ISO setting poll

[Davros]

As was mentioned in another post lets see what people are generally using for their ISO settings

[jjjnettie]

ISO 800 for me, mostly.
Great avatar Mick. There's a little bit of Sheldon in all of us.

[Octane]

ISO-400. Anything higher and you're asking for trouble.

Regards,
Humayun

[jjjnettie]

:lol: Trouble is my middle name Humayun.

[Terry B]

To add a bit of science to the reason for choosing a particulat ISO see
http://www.clarkvision.com/astro/canon-10d-signal-to-noise/

[rogerg]

Interesting. Shame it's with such an old camera. It would be interesting to see for one of the new line of cameras (5D/50D/500D).

Roger.

[leon]

I never shoot any higher than 400 ISO, maybe on the rare occasion it could be 500, but this is not often.

Leon

[Paul Haese]

ISO 800 and I stand by it. I have seen plenty of good images taken with this level of sensitivity.

[avandonk]

Read noise is far less at 1600 ISO than at lower for a twelve bit DSLR. If you want to map very faint stuff to your available dynamic range then use 1600 ISO.

You will lose dynamic range at high ISO settings. Bright stars will saturate but at least you have the faint data.

If you need a high dynamic range then 400 ISO is a good compromise.

That is why I am working on my HDR process.

There is no correct answer it all depends on the objects dynamic range and your optical train including camera.

All data for this image was taken at 1600 ISO. 11MB

http://d1355990.i49.quadrahosting.com.au/2009_09/SMCmosenhc2.jpg

See here

http://www.iceinspace.com.au/forum/showthread.php?t=50390

Bert

[dugnsuz]

iso1600 subs and lots of 'em.
I like to push for as much as I can get from the DSLR.
iso1600 seems to work pretty well on the 40D in my location - temperatures usually drop sharply at night in my neck of the woods so that's significant too.
1600 in summer is a P.I.T.A!!
No hard and fast as the replies indicate - experiment!
Doug

[White Rabbit]

800 for me, when time is in short supply you need to catch as many photons as you can. I'd go 1600, buy on a 1000D it looks pretty bad.

[Garyh]

I like anything from 400 to 1600. Depends on the target. Bright nebs I use 400 and fainter objects I go higher to 800 or 1600 if it`s a cool night.
I have tried a comparison and all the images once stacked for the same period of time (say a hours worth) look pretty similar.

[RobF]

800 most of the time - 1600 rarely a goer at Qld temps. 400 if imaging an object with wide dynamic range (e.g Veil nebula has a bright star in the middle of it) or have the luxury of going for >1.5hrs worth of data.

[Geoff45]

The number of photons caught has nothing to do with the ISO setting. Photons hit the telescope objective and are reflected onto the sensor. Changing the ISO can't generate any more. If you expose at 400 ISO for 10 min or 800 ISO for 10 min, you collect exactly the same number of photons.

Geoff

[Geoff45]

Very true. As long as you taking RAW and are not saturating pixels ISO is almost irrelevant.
Geoff

[Octane]

ISO is relevant, though.

The higher the ISO, the more noise in your final image.

Stick with a lower ISO for a clean and (quite possibly) noise free image.

Regards,
Humayun

[telecasterguru]

What about ISO setings when using filters e.g. Ha. Do you need to bump the iso up and use longer exposures?

Frank

[jjjnettie]

In the near 3 months since this poll was posted I've taken on board what's been said.
I will only shoot in ISO 400 now.
The difference is incredible.

[Octane]

Thank you for vindicating me, Jeanette. ;)

Regards,
Humayun

[jjjnettie]

The lure of more instant gratification when you use high iso's though is hard to resist.:P

[troypiggo]

Is Humayun corrupting you too, JJJ? Taking away our quick gratification with the promise of cleaner, better quality images. It's a dirty trick, I tells ya.

[jjjnettie]

It's a sacrifice one has to make for the art.;)

[[1ponders]]

Unless its a good bright object ISO800 for me. Its the closest setting for unity gain (thought with the 20D it really splits the ISO at 1200, but being modded I'll still use ISO800). For me its a case of multiple images with higher ISO to improve the quality and S/N ratio rather than more -e/ADU to reduce the noise. (http://www.clarkvision.com/articles/digital.sensor.performance.summary/index.html#unity_gain)


If you've not taken the time to read the Clarkvision site I'd recommend it for those that would like to know a bit more about the inner machinations of DSLR chips. Slip down to part 4 and check out the links
http://www.clarkvision.com/articles/index.html#part_4

[RobF]

Interesting read. Thanks Paul. I won't feel quite so guilty sticking with 800 most of the time.

[jjjnettie]

I believe that the results speak for themselves.

[duncan]

Hi All,

I just voted 400 because of what i used to use with film SLR's.

Having said that i am thinking longer exposure = more noise due to thermal and electrical interference in a DSLR, so after trial and error 800 would be where i would probably end up.

Does my thinking make sense?

Cheers, Duncan:question:

[Phil Hart]

good topic for a hearty debate! I agree with the general sentiment from others that it often makes little difference.

In my view, it is not possible to make any generalisations across cameras.. you have to test your own camera to find out what works best. with my old 20D, i proved to myself that ISO1600 gave the best results for faint details.

with the 40D, there is very little difference between different ISO settings. here is my test comparing same total exposure time with different ISO settings (among other things):

http://www.philhart.com/canon_test

Here was my finding at the time: "There is little difference between ISO1600 and ISO800 with the 40D, with 1600 perhaps having a slight edge. Noise increases (only slightly!) at ISO400 and ISO200 without delivering any benefit in saturation or bright area detail."

Obviously higher ISO settings have higher noise in an individual exposure, but the signal also goes up. So what matters is the signal to noise ratio and whether that ratio gets better or worse as the ISO setting increases. The differences are often subtle since the ISO amplification will necessarily increase both signal and noise by close to the same amount (there being no such thing as a free lunch) with the end result being at least partly governed by read noise and other factors.

So every camera performs differently, but I think the 40D performance would be typical of a well engineered camera. But I encourage you not to place blind faith in generalisations nor pay attention to the grainy appearance of one high ISO sub. Take a series of subs with your camera under the same conditions at different ISO settings, stack them together and make an objective assessment of what works best.

Phil

[stevous67]

Noise? With or without cooling.

http://www.mpas.asn.au/Astro/Tips/cool_or_not.htm

Bye

Steve

[opticalsupports]

I've used both 800 and 1600 on a Canon 350D with roughly equal results. After post-processing I've never been able to notice a substantial advantage to either one, but my experience may be camera-specific.