amul Posted October 4, 2005 Share Posted October 4, 2005 Dammit, why is it that I can program a VCR and calculate IR exposures accurately, but I CANNOT figure out which lenses go with my cameras? <p>I have an *ist DS, a ZX-5n, and an MX. According to <a href="http: //kmp.bdimitrov.de/">KMP's Pentax Guide</a>, (which has sadly not been updated for digital), that means that means I can use all the lenses, and I want to buy lenses marked SMC-FA ? So what's an SMCP-FA? Is that good for digital? What happens if I stick my old SMCx-XX's onto my digital? Link to comment Share on other sites More sharing options...
del_gray Posted October 4, 2005 Share Posted October 4, 2005 Amul, it can be real confusing, but it helps if you think in broad categories. The FA and F lenses are both auto-focus and auto-exposure lenses(they have an "A" setting on the aperture ring that lets you control the aperture from the body and then the lens will stop down just as you push the shutter release). The A lenses are also auto-exposure, but they are manual focus. The K lenses and manual focus and manual aperture (you manually set the ring to the desired aperture). The old screwmounts can also work, but they need an adaptor. SMC refers to the wonderful Pentax coating on the glass to cut down flare. Digital body or not has nothing to do with lens compatibility, it's basically whether the body is autofocus and/or autoexposure that matters. So, go ahead and use any of those previous lenses on your *ist DS - they work great, especially the A, F, and FA lenses (the older K lenses work fine, but they require you to push an extra button to meter - but see the many other threads on this issue). Link to comment Share on other sites More sharing options...
mawz Posted October 6, 2005 Share Posted October 6, 2005 The digital bodies work fully with all lenses from KA (SMC-A, Takumar-A) on. These lenses all have an A position on the Aperture ring, or lack an Aperture Ring (DA and FA-J lenses lack the aperture ring and are permanently set to 'A'). All these lenses must be set to A to work correctly Older lenses (SMC, SMC-M, Takumar-M as well as any lens with an adaptor) will work three ways on a DSLR, provided that you set the Custom Function which allows Shutter Release with lens set to Other than A. With these lenses, you can shoot wide-open in Aperture Priority (Setting the camera to P, TV or any Program modes will default to Av), but the camera will not stop the lens down. If using a lens with an adaptor (M42, 645 or 67 lenses) the lens will stop down as you adjust the aperture ring, so you will get full aperture priority. The next two options only work in M mode. You can adjust the aperture then press the AE-L Button (Green Button on the *istD) and the camera will stop down, meter and then set the appropriate Shutter Speed, or you can use the DoF preview to stop down and you will get a metering readout, which you can then adjust. Link to comment Share on other sites More sharing options...
amul Posted October 6, 2005 Author Share Posted October 6, 2005 Adam, <p>Thanks for that explanation, but I am familiar with how to operate in those modes. (Although the subtle difference between auto-Av and manual-Av was new to me). My question, though, is about the specific differences between types of lenses. <p>For instance, this thread has already explained that: <ul><li>FA, F = auto-focus, auto-aperture with option to switch to manual aperture adjustment. </li><li>A = auto-aperture, manual focus (which apparently = KA) </li><li>K = manual focus, manual aperture </li><li>DA, FA-J = fully auto, no option for manual </li><li>screwmounts are completely manual </li><li>SMC, I already knew, although I am still wondering what SMCP is. </li></ul> <p>To put it another way, I'm still trying to understand how to look at a webpage on, say, B&H, and figure out what options the lens offers. To put it yet another way, I am trying to figure out which lenses will be compatible with all three body types (the fully manual MX, the full-auto ZX-5N, and the DSLR). Clearly, DA and FA-J lenses should be avoided in this situation. The designations given by Pentax seem different than the ones used when talking about them (eg, FA versus KA). But still there are questions: What's the difference between F, FA, and FA-J? What do these letters STAND for? The Pentax sight does not seem to offer any insight, or if it does, I cannot find it. <p>I've been told that the DA lenses are "specifically designed" for the smaller DSLR sensor plate. Is there some image quality issue that will arise from using pre-digital lenses on DSLRs? Link to comment Share on other sites More sharing options...
david_white13 Posted October 6, 2005 Share Posted October 6, 2005 Keep it up Amul, we're all learning! Link to comment Share on other sites More sharing options...
james_king9 Posted October 8, 2005 Share Posted October 8, 2005 Amul asked: "But still there are questions: What's the difference between F, FA, and FA-J? What do these letters STAND for? The Pentax sight does not seem to offer any insight, or if it does, I cannot find it. "I've been told that the DA lenses are "specifically designed" for the smaller DSLR sensor plate. Is there some image quality issue that will arise from using pre-digital lenses on DSLRs?" Here is a short description of the various Pentax K-mount lens families: - The first generation of K-mount manual focus lenses (pre-M type) didn't really have an official identifying letter but are usually referred to as "K" lenses. - "M" lenses are a later more compact manual focus design than "K" lenses; They were designed to complement the Pentax M series bodies - "A" lenses are a still later manual focus design offering optional aperture control by the body and the first with electrical contacts to transmit information from the lens to the body. - "F" lenses are Pentax's first generation of autofocus lenses. They offer optional aperture control by the body as well. - "FA" lenses are the second generation of autofocus lenses; in addition to providing autofocus and optional aperture control by the body they transmit additional information to the camera body such as the maximum aperture of that specific lens for optimum MTF. - "FA-J" lenses are low-cost third generation autofocus consumer zooms without an aperture ring; the aperture is only controllable by the body, usually in autoexposure mode. Not all Pentax bodies have the necessary controls to allow the user to control the aperture. - "D-FA" lenses are the fourth generation of full frame autofocus lenses; they are supposedly optimized to work well with both digital and 35mm film bodies. Unlike the FA-J lenses the D-FA lenses have an aperture ring like the FA lenses, so the aperture can be controlled either using the ring or from the body. - "D" lenses are the first generation of Pentax lenses designed to cover the smaller 18x24mm digital APS image format only. Because of this they can be made smaller and lighter than lenses designed to cover the larger 35mm format, but they will usually vignette the image (yield dark corners) if used on a 35mm SLR because the image circle they project is too small to cover the full frame 24x26mm image. They do not have an aperture ring so aperture can only be contolled by the body. All Pentax digital bodies offer this control. I hope that this summary answers your questions. If you would like to know more, I recommend that you go to Bojidar Dimitrov's Pentax K-Mount Page at <http:// kmp.bdimitrov.de/> for a full description of all Pentax K-mount bodies and lenses. Regards, Jim Link to comment Share on other sites More sharing options...
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