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View Full Version : using the 70-300 at high iso


alexs
20th May 2010, 12:57 PM
I've been learning the ropes with this lens and experimenting with high iso so I thought I'd share my experience...
Basically I started off trying iso 1600 on my e-520... weirdly I got 99% grainy rubbish except this one, and I think a couple of others. I've no real idea why except perhaps that it didn't need to be cropped (or very little) and the subject was nice and close. I'm thinking that "might" be the secret to iso 1600?? could well be wrong though...

http://i42.photobucket.com/albums/e309/alexsally/P2123330-1.jpg

When I shoot iso100-200 I can crop (hard) and still get a clear (ish) result. Also this fella was about 90 feet away! not bad... but you need better light than we often get..

http://i42.photobucket.com/albums/e309/alexsally/P1302491.jpg


Finally this singing robin was at iso-800 and about 12 feet away. I've no idea what the rule of thumb is here. 800 is sometimes ok? All of the ones i took at iso 800 I ran through the free noiseware software and set the filter to "weak noise". Don't really know what I'm doing withh it but the result is ok...


http://i42.photobucket.com/albums/e309/alexsally/P5014528_filteredWEAK.jpg



I think so far I'm concluding that the raising the ISO is somewhat like lowering the pixel count.... THe result will be fine but you can't expect to crop so heavy. Also as Zig says its not to be feared, the results can be good. Oh and the noiseware stuff works a treat and takes about 3 seconds

al


155314

Nick Temple-Fry
20th May 2010, 01:26 PM
Three nice bird photos.

You are right in your comment about cropping or indeed enlarging, either spreads the available pixels over a larger area and makes things like noise more apparent.

The other thing I notice is you've got good exposure on all three images (particularly the last two) - not only on the subject but also the background. And good exposure is the key to combatting noise (better the exposure then the better the ratio of good information to bad noise). If you are after the iso limit then watch the histogram, a good strong centred histogram is a good indicator of lots of healthy pixel information.

Nick

alexs
20th May 2010, 01:30 PM
Three nice bird photos.

You are right in your comment about cropping or indeed enlarging, either spreads the available pixels over a larger area and makes things like noise more apparent.

The other thing I notice is you've got good exposure on all three images (particularly the last two) - not only on the subject but also the background. And good exposure is the key to combatting noise (better the exposure then the better the ratio of good information to bad noise). If you are after the iso limit then watch the histogram, a good strong centred histogram is a good indicator of lots of healthy pixel information.

Nick


wow, thats good to know :)
by good exposure do you mean no blown highlights and not too dark. I noticed if they were too dark at high ISO then there was no saving them...
al:)

Nick Temple-Fry
20th May 2010, 02:01 PM
Well the histogram is a mysterious beast, very much the chameleon of digital photography. But its worth watching and it should follow what you expect from the scene. So in the first shot it is bunched around the middle, which is what you would expect for a shot of a robin against a dark back ground, the other two shots show histograms with wider distributions - again what you would expect. Luminous landscape do a good introduction

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

Your too dark comment is a good one - if everything is dark then you've got the noise (which always follows the iso, it's a characteristic of the sensor) but relatively little actual picture information, so the noise wins). So a good exposure should have good strong peaks where you would want/expect them.

Nick

alexs
20th May 2010, 02:07 PM
good link thanks.. With a bit more practice and the histogram info hopefully I should get my "keeper" rate up a bit..:)
al

Jim Ford
20th May 2010, 07:54 PM
... and the exposure of the histogram shall be to the right.
Neither shall it be to the left, lest it be also spread to the right.
Bunched to the left is right out!

(Apologies to Monty Python)

Jim