A Usage Guide to Spanish Grammar and Idioms (ISBN 0 -673 - 57609-A) presents one use of "cuanto (a - os - as)" thusly: As an indefinite adjective = "As many as, as much as, whatever." It then presents these examples; (1) Te daré cuantas fotografías quieres. (If the number is known: the indicative is used.) (2) Te daré cuantas fotografías quieras." (if the number is not known: the subjunctive is used).
It gives the translation to English in both examples as: "I shall give you as many photographs as you want." Why is there a "choice" of verb forms in Spanish?
One more related question: I read the subjunctive is used when an uncertainty is expressed in the independent clause. Isn't an "uncertainty" clearly established by the use of "cuantas" in this example, therefore making the use of the indicative form erroneous?