...
class ModelWithDefaultStaticImage(models.Model):
    image_file = models.ImageField(default='img.png')class officeUsers(models.Model):
    ....
    photo = models.ImageField(verbose_name='Фотография',
                              upload_to='photos/%Y/%m/%d',
                              blank=True)
    ....<div class="user_img">
      <img src="{% if user.photo %}{{ user.photo.url }}{% else %}{% static 'sysadmins/img/avatar.jpg' %}{% endif %}" alt="">
</div>