[TwoUptons]

Here's a sample... not fancy...
Cat asleep on the sofa, OOC Jpeg cropped to 15Mp then downsampled to 1024 pixels across for the forum's happiness...



There's plenty of "grain" in the original, but the hair holds its detail pretty well considering this is ISO 25,600...

Would I put this in a gallery? of course not, but it would look fine on a phone screen or small print.

That's from a K1 upgraded to a K1ii (K1.5?) with a FA 50 f2.5 Macro.

-Eric

[microlight]

Any ISO that gets the shot; in some beach penguin shots in New Zealand last year, I was up around 10000/12800 to make sure that motion blur is minimised. A high-ISO blur-free picture is certainly better than no picture!

[stevebrot]

My auto-ISO range is set from 100 - 3200 on the K-3. I would likely use a similar range if I owned a K-1. That said, I seldom use auto ISO. With manual ISO, I usually shoot at 400 or below and almost never above 1600.


Steve

[rawr]

FWIW, DxO says the highest ISO that still delivers acceptable image quality [the highest ISO setting for a camera that allows it to achieve a SNR of 30dB while keeping a good dynamic range of 9 EVs and a color depth of 18bits) for Pentax DSLR's is below:



(Notably absent are cameras with the Accelerator chip, which DxO hates).

In my experience, the scores are about right. But even with the K-x I never really worried about doing ISO 1600. Of course, working with a good RAW processor can substantially boost the effective high ISO of these cameras even further.

[dms]

Generally where the slope of DR versus ISO becomes -1 stop/stop. Although if it happens at less than iso 400 I often use 400. Highest iso is 800 on my Nikon D700 and iso 1600 on my K-20D.

[7.62lew]

Exposed correctly, I will go to 6400 with K5IIs. But mostly not beyond 3200 normally. RAW with DXO photolab 2 noise reduction👍

[Aaron28]

in general not past 800 whether k-r, k-50, k-3ii or K-1......but will go beyond if need be depending on what is being shot

[reh321]

Exposed correctly, I will go to 6400 with K5IIs. But mostly not beyond 3200 normally. RAW with DXO photolab 2 noise reduction👍

With my Q-7 I limit myself to ISO 400, but IBIS allows me to use very slow shutter speeds.

With my K-30 I limited myself to ISO 800, which means TAv mode was of limited value.

With my KP - after much experimentation - I set the limit to 12800, which means TAv mode is finally of value to me.

I use the generated JPEG whenever possible.

[08amczb]

On the K-30 ISO 1600, but if I really need to freez some motion I go to 3200-6400. For extreme low light 12800 in BW can work if there is enought contrast.
With the KP I go up to 3200 without any hesitation. It can produce fine color images up to 25600. Up to 102400 the images are useable, but the moment must be really interesting to create a keeper in this range. BW helps a lot here too.
My Nikon D750 goes up to 6400 without any complaint. ISO 12800-25600 is okey, if i really need it. It's better then the KP.

[c.a.m]

Here's what Imaging Resource says about the print quality from the K-3 II at various ISO settings. I don't think they state whether the prints are from out-of-camera JPEGs or from processed RAW files.

My table below summarizes their analysis that they present at: Pentax K-3 II Review - Image Quality

Imaging Resource also assessed the print quality for the K-1 II. In summary:

Pentax K-1 II Print Quality Analysis (single shot): Excellent 30 x 40 inch prints and larger up to ISO 400; a good 20 x 30 inch print at ISO 1600; a great 8 x 10 inch print at ISO 12,800.

https://www.imaging-resource.com/PRODS/pentax-k1-ii/pentax-k1-ii-image-quality.htm


- Craig

[Digitalis]

With the Pentax K5IIs I found natively ISO6400 would deliver acceptable image quality without any NR, ISO12800 on the Pentax K-1, and the 645Z 25600 - bear in mind this is for web display in a 1080p web gallery, 4K raises the bar for image quality considerably* making ISO 3200 the limit on the K5IIs.


In print form, Image quality is again, very important with the 645Z ISO1600 is the limit for a 20"X16" print. Mind you on my 8X10 format you could shoot ISO 1600 film and be able to print 40"X60" with nary a grain to be seen.


In commercial studio work ISO 100 is the gold standard, lower is better. It really depends on the clients output expectations: and they usually include this in the design brief, if the image is to be printed in a wall spanning mural ISO 100 or lower, for a cheezy 1024X300 web banner** you can go for ISO 204,800!


* Though with the native resolutions of the Pentax K-1 and Pentax 645Z being so high, Pixel binning Via down rezzing can improve High ISO images: when you reduce the image resolution by half, you gain about 1 stop of NR.

** I don't think I have ever done work that has exclusively been used for such a thing.

[photoptimist]

There's no fixed upper limit for me. The highest acceptable ISO depends on the slowest acceptable shutter speed and the widest acceptable aperture (for lens softness or DoF issue).

Sometimes, more ISO noise is better than more motion blur. Sometimes, more ISO noise is better than too shallow a DoF or softness from the lens.

That said, prefer to keep ISO at 3200 or below, do start to seriously think about the ISO-speed-aperture trade-offs if the TAv ISO value is 6400 or above, and rarely go above ISO 51200,

[northcoastgreg]

With the K-5 series of cameras, I hardly ever shot above ISO 1,600; with the KP, hardly ever above 3,200; and with the K-1, hardly ever above ISO 6,400.

[Not a Number]

Refer to an earlier thread on the same subject:

Iso .. how high is too high for you? - PentaxForums.com