Bryan Posted August 16, 2015 Share Posted August 16, 2015 I have a Pentax M 200 mm f4 lens in very good condition, but I recently discovered that it's not able to focus to infinity - checked on NEX 6 with adapter and with a Pentax MX film camera body. I know that it should be possible to adjust the infinity focus, but I can't find anything useful on the Internet directly applicable to this lens. What I have found is that the lens body should and does screw apart to gain access to the focusing section, but Internet articles all refer to 3 small adjustment screws that my lens does not have. There is a good local camera technician who should be able to sort this out, and will probably get the work in due course, but I feel that it should be a reasonably easy DIY task. Anybody got any clues? Link to comment Share on other sites More sharing options...
spacecadet Posted August 16, 2015 Share Posted August 16, 2015 I'd check the mounting flange first although any wear or play there ought to be pretty obvious.Did it work OK when you got it? You probably remember this, but the racking action ought to stop sharply at infinity, as if it's come up against a stop, which it has. If it's a bit soft, maybe the rack is bunged up with old grease which has gone sticky and it can't quite get there. The screws are probably under the leatherette. BTW I have quite a poor record for dismantling lenses so be warned. Link to comment Share on other sites More sharing options...
Bryan Posted August 16, 2015 Author Share Posted August 16, 2015 Thanks for your response Mark. Many moons ago, when still using film, I can recall dropping this lens and having the bayonet mount replaced, but I very rarely use it and can't remember testing it or being aware of the problem until last week. The focus is smooth over the range and comes to a definite stop. It isn't reaching infinity on the focusing scale so there is a fundamental problem there somewhere. Sadly there is no leatherette to probe under, but there is a thick plastic sheath to provide a grip for focusing, it looks to be pretty well immovable without catastrophic consequences. Link to comment Share on other sites More sharing options...
spacecadet Posted August 16, 2015 Share Posted August 16, 2015 If the mount was replaced perhaps the flange focal depth wasn't checked, but if the scale doesn't go to infinity that does suggest something else. Maybe the barrel was knocked askew and never checked. Those lenses aren't all that pricey so it may not be worth your tech's fee. Too bad. Link to comment Share on other sites More sharing options...
Banet Posted August 25, 2015 Share Posted August 25, 2015 If you have problem with other Pentax lenses than you should buy another adapter. I had similar problem with M42->K mount adapter because some of them does not focus to infinity. If you have problem only with that lens try to put some thin spacer under the mount and check focus or replace the mount from another lens which is not functional anymore. M200/4 is full manual lens without electrical contacts and it will be very easy to do that. Link to comment Share on other sites More sharing options...
spacecadet Posted August 25, 2015 Share Posted August 25, 2015 If you have problem with other Pentax lenses than you should buy another adapter. I had similar problem with M42->K mount adapter because some of them does not focus to infinity. If you have problem only with that lens try to put some thin spacer under the mount and check focus or replace the mount from another lens which is not functional anymore. M200/4 is full manual lens without electrical contacts and it will be very easy to do that. The OP said that it wasn't down to the adapter because he tried it on an MX. Link to comment Share on other sites More sharing options...
Bryan Posted August 27, 2015 Author Share Posted August 27, 2015 You're quite right Jeff, and the lens does produce an almost acceptable image at infinity when stopped down, but I would be living in fear of the dreaded SOLD should I submit. I've since found a series of photos showing how to strip the lens down, and Mark was correct when he suggested that you need to peel back the rubber grip to access the screws. Looks a tad complex though, might still be visiting my local technician as this lens is in otherwise perfect condition. Link to comment Share on other sites More sharing options...
Bryan Posted September 24, 2015 Author Share Posted September 24, 2015 The ever reliable camera technician in Old Eldon Square, Newcastle, fixed the lens for £10.Given it a brief trial. It appears to be slightly sharper than the Sony 55 - 210 but rather prone to CA. The default LR CA fix is not strong enough medicine, but notching up the strength a bit provides a cure.I've also got an old Tamron 200 mm f3.5, which looks to be an interesting option. Rather more CA, but at least as sharp. Need to do some proper tests. Link to comment Share on other sites More sharing options...
