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11-26-2015, 10:08 AM   #16
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QuoteOriginally posted by Rondec Quote
Interesting collection of data. I think there may be an error under the DA 560 where there is data listed for f4 and above, but I believe it is an f5.6 lens?

DA *200 seems odd to me. My experience was that it got to excellent at f4, but data shows a very narrow window where it has excellent performance.

Thanks for sharing this.
Thanks for the feedback. I'll sort out the DA 560 entry - well spotted (not a lens I own, sadly !!!). I'll also see what else I can find on the DA*200. In some cases, the analysis data from the websites was quite different - the FA43 being a case in point - which leads me to think sample variation could be at play. Where there was no obvious correlation, I picked one set of data and went with that as a starting point. Hence, feedback like this is very useful as I can compare what you're saying with available data.

---------- Post added 11-26-2015 at 05:11 PM ----------

QuoteOriginally posted by pathdoc Quote
I know there are charts for much older lenses (M, A, even K), but they are given in terms of lp/mm, with the best topping out around 100. How does this translate to lw/ph, or is there no reasonable comparison?
Yes, I noticed that when I was browsing some of the older lens reviews. Honestly, I don't know how it translates - but, so long as I can get sufficient data together, there's no reason I can't extend this to the older lenses. Again, it's not a relative comparison of lenses, but a set of individual profiles showing where the lenses are reputed to perform at their best - so it's still relevant to act on that older data, even if modern sensors might show better resolutions at peak performance...

11-26-2015, 10:12 AM   #17
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Very good work. As a consumer/hobbyist, I don't necessarily shoot all the time and can forget some of these simple tips but this is very helpful as a simple reminder. Much like a ballistics chart for one of my rifles, I usually can remember some basics but I usually have a chart taped to the stock just so I don't have to go on memory alone.

Might I suggest making this a document perhaps on Google docs? You don't have to let others edit it per se but it would be nice to have it in document form. That way, as it is updated, the document is still live. This would also allow people to download it and manipulate the content for their specific kit. I could easily create a "cheat" card for the lenses in my kit.
11-26-2015, 10:15 AM   #18
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QuoteOriginally posted by fwcetus Quote
Thank you very much for your work. I am impressed with what you have so far, and I think you have handled the variables involved the best you can.

However, one question (or actually two questions) that I have -

1. Are the results shown from FF, cropped, or both formats?

2. How are you handling the difference (primarily in the "Border" data) between FF and cropped sensors?
You're welcome - and thanks for the feedback

The results are from crop sensor, as far as I'm aware (some sites mention only the sensor resolution, others mention the specific camera used, and in the latter cases it was always a Pentax DSLR - hence APS-C). It's a good point - the performance on the up-coming Pentax FF may vary.

---------- Post added 11-26-2015 at 05:19 PM ----------

QuoteOriginally posted by colonel00 Quote
Very good work. As a consumer/hobbyist, I don't necessarily shoot all the time and can forget some of these simple tips but this is very helpful as a simple reminder. Much like a ballistics chart for one of my rifles, I usually can remember some basics but I usually have a chart taped to the stock just so I don't have to go on memory alone.

Might I suggest making this a document perhaps on Google docs? You don't have to let others edit it per se but it would be nice to have it in document form. That way, as it is updated, the document is still live. This would also allow people to download it and manipulate the content for their specific kit. I could easily create a "cheat" card for the lenses in my kit.
Thanks for the feedback. In fact, the main reason I started out on this was to have a cheat sheet for the lenses I use less frequently.

I'll look into the Google docs idea. Some means of providing a permanent document is certainly a good move. I could also extend the spreadsheet to allow lenses to be selected / de-selected from a visible list... thinking ahead here. Anyway, it'll be a couple of days before I do any more work on this, but I do intend to grow and refine it further.
11-26-2015, 10:24 AM   #19
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QuoteOriginally posted by BigMackCam Quote
it's still relevant to act on that older data, even if modern sensors might show better resolutions at peak performance...
I should expect that the older lenses would maintain their positions relative to each other as far as peak performance was concerned, especially on a full-frame sensor (whether the K-1 when released or other platforms with adapters until that time). There might be some rank-order changes for lenses that performed very well in the centre and not so well in the edges if tested on an APS-C sensor, since that would eliminate the worst-performing areas. Those that performed well across the field would not see so much of a benefit.

