The little girl wants to buy a SLR camera. Let an expert recommend it!

The background blur effect is determined by the lens. If you use your 350D with a 50/1.4 or 85/1.8 lens, the blur will be a mess, so I suggest you consider changing the lens and camera. It doesn't solve your problem. Even if you change your camera, you still have to consider what lens to use.

You are right, 50/1.4 refers to the focal length of 50 and the aperture of f1.4. There are also 50/1.8. Remember, the smaller the f number, the more expensive the lens, and of course the effect will be better. If you are not a professional photographer, 50/1.8 is enough. The cheapest one is less than 700 yuan. The 50/1.4 costs two to three thousand (but this lens is indeed one of the favorite lenses among photography enthusiasts). Prices vary from place to place, so ask yourself. Fixed-focus lenses like those 85/1.8, 100/2, etc. are very expensive and have a small practical range. Non-professionals usually do not consider these lenses. It is recommended that you ask experienced people to find out first, because Canon has more than 60 types of lenses, and the prices range from a few hundred to hundreds of thousands. Not everyone can afford it. As the saying goes, only buy the right one and not the other way around. Expensive ones are the most suitable ones that meet your needs. You must carefully consider spending money on them.