A DSLR copy setup can work well, especially for quickly archiving lots of 35mm color negatives or slides if you already own the gear. RAW capture also gives flexible editing.

The main advantages of a dedicated film scanner are:

• dust/scratch removal via infrared systems such as ICE/FARE, which can make a huge difference on old film
• features like multi-scan to reduce noise
• a purpose-built holder/alignment system, so geometry is more consistent

The main drawbacks of the DSLR method are:

• more manual setup and alignment
• extra post-processing for rotation, cropping, and possible lens distortion correction
• dust becomes a bigger cleanup problem because you don’t get scanner-style IR dust removal

Resolution depends on your camera and setup. A DSLR may be good enough for many 35mm archiving needs, but it may be less convincing for medium format color or very fine-grained 35mm black-and-white if maximum detail is the goal.

So the DSLR approach is strongest when speed of capture and low cost matter, and when archiving is more important than extracting every last bit of quality. A good scanner is usually better for consistent quality, cleaner results, and damaged or dusty film.