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02-12-2017, 11:10 AM   #31
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QuoteOriginally posted by BarryE Quote
There's something in this argument. Standing next to busy roads, a cliff edge etc - all similar. But, with a prime you do seem to get tuned into a FL more astutely. This in turn lets you see the better near-by duck-in-the-rushes shot as you couldn't care about the distant bather on the other side of the pond - who ever they may be ;-) Kind of changes the approach. I remember once when I was set up to take some 2 second delay near shots on a tripod when a deer poked up in the mid-distance. I knew I couldn't capture the deer shot so just watched it - quietly. I remember the details of that incident much better from studying the animal than zoomed in and firing away. The missing stuff works both ways ...Tomorrow I've some spare time and I'll be going out with a zoom for a walkabout. I'll probably end up with dry feet, but I suspect I'll have more boring images with fuzzy edges to delete ...
That a good comment. You are right, anyway, if you miss a shot, it is only a postponed opportunity. Yes, sometimes, the camera get in the way of enjoying the moment.

02-12-2017, 11:46 AM   #32
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QuoteOriginally posted by biz-engineer Quote
Browsing in LensTip dot com, a while ago, I observed that primes usually can resolve >50 lpmm in the center, while zooms don't peak that high, usually around 40lpmm. Zoom have flattened responses versus aperture. A good hint that MTF response curves can be compared is that MTF of both primes and zooms join the same point once diffraction kicks in at f16, f22, then the difference between prime and zoom is negligible.
I think the best zooms, optically speaking, match up pretty well with primes. The DFA *70-200 really is at the least equivalent to the DA *200 and probably just a little better. The Sigma 18-35 f1.8 is, optically speaking, as good as most primes in its range (its issues were more auto focus related). But for this sort of performance, you need a pretty good sized lens and no more than a 3x zoom range.

For whatever reason, normal zooms (16-50 on APS-C and 24-70 on full frame) seem to be a weaker crop than some of the others out there and have quite a bit more distortion on the wide end and weaker corners in spots than primes with similar focal lengths.
02-12-2017, 11:53 AM   #33
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QuoteOriginally posted by Rondec Quote
For whatever reason, normal zooms (16-50 on APS-C and 24-70 on full frame) seem to be a weaker crop than some of the others out there and have quite a bit more distortion on the wide end and weaker corners in spots than primes with similar focal lengths.
I think those kind of zooms are design for being affordable, sold in higher volumes. No everyone gets a 18-35, the zooms ratio is 2x, it is heavy and expensive, as you point it out , in fact.
02-12-2017, 02:34 PM   #34
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"I completely understand when the artist tells me that all testing in the world doesn’t influence his choice of equipment at all.
I accept when he or she says a lens is perfect for them. That’s the bottom line.

So What Does It Mean?

For practical photography not much really, other than just to make you more aware of reality. Here are the few takeaway messages for photographers:

1. A great zoom is not as good as a good prime at comparable apertures, but it’s plenty good, especially in the center of the image.
2. Zooms have more variation, and most copies of a given zoom will vary at different focal lengths. "

End of quote from article.
------------------------------------------------------------------------
OK I'll take him at his word.
Last December I cleaned up and restructured my picture database of ten years or so. Among other things I created a folder where I put only the best of my best. By "best" I mean those images that I most valued for whatever reason - technical and/ or aesthetic but with an emphases on compelling content.

Results 117 files from a variety of glass but it must be said none of them over a retail price of about $500. or over 300mm..In other words none of my bird pics.
Without boring you with a lot of numbers the list was dominated by two lens' - the FA 35, and a close second the Sigma 18-250mm macro zoom.

Why? My opinion is because they are both versatile in their own way.
The FA 35 is fast, light, small, focuses close, inconspicuous,and sharp wide open. For available light indoor shots it gets the job done.
For daylight outdoor shots the Siggy comes into it's own.where you need the extra reach and while not small nor light it's manageable and optical performance is just fine for my purposes.

But considering these were my "best" shots what jumped out at me was that, within limits, pure raw bleeding edge optical performance was not a big factor in getting any of the shots on my "A list" but content and aesthetics was.

Final conclusion - so called "consumer grade" glass whether prime or not meets my normal focal length needs just fine.

02-12-2017, 02:36 PM   #35
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After reading this article (thanks for the link @hcc) I'm going to be much more circumspect in commenting on lens choices. One common example: prime + TC or tele-zoom. Beyond the difference in specs that are obvious on paper (e.g. weight/bulk, versatility and sometimes maximum aperture at a particular focal length), what can we conclude from looking at a few sample shots, particularly from just one copy of a lens, and at web res, or even from tests of one particular copy? I now see why people spend time looking at many many shots from different lenses to get a more general impression of the typical characteristics of a lens.

