[biz-engineer]

Pentax K1 reaer LCD resolution specification is 1,036,800 dots or 345,600 RGB pixels. But how much should I zoom in the rear display when evaluating the sharpness of an image after I took it? Quick simple maths based on camera rear display resolution per inch and intended print PPI, give interesting results. Here is what I find.

K-1 rear LCD zoom value -> Print PPI
x 1 -----------------------------> 27
x 1.4 ---------------------------> 38
x 2 ------------------------------> 54
x 2.8 ---------------------------> 75
x 4 -----------------------------> 108
x 5.6 ---------------------------> 151
x 8 ------------------------------> 215
x 10 (100%) ------------------> 269
x 11 ----------------------------> 296
x 16 ----------------------------> 430

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Last edited by biz-engineer; 10-05-2019 at 05:51 AM.

[Madaboutpix]

Can only base my answer on my experience with a K-3, which I've shot for more than five years now. At any rate, I have not found LCD chimping, even at full zoom-in, a reliable predictor of critical sharpness. Which doesn't mean that I no longer zoom-chimp, but that I only use it for a first guess if a frame could possibly be sharp.

I recall various instances where I found images that looked pretty good on the LCD to be goners when inspected on my PC monitor, and images I had more or less given up on to be keepers.

But I sense you want clean numbers ...

[tvdtvdtvd]

Can only base my answer on my experience with a K-3, which I've shot for more than five years now. At any rate, I have not found LCD chimping, even at full zoom-in, a reliable predictor of critical sharpness. Which doesn't mean that I no longer zoom-chimp, but that I only use it for a first guess if a frame could possibly be sharp.

I recall various instances where I found images that looked pretty good on the LCD to be goners when inspected on my PC monitor, and images I had more or less given up on to be keepers.

I have the same experience. I find zooming into an image in playback to be much more useful in spotting motion blur than critical sharpness.

[Mikesul]

There must be a reason Pentax chose 10 as 100%.

[Cerebum]

42

Sorry, I panicked

From memory we don't have such precise options. Also I suspect this may be another personal preference thing. Presumably, depending on the size of the screen there is a point at which you can see sharpness and another at which all detail is indistinguishable, so the right answer is somewhere in between. I zoom in to 8x then dial it in to max.

Kudos on the maths

[MrB1]

To get a rough idea of image quality I have always set quick zoom to 8x for APS-C, on the basis that the screen is about 6cm wide and the largest I can print is A3+ or about 48cm. This might be completely wrong but it seems reasonable to me!

Philip

[pschlute]

100% ie 10x zoom. No point zooming further or you just get pixelation. If you dont intend to crop and depending on the image using a lesser zoom may be sufficient.

I have miy K1 set up so one click of the rear wheel in playback mode zooms straight to 100%

[marcusBMG]

Depends a bit on subject and circumstance but almost always I use max 10x zoom on my K3 for max accuracy. And a lcd loupe. That would be tripod mounted or bean bag. No point on zooming in too much hand held, the image jigs around too much.
My complaint with my samsung NX20 is that it only has 5x and 8x (IIRC), I wish it had 2x for hand holding ..

[sergysergy]

x8 or x10, but then I also check when in Photoshop

[photoptimist]

Although 16x does have pixelation, it provides useful magnification of focus/motion/aberration artifacts when reviewing shots or doing live view focusing outdoors.

The only problem with 16X is that it takes FOREVER to scroll the tiny window over to the edges or corners to check IQ across the image.

[ChatMechant]

Intersting numbers there. 5.6x is usually enough for me to check whether a shot is botched or not. Takes forever to scroll around if its smaller than that.

[biz-engineer]

There must be a reason Pentax chose 10 as 100%.

humm.. my quick calc. got it wrong. The display is 68mm wide (2.677 inches wide) for 345,600 pixels (of the display), so that's 129 PPI for the display. The number of PPI in print as the eye you see it (via display) at x1 is 7360/2.677 = 2749 PPI for a print printed at the size of the display. At x 2 LCD zoom that's 1374, at x 4 LCD zoom that's 687 .... at x 10 that's 274 (x 10 is not 100%... because 100% would be x 10.22), at x 16 that 172 PPI in print... it not very sharp looking close but it's like printed 16 x 2.677 = 42 inches wide.

---------- Post added 05-10-19 at 18:03 ----------

Intersting numbers there. 5.6x is usually enough for me to check whether a shot is botched or not. Takes forever to scroll around if its smaller than that.

Yep, I share a similar setting, I use x 4 default so that I can check quickly, otherwise it takes forever to scroll down the corner of that screen if I'd use x 10.

[barondla]

Doesn't zooming in sometimes fail to predict sharpness because the image is a small portion of the original file? I find some cameras can be zoomed much more on play back than others. My Sigma DP1 Merrill can be zoomed all the way up and the image appears as sharp as standard magnification. There's no pixelation. The down side is it takes forever to review an image. Pentax cameras never get close to 16x without pixelation.
Thanks,
barondla

[StiffLegged]

I don't rely on the LCD. Unless chimping shows it's hideously unsharp I'll wait for reviewing on the PC before binning images. I'll miss opportunities with overmuch chimping. Use a big enough memory card and keep shooting!

[alfa75ts]

I'll wait for reviewing on the PC before binning images

Yep, nothing gets binned before it goes on the big screen.