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09-11-2019, 05:16 PM   #1
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How to use manual zoom lenses on K1

Hi, I am new to the forum. I have sold my canon SLR and DSLR systems and I am currently using 5 Pentax SLRs with a whole bunch of Pentax manual lenses. This is a love affair with Pentax ! I am also expecting a K1 from the ebay. As I've watched in Youtube and have seen in this forum, it seems that in order to use a manual lens on a K1 camera, I have to specify the focal length with the help of the menu. What do I do if I want to use a manual zoom lens? I have read some replies to the question, but it seems to me that if the problem is the shake reduction, either you don't care about it -especially if you are using a tripod- or you set the maximum value in order to be at the safe side. Am I right or wrong ?


Last edited by soharl; 09-11-2019 at 05:40 PM.
09-11-2019, 05:29 PM   #2
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QuoteOriginally posted by soharl Quote
Do I have to read on the lens -every time- the focal length and let the camera know? Is there an easier way to do the job?
Each time you turn the camera on with a manual lens attached it will ask for the FL. This is for SR system

You do not need to get too obsessive over giving the correct number. If you are using say a 70-150 zoom and expect to use it mostly at 100mm, then tell the camera 100 mm, The SR will only kick in when using a slow shutter speed, so keep the speed up and it wont matter what you input. If you expect to use all ranges of a zoom then tell the camera the shortest FL. This is because using a longer FL setting than what you actually use on the lens can lead to the camera over-correcting the SR and actually adding blur to the image. Using a shorter FL setting than what you use on the lens cannot add blur to the image, but may not correct the hand-holding induced blur enough.
09-11-2019, 05:33 PM   #3
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When you put the lens on the camera and turn it on it will ask you to put the focal length in, for reason of shake reduction. As far as a zoom there are different ideas, select something close to what you my be shooting the most, if you want to get more specific on each shot, turn the camera off, then back on and it will ask you.
09-11-2019, 05:52 PM   #4
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I normally set my focal length as the midpoint of the focal range of the lens, if I think I might use the full zoom range. Ex: 28-105mm I set at 70 (105-28/2 + 28 = 66) Otherwise, I set it at the focal length I plan on using that outing. That's my routine, others may do it differently.

09-11-2019, 06:56 PM   #5
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How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc) - PentaxForums.com
09-12-2019, 07:10 AM   #6
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See the post:
Using manual legacy Pentax zoom KA lenses and shake reduction with K1 - PentaxForums.com
09-12-2019, 07:23 AM - 1 Like   #7
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QuoteOriginally posted by soharl Quote
Hi, I am new to the forum. I have sold my canon SLR and DSLR systems and I am currently using 5 Pentax SLRs with a whole bunch of Pentax manual lenses. This is a love affair with Pentax ! I am also expecting a K1 from the ebay. As I've watched in Youtube and have seen in this forum, it seems that in order to use a manual lens on a K1 camera, I have to specify the focal length with the help of the menu. What do I do if I want to use a manual zoom lens? I have read some replies to the question, but it seems to me that if the problem is the shake reduction, either you don't care about it -especially if you are using a tripod- or you set the maximum value in order to be at the safe side. Am I right or wrong ?
Actually, the maximum is not "safe" at all because the SR system will over-correct when you shoot at focal lengths less than the SR setting. The amount of over-correction won't be a problem unless the focal length you shoot at is less than 1/2 the focal length you entered into the SR.

For a 28-105 zoom, a setting of 56 mm will correct about half the shake at the 105 mm end, all of the shake at 56 mm, but none of the shake at 28 because of overcorrection effects. (With SR set to 56 mm and the lens set to 28, if you twitch 10 pixels to the right, the SR system will correct by 20 pixels to the left and leave a net 10 pixel shake.) Of course shake usually isn't a problem at 28 so the lack fo correction is probably OK.

The "safe" strategy is to set focal length to no more than twice the minimum focal length to prevent making the shortest focal lengths worse than if the SR system was off. Of course if you have a super-zoom like a 28-200, then a setting of 56 barely corrects any shake at the 200 end.

What I usually do with manual zooms is start framing the picture with the camera off, look at the kind of focal length I'm planning to use, then turn the camera on and then enter that number. Usually, it's pretty obvious whether the shot calls for the wide, middle, or tele end of the zoom range so it's not hard to guess a good value for the SR system on a shot by shot basis.
09-13-2019, 01:44 AM - 1 Like   #8
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Note that you can assign the focal length setting as a tile on the info panel, for quick changes.

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