Last edited by Des; 02-12-2017 at 04:39 PM.
02-12-2017, 02:43 PM   #36
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QuoteOriginally posted by Kerrowdown Quote
I think I may well be considered as a tad bias...
You? Noooo... tell me it's not true.
For me, in APS-c my 18-135 covers what I'd buy a 24 prime and a 28 prime, and that's what I look for in a zoom. I want it to take the place of at least two primes, and be useful with caveats the rest of it's range. I actually find it more difficult buying primes, because if i don't like how it renders it's useless to me. Fact is, I'd rather put my 35-80 on my K-1 than my DA 35. I like how it renders. But at 50 mm, my favourite as my FA 50 macro. You have to like the lens. Zoom or prime is sort of a red herring.

Unfortunately for Kerrowdown, manual focus primes were for the most part terrible. With zooms, computer aided design and modern manufacturing process seems to be key. At this stage I'm not sure I would consider a design older than my DA* 60-250 which is a fantastic lens. I do own an F 70-210, but, the purple fringing makes me nervous. Summer use only. High contrast in the snow is a recipe for disaster although at times, I do get lucky.

The F 70-210 is 13 elements and represents a major effort to control CA using the technology of the day. These days, it's middle of the road or less. But sometimes as in the image below which has everything you need t provoke major CA or purple fringing, it gave me 20 nice clean images. When you're lucky, it's really good. Are you feeling lucky?


Last edited by normhead; 02-12-2017 at 02:56 PM.
02-12-2017, 02:45 PM   #37
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QuoteOriginally posted by normhead Quote
You? Noooo... tell me it's not true.
Not I... but others seem to think so.
02-12-2017, 03:00 PM   #38
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QuoteOriginally posted by Kerrowdown Quote
Not I... but others seem to think so.
Ya, what's wrong with those people?.

---------- Post added 02-12-17 at 05:02 PM ----------

QuoteOriginally posted by someone Quote
1. A great zoom is not as good as a good prime at comparable apertures, but it’s plenty good, especially in the center of the image.
Unless you miss the image because the prime you had on the camera isn't the FL you needed for the image that presented itself. Primes are an all or nothing gamble.

An image shot filling the frame with my 18-135 ( or DFA 28-105)at 105mm, is going to be better than any image shot with a 50mm prime then enlarged to be a 105mm FoV.


Last edited by normhead; 02-12-2017 at 03:16 PM.
02-12-2017, 03:15 PM   #39
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QuoteOriginally posted by normhead Quote
Unless you miss the image because
Not from my post.
02-12-2017, 03:16 PM   #40
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QuoteOriginally posted by normhead Quote
Primes are an all or nothing gamble.
That is exactly it. And when you get an "all" it is a 10/10 were the best a zoom can do is an 8/10.
I think another way - how much can I crop the image from my prime and have it still comparable to a zoom shot at a longer focal length?
Need a wider shot - well just stitch it and end up with an image vastly better than any zoom can do.
With the capabilities of modern sensors we should be thinking more and more this way.
02-12-2017, 03:17 PM   #41
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QuoteOriginally posted by wildman Quote
Not from my post.
Fixed.

\

---------- Post added 02-12-17 at 05:26 PM ----------

QuoteOriginally posted by GUB Quote
That is exactly it. And when you get an "all" it is a 10/10 were the best a zoom can do is an 8/10.
I think another way - how much can I crop the image from my prime and have it still comparable to a zoom shot at a longer focal length?
Need a wider shot - well just stitch it and end up with an image vastly better than any zoom can do.
With the capabilities of modern sensors we should be thinking more and more this way.
Except using a good zoom the difference is 9.8 instead of a 10. You vastly underestimate how good zooms are these days.

Two lenses close in cost both DA* lenses. On the left DA*60-250 on the right DA*200



The zoom has better resolution, the prime has better control of CA. One could argue in many images (without hazarding a guess on percentages) the DA*60-250 is going to give you the better image. It may be that a prime gives you a better image, but it's certainly not automatic. And sometimes the zoom is going to give you both more flexibility and a better image straight up.

This is complicated with Pentax in that there are very few modern FF primes, the DA*55 comes to mind as one of the few. And the numbers on lenses like the FA 24 and FA 28 don't even compare favourably with my much maligned 18-135 on APS-c.

If you have a lens as good as the DFA 28-105, I seriously question whether any lens I own apart from my FA 50 macro and 40XS but including my DA*35 2.4 and FA 50 1.7 are as good. That's about 50/50 when the prime is better than the zoom at least from my perspective. And if it's 50/50, is it really safe even thinking it? You have to go lens by lens, circumstance by circumstance, based on your experience. While "primes are better than zooms" might be a simple way to to try and make sense of a complicated process, in the end like all cliche's in the end it does more harm than good.

