ISO setting for Coolpix 4500? (1 Viewer)

Firstly, thanks to everyone who has taken the time and trouble to post on this site. I've been 'digiscoping' for a while using a cheap fuji, handheld in front of the eyepiece. Mostly the results were poor, but I've had enough fun to want to do this properly now. I've just bought a Coolpix 4500 which I am using with an Eagle Eye adaptor on an Optictron HR80 with a 24-72 zoom. The hep and advice on the forum has been invaluable, with a special mention to Andy Bright's site which is great. The only thing I haven't been able to find is what ISO setting is generally used. It's probably on the forum somewhere, but the search engine won't work with words of less than four letters.....I know that higher values can be a bit grainy, but let more light through, with consequently higher shutter speeds. Is there a happy medium or do most people stick with 100?

Thanks

Hi Chris and a warm welcome to birdforum from all the staff here. Thanks for the kind words about my site.
In ideal situations you should use the default setting of iso100, the image quality from this setting will be better than any higher setting.

Increasing the iso setting makes the image capture device in the camera (ccd) more sensitive to light, therefore allowing a doubling of the shutter-speed every time you go upwards with the iso setting. When light is bad you may be better to go to iso200 to get a shutter-speed capable of freezing the bird's movement (or your camera's movement!). On the CP4500, iso 200 isn't too bad and can improved in-computer, iso settings of above 200 are pretty grainy....but still, better to get some sort of shot than no shot at times.
Regards,
Andy

The CD4500 defaults at 100ASA equivalent, I feel pretty sure. Above this sensitivity, you will find increasing amounts of "noise" on your photos - but this is just when one of the noise-reducing bits of software would come into their own. Higher speeds don't "let more light through" as such, they act to increase the sensitivity of the electronic "film" or charge-coupled device / CCD.

I noticed there is a competitor to "Neat Image" for reducing image noise called "Noise Ninja"; in reviews it's been shown to be as good as or better than "Neat Image" and had the advantage of working far more quickly. I think a free trial can be downloaded. I like "Neat Image", though, as it also allows for decent sharpening.

Here's an interesting web page on just this topic:

http://webpages.charter.net/bbiggers/DCExperiments/html/body_iso800.html

Staying at 100 will be impractical in some conditions, but I wouldn't recommend exceeding ISO 200 with the CP4500.

Also, whatever noise there is in the image will be amplified if you need to heavily correct under-exposure. I think its something to do with the ratio of the signal (the image you're trying to get) to the noise (the results of amplifying the signal coming out of the camera CCD by stepping up the ISO). You can still hide the noise at ISO 200 if you get the exposure correct.

Regards,
Graham.