Hi Folks. I have the k10 and i'm trying to work out how my 35mm lens will work with this body. I have enabled the aperature in Settings. This enables me to use 'A' lens when the aperature ring is set to the 'A' mark. I have a prime 200mm lens with no 'A' setting. I have read a lot of literature but am still somewhat confused. Do I understand that with this 200mm lens I can use it but the aperature will remain wide open, this being f4.0 with this lens? Am I correct in understanding that the only way I can take successful shots is to adjust the speed in relation to the f4.0 setting bearing in mind the light conditions. I apologise for my dotage. This is all a big learning curve for me...regards Ron.