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Forum: Digital Processing, Software, and Printing 06-05-2020, 10:40 PM  
Printing for beginners - dark prints
Posted By biz-engineer
Replies: 18
Views: 923
I guess adjusting image brightness when viewing it on a monitor is what people can do because it's a natural action (without thinking), although the right thing to do is to adjust monitor brightness based on ambient light with basic monitor calibration scheme, and adjust image brightness based on histogram. When the image is adjusted based on its histogram, dark looking prints may then only come from printer issues or lack of proper illumination of the print itself.
Forum: Digital Processing, Software, and Printing 06-05-2020, 01:18 PM  
Megapixels vs Maximum Printing Size
Posted By biz-engineer
Replies: 32
Views: 1,744
I would add: If the photograph is one of a center subject in focus, with everything around out of focus (e.g background), corner + edge sharpness of lens don't matter. I define photographic quality as sharp detail when viewed at 16 inches (~40cm) since this is (sorry...) the distance when my eyes can resolve the highest detail, closer to 16 inches I see less detail, further away from 16 inches I see less details. For me it is impossible to see any sharpness flaw on a print from a K1 at 16x24" (300ppi), I can only distinguish drop of crispness below 250ppi, for me photographic quality is already there at 200ppi, very good between 200 and 300. I consider lower end photographic print quality (at 16 inch viewing), below 200 ppi, but since pixel pitch is the same accross the same print lower pixel pitch isn't catching attention as much as CA or fuzzy corner (as if the image detail is stretched in the corner according to a pattern of lens optic, distorsion of shape). Of course, 8 mega pixel with a low quality lens can be printed 20 feet wide looking good from far away, but I do not consider this as photographic quality, and because you can doesn't mean that the result is good. I was told that "you can print 10 feet wide from a Fuji X-T3", but the language here is to be taken word for word, "can" means it is possible to do so. Even 150 ppi would be Ok, at the condition that the lens is super-sharp, each pixel given a contribution to detail and contrast: David Yarrow / london exhibits gallery prints 150 cm to 180 cm wide (less than 150 ppi), from images captured with a D800E/D810 with Nikkor 28mm 1.4, 35mm 1.4 primes, aperture f4...f5.6 (wide angle give more DoF and no diffraction), large subject (animal) filling the frame, so a lion's face if defined by lots and lots of pixels.., exceptional lens sharpness and very low CA edge to edge, he wouldn't be using a 24-120 kit zoom for this type of enlargement.
Forum: Digital Processing, Software, and Printing 06-05-2020, 06:41 AM  
Printing for beginners - dark prints
Posted By biz-engineer
Replies: 18
Views: 923
What if the histogram is already bordering the left limit?


Yes. To me, that is the most important to understand. A photograph with normally centered histogram, without clipping, will look great on print when lit with neutral while reflector (~5000K) at a 30 degree angle relative to print plane, assuming the viewing axis is perpendicular to the print. Noting the effect of inverse square law of projected light, a 3:2 print in landscape orientation will preferably be lit by two reflectors, while a single reflector will be do well to illuminate a square print, and a three or four reflectors configuration will optimize lighting for a long panoramic print.
Forum: Digital Processing, Software, and Printing 06-05-2020, 04:00 AM  
Megapixels vs Maximum Printing Size
Posted By biz-engineer
Replies: 32
Views: 1,744
There is the relative enlargement , viewing distance , image detail content etc. as mentioned above.

In absolute terms, experience shows that pixel count comes last as enlargement limit.

1) What comes first is lens CA => manual CA correction (automatic correction only does a partial job).
2) Lens corner sharpness (lack of) shows second, local sharpening can help a bit, but what can be done is limited
3) Eventual diffraction softening can show up depending on aperture

4) Pixel pitch vs image detail (contour description, up-sampling avoid visible pixelation, sharpening has limits

Print at 150 ppi still delivers good quality if lens is sharp corner to corner or in case of center square crop (removing softer / fuzzy area of image).
Print at 300 ppi is overkill for 100% sharp lens, 200 ppi is very good already. Having said that , sharpness drops from center to corners for all lenses, to lesser extent for the best lenses (e.g macro lenses).
Lens circular properties vs rectangle sensor plays such role that a square crop can be printed at the same size as the long size of a 3:2 print of an image capture with the same lens and same camera.

