Hi Kristie- It is very difficult to shoot indoors without a flash. What is required is a fast lens, which the Diana does not have,maxing out at F/8. For comparison, a good 35mm slr can have a lens that can open up to F/1.4 or better which is a much larger aperture than what the Diana Mini has.

What does that mean? Let's say that in a room with a lamp or two on, the SLR requires an exposure of 1/4 of a sec, at F/1.4 on a ISO 200 film. To get an equivalent exposure with a Diana Mini with an aperture of F/8 would require a 2s exposure.
The F/stop progression goes like this.
F/1.4 - 1/4s, F/2.8 - 1/2s, F/5.6 -1s, F/8 - 2s
These are all equivalent exposures, under a hypothetical situation. The correct exposure in a real situation will depend on how much light is present.

Now, to get back to what it would take to shoot with the Diana Mini indoors. We can't change the lens, because we're stuck with f/8 being the fastest lens available. We can extend the exposure, but our only shutter option is N (1/100s) and B (open for as long as you hold the shutter down). You can use the B setting, but doing so will require a support of some kind. You need to brace the camera or mount it on something like a tripod. This will help reduce camera shake. You should also use a cable release, because pushing down on the shutter lever can also cause camera shake, which will give you blurry photos.

Another thing we can do to improve our chances of getting a photo is to increase the film sensitivity. Using a higher ISO film can help the Diana Mini get a better low-light exposure. Look for film with ISO 800 or 1600.