Sewing machine and non-transitory computer-readable medium storing sewing machine control program

A sewing machine, comprising:

• a needle bar;
• a sewing machine motor configured to drive the needle bar up and down;
• an acquisition portion configured to acquire a reference length that is a length of a stitch portion in a reference direction, the stitch portion being at least one part of a stitch set that is to be sewn on a sewing object;
• an image capture portion configured to generate image data by image capture of one of the sewing object and at least one marker that is moved together with the sewing object;
• a computation portion configured to compute an amount of movement of one of the sewing object and the at least one marker, based on at least the image data that have been generated by the image capture portion;
• a speed control portion configured to set a revolution speed of the sewing machine motor to not greater than a specified value in a case where it is determined, based on the amount of movement that has been computed by the computation portion, that sewing is being performed in a specified range that has been set at an opposite side of the stitch portion from a starting point of the stitch portion in the reference direction;
• a sewing control portion configured to terminate the sewing of the stitch portion in a case where it is determined, based on the amount of movement that has been computed by the computation portion, that a length that has been sewn in the reference direction of the stitch portion is not less than the reference length that was acquired by the acquisition portion:
• and
• a presser bar to which a presser that is to be used when a buttonhole stitch is sewn is detachably attachable, the presser including a support portion detachably attachable to the presser bar and a presser portion configured to press on at least a portion of the sewing object and supported by the support portion such that the presser portion is movable together with the sewing object,
• wherein a plurality of the markers are provided on the presser portion, and an interval between the plurality of markers in the reference direction is shorter than a length in the reference direction of an image capture area of the image capture portion.