ISO 3200 with a Minolta A2

Last Updated 17 Nov 04
Copyright 2004 by Stephen Vermeulen

The Minolta A2 normally only lets one set a film speed of ISO 800. For the most part that's high enough, especially with the amount of noise one gets in the images. But there are times when one might wish for more, such as:

Taking action photographs in available (low) light, where you wish to use a higher shutter speed to minimize motion blur
Pushing the limits of hand held photography

But what about the noise? There exist a number of noise reduction programs, which do a pretty good (even remarkable) job of eliminating the high ISO noise. The downside is that they also introduce some filtering of the image, so sharp details start to get lost. But these programs do allow you to get some nice photos under lighting conditions that would otherwise make the task impossible. Take a look at these packages:

Helicon makes NoiseFilter, a image noise filtering program that is available in free and professional versions.
NoiseNinja2 gets reviewed here, this is a commercial package that is highly recommended by others
Noiseware, from Imagenomic, looks like a good (free) noise reduction package for high ISO shooting. This is quite impressive at what it can do with ISO 800 shots from a Minolta A2 (which are quite noisy). Have a look at this gallery for some examples that have been processed by it. Also have a look at these images I processed with it.

After playing with Noiseware on some photos that I had shot in available light at ISO 800 at the Calgary Zoo I realized that this noise reduction package was providing me with a significant functional gain: while there was some loss of image sharpness due to the filtering it was more than offset by the reduction in the noise level. This meant that instead of generally shooting only up to ISO 200 I could now push things to ISO 800 and still get reasonable photographs.

I showed the results of these tests to a friend of mine who shoots with a Canon Digital Rebel, thinking that he might be only academically interested in this, as his D-SLR has much lower noise than my A2 due to its larger sensor. However, to my surprise, he sent me a couple of sample photos where he had used this tool to good effect. Turns out he's had some under exposed photos that he had been partially able to salvage by increasing the brightness in PaintShop Pro, but when he did this the noise became an issue, running Noiseware on these helped a lot.

This got me thinking, perhaps if one intentionally underexposed one might be able to salvage the results in post-processing and thus simulate the existance of higher ISO settings. To do this on the Minolta A2 is quite easy, just select the basic ISO you want to shoot at and then hit the exposure compensation button and dial in a -1.0 or -2.0 setting. Then the camera will meter the scene as if you were shooting with high ISO settings. For example if you set the camera to ISO 800, the exposure compensation of -1.0 yields an ISO 1600 exposure and a -2.0 compensation yields an ISO 3200 compensation.

To try this out I shot a few pictures of the street outside my house at night (all handheld with the aid of the A2's antishake, and lens set to the 28mm wide angle for the first one), the first is a 1.6 second F3.2 exposure at ISO 800:

[Click on these photos to see full sized versions]

when this is processed by Noiseware on default settings I got:

Which is actually pretty amazing considering this is a handheld shot by street lighting. I was pretty lucky with the camera shake, I don't think I'd be able to take many like this at 1.6 seconds, even with the anti-shake system. Because of this I dialed in a -2.0 exposure correction (to underexpose as if I was pushing the sensor to ISO 3200) and shot the following (I must have moved the zoom a bit, as this photo is a 33mm lens setting):

Simulated ISO 3200, 1/3 sec F3.2, handheld

Now I have not made any attempt to brighten the image at this point. And here is the image with noise filtering applied:

this time I applied a bit less than the default noise filtering settings.

Next I brightend the initial (unfiltered ISO 3200 shot), to get this:

You can see there is a lot of noise now, so I applied the noise filtering to get this:

All of the above work was done in JPEG mode. Since RAW format records 12 bits per pixel rather than 8 bits in JPEG I would like to try shooting in RAW and then doing more post processing.

In November 2004 this thread started discussing the same sort of idea, in this case they were intentionally underexposing but setting the camera to ISO 64 instead of ISO 800 as I had done. It appears that one might get better results this way.

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