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04-20-2017, 02:47 PM   #1
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Lens performance on my K-1

Like many an old Pentaxian, I've got some old Pentax film and ASP-C lenses.

Lately I've been trying them on my K-1, checking out F stops, zoom settings...seeing how they work. Much to my surprise some of them do just fine. I've set the camera's crop setting at Full Frame.

So far, here's what I've found and I still have a quite a few left to test.

I have three Limited lenses, all ASP-C. My 21mm, no, not very usable, too much vignetting.

My 40 mm Limited, seems excellent throughout. My 70 mm Limited, has some vignetting...barely noticeable at F 2.4. Both 40 and 70 appear to be great lenses ...without any concerns for full use on the K-1.

One of my all time favourite lenses is my Pentax 12-24. Vignetting from 12 to 17....18 mm to 24 is fine. I wish I knew what 18mm---ASP-C converts to FF ? Seem quite wide. Very usable.

Still have my 10-17 Fisheye, which on my ASP-C bodies have ever only used 17 mm.

Left to test, my 55-300 (old version, bought June 2008 when it first came out), my 16-45, my Sigma 150-500 (don't want to get K-1 body scratched) and I think I'll continue to use my K-5 with it...much further reach with the ASP-C.

I recently dug out my Pentax M Macro F4, 50mm and my Takumar screwmount 135mm F 3.5. I also came across my Pentax screwmount to bayonet converter mount. Also have my Pentax 35-105 A Zoom Macro which should do just fine. Still have some others and I know my two AF 50's ...the normal 1.4 and macro 2.8 will do fine.

I know other Pentaxians have/ are doing the same thing as me. Wonder how your testing is going ?

04-20-2017, 03:44 PM   #2
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QuoteOriginally posted by lesmore49 Quote
I wish I knew what 18mm---ASP-C converts to FF


Focal length is the same. 18mm is 18mm on APS-C or FF. It is the angle of view which is different. 18mm on APS-C gives you roughly the same angle of view as 27mm on FF.
04-20-2017, 04:15 PM   #3
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QuoteOriginally posted by lesmore49 Quote
Left to test, my 55-300 (old version, bought June 2008 when it first came out), my 16-45, my Sigma 150-500 (don't want to get K-1 body scratched) and I think I'll continue to use my K-5 with it...much further reach with the ASP-C.
The "further reach" with the K5 aps-c is illusory. The K5 has a 16mp sensor. The K1 in crop mode uses a 15mp aps-c sized portion of the sensor. So whether you use the K1 in FF mode and crop the picture in pp, or use the K1 in crop mode, the images will be identical to using the same lens on the K5.
04-20-2017, 04:18 PM   #4
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QuoteOriginally posted by PJ1 Quote
Focal length is the same. 18mm is 18mm on APS-C or FF. It is the angle of view which is different. 18mm on APS-C gives you roughly the same angle of view as 27mm on FF.
And that FoV of 18mm on fullframe would be equal to about 12mm on APSC, so nothing lost there

04-20-2017, 04:25 PM   #5
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I tried the 21 but I knew what the result was going to be - black circle of doom, like staring through a porthole. It's worth it, though, if you want to use that black surround for a visual effect, or if you are prepared to crop in post to eke every little last bit out of the frame. Coming up from a K-5 I lose not enough MP to matter by using crop mode, and I gain the improved focus point density and AF control, better shake reduction, etc; I think I still win out overall.

My 70 HD Limited showed significant corner darkening at f/2.4 on a blank white wall test; I would have doubts using it unless the background were something that would hide that, or unless it was a portrait in which the darkening fed the eye towards the central subject anyway. I haven't tried the 40 yet.

I have an SMC Takumar 135/3.5 that I tried out over the weekend - I think you'll like what yours does.

I'm waiting for it to stop snowing here (which it is still doing intermittently) and warm up a little so I can get out and about with my older lenses safely.
04-20-2017, 04:36 PM   #6
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I also have many of those lenses. The 12-24 does work ok on the K-1 from 18-24. Edges are not great 18-20. The FoV is similar between 18 FF and 12 in crop. Edge correction is better using crop. Both the DA 40 and 70 are OK on the K-1 full frame. The DA 14 and 21 are useful crop only. I have both the 17-28 and 10-17 fisheye zooms. The 17-28 is perfect for the K-1. The 10-17 is OK from about 15 to 17. The 55-300 is really useful only with 1:1 crop and APS-C crop.
04-20-2017, 04:55 PM   #7
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@pschlute - The images will not be identical in all aspects, The K-1 sensor characteristics of noise, dynamic range, etc., are different from the K5 and thus cannot be identical.

04-20-2017, 05:42 PM   #8
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QuoteOriginally posted by PJ1 Quote
Focal length is the same. 18mm is 18mm on APS-C or FF. It is the angle of view which is different. 18mm on APS-C gives you roughly the same angle of view as 27mm on FF.
Thanks that's what I wanted to know...the field of view. One mm is not much more than my 28-105 FF lens, interesting to know.
04-20-2017, 05:47 PM   #9
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I have all the DA Limiteds, in SMC except the HD 70. I'm selling all of them except the 35/2.8 Macro + 40 Limited. I'm keeping the 40 partly because it doesn't fetch much money any more and partly because it seems to work well in FF crop. The 35 is the 35 - even in crop mode it's an awesome lens, but I think it works very well in FF.

