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05-19-2022, 01:36 PM   #16
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A lot of nonsense about measurable qualities above. Data about a lens and proper tests and reviews are very useful. It means you can look at samples with that information in mind. It means you'll find that issue that are deal breakers for you before you have purchased and used the lens for a month. Charts and tests aren't the be-all end-all but very useful *part* of assessing a lens you don't own. Real high level discussions about subjective qualities are also useful but it's rare to find people who can do it properly.

Normal user samples are close to useless because failed shots that reveal the stress points get culled and never displayed/uploaded. All you get is sweet spot photos. The post processing is often so damaging that you can't know what the camera/lens system produced and what has been mangled in post. Finally finding a user that use the camera in similar ways to yourself is time consuming.

The more tests and proper critical reviews the better. Overly positive and uncritical reviews and comments are completely unhelpful. Real information and qualified comments mean someone like myself can buy and use the FA50/1.4 wide open when a certain soft atmosphere is sought after.

05-19-2022, 01:36 PM - 1 Like   #17
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Then there is this kind of article:

Nikon's 'Worst' and 'Best' Zoom Lenses Compared | PetaPixel

It turns out a crappy lens can still make great images.

(And yes I parade this link often…)
05-19-2022, 01:45 PM   #18
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QuoteOriginally posted by UncleVanya Quote
Then there is this kind of article:

Nikon's 'Worst' and 'Best' Zoom Lenses Compared | PetaPixel

It turns out a crappy lens can still make great images.

(And yes I parade this link often…)
Everyone who has done a bit photography should know that you pay largely for the "shooting envelope". The worst possible lens will have images it's perfect for. Expensive lenses (and cameras) will handle more situations (except for things like shift lenses) and take more stress before the gear and the image falls apart. A f1.2 lens stops down to f22 a 20 fps camera can shoot singles etc.

Knowing exactly what you need and sticking to one style of photography can save a lot of money. Thing is to figure out what fit's that need tests that stress the lenses and charts that dissect performance are very helpful.

Last edited by house; 05-19-2022 at 01:54 PM.
05-19-2022, 01:49 PM   #19
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QuoteOriginally posted by house Quote
Everyone who has done a bit photography should know that you pay largely for the "shooting envelope". The worst possible lens will have images it's perfect for. Expensive lenses (and cameras) will handle more situations (except for things like shift lenses) and take more stress before the gear and the image falls apart. A f1.2 lens stops down to f22 a 20 fps camera can shoot singles etc.
Correct on all points. The specifics of fashion and glamour shooting for money is a high standard but it has things going for it - artificial lighting control with pro level strobes as an example. The point is that this photo found the delta was far narrower between the output of the lenses and the envelope was expanded but it wasn’t a massive benefit to his use cases.

05-19-2022, 01:53 PM - 2 Likes   #20
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If you want test charts and numbers that don’t really tell you much about a lens look at DXO Mark. They put a lot of numbers up but they don’t really tell you how a lens will perform.
05-19-2022, 02:00 PM   #21
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QuoteOriginally posted by KiloHotelphoto Quote
If you want test charts and numbers that don’t really tell you much about a lens look at DXO Mark. They put a lot of numbers up but they don’t really tell you how a lens will perform.
The latest Pentax lens measured by dxomark was released 2013, the oldest 1991. All tested on apsc cameras. There are also a lot of lenses at either side of those dates. So dxomak isn't very useful for a Pentaxian. Although it did explain why my DA15 was so soft at the edges, their "field map" sharpness chart is great.

Edit:
Just compared that atrocious software corrected RF 16mm lens with the DA15... both at f4 and the former is ff, priced about the same.
https://www.dxomark.com/Lenses/Canon/Canon-RF-16mm-F28-STM-mounted-on-Canon-...urements__1355
https://www.dxomark.com/Lenses/Pentax/Pentax-HD-DA-15mm-F4-ED-AL-Limited-mou...surements__830



Last edited by house; 05-19-2022 at 02:08 PM.
05-19-2022, 02:06 PM - 3 Likes   #22
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QuoteOriginally posted by house Quote
A lot of nonsense about measurable qualities above. Data about a lens and proper tests and reviews are very useful. It means you can look at samples with that information in mind. It means you'll find that issue that are deal breakers for you before you have purchased and used the lens for a month. Charts and tests aren't the be-all end-all but very useful *part* of assessing a lens you don't own. Real high level discussions about subjective qualities are also useful but it's rare to find people who can do it properly.

Normal user samples are close to useless because failed shots that reveal the stress points get culled and never displayed/uploaded. All you get is sweet spot photos. The post processing is often so damaging that you can't know what the camera/lens system produced and what has been mangled in post. Finally finding a user that use the camera in similar ways to yourself is time consuming.

