.5 lens. I especially like using the f/3.5 wide open with a 360PX flash and 800 speed film. The range is very good. I have never used the 200/2.8 MD but one of my 200/3 Vivitar Series 1 lenses is in M42 mount so I can use it on a Minolta with an adapter. I think the Panagor 200/3.5 which was mentioned is the same as the 200/3.5 Vivitar Fixed Mount.