I haven't tested my 55-300 yet - I have the same version as you - but I'll be interested to trade images and impressions. The idea of the selling is to buy a DA*300.
04-20-2017, 05:47 PM   #10
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QuoteOriginally posted by Pentax Syntax Quote
I also have many of those lenses. The 12-24 does work ok on the K-1 from 18-24. Edges are not great 18-20. The FoV is similar between 18 FF and 12 in crop. Edge correction is better using crop. Both the DA 40 and 70 are OK on the K-1 full frame. The DA 14 and 21 are useful crop only. I have both the 17-28 and 10-17 fisheye zooms. The 17-28 is perfect for the K-1. The 10-17 is OK from about 15 to 17. The 55-300 is really useful only with 1:1 crop and APS-C crop.
Good to know. I've for the most part only used the 10-17 FE @ 17. I'm not a real fan of novelty fisheye pix, but I do like the 'wide angle; perspective I get from 17 mm with this lens. I find I have to play around with it...until I get the right 'look'....but when I do ..it's great.

As far as edges go with the 12-24, I'm not too concerned as I usually crop out the edges, however I think I still will want a prime wide angle...such as a 14-15mm (full frame) field of view.
04-20-2017, 05:49 PM   #11
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QuoteOriginally posted by jbinpg Quote
@pschlute - The images will not be identical in all aspects, The K-1 sensor characteristics of noise, dynamic range, etc., are different from the K5 and thus cannot be identical.
You are correct but that was not the point of my post which was to point out that you do not get longer "reach" by using a lens on a K5 versus a K1.
04-20-2017, 05:50 PM   #12
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QuoteOriginally posted by pathdoc Quote
I tried the 21 but I knew what the result was going to be - black circle of doom, like staring through a porthole. It's worth it, though, if you want to use that black surround for a visual effect, or if you are prepared to crop in post to eke every little last bit out of the frame. Coming up from a K-5 I lose not enough MP to matter by using crop mode, and I gain the improved focus point density and AF control, better shake reduction, etc; I think I still win out overall.

My 70 HD Limited showed significant corner darkening at f/2.4 on a blank white wall test; I would have doubts using it unless the background were something that would hide that, or unless it was a portrait in which the darkening fed the eye towards the central subject anyway. I haven't tried the 40 yet.

I have an SMC Takumar 135/3.5 that I tried out over the weekend - I think you'll like what yours does.

I'm waiting for it to stop snowing here (which it is still doing intermittently) and warm up a little so I can get out and about with my older lenses safely.
Thanks for the input. Much appreciated. BTW my daughter lives in Newfoundland (your home base ?) and what a winter Newfoundlanders have had. Betcha Screech sales have gone up dramatically in that province this winter.

Les
04-20-2017, 06:12 PM   #13
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QuoteOriginally posted by lesmore49 Quote
Thanks that's what I wanted to know...the field of view. One mm is not much more than my 28-105 FF lens, interesting to know.
No. I think you have fundamentally misunderstood this. If your DA12-24 works on the K-1 from 18mm it is giving you a FULL FRAME 18mm field of view. So it is MUCH wider than the DFA28-105.

The image quality in the corners is another question. Of the crop lenses I have tested on the K-1, the DA35 macro covers the full frame at close focal distances, but the IQ falloff at the edges is dramatic. I consider it to be crop lens only. Likewise, the DA10-17 fisheye covers the full frame from about 14-15mm, but the IQ at the periphery is so poor you're better off shooting in crop mode at 10mm to get the same field of view.

DA15 and DA21 aren't within a bull's roar of covering FF, nor is the DA*50-135 (at any focal length). The DA55-300 comes pretty close longer than around 190mm, but I prefer crop mode because I only use it for reach and like having AF sensors all the way to the edge of the viewfinder frame.

The DA*55 is fantastic on FF. The IQ is superb, but stopped right down the hood does just creep into the extreme corners. As I generally use it at wider apertures it's rarely an issue, and a tiny crop eliminates it when it is.
04-20-2017, 06:22 PM   #14
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I had what was probably the original version of the Takumar 135mm f3.5, a preset lens used on my Asahi Pentax S. I thought at the time that it was very sharp, but what did I know of lenses back then?
04-20-2017, 07:23 PM   #15
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QuoteOriginally posted by lesmore49 Quote

I know other Pentaxians have/ are doing the same thing as me. Wonder how your testing is going ?
It's all pretty well known, Les. There were many threads, including the one started by Falco. Ricehigh, a Pentaxforums émigré, showed results in his blog, too.

As a result, before I bought a K-1 in April last year, I already knew which of my DA lenses worked and which didn't.

Your 55-300 will be fine at the long end, as is apparently the 16-45. I have happily been using the Sigma 150-500, but I did get it and my Sigma 35mm Art converted for free by the dealer here in Melbourne.

See here: DA lenses on Full Frame: Test Shots thread - PentaxForums.com
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