Originally posted by jaieger Hey, just wondering - do the Spotmatic or ESII allow you to remove lenses? The reason I ask is cause I've seen some good deals for a takumar 50mm/1.4 but they come with the aforementioned SLRs, and I've heard of cameras where the lens isn't interchangeable, and just wanted to make sure this wasn't the case before I went for it. Thanks!
Yes, both those cameras have interchangeable lenses. All Pentax film SLR's had interchangeable lenses. Those are both good cameras, as well.
Please note that both use the M42, or so-called Universal/Pentax/Mamiya/Praktica screw mount system. They are not k-mount bayonet lenses. They will work fine on Pentax dslrs, but will require an adapter. Search this forums for many discussions about the various adapters that are available.
Many people swear by the geniune Pentax mount adapter. It is still available from Pentax, but they are sometimes out of stock. They're on eBay frequently and will cost around $30.
There are third-party adapters that work with varying degrees of success. The ones to really watch out for are the ones with a large wide flange that sits outside the camera mount opening. This adds a mm or so and prevents infinity focus. The genuine Pentax adapter and the better clones, fit entirely within the camera's mount opening, and do allow infinity focus.
You must set your camera to allow the use of the aperture ring. Otherwise, the camera will refuse to do anything. There is a sticky thread in the beginners forum about this.
I use a 50mm, f/1.4 Super Takumar, with a Bower adapter on my K10D. It works very well in Av mode.
All Pentax brand screw-mount lenses and many third-party lenses have an auto/manual aperture switch. In auto mode, the aperture stays open until the camera pushes a little pin on the back of the lens, to stop it down for shooting. Dslrs do not have the mechanism to push that pin, so the lens stays wide open. That is where the auto/manual switch comes in handy. Put the lens in manual mode and the aperture will immediately stop down to the value selected on the aperture ring.
You must use a metering technique called "stop-down" metering. This simply means that the lens must actually close down (darkening the viewfinder) to meter the scene. In Av mode, you just stop the lens down to the desired aperture and the camera will pick the shutter speed.