ISO Sweet Spot

I was having a chat over lunch with a photographer friend who said he had come across a site (but couldn't remember where !)where someone was contending that the best IQ from a digital camera was not necessarily from it's lowest ISO setting. This got me thinking that it could be correct as this is essentially applying film based thinking to the digital world.

Alternatively this could of course be another urban myth and therefore a load of old toilet.

Anyone care to comment or provide a link to any tests online of this theory

I shoot in hard sunlight at ISO 200 all day long.

I want the dynamic range that the camera offers with a bumped ISO. So not myth for me.

cosworth wrote in post #2339164
I shoot in hard sunlight at ISO 200 all day long.

I want the dynamic range that the camera offers with a bumped ISO. So not myth for me.

sorry for my ignorance...but I'm very new and trying my best to get great quality photos lately...

what do you mean by dynamic range and how does a higher ISO help that? thanks, just a couple days into my SLR hobby

I also shoot at ISO 200, mostly because I don't trust the idea of an "L" setting on my 1D

L drops your dynamic range by a stop or two I've read. So I never use it.

Dynamic range is the ability ro see dark when there are bright highlights. Think black guy on the beach, sun behind him. Think you'll see him just fine in your pics? Nope. Lack of dynamic range from bright to dark. Metering plays big in this balance.

Cameras just can't see what your eyes do. It's out job with filters, polarizers, fill flash, lighting, exposure, good lenses etc. to mimic this to the best of our abilities.

Depending on the camera is where the sweet spot for ISO is.
For example I have been told that for 1DsMkII the sweet spot is at ISO200, however you will still get ever so slightly better pictures at ISO 100, because of other factors, but IQ will drop with ISO 50.

For the D60 it was ISO 100 (which was the lowest) and I suspect this was true for 10D as well.

I do know the sweet spot for Kodak SLR/C which I followed until I got a 1DsMkII was at ISO 64, even though the camera would go lower.

And a statement by Canon Rep said they are working on a base ISO 6400 camera.

Note that the sweet spot does not necessarily mean that is the ISO to get the best image quality from, It is just the spot at which the SNR for that sensor tends to be the best. This if course is likely to be the best spot, but not all the time.

I found that shooting 400 ISO or 200 ISO with Center Weight Averge Metering works well for me.

There was a thread on this yesturday, which mentioned this thread;
http://forums.dpreview​.com …19&thread=19721​647&page=1

A lot of good info.

I've read similar articles (and also can't remember where) that talked about sweet spots in ISO. The article pertained to the 30D since that's the camera I got. They pointed out that although it's nice to have the 1/3 stop ISO settings it was not desirable to use many of the 1/3 and 2/3 ISO's. I do recall they pointed out that ISO600 has less noise than ISO400 and there were a few other anomalies. I try to keep my ISO low but never heard anything about staying away from ISO100. I do happen to use 200 a lot but not because I was intentionally not using 100.

Any definitive information or stats on this?

EDIT: OOps. As I was posting the above post was created so I did not see that DPReview link.

I also shoot normally @ iso 200 but have no prob jumping it up whenever I need too. I normally never use iso 100.

There is no scentific basis to suggest higher ISO boosts dynamic range. In fact it decreases it. I am afraid this is little more than rumor.

Dynamic range is the range covered by the shadows and the highlights. The greater the dynamic range the less likely you will lose the shadow detail but also the highlight detail.

http://www.cambridgein​colour.com/tutorials/d​ynamic-range.htm

http://www.dpreview.co​m …/00111608dynami​crange.asp

The 30D's is apparently 160

John Sheehy, the OP in the above linked DPR thread, showed last year on the Rob Galbreith site (RIP)that for the 20D a 200 ISO RAW has greater DR than a 100 ISO because at the lower ISO the camera sets a RAW whitepoint of around 3500 instead of using the full 4095 levels afforded by 12 bit. At the other end of the DR, if 100 ISO gave a better S/N ratio in the shadows that would compensate for the loss at the high end, but in fact there is hardly any difference, so 200 ISO is the better choice.

http://forums.dpreview​.com …rum=1019&messag​e=19721647
160 ISO is the best for the 30D

siejones wrote in post #2339996
There is no scentific basis to suggest higher ISO boosts dynamic range. In fact it decreases it. I am afraid this is little more than rumor.

Dynamic range is the range covered by the shadows and the highlights. The greater the dynamic range the less likely you will lose the shadow detail but also the highlight detail.

http://www.cambridgein​colour.com/tutorials/d​ynamic-range.htm

http://www.dpreview.co​m …/00111608dynami​crange.asp

Well on my camera it does (1Ds). I shoot on the beach all day long. My jpgs at ISO 50 look like crap and demand fill flash. Iso 200 and I can get the most from my metering system and require less fill flash.

Real world experience, not some guys testing one camera model against a wall.

Read your Cambridge colour link again:


"Note: In some digital cameras, there is an extended low ISO setting which produces less noise, but also decreases dynamic range. This is because the setting in effect overexposes the image by a full f-stop, but then later truncates the highlights-- thereby increasing the light signal. An example of this is many of the Canon cameras, which have an ISO-50 speed below the ordinary ISO-100. "