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Forum: Pentax DSLR Discussion
11-16-2018, 08:24 AM
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If you lived within 50 miles I probably be driving over for a DFA 28-105 FA 28-105 comparison test. You probably already have the lens you'd need. All I could find was a 28-200, and it's terrible lens. Sill good for 4k TV images though. It's amazing how much can be hidden reducing the size of an image.
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Forum: Pentax DSLR Discussion
11-15-2018, 02:04 PM
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The didn't work for me, but I guess it might work for you. For me the K-1 wasn't functional until I broke down and bought the 28-105/. My style has always been have walk around lens but have somthing to change to.
Before I got my K-1 I had the FA 35-80, F 70-210, FA 50 1.7, DA 35 @.4, Sigma 70 macro, DA*60-250, DA* 200 FA-J 18-35, 40 XS, DFA 100 macro - Tamron 90 macro, FA 50 macro,Tamron 300 2.8.and a number of SMC super taks, it didn't make any difference, I wasn't happy until I got the 28-105. Then it seemed like a workable system. I held out for bit because the 28-105 wasn't 24 -105, but I got over it. :D
I was convinced I'd be fine without the 28-105, but experience said different.
If you are like me. Everything strats from a walk around lens. I take that, and whatever else I think I might need that day.
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Forum: Pentax DSLR Discussion
11-15-2018, 06:51 AM
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But you know it when you see it. :D
My wife and I are the same. We know when she takes out the 28-105 and K1 we like the images better, on the whole, but we don't know exactly why. It's difference not based on any metrics we've been able to come up with. A lot of the time we can't even define which picture it is that makes us feel that way. It seems to be some kind of composite, you come home, you process and look at all your images. At the end, on average, the K-1 images are likely to be more satisfying. How do you quantify that?
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Forum: Pentax DSLR Discussion
11-12-2018, 08:29 PM
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It's really hard to document,ent that but every FF user knows its true. You get a few images you know wouldn't have been as good on APS-c, but you didn't have an APS_c camera with you that day so there's not comparison image to prove it. Every now and then you get an image where resolution, dynamic range, low light performance all come together to produce a stellar image. I think 645 is more of the same.
I suspect this is one of those images, but, i can't prove it. It's just not that often I'm carrying both the K-1 and K-3 and have time to take an image twice.
 2017-10-10-Park-colours-3 by Norm Head, on Flickr
I can show you comparative images that are quite good where APS-c was up to the job... but it sure is rewarding when you hit that FF sweet spot.
But APS-c isn't too shabby either.
 2018-10-18-Fall-fall-colours-3 by Norm Head, on Flickr
As I see it, it's a continuum. The larger group being images both APS-c can handle and taking them with FF doesn't make much difference. We have lots of those. Then comes the images where they would look a little better shot with an FF, for whatever reason, resolution, more DR, better high ISO performance,, whatever. That's a pretty small group. The there's those for which nether FF nor APS-c will do the trick. A smaller portion of those will be resolved by MF. Then there are those that just aren't going to work, no matter what you shoot.
Going FF is meaning maybe 5% of my images that will be noticeably better, but you're buying heavier more expensive gear to get that 5%. You have to ask yourself, "Do I take the images that will benefit from FF." That's very individual, if I'm MIkSF the answer is "heck yes". If I'm normhead the answer is "it might be" and I'm still undecided. And the numbers above are my numbers. Someone else might have half to all their images improved by FF, a lot depends on what you shoot, and what you expect from it.
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Forum: Pentax DSLR Discussion
11-12-2018, 02:45 PM
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Some actual numbers from IR...
16 MP APS_c tested out at 2100 lw/ph
24 MP APS-c tested out at 2700 lw/ph/
36 MP FF (K-1) tested out at 3500 lw/ph.
20 MP FF Canon 6D test at 2400 lw/ph
The difference between 24 MP APS-c and 24 MP FF is about 100 lw/ph or 2800 for 24 MP FF. Functionally identical. If you are to break that down into lines per mm, the 24 MP APS-c is way more.
In the case of a 20 MP FF (6D) 24 MP APS_c gives you a couple hundred more lw/ph plus it's smaller sensorr, so in terms of line per mm, it serious kicks the 6D's butt. Or to summarize, Pixel Density is way more important than format in determining lw/ph,
The king has to be something like the Panasonic FZ 2500 which gets 2500 lw/ph on a one inch sensor. 9mm c 12mm.
SO get this, the Panasonic in good light gets 2500 distinct lines out of a 9mm deep sensor. That's 277 distinct lines per mm. That's some serious resolution.
I think the error in your thought is thinking there are lenses that top out at 45 lines per mm.
An APS-c sensor has a depth of 16mm. So on a K5 2100 lw/ph divided by 16 gives you 133 line per mm.
A K-3 179 line per mm.
Using the same lens you're getting an extra 63 lines by increasing your pixel density.
Lets take the crappiest lens we know. The 18-55 kit lens. At 10MP, it produces max of about 2100 lw/ph (not the same measurement as the above.No one knows why klaus' numbers are so ,much higher than everyone else, it's one of those mysteries of the universe.) hopefully they are consistent,) At 16 MP that grows to 2604 lw/ph. Using the cheapest lens you can find, it's not the lens that limits the resolution, it's the pixel density. Hence the whole part about the lens producing 45mm across various sensors is in error. There is not a lens I know of that doesn't produce a higher lw/ph count with a denser sensor. And part of that will be that the smaller the sensor, the more of the sharpest part of the lens it uses.
If you don't look at real tests done with real lenses and sensors, it's easy to make this kind mistake.
If looking at older lens tests, many were done in paired line per mm, which would mean you have to cut the numbers in half to compare apples to apples. But you're still looking at 140 paired line per mm for the Panasonic, even if that's true. The resolution folks get out of even small sensor small lens cameras in digital leaves film in the dust. A lens producing 45 lines per mmm on digital would be piece of junk.
People who formulate this kind of intellectual notion without any kind of real world input, often screw up really bad. It may sound logical, but that in no way suggests it has anything to do with the real world. There are few theories in earth so simple someone somewhere can't take it, apply it incorrectly, and produce ridiculous results, and then claim science proves them right. It's especially common in photo blogs.The big question should be, who checked your work? Even real scientists have checks and balances.
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