The following quote has a comma after it:
There is, in fact, not much point in writing a novel unless you can show the possibility of moral transformation, or an increase in wisdom, operating in your chief character or characters.
But [this quote](www.goodreads.com/quotes/312171-there-is-in-fact-something-obscene-and-sinister-about-photography ) doesn't:
There is in fact something obscene and sinister about photography, a desire to imprison, to incorporate, a sexual intensity of pursuit.
When should you use a comma after "there is in fact"?
Is it necessary to put a comma after "there is in fact"?