Examples of prints all upsampled at 300 ppi , with optimal sharpening / unsharpmasking:
- K1 D-FA 28-105 print 28x41", ISO200, @ 28mm f10: softness in corners visible, some minimal diffraction (softening tiny details)

- K1 D-FA 28-105 print 24x36", @ 28mm f8: very good perceived quality edge to edge (corner softness almost invisible with best efforts)
- K1 D-FA 28-105 print 32x32", @ 35mm f8 center square crop: very good quality edge to edge , that's ~150 ppi (4912/32).

- K1 HD-FA 35 2 print 28x41", @ f8: very good quality edge to edge.
- K1 D-FA 100 macro @ f8, print 24x36": to quality edge to edge


- K3 Tamron 17-50 SP @ 17mm f8, print 19x28": square center of print is crisp, visible softness in corners and top/bottom of frame long side.
- K3 DA 15 ltd f11, print 19x28": square center of print is good, distracting fuzzy corners very visible.
- K3 Tamron 17-50 SP @ 50mm f5.6, ISO 100, shutter speed 1/500th, print 20x30", very sharp across the frame
- K5 DA 17-70 @ 17mm f8, ISO100 (long exposure), print 20x30", sharp in center, distracting fuzz + CA in corners.
- K200D, DA 18-250 @ 35mm, ISO 800, print 20x30", sharp in center, bits of softness visible in corners, but CCD noise limits overall image crispness.
- K200D, DA 18-250 @ 135mm, f8, ISO200, print 20x30", sharpness in center, visible fuzz at corners and the 4 edges of the frame (lens is soft at 135 , except decently sharp in center)

With mediocre lens, the 3:2 aspect ratio enlargement can be enlarged the same as center square crop, simply due to edges and corners limiting the enlargement.
With edge to edge sharp lens, same camera, image print can be enlarged 1.5x as much as same shot taken with low end not corner to corner sharp lens.
So , the lens is big deal to such an extent that you could print larger from a 24Mp camera and sharp primes, than from a 50Mp camera with an entry level zoom not used at it's maximum optical performance.
Up-sampling prevent pixelation, but doesn't help solve lens resolution drop from center to corners.
Forum: Pentax News and Rumors 05-15-2020, 03:49 AM  
New APS-C is
Posted By biz-engineer
Replies: 845
Views: 46,618
Understanding camera mission profile is fundamental in selecting the right tool.
Forum: Pentax News and Rumors 05-15-2020, 03:47 AM  
New APS-C is
Posted By biz-engineer
Replies: 845
Views: 46,618
Camera concept logic.
I think the Canon 1Dx and Nikon D6 series don't have a tilt screen
The EOS R has a flip screen (video logging, on tripod / selfie)

The Pentax K1 has a tilt screen (field cameras, landscape on a tripod, no optimized to burst and af tracking)
The Pentax Kp is an apsc version of the K1 (same design look, accelerator chip, slow burst rate and short buffer)

