Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old May 22, 2008, 8:03 AM   #11
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Gábor Horváth (the author of Raw Therapee ) is one of the people that have analyzed the 40D raw files, and he's gots some posts on the subject in some of the other forums.

Apparently, Canon is either pushing or pulling some of the values (sometimes pushing, sometimes pulling from 100, 200, 400, etc.) to simulate the ISO speed settings used in the intermediate steps, based on his analysis of the raw data. For example, ISO 125 is pushing ISO 100. ISO 160 is pulling ISO 200. He refers to it as stretching or shrinking. He says that if you are shooting raw, there is no need to use the intermediate values. As for jpeg, he's got comments on the impact of approaching it this way.

He's very good at this stuff. Make sure to try his raw converter if you have a chance. It's free, and you can dowload version for Windows or Linux. Here's a list of some of it's features (not including those added in the latest version 2.4 Milestone 1 development snapshot that you'll see links to at the bottom of the download page).

Raw Therapee v2.3 Features

I don't like to send others to another forum. But, I'll make an exception so you can see the data and how it works. You'll find multiple posts from him with different info in This Thread

JimC is offline   Reply With Quote
Old May 22, 2008, 12:46 PM   #12
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

My bad (open mouth, insert foot). It looks like this might be a different Gaybor judging by the signature on his Panos (but, he still develops imaging related applications, raw analysis tools, raw conversion tools, etc.) if you check his posting history.

JimC is offline   Reply With Quote
Old Jun 11, 2008, 10:18 PM   #13
Senior Member
 
airbrushjohn's Avatar
 
Join Date: Feb 2007
Posts: 747
Default

well i'm really confused about all of this techie stuff, so i'll just post a shot i took at 3200 with no noise reduction, just a lil usm.
Attached Images
 
airbrushjohn is offline   Reply With Quote
Old Jun 13, 2008, 12:19 PM   #14
Junior Member
 
Join Date: Feb 2007
Posts: 27
Default

I found these sites about this...

http://www.adidap.com/2006/09/09/can...-iso-vs-noise/

http://forums.canonphotogroup.com/showthread.php?p=5225

As for the upper end...I find the limit of smooth noise on my 30D to be 1250...at 1600 noise starts getting blotchy...
digikita is offline   Reply With Quote
Old Jun 23, 2008, 11:02 AM   #15
Senior Member
 
aladyforty's Avatar
 
Join Date: Jan 2004
Posts: 6,964
Default

I knew ISO640 had less noise than 400 in my camera:-) and the graphs pove it
aladyforty is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 3:29 AM.