John Mitchell Posted September 25, 2015 Share Posted September 25, 2015 The ever reliable camera technician in Old Eldon Square, Newcastle, fixed the lens for £10. Given it a brief trial. It appears to be slightly sharper than the Sony 55 - 210 but rather prone to CA. The default LR CA fix is not strong enough medecine, but notching up the strength a bit provides a cure. I've also got an old Tamron 200 mm f3.5, which looks to be an interesting option. Rather more CA, but at least as sharp. Need to do some proper tests. Don't you find those old MF telephotos cumbersome on the NEX-6? They are usually quite heavy. Even with a tripod, you would probably need a lens collar of some kind, or an adapter with a built-in tripod mount. Link to comment Share on other sites More sharing options...
Bryan Posted September 25, 2015 Author Share Posted September 25, 2015 Don't you find those old MF telephotos cumbersome on the NEX-6? They are usually quite heavy. Even with a tripod, you would probably need a lens collar of some kind, or an adapter with a built-in tripod mount. Certainly heavier than the Sony 55-210 John, but quite usable. The Pentax 200 mm is a compact lens, and, if a high enough shutter speed is selected, can be used hand held. After picking up the lens I took some shots with it around the city and uploaded a couple of them here. They both passed QC, but I subsequently noticed that there was excessive CA on one of them and deleted it before keywording! I'll attach a thumbnail when the remaining photo becomes live. I normally shoot aperture priority, but when using the 200 (300 FF equivalent) I fix the shutter speed and allow the ISO to drift to get a correct exposure. It's probably not worth buying one of these old telephotos as the improvement in IQ over the Sony zoom is not massive, and the zoom is much more convenient, but I guess that I like playing with these old, but beautifully made, photo tools. Link to comment Share on other sites More sharing options...
John Mitchell Posted September 25, 2015 Share Posted September 25, 2015 Don't you find those old MF telephotos cumbersome on the NEX-6? They are usually quite heavy. Even with a tripod, you would probably need a lens collar of some kind, or an adapter with a built-in tripod mount.Certainly heavier than the Sony 55-210 John, but quite usable. The Pentax 200 mm is a compact lens, and, if a high enough shutter speed is selected, can be used hand held. After picking up the lens I took some shots with it around the city and uploaded a couple of them here. They both passed QC, but I subsequently noticed that there was excessive CA on one of them and deleted it before keywording! I'll attach a thumbnail when the remaining photo becomes live. I normally shoot aperture priority, but when using the 200 (300 FF equivalent) I fix the shutter speed and allow the ISO to drift to get a correct exposure. It's probably not worth buying one of these old telephotos as the improvement in IQ over the Sony zoom is not massive, and the zoom is much more convenient, but I guess that I like playing with these old, but beautifully made, photo tools. Right. You no doubt know this already, but using the two-second timer while hand-holding long lenses with the small NEX cameras can minimize camera/shutter shake and result in more keepers. I too enjoy those lovely old lenses. Think I'll stick with shorter focal lengths, though. Link to comment Share on other sites More sharing options...
Bryan Posted September 25, 2015 Author Share Posted September 25, 2015 Right. You no doubt know this already, but using the two-second timer while hand-holding long lenses with the small NEX cameras can minimize camera/shutter shake and result in more keepers. I too enjoy those lovely old lenses. Think I'll stick with shorter focal lengths, though. Thanks for the tip, hadn't thought of that! Link to comment Share on other sites More sharing options...
John Mitchell Posted September 25, 2015 Share Posted September 25, 2015 Right. You no doubt know this already, but using the two-second timer while hand-holding long lenses with the small NEX cameras can minimize camera/shutter shake and result in more keepers. I too enjoy those lovely old lenses. Think I'll stick with shorter focal lengths, though. Thanks for the tip, hadn't thought of that! I used to do this sometimes with film cameras in low light. But ten seconds was a long time to wait. The two-second timer works a lot better. It seems to improve image stabilization with the Sony 55-210 as well if you keep the shutter release pressed during the wait. Not much use at the races, though. P.S. The ornate clock above certainly does look nice and sharp. Great shot. Link to comment Share on other sites More sharing options...
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