To avoid blurry photos you have to know the shutter speed limit for yourself. There are several things that have an impact on that:
- Your physical condition, weight of equipment, position
- Focal Length
- Crop factor
To be able to calculate the minimum shutter speed limit, you have to take lens’ focal length, then take the crop factor and multiply your focal length by crop factor. OIS can help you to gain from 1 to 3 stops so it may be less than that. However, this will only work if the person or element you are trying to photograph is stable.