SLR Pentax kr rookie asked, what aperture and focal length is better for taking a group photo of about 70 people? How to set it if it is all manual?

If you take a group photo, a small aperture is necessary because you want to lengthen the depth of field.

If it is 18-55, the best aperture of this head is 8- 1 1, and better image quality and less dispersion can be obtained within this aperture range. For other lenses, the best aperture may be larger than f8, but considering the depth of field, a large aperture is not recommended, so unless there are special circumstances, the aperture of f8-f 1 1 is a reasonable choice.

Full manual exposure is not recommended here, because SLR provides metering function, and the exposure time depends entirely on the scene. My suggestion is to use Av files, set the aperture, and then use partial metering or global metering.

The most direct solution is to take more photos under various settings and choose the best one.