So if the Pentax new apsc is a K3 successor and not a Kp successor, supposed to be an action camera concept, like 1Dx / D6, it should have a fixed screen.
Customers wanting an apsc with tilt screen can buy a Pentax Kp.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 05-12-2020, 10:53 AM  
Just when you thought you had enough Mega Pixels
Posted By biz-engineer
Replies: 17
Views: 745
No so much the high pixel count that matter the most, especially for wide angle images. A 20x30" print viewed 7 feet away, image taken with DA 15 ltd at 100 ISO and f9 shows distracting image corners due to field curvature of that lens whether the image is captured with a 10Mp K10, 16Mp K5 or 24Mp K3, the blur of image corner projected by the lens is just sampled more precisely on the K3. BTW, 100Mp is only a 26x40" print at 300ppi, of course I'd prefer 50Mp on a sharp lens as opposed to 100Mp on bad lens. Even 24Mp is actually very good if the lens is excellent. IMO, 100Mp on such 33x44mm format is mostly usable in square crop mode, more like ~60 effective Mpixels. The bottom line is: most lenses have their resolution drops 15% to 50% around the edges, oversampling is doesn't help very much, the max print width from a 3:2 digital camera is about the same whether it is a 1:1 square print from center crop or a 3:2 print from the full sensor.
Forum: Pentax K-1 05-05-2020, 10:20 AM  
Issue switching from SD card 2 to 1
Posted By biz-engineer
Replies: 21
Views: 791
That is not working. Removing and inserting SD cards without turning off/on the K1 doesn't change what SD card slot is selected. For SD1 to become the data destination card, the steps are as follow:
- turn off K1
- remove SD2
- turn on K1 (that forces the camera to select SD1 due to SD2 missing in slot 2)

- turn off K1
- insert SD2
- turn on K1
SD1 is being selected.
Forum: Pentax Full Frame 05-03-2020, 02:43 AM  
Response from other K-1 owners
Posted By biz-engineer
Replies: 11
Views: 1,023
Yes.


Yes, because you have switched the display off and in that case you can't see camera setting displayed on the back LCD.
Forum: Pentax News and Rumors 05-03-2020, 02:34 AM  
K-New: still kickin'...
Posted By biz-engineer
Replies: 179
Views: 17,384
It's bad thinking to be cost only driven. You have to balance the cost of time lost vs the cost of money. Otherwise your employer would never hire you because you are expensive? Your employer employs you because , although you are expensive, you save him more time value than you cost. What cost more? Messing around tried to make do with the Pentax system? or spend the money for the system that just does what you want and be done with it?
Forum: Pentax News and Rumors 05-02-2020, 10:15 AM  
K-New: still kickin'...
Posted By biz-engineer
Replies: 179
Views: 17,384
That's right, I'd have to spend again a bunch of money, but from the results I've seen I'm confident that I'd enjoy the results.
Forum: Photographic Technique 05-02-2020, 10:14 AM  
Landscape Diffraction is my enemy
Posted By biz-engineer
Replies: 70
Views: 2,349
Sharp primes, the ones that I don't have, would contribute. From what I've seen with some of the best primes, I'd say primes are even better than using a mediocre lens on a larger sensor.... things like chromatic aberrations that can never be corrected fully.
Forum: Pentax News and Rumors 05-02-2020, 10:10 AM  
K-New: still kickin'...
Posted By biz-engineer
Replies: 179
Views: 17,384
It's true that the K1 at its price point is hard to beat on image quality. But newer models from competition do have improvements: slightly more resolution, slightly more image quality, (much) faster memory cards, very good image stabilization, some nice to have software features and excellent prime lenses; the combination of top notch prime lenses with slightly better sensor and features combined can make a difference on images.
Forum: Pentax DSLR Discussion 05-02-2020, 04:38 AM  
Further reflections on my K3, KP and the "new" Fuji X-T1 and not so new X-E2s.
Posted By biz-engineer
Replies: 21
Views: 1,465
Fuji X easily win over Pentax autofocus, from X-T2 onward, quick and accurate, X-T1 and earlier models not. I much prefer the camera JPEG syles of Fuji, especially black & whites. Pentax B&W is botched, we have the choice between flat (low contrast) or bold monochrome that has way too much contrast that obliterate a lot of tone details. Taking a close look at Fuji GFX50R, feature set is rather basic (Pentax menu system is better), the Fuji is a metal box with a good sensor inside, with a basic contrast detect AF, no better than Pentax live view. No new lenses for the Pentaxes, Fuji releases new lenses more frequently and do a lot of online promotion (via sponsored reviews of Fuji equipment), Fuji advertise their GFX50 a lot, Ricoh are absent, silence for their 645z, there hasn't been a promotion of 645z for years already, while Fuji keeps hammering social media with their GFX50 series.
Forum: Pentax News and Rumors 05-02-2020, 04:18 AM  
K-New: still kickin'...
Posted By biz-engineer
Replies: 179
Views: 17,384
It's going to be hard to sustain the Pentax brand without Ricoh keeping in touch with customers by doing something like firmware updates for the current camera models. There would be some room to add a feature or two. With Ricoh doing nothing, you may eventually sell the Pentax camera/lenses you have to fund the purchase of another better system, spending a thousand or two, to get something better.
Forum: Pentax DSLR Discussion 05-02-2020, 02:51 AM  
Luxury Problems...
Posted By biz-engineer
Replies: 12
Views: 853
Keep the camera until you give it as as present to a kid from a poor background but well minded, it can have a long term impact.
Forum: Photographic Technique 05-02-2020, 01:06 AM  
Landscape Diffraction is my enemy
Posted By biz-engineer
Replies: 70
Views: 2,349
Printing large and sharp has a steep photo technique curve, we get diffraction that was invisible at small size, front & back out of focus that wasn't visible at small size, and not enough pixels. A steep learning curve but great opportunity to improve the shooting technique, even benefiting smaller size prints. I had never tried layering of aperture bracketed frames, but it turns out to be very good, having much more smooth transitions than focusing stacking, and zero focus breathing from the lens. In camera aperture bracketing (K-5 feature) would be nice to have back, much more simple than focus stacking.
Forum: General Photography 04-30-2020, 05:25 AM  
DPReview amends S1R review conclusion with notes about mandatory noise reduction
Posted By biz-engineer
Replies: 36
Views: 1,575
Of course.

