ISO L

[gregf]

<p>Back in the film days I frequently shot ISO 25 or 64 Kodachrome for waterfalls, it avoided having to use a ND filter. Those days are gone (RIP Kodachrome).</p>

<p>So here is my question, if read conflicting accounts: How does ISO L (sic 50) impact IQ? As an FYI, I'm using a 5D Mk2. Any thought are appreciated.</p>

<p>Thanks</p>

[William Michael]

<p>No theory from me on the topic - only practical testing (aka “lots of controlled playing” with it).<br>

I cannot detect any notable IQ difference using “L” (AKA ISO 50 i.e. Cf.I-3) than from using ISO100, on my 5D MkII.</p>

<p>My suggestion – let it rip (RIP) – pun intended - just use ISO50 and decide for yourself: I doubt you will be disappointed.</p>

<p>WW</p>

<p>. </p>

 

[William Kahn]

<p>I agree with the other William (5D2 here, also). Perhaps, to a seriously compulsive pixel peeper, there might be some difference betwee ISO 50 and 100. But, on the web, or in a, say, 16X20 print, I doubt it...</p>

[ed_avis2]

<p>My understanding is that the 'L' setting is not a real change to the light sensitivity of the sensor. Instead it overexposes the image by one stop and then undoes that in software. Your manual will probably warn that using 'L' loses one stop of dynamic range. What this means is that highlights will get blown out at one stop less brightness than normal. So I don't think the 'L' setting achieves anything you couldn't do yourself by putting in +1 stop exposure compensation.</p>

<p><br />(If this isn't the case on the 5D Mark II I apologize - this is what I recall about 'L' on other Canon bodies.)</p>

<p>You do have the option of taking several exposures and merging them in software. Instead of one five second exposure, take five of one second each. Any image editing or photo editing program will let you blend them into one image.</p>

[nathangardner]

<p>Ed is right, ISO 50 is simply a one stop pull of ISO 100. You could shoot ISO 100 then pull the exposure a stop in post and essentially get the same thing. I try to always use ISO 100, but I will bump down to ISO 50 to avoid adding a ND filter if I need to slow the shutter, but if a filter is inevitible, then ISO 100 is your winner. The only time I use ISO 50 is if I can get away with it without using a filter.</p>

[JDMvW]

<p>Ed+Nathan +me, from what I hear. However, I have gone to ISO 50 for the very reason you mention:</p>

[JDMvW]

<p>.</p><div></div>

[William Michael]

<blockquote>

<p>“My understanding is that the 'L' setting is not a real change to the light sensitivity of the sensor. Instead it overexposes the image by one stop and then undoes that in software.”</p>

</blockquote>

 

<blockquote>

<p>“Ed is right, ISO 50 is simply a one stop pull of ISO 100.”</p>

</blockquote>

<p>For clarity of my comment, I was not suggesting otherwise – just stating that I cannot see any significant difference in the comparative shots I’ve made: ISO50 vs. ISO100. Also, I suggest I am pretty conservative about the blown highlights, anyway.</p>

<p>WW<br>

</p>

[denisbergeron]

<p>Use iso-100 and multiple (3) exposures and merge them in you favorite image manipulator program... you will have better DR and a quasi iso-33 exposure.</p>