It is ALWAYS better to shoot at a low ISO if you don’t want a lot of grain in your images. 100 or 200 are the best to work with if you don’t want any grain. The more light you have the less chance you have of shooting a large ISO. If you can’t afford strobes you can look for cheap work lights work lights from Home Depot or a hardware store.
Using a lens with a wider aperture will allow more light to come in, something like the 5omm 1.4 is a great choice.
Open up your aperture and slow down your shutter speed with a tripod to get a lower number. Newer DSLRs allow you to shoot at a higher ISO without noise, but be careful how far you push it. Shooting tethered is a good idea to check and make sure you’re getting the effect you want.
If you have noise in your image and you can change it to black and white it often times looks much better.
If that’s not an option there are a couple options for fixing it in post. The one that I think works best is Filter-Noise-Reduce Noise. I always bump up the Strength all the way and check preview to see the difference in my photo. You can then bring up the Preserve Details slider to keep information and make the image less blurry, but do it subtly or you will just add the grain back in.
The next step we’ll try is Filter-Blur-Surface Blur. This can be used to blur the background slightly to make the image look overall cleaner. You can play around with the Radius and Threshold level. Some areas will look great while others don’t, so use a layer mask to affect only the areas that don’t have a lot of detail.
I’ve never used Noise Ninja but it has great reviews. This is a plug-in you can use with photoshop to reduce grain in your photos.
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