There is a certain disconnect between camera marketing and real world usage. When the use the camera in the field, is when some of the claimed feature start to itch a little bit. And the very first thing that itch is the ergonomics, but usabilty is the very least thing considered in most camera reviews. Honestly, the more time goes the more I think pixels shift is a gimmick , or at least the benefits are small and in rare conditions. Yet, pixels shift is sold as a differentiating feature. Camera tech is too complex for most customers to exactly understand it, so most customers take the short cut of reviews. Even reviewers don't understand all of what they are talking about anyway, some reviews show that the guy doing the review doesn't know what he is talking about.

---------- Post added 30-04-20 at 14:35 ----------


It's not the problem of the 40x60", it's the problem that it's more like 5x the cost of camera system leads to 15% better image quality only, e.g print at 20"x30" from a $1500 apsc kit to 24x36" (same quality per square inch) from a $5000 full frame mirrorless kit. The difference between apsc kits (even some kit cost about $500) and $5000 is very small. Full frame is sold like it is the top , but it's not at all.

---------- Post added 30-04-20 at 14:57 ----------

Most importantly, if you don't print , all you need is 4K and in that case all internet discussions are for exercising the brain. Internet reviews of cameras nicely avoid to evaluate the capability of a camera systems with regards to printing photographs, so what they are talking about is total vaporware.
Forum: General Photography 04-30-2020, 12:24 AM  
DPReview amends S1R review conclusion with notes about mandatory noise reduction
Posted By biz-engineer
Replies: 36
Views: 1,575
It appears (source: DXO, photon2photo), that Pana smoothed the lower ISO to break beyond the 12ev of DR and 21 bits color depth. You'll get softness of detail when pulling shadows.

