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Forum: Pentax SLR Lens Discussion
01-22-2021, 02:38 PM
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Converted my SDM 300/4 to screw drive. The process is easy. The hard part is finding a K5 to do it with.
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Forum: Pentax SLR Lens Discussion
02-09-2019, 05:17 PM
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Just converted my DA 300 4 to screw drive using a K5 and PK Tether which I've used since 2011 or so (I did all the updates until Tomasz abandoned the project in 2012 at v 0.7.0).
The SDM did work just fine and I wanted to see how screw drive performed.
SDM focus is silent. Screw drive focus is noisier, as expected but I will stick with it. Love the lens.
Great instructions here; thanks.
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Forum: Pentax SLR Lens Discussion
02-08-2019, 01:10 PM
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I have noticed that the non SMC version of the Takumar 35 3.5 has no aperture "activation" arm at the back of the lens and just the "pin". The newer SMC version has both a pin and an aperture activaton arm.
Does the arm on the later version of this lens work in such a way in conjucntion with the "green button" on a K5, for example, to get a quick exposure reading as it would on a manual K series lens?
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Forum: Pentax SLR Lens Discussion
02-04-2019, 01:42 PM
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I just recieved, less than an hour ago, a K 28 3.5 for $61USD, all in, off of EBay. It is clean, snappy and, well, I can't believe how good the images are, even wide open.
Thank you again for your commentary.
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Forum: Pentax SLR Lens Discussion
02-03-2019, 11:37 AM
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I heard a documentary on the radio less than a year ago concerning human color perception. Remarkably, certain populations in eastern Europe were found to have insensivity to dark blues and purples (short wavelength end of the visible spectrum). This was discovered in relation to noticing that this group of people had no word that describes the color blue/purple in their language. As it turned out, none of these folks could see color in that range, thus the sky was just the sky and never described to have a color.
Frankly, the deep purplish cast described as a "Pentax" signature is mostly absent in my vision. I do see the sky as blue, though, but not harsh purples in the images described for certain Pentax lens images. That is what I call an innate corrective feature for purple or violet.
A link to the story can be found here:
https://www.businessinsider.com/what-is-blue-and-how-do-we-see-color-2015-2 |
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Forum: Pentax SLR Lens Discussion
02-02-2019, 07:03 AM
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Thank you so much for the comparison images.
I took a look at these in some detail and my impressions are:
1. The K 28 2 has the best bokeh wide open. The out of focus areas are smooth and not 'pixelated' in appearance.
2. The central sharpness at f11 is ~ the same across the board without disceranable differences (I have one eye that is at 15/20 still).
3. All showed chromatic aberrations (fringing) when wide open at the high contrast areas where the sea spray meets the land, however, the K 28 2 and K 28 3.5 have much less than the A a M lenses (the A seems to have the most fringing).
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Forum: Pentax SLR Lens Discussion
02-01-2019, 08:11 PM
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I'd love to see those shots of the M 28 f2 compared to those of the A 28 f2. Also, your review of the results would be much appreciated.
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Forum: Pentax SLR Lens Discussion
02-01-2019, 07:17 PM
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Yoshihiko Takinami's methodology is detailed here: http://www.takinami.com/yoshihiko/photo/lens_test/procedure.html .... and here : PDML Lens Testing Procedure . I take it his averages come from the process described in the first link where measurements are taken from many observations.
All I was looking for was a good landscape lens.
The K 28 f2, with its greater fall off would be ideal for central objectivity, as in a movies, with the surroundings "blurred" out. I read that the lens was designed with movie photography in mind, thus the "Hollywood 28" moniker often applied to it. Yes, the K 28 f2 is far more flexible in nature having great central sharpness and capabilites at all f stops superior to all others in the list. What I am intersted in is trying out is the M 28 f2, its successor.
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Forum: Pentax SLR Lens Discussion
02-01-2019, 06:11 PM
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This web page has good comparitive data on many Pentax lenses : Measured Resolution Numbers | The K-Mount Page
As stated on that page : Do not compare results from different testers!
I refer to the extensive tests by Yoshihiko Takinami and not those by Frederick Wasti.
In examining the resolution number and basing a ranking on their center to edge sharpness drop off and central sharpness, some observations can be made. The sole macro lens tested by Yoshihiko Takinami (FA 50 2.8) is way ahead of the rest of the field.