The more tests and proper critical reviews the better. Overly positive and uncritical reviews and comments are completely unhelpful. Real information and qualified comments mean someone like myself can buy and use the FA50/1.4 wide open when a certain soft atmosphere is sought after.
With respect, that's pretty dismissive of fellow members' input, house... I don't believe anyone suggested data about a lens can't be useful; just that it may not be as important as some folks think. Again, it's subjective... You might consider what's been said to be nonsense, but that doesn't make it so. Those views are working out well for a good number of photographers here, whether-or-not you and/or I agree with them.

As I inferred in my previous post, if you know what you're looking for in test data... if and/or why it's truly important to your use-case(s) and/or personal preferences (rather than what's touted as important by review websites, or owners exercising bragging rights)... great. By all means, use that data. I suspect, however, a lot of folks these days are choosing lenses based largely on data rather than overall rendering (e.g. which lens is sharpest, edge-to-edge, at every aperture, with minimal aberrations) because that's what they see, hear or read being discussed as most important.

I own lenses that perform very well according to test data yet produce images I personally find quite soulless. I have other lenses that perform far-less-than-spectacularly according to the data, yet they render beautifully... And then I have lenses where the rendering is, more-or-less, as good or bad as the test-bench data. The point is, as you say, charts and tests aren't the be-all and end-all... far from it, actually. They can be very useful factors in one's assessment - but only if you understand how the data might be relevant to your specific use of the lens. The OP may indeed understand that... but many others certainly don't.

As a related aside, I own a plethora of vintage lenses - mostly from the former Soviet Union - for which I have no reliable test-bench data. The results from some are quite poor, others are generally useable, and some are absolutely stellar - but this is my own subjective assessment based on what I like and dislike in optical rendering, and my own range of use-cases. Your assessment and that of others may be entirely different. Test data wouldn't have told us that...

Out of curiosity, did test data tell you how the out-of-focus rendering of the FA50/1.4 varies in character from f/1.4 (where it's harsh and busy in detail transitions, despite the overall softness) to f/2.8 (where it's much smoother in those transitions)? No... I thought not...

QuoteOriginally posted by house Quote
The latest Pentax lens measured by dxomark was released 2013, the oldest 1991. All tested on apsc cameras. There are also a lot of lenses at either side of those dates. So dxomak isn't very useful for a Pentaxian. Although it did explain why my DA15 was so soft at the edges, their "field map" sharpness chart is great.
One of the problems with DxOMark's data is that it doesn't show the field map for various focus distances, or when off-centre focus points are used (it just shows the results for centre focus at a single test-chart distance). That can make a huge difference to results, and frequently renders knee-jerk conclusions from DxOMark's data utterly useless...

QuoteOriginally posted by house Quote
Just compared that atrocious software corrected RF 16mm lens with the DA15... both at f4 and the former is ff, priced about the same.
Yep, it's so often the case that you have to trade one set of compromises for another. Some (you, presumably) would prefer the flatter field from a software corrected Canon lens. Others prefer the less-flat-field but truly rectilinear, uncorrected performance from the Pentax lens. As always, you pays your money and takes your choice, based on your own personal preferences

Here's why, for many folks, the test data for the DA15 - and that field-curvature softness you noticed with it - doesn't matter, based on their personal preferences and use-cases:

The 15mm Limited controls my mind - club - PentaxForums.com

EDIT: I couldn't begin to tell you which lens - Canon 16mm or Pentax 15mm - is "test-bench" better than the other, as I haven't seen the data and I'm not especially interested in it...and in any case, which is truly "better" is subjective. I can only say that I personally prefer an instrument that performs - as much as possible - based on its inherent optical properties rather than those provided by software massaging (especially where primes are concerned), and I happen to quite like the DA15 (I'm not as passionate about it as some, but I do like it)... especially since it's compatible with the system I shoot, whereas the Canon lens is pretty irrelevant to me as a K-mount user, whatever its price (I'm sure the folks at CanonForums might disagree, and that's fine ). That's not a judgement, just a personal, subjective view...


Last edited by BigMackCam; 05-19-2022 at 11:53 PM.
05-19-2022, 03:27 PM - 3 Likes   #23
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Here are 3 tests by one individual on ephotozine done on the K-1
By looking at the tests alone can you tell
Which one is still available new at US$1000 + ?
Which one is 40 to fifty years old and is probably the cheapest and best "bang for buck" of any lens available on the 2nd hand market for a pittance ?
Which one is almost fifty years old and is sort out by enthusiasts for it's qualities wide open and achieves a premium on the 2nd hand market ?
My suggestion is to read the reviews here on PF, strain the "chaff" out and learn about the real qualities of the lenses.

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05-19-2022, 03:35 PM   #24
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One thing that I would be interested in knowing objectively would be about the new 50 and 85 star lenses. Are they engineered such that a new camera like a K-1 Mark 3 that raised the pixel resolution from 36 to 48 Mpixels, would have enough quality that you actually got more detail, and not just a larger image with no real increase in quality. Without any real lens measurements its not possible to know ahead of time.

