[MichaelErlewine]

Is there Any True ISO less than 100 and how would we set it please?

[Digitalis]

On the K-1 there is no ISO lower than 100.

[MarkJerling]

You need a K-5. ISO-80 for that one! I'd much rather have the K-1 though.

[rawr]

NB: using Pixel Shift will effectively give you the advantages of lower ISO.
So K-1 ISO 100 pixel-shifted may as well be ISO 50.

[Digitalis]

using Pixel Shift will effectively give you the advantages of lower ISO.

The only Caveat there is your scene has to be effectively stationary to gain the full advantage of it.

[WPRESTO]

Looking for an ISO less than 100? By my measure you are a newbie to photography. The first roll of 35mm film I put through my first SLR, an Asahi Pentax S, was original Kodachrome, ASA (ISO) 10. When Kodachrome (ASA/ISO) 25 was introduced, we all cheered, except the color rendition was more "pastel," not as dramatically contrasty as the original version. If you need the equivalent of lower ISO for some specific purpose (=long exposures at large apertures), go for an ND filter.

[Gimbal]

Multiexposure would be faster the PS.

[rawr]

The only Caveat there is your scene has to be effectively stationary to gain the full advantage of it.

The full advantage, yes.
But, depending on the scene or subject, merely the noise reduction effect may be valuable.

[MichaelErlewine]

Looking for an ISO less than 100? By my measure you are a newbie to photography. The first roll of 35mm film I put through my first SLR, an Asahi Pentax S, was original Kodachrome, ASA (ISO) 10. When Kodachrome (ASA/ISO) 25 was introduced, we all cheered, except the color rendition was more "pastel," not as dramatically contrasty as the original version. If you need the equivalent of lower ISO for some specific purpose (=long exposures at large apertures), go for an ND filter.

Newbie? No. I am used to a true base ISO of 64 on the Nikon D810. Makes a huge difference, mostly because of the blacks. Fake low ISOs, no. But true ISO such as I described, Yes!

[WPRESTO]

Newbie? No.

So you also started with original ASA 10 Kodachrome? Remember the settings for "cloudy bright" and keeping the sun over your left shoulder?Actually, if you want to lay claim to greater age, I concede!

[K-amps]

As I understand it, The D810's Lower ISO is Hardware based. It represents true increase in sensor full well capacities that are larger than normal iso 100 sensor dies. Think of it as a deeper bucket that can collect more photons on sensor. This is why the D810 has industry leading DR. It has true hardware based lower iso. What this means is, it does not need signal gain, rather relies on a longer exposure to get a truer signal.


Of course iso 64 means longer exposure, but also Yields lower noise and higher Dynamic Range, both of which are desirable especially in the case of Landscapes and other non moving subjects.


With improvements in technology and Pentax's cleaner processing engine, I suspect the Pixel Shift on the K1 with iso 100 , will yield better results than the D810 with iso 64...


Consider the following simulation of Shadow pushes. Taking a +5EV push and seeing the amount of noise (which is one approximation on the DR of the Camera) for the following:


D810 at iso 64

5dsr at iso 100

K1 at 100

K1 at 100 + Pixel shift

You will note that even at iso 100 and a 5 stop push, the K1 marginally edges out the mighty D810 at iso 64 on normal shutter, but then in pixel shift mode, it increases its lead even further...


I do not think we will miss iso 64 on the K1 :-D

[MichaelErlewine]

K-amps wrote:

"I do not think we will miss iso 64 on the K1"


That's my understanding as well, and I have been using the D810 since it first came out. I was asking if there was any "true" ISO on the K1 lower than 100. I recognize that what we have in Pixel-Shift, like we did with the Sony A7s, is not an increase in Mpx, but an improvement in color representation. I have studied apochromatic lenses for some years, working beyond just acutance and resolution, with the various aberration corrections and so on. With the K1 (and the K3 and some Hassleblad cameras, we have a new paradigm IMO, at least for my work. I do still life, stacked focus, so the K1 was made for me, once I get used to it. I am still trying to make it do simple things, but I am getting it. I have published a lot books, articles, and videos on focus stacking..... at MacroStop.com.

Anyway, the improvement of color (and bypassing the Bayer interpolation) is a wonderful opportunity for my kind of work.

[Fogel70]

NB: using Pixel Shift will effectively give you the advantages of lower ISO.
So K-1 ISO 100 pixel-shifted may as well be ISO 50.

It's even easier to use multi-exposure for this.

I believe most Pentax DSLR since K10D can multi expose up to 10 images, which gives equivalent exposure of ISO10 (if using ISO100 on all images).
But on the other hand you can do the same in post processing, where you can use any number of picture you like.

[Na Horuk]

Some cameras have "Boost ISO" or "Expand ISO" or something similar in their Menu. You should enable that, though the highest ISO settings are usually almost useless anyway.
Regarding lowest ISO, even once boosted or extended, I dont think many DSLRs have anything under 100. The K-5 was quite special in that it allows ISO 80 (once enabled). I think there might be a couple flagships from other brands that allow ISO under 100, but those are exceptional.

But I see you already got good replies about the K-1. Is there a particular need why you need such a low ISO? You can usually compensate by shutter, aperture, or even ND filters.

[WPRESTO]

Going back to Michael's original search for deep blacks. At least to my eye, the black square, lower right, taken with the D810 is significantly the darkest of the four.