"They are quite valuable; but even with a card one must often use
his own judgment as to just what stop to use and how much time.
If you are particularly anxious about a picture you had better take
two or three exposures of it, instead of only one. Even the best
of photographers occasionally fail to get good results on a first
trial."

After that Mr. Jally brought forth several cameras he had used in
outdoor work and explained how they might be used to the best
advantage in taking different kinds of pictures and under various
conditions.

"Strange as it may seem," he said, "no two scenes can be handled
alike. In one the background may be very light and in the other very
dark. One day the atmosphere may be very clear, the next it may be
very dense."

"Yes, we know that, and we have found out that clouds over the sun
make a big difference," said Snap.

The boys spent the balance of the morning and nearly all of the
afternoon with the photographer, and learned many things of which
they had been formerly ignorant. He recommended that they purchase
and study several books on photography, and this they agreed to do.

"I see by the letter that Dr. Reed wishes me to pick out your
cameras," said Mr. Jally. "I am going to the city Saturday and
will get them and leave them at the doctor's house Saturday evening."

"And will you get the films and plates and other things, too?"