ISO 100 vs 400

I was doing some lens testing today looking for the sweet spot on all of my lens. It was a nice bright sunny day and after getting back and checking the results I noticed that all of the test I shot at 400 iso was better than the ones I shot at iso 100. I was using a 7d and various lens. As anyone found 400 iso is giving you better results than iso 100? All my photos were taken on a tripod using a timer.

Better how? If you're underexposing at 100, then properly exposing at 400 is going to look better.

I was shooting in av and letting the camera adjust the shutter speed using the same location to get the meter reading all look properly exposed. It just seemed the color and detail was a little better at 400 on all 8 lens I tested. I did not keep the photos but I think I will run the test again this weekend. I also used a few nikon lens and got the same results.

That was probably your camera's way of telling you to stop using Nikon lenses.

What mode were you shooting in? Unless our were shooting manual, changing iso is going to either change your aperture or change your shutter speed. Both of which could have an effect on IQ.

Can you post some images and some 100% crops of them? Your statement is kind of vague to consider "better" in ISO 100 vs 400... Was it the same exposure? Same focus? Did the iso 400 shots have better sharpness, highlights, shadows, contrast, saturation?

It sounds like you were having some sort of vibration issue with your tripod, and that the faster shutter speed at ISO 400 isolated you from it, but ISO 100 didn't.

Whenever I use higher ISO, my images turn to magic! Significant improvment!!!

ISO 6400 is my sweet spot! I get the best colors/contrast with a pinch of pixie dust in there too

Going from an iso of 100 to 400 will give you 4 x the shutter speed assuming aperture remained constant. That's what is most likely skewing our results.

Hard to believe. Pics?

stlouis_26 wrote in post #12347582
I was doing some lens testing today looking for the sweet spot on all of my lens. It was a nice bright sunny day and after getting back and checking the results I noticed that all of the test I shot at 400 iso was better than the ones I shot at iso 100. I was using a 7d and various lens. As anyone found 400 iso is giving you better results than iso 100? All my photos were taken on a tripod using a timer.

Just post a pic of the best ISO100 capture & the best of the ISO400 and let us see them with the exif intact. If you used a tripod and the 2sec. delay timer in AV mode the only difference would be a higher SS with the ISO400 providing the ambient lighting conditions remained the same during your captures with the same specific lens.

If you were outside and taking shots in between cloud cover and bright sun that would have an effect in AV mode.

What metering mode were you using and were you using AWB ?

Lots of variables can effect time lapsed shots.

Regards,

What tripod? BTW, the sweet spot on all of your lenses should be somewhere 1 to 2 stops from wide open. That's a good rule of thumb for just about any lens.

ISO 100 will always produce better images than ISO 400 assuming that both are properly exposed. That is, the noise will always be lowest at ISO 100, so the image will also hold more detail. However, ISO 400 is so good these days that the difference may be almost impossible to see even in a 12"x18" print. My standard ISO is 200, but I'll go up to 800, 1600, or 3200 if I need it for low light without flash.

There are only two possibilities for why your ISO 400 may have been better than ISO 100:
1. Something was moving in the scene (wind in the trees? subject motion?), so scene motion was frozen better at a higher shutter speed using ISO 400.
2. If the exposure change between ISO 400 and ISO 100 was accomplished by opening up the aperture by two stops, then ISO 400 could well have been shot at the best aperture for each lens (typically about 2 stops down from wide open), while ISO 100 was shot wide open and thus not at the optimum aperture.

If you're testing anything, the lowest ISO and tripod is paramount.

Actually I did not keep the photos after I got the best f/stops recorded. I will try and do a re-test this weekend. By the way I switched to Canon from Nikon when I went digital. I could see no need to get rid of my lens so I got a converter and it works fine. I find both cameras produce good results but I really like the Canon controls layout much better than the Nikon.