When choosing a LED light pad with a high CRI rating for digitizing negatives with a digital camera, there are a few factors to consider:

CRI rating: Choose a light pad with a high CRI rating, ideally above 90. CRI stands for Color Rendering Index and measures how accurately a light source displays colors compared to natural daylight. A high CRI rating will ensure that the colors in your negatives are accurately captured and reproduced.

Size: Make sure the light pad is large enough to accommodate the size of negatives you plan to digitize. Some common sizes for 35mm negatives are 8.5 x 11 inches or 9 x 12 inches, but larger negatives will require a larger light pad.

Color temperature: The color temperature of the light pad should be around 5500K to 6500K, which is close to daylight. This will provide a neutral white balance and prevent color casts in your images.

Even illumination: The light pad should provide even illumination across the entire surface, without any hotspots or dim areas. Look for a light pad with a diffuser panel or frosted surface to ensure even illumination.

Portability: If you plan to use the light pad in different locations or for travel, consider a light pad that is lightweight and slim, with a USB connection for easy connectivity to your computer.

Some popular LED light pads with high CRI ratings for digitizing negatives include the Huion LB4H. Ultimately, the best choice will depend on your specific needs and budget.