Anyway, I'm not convinced you can do miracles with all those digital cameras that are nowhere near medium format and large format cameras. Take any of these $2500 <> $3500 cameras, at best can make fine detailed prints at 20 x 30, up to 24 x 36 in perfect shooting conditions. The making of 300Mpixels focus stack & stitched image composite (~ for free) just crushes anything tested by any camera review site.
Forum: General Photography 04-29-2020, 11:07 PM  
DPReview amends S1R review conclusion with notes about mandatory noise reduction
Posted By biz-engineer
Replies: 36
Views: 1,575
Comparing real images from imaging-resources site comparometer, the S1R resolves at least as well as other ~45Mp cameras. S1R is the best, especially at low ISO.
Forum: Photographic Industry and Professionals 04-29-2020, 02:49 AM  
He Jumped.
Posted By biz-engineer
Replies: 97
Views: 4,132
Usually , I get from youtube some introduction to a subject, but then if I want more solid and more in depth information I'd rather use books and even books from the good old paper book library at some local universities.
Forum: General Photography 04-29-2020, 02:46 AM  
Human eye perception of black & white photos
Posted By biz-engineer
Replies: 31
Views: 925
The human eye is said to have about 6 million cones and 120 million rods. Cones discriminate colors, rods are sensitive to light intensity, from darkness to full sun levels.
When I look at the black & white version of a color image, I tend to feel as if the black & white image looks sharper than its color equivalent. I'm be interested to know if others also share the same experience.
Now if black & white images do look sharper than their color versions, would that come from removing color information let the brain with visual information coming only from the rods cells in our eyes, the 120 million rods instead of 6 million cones delivering more subtle gradation of light to the brain?
Forum: Photographic Industry and Professionals 04-29-2020, 01:09 AM  
He Jumped.
Posted By biz-engineer
Replies: 97
Views: 4,132
He gives some very interesting hints about what a YouTube channel is about... (advertising). Interestingly , there aren't that many Youtube channels reviewing Phase One, or Alpa, and when they do, they do it with a certain dislike (read disdain) from the point of view of the average consumer. The smaller the camera systems, the more fuzz is done about is. It's comparable to how much review is done on Youtube for Caterpillar excavators compared to the Lego versions of it :lol::lol::lol: YouTube is the new TV of 1980 - 2020 where you had no choice but have your favorite movie series interrupted every 40 minutes, then every 30 minutes , then every 15 minutes , for a paid Advertisement. YouTube becomes the same as TV: a few years ago you could watch a Youtube Vid without Ads, and now you get Youtube Vids interrupted by a half dozen Ads trying to sell you something, in addition to the Ads you get dynamically refreshed in web pages. Internet Advertising is a massive market, Google generated more than 9 Billion revenue in 2019 and this is increasing. All these online businesses wants is: 1) your attention 2) your interests (via cookies etc, what sites you visit, what videos you watch and what is your IP number). Reviews are essentially attention catchers, the content part of the videos seldom goes beyond teaser. Time to go offline.
Forum: Photographic Industry and Professionals 04-28-2020, 10:47 PM  
K-next?
Posted By biz-engineer
Replies: 7
Views: 1,261
It's about one year old. And it was already posted in PF last year.
Forum: Pentax SLR Lens Discussion 04-28-2020, 10:32 PM  
D FA 70-210 f4
Posted By biz-engineer
Replies: 31
Views: 1,764
That is so true. Should lenses be cheaper than cameras? Pictures on our hard drives are not worth much. Even a lens at $300 is extremely expensive considering that $300 is the kind of money that can feed a human being for one year in Ethiopia.

---------- Post added 29-04-20 at 07:41 ----------


No quite. Please bear in mind that Tamron has designed their lens with manufacturing costs low enough to be able to make money out of it even at selling price down to $450. An OEM lens targeted at $1500 selling price is certainly not designed with the same cost saving approach (on choice of materials) than the Tamron lens designed for selling it at $450 and making money. So, while the Pentax D-FA 70-210 f4 is certainly a good lens from the outside look and how it compares to OEM alternatives, but it still is a $450 lens design... designed with low cost inner plastics and optics to turn a profit at $450. Take the Pentax D-FA* 70-200 f2.8, it's a completely difference class, sharpness edge to edge is a lot better, build quality is a lot better.

---------- Post added 29-04-20 at 07:45 ----------


Optically stellar, but:
- designed for apsc (corner sharpness on FF is hum humm)
- autofocus slow like hell
- SDM reliability issues, you never know when it's going to break and how you are going to repair it or ditch it and get the D-FA 70-210 instead.
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