11-26-2015, 10:36 AM   #20
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Very useful collection of data. Thank You very much!
11-26-2015, 11:09 AM   #21
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This is excellent!!!! ... and a lot of work! The suggestion about Google Documents is an excellent idea. Having it linked or available somewhere on the Pentax Lens Database area would be extremely useful.

11-26-2015, 11:11 AM   #22
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BigMackCam, if you have the original Excel document you could email me it and I could put it on Google Docs for you.
11-26-2015, 11:13 AM   #23
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QuoteOriginally posted by bertwert Quote
BigMackCam, if you have the original Excel document you could email me it and I could put it on Google Docs for you.
Thanks - I may well take you up on that. I want to do a little more work to it first, and it will need some prep before I can roll it out as a public document. I'll get back to you, if I may?

11-26-2015, 11:14 AM   #24
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QuoteOriginally posted by BigMackCam Quote
Thanks - I may well take you up on that. I want to do a little more work to it first, and it will need some prep before I can roll it out as a public document. I'll get back to you, if I may?
Sure I'll PM you my email address.
11-26-2015, 10:44 PM   #25
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Thanks! I would concur with the results you've collected with the lenses I have:
DA 21, DA 35 f2.4, DA 50 f1.8, DA(L) 18-55, and DA(L) 55-300.
Only one lens where I have significantly different results, namely the DA 18-135 where I use f5.6>8 at wide end and f8-11 at long end and have quite good results on the long end.
I suspect that there is always the matters of lens quality control and lens/camera interaction. (I use a K-30).
Thanks again!
11-26-2015, 11:53 PM   #26
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QuoteOriginally posted by mgvh Quote
Thanks! I would concur with the results you've collected with the lenses I have:
DA 21, DA 35 f2.4, DA 50 f1.8, DA(L) 18-55, and DA(L) 55-300.
Only one lens where I have significantly different results, namely the DA 18-135 where I use f5.6>8 at wide end and f8-11 at long end and have quite good results on the long end.
I suspect that there is always the matters of lens quality control and lens/camera interaction. (I use a K-30).
Thanks again!
Thanks for the feedback Re the DA18-135, at the wide end, f/5.6 - f/8 is about right for peak performance. At the long end, f/8 is slap bang in the middle between best center and edge sharpness. So that makes sense based on the data. Then, as you say, there's sample variation and lens-to-camera matching.

I also have an example of a lens that out-performs the review data - my DA20-40. It's very useable at wider apertures and - to me, at least - pretty sharp across the frame (although it does peak between f/5.6 and f/8 per the data). Then again, I haven't pixel-peeped it for a while - its just that the perception I get of its images is one of clarity and sharpness...
11-28-2015, 04:05 AM   #27
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Shows how good that hd 16-85mm is. Blows away the new nikon dx lens in every aspect other than aperture
11-28-2015, 04:07 AM   #28
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QuoteOriginally posted by y0chang Quote
Shows how good that hd 16-85mm is. Blows away the new nikon dx lens in every aspect other than aperture
Yes indeed. Unfortunately, I've had two with problems (one of which was de-centered) and now awaiting either a replacement or refund. If I get the refund, I'm not sure I want to risk a third...
12-23-2015, 01:09 PM   #29
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Just bumping this up again. If you would like some help with the database and converting it to an online resource, I should have a bit of spare time over the holidays.
12-24-2015, 02:08 PM - 1 Like   #30
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QuoteOriginally posted by colonel00 Quote
Just bumping this up again. If you would like some help with the database and converting it to an online resource, I should have a bit of spare time over the holidays.
Thanks for the offer. After Christmas, I should get a chance to update the spreadsheet with a whole bunch of additional zoom lenses, and some filtering functionality. I also took the plunge and registered a Google account so I believe this gives me the capability to to store it online and allow access to it. Will keep this thread posted...
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