This picture is definitely not anything to do with lenses, but shows the sort of graph that could be produced.

How much do we have to raise on KickStarter to pay for real lens tests for the website.
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Last edited by dkpentax; 05-19-2022 at 03:58 PM. Reason: adding an image
05-19-2022, 03:54 PM   #25
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QuoteOriginally posted by dkpentax Quote
How much do we have to raise on KickStarter to pay for real lens tests for the website.
We're all just members like you, so we have no inside info on that. If it's something you're personally interested in, you'd have to talk to @Adam (the site owner) about it. Frankly, I have my doubts as to how much support there'd be from other members... As per some of the replies you've received to your original post, many folks simply aren't that concerned with test-bench data... They're more interested in how a lens performs in the field, in relation to their own use-cases, preferences and expectations.

Still, you could start a survey post to see how many members would contribute to a Kickstarter project, and how much they'd be prepared to pay. That should tell you once and for all how much interest there is in the idea, at least in terms of currently active users... My guess would be, not a huge amount.

Whilst I have no objections to it, I've not yet seen formal test data for any lens that accurately predicted how much I would like or dislike it when applied to my own use-cases. I find real-world user opinions and photos taken with a lens to be more helpful - though as @house suggests, they may not reveal the worst (nor indeed the best) aspects of the lens. Ultimately, the only way I can know for sure is to use it myself and draw my own conclusions.

EDIT: If it's something you feel strongly about, you could volunteer to drive, research, plan and co-ordinate the reviewing effort and reviewers as a service to the community here? Lots of work, though...

Last edited by BigMackCam; 05-20-2022 at 12:00 AM.
05-19-2022, 04:16 PM   #26
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QuoteOriginally posted by dkpentax Quote
I see lots of lens reviews on the site, but why aren't there any real lens measurements for any lenses. im interested in how sharp lenses are, not vague pictures of test charts.

isn't it possible to determine the lines per inch that the full size K-1 and APS-C K-3 sensors can achieve, then measure every lens of some kind of lens bench, and determine the real resolving power at all the different combinations of aperture and position across the image plane.
I for one would hate that idea. To me and in my opinion it would be a complete waste of time to produce or read such information.

To me that kind of thing is completely clinical at best. That stuff has zero use for anything artistic at all.

Some people love those technical discussions but to me, beyond a certain point it doesn't contribute at all to any kind of creative process.

Some people really get wrapped up in the technology and technical stuff but me personally, I kind of dislike those things (to a degree).
05-19-2022, 04:51 PM   #27
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who has equipment to do these sorts of tests. you cant just test on a camera, as that by definition limits the results to the camera sensor's quality.
05-19-2022, 04:55 PM - 1 Like   #28
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QuoteOriginally posted by dkpentax Quote
who has equipment to do these sorts of tests. you cant just test on a camera, as that by definition limits the results to the camera sensor's quality.
Lensrentals.com - they professionally test lenses and could tell you the kit they use. They might even give you an idea of the time and cost to fully test and document results for typical prime and zoom lenses...

See the following for some idea of what's involved:

https://www.lensrentals.com/blog/2018/06/developing-a-rapid-mtf-test-for-pho...-video-lenses/

Last edited by BigMackCam; 05-19-2022 at 05:02 PM.
05-19-2022, 07:28 PM   #29
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I have shot a lot of 50mm over the last few years. I really liked the FA 50mm f1.4 despite it's low contrast and glowy highlights wide open. It rendered beautifully and for portraits was plenty sharp enough. I now shoot the DFA*50. It also renders beautifully and it is very sharp in comparison. It holds up well against the Canon RF and Nikon Z 50mm f1.2 lenses. Have you looked around for reviews not on this forum? The DFA*50 will do fine on a 50mp sensor. It does fine on the K3III and the pixel density there is higher than a 50mp FF sensor.

https://www.ephotozine.com/article/hd-pentax-d-fa-50mm-f-1-4-sdm-aw-lens-rev...31/performance
05-19-2022, 08:17 PM - 1 Like   #30
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I pose this as a question, as I do not know the answer :

Has not the "tech" changed in recent years from the physical attributes of lens and sensor to the software ability of Super Resolution ? If a new FF Pentax of 48MP "requires" a new D-FA STAR+ series of lenses to keep up with sensor, you are then talking of '000 of dollars more for both camera and especially lenses. Who but a few would be interested in that investment when the same results can be achieved with a couple of hundred dollars worth of software upgrade ?

There may be scientific reasons for wanting a lens to have greater resolving power, but it does not feature in my workflow. The maximum image I post online is a little over 3MP. When I print at 300ppi I can do so at 24"x16" with the K1 images without any up-sampling. I regularly print at this size even when using old legacy lenses, like the M series 85mm f2.0. Maybe a "bench test" will tell me that the lens is not up to the task of providing the K1's sensor with enough resolution, but my printed results tell me otherwise.
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