I shoot in Auto ISO most of the time. One thing I notice, is that sometimes it kicks or skips ISOs to the top you select. The only way I have found is just playing around with it on different lenses. For instance on my 70-300 VR and trying to shoot birds I set the shutter to about 1/200 - and my 70-200vr to 1/300 and both to iso of 400. That seems to work for me - no logic there, just trial and error. It does seem counter intuitive but to keep sharp detail it works. It would be interesting to know the details behind the programming. For instance on my 85mm 1.8 it will almost always skip iso 200-1100 and shoot at 1250+ if the shutter matches my selected shutter. It is a pain if you don't remember to set your high iso where you want it.

I have not looked at the CLS book by them. Most I have gone through seem to come up short. I do like the "body" books as reference points. I'm not big on examples, just simple answers.

Didn't intend to veer so far off. I've noticed oddish behavior in my pictures when I go to auto ISO also. Think if the camera knows that I have a tele on the body and I am in auto, it should fiddle things around so the ISO is lowest and the shutter speed is highest. Sometimes it seems to, other times it seems to go off on creative tangents on it's own. It is more often a deal maker than a deal breaker so I use it often when I am trying to get that darn cardinal to fly just a little closer so that I can fill the frame.

To TAO..., I have not been impressed by the Rocky Nook Nikonians books. I have one on the CLS and it just seems thin on content. It is professionally formatted and filled with example photos, I just don't come away with much new information. Glad it is to your liking, it pleases me no end that there are so many good books out there with so many different styles portrayed.

Really an odd thread for this post post this...

There is a good page of recommended books (all around) that will give you some info.

Personally I have Darrell Young's "Mastering the Nikon D300" (there is an "s" version now.) Laid out very well and gets you to answers fast.

Drab, It was more like, I am ready to play, this thing is a reference, I'll refer to it as needed. I will sit down to it from end to end, I just seem to be more willing to play and learn and get stuff from the Internet than to face that tomb. Funny, I never used to be like that, gettin' old and lazy. It was very helpful in teaching me the proper use of the autofocus assist lamp, and several other details. Yup, this weekend is looking good to begin from the first page... again. It is remarkable how easy it is to get right to work with the camera, and I've been reading David Busch's book first. I don't remember seeing a book on the D300s by Thom, I thought it was the D300. Back to the topic, the autoISO has been, in a word, terrific. I leave the camera on almost auto everything when it is in the bag and can reach in, pull off the lens cap and start shooting with confidence. The auto bracketing of white balance has also been a learning experience, even though I shoot in Raw + Jpg. Helps me think about what I am up to.

The SDK (Software Development Kit) will not help you understand the D300s at all. It is a set of Lego blocks from which one can make software tools which interface with Nikon cameras and to a lesser degree Nikon software products.*

Thom Hogan writes some excellent guides for the Nikon bodies, and is much closer to a "complete reference" than anything else I've seen on the market. That said, if you have not yet read the 240 page manual already provided to you perhaps you're looking for a more casual read than the thick tome Thom has to offer?

*I've been struggling for a better analogy - this one has flaws, but it makes the point.

Is there any documentation on the D300s that would serve as a complete reference of the mechanism for these very sophisticated machines?
Admittedly I have not read the 240page user manual from cover to cover, but I would very much like to know all about the mechanism of this photo computer. If I get the SDK would that lead me to the details that I am seeking? So many nuances, so much to absorb. Mostly I want to eventually learn all about the interactions with the CLS, my SB-900 manual is bigger than my F3 manual!

I don't shoot CLS so I don't know if the on-body flash can be set thusly, but Nikon external speedlights have the ability to turn off the default setting, which is "balanced fill". Balanced fill (regardless of the power ratio of strobe to ambient) does what the name implies in that it allows enough ambient in to balance the stobe's light. In dark situations, obviously, this leads to slow shutter speeds.

What you appear to want is for the strobe to be the primary light instead of a balancing light, and you need to turn off balanced fill to accomplish this.

The camera will first check the ambient light and determine exposure when you half press the shutter . I don't know what happens when you press the shutter and shoot. . Obviously, the light coming from the manual flash will be too much but I don't know if the camera will re-meter and try to compensate the exposure during the "exposure" .

I doubt it but if it can , it still will have the option of reducing the aperture so I don't see a reason for it to lower the ISO .

Honestly , what happens between flash & camera during an exposure is still very complex to me. :-)

i wonder if keeping everything the same, but shooting with manual flash, could work.

that would remove one variable for the camera and it would be forced to reduce ISO.

just a thought.

In AUTO ISO , it keeps ISO as low as it can . It goes up to the ISO limit set if necessary .

In AUTO ISO with FLASH , the camera measures ambient light and chooses ISO for the existing condition ( which usually requires high ISO considering flash is needed ). Then it adjust exposure with decreasing flash power if necessary . So you are mostly left with shots near / at your maximum set ISO - 800/1600/3200 - whatever it is even though the subject may be 2 meters away . It will not go down to minimum ISO as it would in previous models.

Pro: Better overall exposure , no white faces against black backgrounds .
Con : End up having noisy high ISO shots even though minimum ISO was possible.

So either turn AUTO ISO OFF with flash or set limits accordingly.

what happens when you do?

Just be careful that the Auto ISO with FLASH does not work in D300s ( and all the newer models )the way it did with D300/D80/D90 ( uses different priorties ) - I just learned that .

auto iso is very handy in manual mode.

it also can use iso's that you can't in manual iso like 900 and 1400. i use it a lot.

PB is correct - I have the D300 and it will only drop to Low 1 when shooting into the sun.

Cool, thank you both for the clarification and help.

agree with PB PM

I believe the cameras will use native ISO settings, unless is absolutely has to do otherwise. So the shutter speed would have to exceed 1/80000s at ISO200 in order for it to go down.

I'm wondering if anyone can clear up an assumption for a n00b:

I have the D300s, and occasionally I use Auto ISO.

The ISO range I use is Lo-1 -> 800 ISO.

However, the camera will never select Lo-1... the lowest ISO it selects is 200, even when there's ample light and in aperture priority mode it selects shutter speeds of 1/1000+.

Is the discrepancy between being able to set Lo-1 as the lowest ISO and the camera picking 200 bad software design or should I check other settings or something?

Thanks in advance for taking the time. :D