I am an Indian passport holder having a Schengen student visa, I have a layover of 22 hours at Istanbul airport on my flight back to Mumbai from Leipzig, Germany.
I want to know if I need a transit visa if I wish to go sightseeing in Istanbul for those 22 hours. If I need one, then is it a different visa for transit or the same as a normal e-visa? Will I be able to travel on my Schengen visa? I am travelling with Turkish airlines.
So, yes it would seem you do need a visa if you want to leave the airport even if you have a valid Schengen visa. This is the relevant portion from the link for Indian citizens,
Ordinary, Special and Service passport holders are required to have visa to enter Turkey. Ordinary, Special and Service passport holders with a valid Schengen or OECD member's visa or residence permit may get their single entry e-Visas valid for one month via the website www.evisa.gov.tr, provided that they meet certain conditions.
http://www.mfa.gov.tr/visa-information-for-foreigners.en.mfa
