I want to buy a Canon 550 SLR. I heard that the lens of SLR is too long and the body is too big, which is not suitable for home use. It is recommended to buy a Canon J 12 SLR standby machine.

The Canon J 12 you mentioned is a slightly better quality card machine. Don't listen to people say "SLR backup machine", there is no such thing. Because its sensor area is much smaller than the entry-level SLR, the imaging quality is necessarily better than that of single contrast, and the lens cannot be changed. The optical quality of this lens is not comparable to the worst lens of SLR camera. Its imaging quality is much better than single contrast.

However, the key question is: Do you want to study photography seriously? If you don't want to just record your life and take commemorative photos, then I advise you not to buy a SLR. Although the SLR is much better than the card machine, the control is not so easy to master. It is not as "stupid" as a card machine, and it only uses automatic function to shoot, and the film it shoots is not much better than a card machine. The film taken by the setting difference is worse than that taken by the card machine.

If you really want to study photography seriously, you can buy a SLR. The entry-level SLR can consider Canon 550D and Pentax K-R. Nikon's entry-level SLR has functional defects. (Canon 550D also has no anti-shake of the fuselage).