When court probation is granted in a felony case, that ruling automatically converts the felony to a misdemeanor. Penal Code 1203(a). When a conditional sentence is granted on a wobbler, the wobbler becomes a misdemeanor by operation of law. People v. Glee (2000) 82 Cal.App.4th 99, 105-106, People v. Taylor (2007) 157 Cal. App. 4th 433, 437. A grant of informal or summary probation is a "conditional sentence." (Pen. Code, 1203(a). (citations omitted). This is because such a disposition is available only in misdemeanor cases (that is, felony probation must be "formal").

Conditional sentences are authorized only in misdemeanor cases. (Pen. Code, 1203, subd. (a) ["It is the intent of the Legislature that both conditional sentence and probation are authorized whenever probation is authorized in any code as a sentencing option for infractions or misdemeanors"]; 1203, subd. (d) ["If a person is convicted of a misdemeanor, the court may either refer the matter to the probation officer for an investigation and a report or summarily pronounce a conditional sentence"]; 1203b ["All courts shall have power to suspend the imposition or execution of a sentence and grant a conditional sentence in misdemeanor and infraction cases without referring such cases to the probation officer"].)

Examples: sentences of:

[1] 30 days in jail and formal probation does not make a felony a misdemeanor.
[2] 30 days in jail with informal probation makes a felony a misdemeanor.
[3] 30 days in jail with no probation makes a felony a misdemeanor.

Thanks to Dan Mayfield and Paul Upton.