165mm LS Clarification

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I know that the 90LS and 165 LS lenses are different and that the 90mm has a "U" and "S" option. One mode for flash and the other for special applications. I don't own either lens but was wondering if it is possible for the 165 to reduce shutter shake by setting the focal plane shutter to 1 sec and setting the lens to 1/125 or so? I had always thought this was possible. I would like responses from owners of the 165LS. SR

-- Steve Rasmussen (srasmuss@flash.net), January 02, 2001

Answers

Milton, you have given some good information here. I didn't realize Pentax had screwed up so badly on the 165 LS vs the 90 Takumar. I don't agree that the mirror dominates in the vibration department with this camera however. In my handheld work, I have had softness of images due to the shutter more than the mirror. This was proven out when I noticed that the left side of some slides were soft and not the middle or right side. This is a shutter induced anomaly. Vertical handheld shots with my 150 Takumar at 1/30 sec have mostly been tack sharp. Horizonals are not quite as good, but it is known that shutter shake is reduced when shooting vertical with this camera. My point is, that the 165LS should do OK even though the leaf shutter is activated right after the mirror moves up. The mirror shake should not be a big issue. Have you tried shooting with the focal plane at long exposures and the LS at short speeds with the 165LS handheld? How about the same situation on the tripod? What were the results?

-- Steve Rasmussen (srasmuss@flash.net), January 02, 2001.

"One mode for flash and the other for special applications"

This is not totally correct. Both modes have the same flash capabilities. The real difference is that the 90LS allows the leaf shutter to be tripped any time after tripping the camera's shutter or locking the mirror. This means that camera shutter vibration and mirror up vibration can be totally eliminated with the lens in the 'S' mode. It makes sense to use this mode in almost all tripod restricted shooting. If you dont believe me check the lens manual. Pentax flat out claims that "vibration reduction" is one of the advantages for this lens. As far as slow shutter speed, it is indeed possible to do what you say but this will not help you in terms of vibration. Remember that the leaf shutter fires almost immediately after the auto-aperture lever is activated (on the P67 this happens as soon as the mirror flips up and this is the reason the lens does not support mirror lock when using the leaf shutter). On the 160 LS as soon as you bring the mirror up the leaf shutter fires even if the camera shutter is not tripped yet (on the P67 auto-aperture lever will activate when either the camera's shutter is tripped or the mirror is locked). What this really means is that mirror lock is not possible at all with this lens (in leaf shutter mode) and hence you get the full mirror vibration effects when the leaf shutter is tripped (so the camera's shutter vibration really becomes irrelevant since the mirror vibration, as I'm sure we all agree, dominates). Setting a slow shutter speed on the camera does nothing to improve mirror vibration. Its a shame Pentax decided to neglect the functionality of the 90LS (I use the 90LS in the S setting probably 85% of the time, and this is probably why I think the images from this lens are so spectacular and make this lens very valuable). I believe they reasoned (for cost savings) that users of the 160 LS use the lens for handheld portraiture using high shutter speed and hence mirror lock is not practical and vibrations are not as much an issue due to the high shutter speeds and flash freeze. I also beleive they reasoned wrong since I only use my 160LS that way maybe 5% of the time so I think the lack of the independent leaf shutter trip severely limits the usefulness of the leaf shutter in this lens. Remember there was a reason Pentax (and other manufacturers) went to the trouble of adding an extra switch and cable release to their leaf shutter lenses. Once you start using these lenses you soon realize its importance. And how much could a simple switch and cable release socket add to the price of the lens? On the 90LS, to me, they are worth 10X their weight in gold, no...no, make that platinum. Coming to think of it Pentax should take the old 90LS tooling modify it to increase the focal length to 100mm and sell this lens as the "normal" lens and scrap the 105mm. This would ensure that every single P67 buyer would buy the "normal" lens and put it to maximum use and further increase the bang-for-the-buck the P67 system delivers.

-- M.BARROCAS (mbarroca@americasm01.nt.com), January 02, 2001.


For me using the leaf shutter handheld without mirror lockup has never provided any measurable improvement over using the camera's shutter without mirror lockup. Again I believe that hand steadiness and mirror vibration are the limiting factors when shooting handheld (I have a hard enough time preventing the camera from turning when the mirror flips up let alone vibration). I have never seen the 'left side' softness gremlin with any of my lenses (I shoot about 500 rolls a year and have a very fine enlarging lens and regularly enlarge to 20X24). I also regularly attempt to use mirror lock when shooting handheld (that's another peeve with the P67II, the MUP switch could not possibly be any harder to activate handheld, why couldn't pentax just add a push button next to the shutter release?). For the love of me I cant disagree with you more regarding getting more vibration from the shutter than the mirror. What vintage of camera do you have? Perhaps I should mention that I own a P67II. But results are results, for me the 90LS has consistently delivered the sharpest pictures ever since I started using the 'S' mode and I would not trade this lens for any other Pentax lens (well maybe the 800ED). A lot of times I use the lens for landscapes at 1/30 sacrificing the extra angle of view and DOF that I would get from my 55mm. The same cannot be said about the 160LS. I've owned this lens for about 2 years and regularly shoot with it but have never noticed any difference in sharpness when using the leaf shutter whether on tripod or handheld. Again I believe the leaf shutter produces less vibration than the camera's shutter but since I cant lock the mirror when using the leaf shutter I wind up shooting with the camera's shutter and ML whenever possible. So in my opinion the only advantage of the leaf shutter is the high flash sync which still makes this lens more valuable than the 160F2.8.

-- M.B. (mbarroca@americasm01.nt.com), January 04, 2001.

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