[wiseman]

I was seriously looking at the K100D. Is the lack of an ISO 100 setting of any significance? I was curious why Pentax would not include that ISO setting on this camera. The K10D (which is very tempting!) has the 100 setting but it is rather expensive. I also like the smaller size of the 100D.

Thanks in advance for your feedback.

[leaton]

There is little to be gained by having an ISO 100 setting.
The intrinsic speed of the sensor is the lowest setting, in this case
200. So faster speeds are tricks of the hardware and firmware.
They amplify the sensor output or multiply it.
At ISO 200, there doesn't need to be any amplification or firmware
tricks.
The greater the pixel density the more light is required to get the
same per pixel output. Thus the 100D is naturally a bit faster than the
10D

[Wethphotography]

I used a Ds for almost 2 years and it only had a 200 ISO. To be honest, I never missed the 100 setting. I know that there are certain situations where you might miss the lower ISO, for example you run out of high shutter speed with an aperture of 2.8 or 4 in bright sunlight. However, with the DS I was never in a situation where 200 wasn't workable. In my opinion, the ISO of 100 is not in and of itself reason to spend more on the K10d, especially if you prefer the size of the K100D.

PS: Welcome to the Forum.

[RBellavance]

ISO 200 is the Sony 6MP sensor's base sensitivity. All cameras based on it start at ISO 200, for instance the Nikon D70, D50 & D40.


'

[davemdsn]

Photographically speaking (not a computer, software, sensor, firmware, or other digital issue), I really like having ISO 100 in the K10D because that is the speed I shot most with film for years. It is easier to balance flash with bright daylight, or even kill the daylight entirely, if you have lower ISO speeds. Fortunately the K10 produces identical results at 100 and 200 so the choice is entirely a matter of artistic expression.

[volosong]

From my understanding, there is not a direct correlation between ISO 200 on a digital sensor camera and ISO 200 or ASA 200 film from any manufacture. Saying that any specific camera is sensitive at ISO 200 doesn't really mean anything if you are thinking of getting the same results from ISO 200 film.

The Sony 6mp sensor ranges from ISO 200 to ISO 3200, the 10mp sensor from ISO 100 to ISO 1600. Same range, and I haven't ran a real test (perhaps I should), but I suspect that there will be very little difference between an ISO 100 image from the K10D and an ISO 200 image from the K100D, and so on.

To me, they are just "funny" numbers. I'm sure someone around here can get an ISO 200 shot from the K100D to look like Kodachrome 64 and for someone to make a K10D ISO 100 shot look like it came from Kodachrome 25.

[davemdsn]

Well, they may not have a difference in perceived image quality, but they are far from "just funny numbers". ISO (International Standards Organization) numbers are a rating of how sensitive to light the film/sensor is. It tells you what setting combinations will yield good exposure for a given amount of light output. If they were funny numbers light meters wouldn't work.

[chedoy]

Would a neutral density filter allow you to simulate ISO 100?

[SupremeMoFo]

Would a neutral density filter allow you to simulate ISO 100?

If you could find a 1 stop ND filter yes - I've only seen 2 or higher stop filters.

[nosnoop]

If you could find a 1 stop ND filter yes - I've only seen 2 or higher stop filters.

Sure:
Hoya 52 mm Neutral Density (ND) 0.3 Glass Filter
B+W 52 mm #101 Neutral Density (ND) 0.3 Slim Glass Filter

[RiceHigh]

I was seriously looking at the K100D. Is the lack of an ISO 100 setting of any significance? I was curious why Pentax would not include that ISO setting on this camera. The K10D (which is very tempting!) has the 100 setting but it is rather expensive. I also like the smaller size of the 100D.

Thanks in advance for your feedback.

ISO 100 is needed only when you want to open the aperture more and/or to use a slower shutter.

In most case, ISO 200 is adequate. It does have the advantage of using faster shutter or more DoF. That all depends what you need..

With ISO 200 and if you need slower Tv or faster Av, just use ND filter, in rare cases.

[Lowell Goudge]

I was seriously looking at the K100D. Is the lack of an ISO 100 setting of any significance? I was curious why Pentax would not include that ISO setting on this camera. The K10D (which is very tempting!) has the 100 setting but it is rather expensive. I also like the smaller size of the 100D.

Thanks in advance for your feedback.

The issue of ISO range on the camera, and this is for all 6MP pentax cameras is that ISO200 was set as the slowest because there was no additional image quality gain for settings slower than ISO200.

What some people failed to think about is not just an issue of image quality, but the fact that some people may have specific reasons for slower ISO settings other than from the bad old days of fiim, the better quality of slower films.

1) if you want very shallow depth of field, you want a lens wide open, but you may also want specific (slow) shutter speeds so that only stationary things are frozen in the image and moving things are blurred. in this case, you would want perhaps ISO100 or even slower.

2) Also you might have a fixed apature lens, like a 500-1000mm mirror, and the only exposure controls yoou have are ISO and shutter.

3) You may also have specific lighting arrangements that you made for shooting slow film, and now have to re-work for the same effect using iso200 as the slowest setting.

I asked pentax about this when I bought my *istD, but they did not move on the issue.

I like the K10D not so much for the ISO 100 setting but that you can set it in 1/3 EV increments, where as the *istD was in 1 EV increments, BUT I bought the K10D for 10 megapixles not ISO100

[wiseman]

Thanks to all for your help. The value of this forum is immeasurable!