Last edited by normhead; 02-12-2017 at 03:43 PM.
02-12-2017, 04:56 PM   #42
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QuoteOriginally posted by normhead Quote
The zoom has better resolution, the prime has better control of CA. One could argue in many images (without hazarding a guess on percentages) the DA*60-250 is going to give you the better image. It may be that a prime gives you a better image, but it's certainly not automatic. And sometimes the zoom is going to give you both more flexibility and a better image straight up.
And, as you have said many times Norm, sometimes you need the prime for f2.8. Horses for courses.

Roger Cicala's point would be that the DA*60-250 is likely to have more variation between different copies and at different focal lengths. Photozone could test a different copy and get quite different numbers. (I won't mention the infamous 18-135 review.) But despite his generalizations about zooms v primes, he emphasizes that for practical purposes, the differences won't matter very much, if at all, most of the time: "Don’t get me wrong. Zooms don’t suck. They’re excellent and very practical lenses. If you knew all the compromises that go into making one, you’d be as amazed as I am that they can make them that good for those prices. Let me add that if forum warriors posted 800 or 1200 pixel-wide images online, you’d probably barely be able to tell the difference between the primes and zooms, much less the differences between the zooms."

In the comments below the article there is a link to this piece by Michael Reichmann from 2009, which is also worth reading: Sharp - Luminous Landscape
Reichmann emphasises that differences between lenses matters far less than the difference in skills and technique.

Last edited by Des; 02-12-2017 at 05:18 PM.
02-12-2017, 06:12 PM   #43
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QuoteOriginally posted by Des Quote
And, as you have said many times Norm, sometimes you need the prime for f2.8. Horses for courses.

Roger Cicala's point would be that the DA*60-250 is likely to have more variation between different copies and at different focal lengths. Photozone could test a different copy and get quite different numbers. (I won't mention the infamous 18-135 review.) But despite his generalizations about zooms v primes, he emphasizes that for practical purposes, the differences won't matter very much, if at all, most of the time: "Don’t get me wrong. Zooms don’t suck. They’re excellent and very practical lenses. If you knew all the compromises that go into making one, you’d be as amazed as I am that they can make them that good for those prices. Let me add that if forum warriors posted 800 or 1200 pixel-wide images online, you’d probably barely be able to tell the difference between the primes and zooms, much less the differences between the zooms."

In the comments below the article there is a link to this piece by Michael Reichmann from 2009, which is also worth reading: Sharp - Luminous Landscape
Reichmann emphasises that differences between lenses matters far less than the difference in skills and technique.
But regardless of Roger's point, we do know that with one copy of the DA* 60-250 and one copy of the DA* 200 the 60-250 was sharper. What the results would be if they tested 5 copies of each is another question, but we know at least one the DA* 60-250 came out on top. SO the DA* could win the shootout 4 to1, but the DA* 60-250 has the chance to win 5-0.

My problem with the 18-135 review was his analysis not his numbers. He took some kind of average and declared it to be a really bad lens. 1.5 stars out of 5. The Sigma 18-250 which I owned got 2.5 stars. We have not one Sigma 18-250 image that comes anywhere close to matching the 18-135 images in it's range. HIs analysis was complete nonsense. The higher rating should go to the camera capable of the best images, not some nonsense average edge to edge. IN many images edge sharpness is not important. Meanwhile the the 18-135 had excellent scores in more categories than the 16-50, any 18 to 200-300 type lens, and all of the older Pentax primes, all of which were rated higher, because he averaged in the borders at the long end, and selected lenses that couldn't match the 18-135 to rate higher. The centre wasn't as sharp, usually much lower, they were just plain average everywhere. Who wants that? So it was Klaus' total lack of understanding of what you needed in a lens to take a great image that was the issue. He looked at the numbers and said "lousy lens." I looked at the same numbers and said "great lens, I can use this". Klaus was one of the gatekeepers of the "edge to edge sharpness is the most important thing" club, and the philosophy that said shooting a brick wall was better than a lens that could show depth and have a 3d look. He's not alone in that. It seem to be the current thing. Well if you really want that, you can do a great job with a cell phone.

TO me, a lens that has Centre Sharpness at 135mm is all I need for more than half my images.

If the Klaus's view of the world is right, why do so many of us still love the rendering of the 77 ltd. and 31 ltd, and the DA18-135 shot at 24mm-28mm?
02-12-2017, 07:10 PM   #44
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QuoteOriginally posted by normhead Quote
If the Klaus's view of the world is right, why do so many of us still love the rendering of the 77 ltd. and 31 ltd, and the DA18-135 shot at 24mm-28mm?
You're preaching to the choir here. For example, I like the DA 35, I get reliable results with good resolution, but it's a bit clinical. I don't love it as I do the FA 43. For all its quirks, and fringing and so on, when it comes right it really comes right.
02-12-2017, 07:34 PM   #45
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QuoteOriginally posted by biz-engineer Quote
Yes, sometimes, the camera get in the way of enjoying the moment.
Very true. I will, now, often leave the camera at home just so I don't miss enjoying the moment.
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