As far as variation from the center to the edge sharpness goes, good wide angle lenses for landscape photography would have high central sharpness with minimal drop off to their edges. With that in mind, my top five list for landscape photography, based on a spreadsheet analysis is:
1. FA 35 f2
2. K 28 f3.5
3. K 35 f3.5
4. K 30 f2.8
5. K 28 f2
Of course none of the resolution data takes into accont chromatic aberrations (fringing), distortion (pin cushion / barrel), vignetting nor bokeh. In that list, the K 28 f2 is the most expensive (and the heaviest). It was based on a Distagon design. The K 28 f3.5 had a differing optical configuration of its predecessor in using 8 elements in 7 groups (M42 Takumar SMC 28 f3.5 used 7 elements with 6 groups) and its successor (Pentax M SMC 28 f3.5 used 6 elements in 6 groups). The K 28 f3.5 center to edge variation in sharpness is relatively small with good central sharpness. Perhaps that is why it is considered a "cult" like lens.
As far as the Kiron 28 f2, I took a look at the 30xxxx series data since one was available recently. The lens (and associated ones) can be seen on this page : Great Vivitar 28mm Bestiary: Details. In the end, it seems to be a good performer too.
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Forum: Photo Critique
01-18-2019, 11:56 AM
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Don't know if this is the right spot for this. Does someone know of a way to colourize old photos such as this one?
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Forum: Lens Clubs
03-07-2016, 09:30 AM
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Forum: Pentax DSLR Discussion
02-16-2013, 07:23 AM
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I like PK Tether. Pentax has to do their own and allow users to be able to "re-program" our cameras to allow us to choose between screw drive or SDM auto-focus for lenses that have both (like the DA 300).
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Forum: Pentax SLR Lens Discussion
02-02-2013, 07:38 PM
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Forum: Pentax SLR Lens Discussion
01-25-2013, 03:57 PM
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The SMC Tak is the best if the bunch including the original 8 IMHO (I have owned them all at one time or another and three 8's at the same time). The coatings on the SMC make the lens work well in glare prone settings.
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Forum: Lens Clubs
01-19-2013, 09:48 AM
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Can you explain how the manual adjustment was accomplished? Thanks.
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Forum: Pentax DSLR Discussion
01-16-2013, 03:58 PM
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I have the KPS UMC on my K5. It has a rubber eye cup that cuts out stray light, magnifies by 30% and I do not wear glasses to take photographs. I cannot comment on the others but I do like the KPS.
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Forum: Pentax SLR Lens Discussion
01-16-2013, 03:10 PM
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Forum: Pentax SLR Lens Discussion
01-16-2013, 03:00 PM
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Pentax does not make the 1.2 anymore so once you have one, someone else does not and you are ahead of the game.
If you can see a difference with your eye, then it is meaningful and you can with the 1.2 vs any 1.4. If you need a machine to detect the difference then it is marginal and meaningless to people. It its like loudness; humans cannot detect an increase/decrease in sound amplitude of 2dB but can if it is 3db.
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Forum: Pentax Camera and Field Accessories
12-29-2012, 07:17 PM
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I used the UMC on my KX and now it is on my K5. It works perfectly for both.
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Forum: Pentax SLR Lens Discussion
12-27-2012, 06:45 PM
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I jumped all over it because the price was right. Manufacturer's full retail is about $200 over what it should be. It works very well on a K5.I have had Super Tak 8 elements (four of them), a non SMC 7 element (very yellow), M and A series 50 1.4's as well as the A 50 macro 2.8. The M and A's were sharper than the Taks. The best 8 element version was later in the series (a 157...... serial number) but the 7 element one worked better than any ofl the 8's. The DA is as sharp (if not sharper) than the best of the previous group, focuses for you, has a quick shift feature for self adjusted focusing, has a hood that increases contrast and is very flare resistant and weather resistant. The focal length of 55 is, IMHO, more usable than the 77 ltd for indoor work.
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Forum: Pentax DSLR Discussion
12-27-2012, 03:36 PM
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Speaking of magnifiers, I forgot to mention that I use the KPS UMC vareity (I took it off my KX and put it on the K5) and it works great. Likely it helps me from gouging my face with my thumb.
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Forum: Pentax DSLR Discussion
12-27-2012, 03:12 PM
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I now use my left eye having given up on my right a while back and also have just switched to the K5 from a KX. One of the first things I looked for was the green button when I used one of my manual lenses. I actually like it better being on the back and not on top (and I can scratch my nose with my right thumb at the same time!).
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Forum: Pentax SLR Lens Discussion
12-25-2012, 07:23 AM
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Use a lens cap instead. Don't forget to remove it for you shots!
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Forum: Lens Clubs
12-25-2012, 06:53 AM
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