Yah; it might be better to buy an app rather than use free, but there are an awful lot of free apps out there you can try.
Check out http://idevicesworld.com/articles/are-all-tuners-created-equal-–-iphone-apps. They do a comparison of a few tuners.
Cleartune is great. Not just equal temperament but many different systems.
To tune or not
I had purchased an iPhone based tuner some time back, but (despite the ease of use) I didn't use it all that much when playing. Aside from keeping me from tuning to the group standard (which can vary if your piano or string section tends sharp), it ran the phone's battery down too much.
And, I'm not one for playing a job with the tuner running on the stand in front of me. If you need a tuner to tell you where you rest within a group's intonation, then there's something wrong with your ears, or your "audible picture" (to coin a phrase). Spending more time playing as a section will help this far more than any mechanical or electronic device.
However, at gigs I do use a iPhone timing application called Chronology, which allows me two custom timers for our fifty minute hours. One count down to zero from 50:00, while the other counts up to 50:00 from zero, making it easy to make the amount of music played fit the time allotted.
If I see, because of extended patter by the vocalists, or because of slight delays caused by audience interaction, that we are going to run a bit long if we do the whole programmed set, I can pick an appropriate tune to drop (I even have three of these preselected and "grayed out" on the set list.) Conversely, if I decide to change out tunes as we go and plug in some from our Reserve set, I can compute the approximate additional running time needed and make decisions from there.
I have a iPhone charger and custom six foot cable (with a locking attachment plug for the phone) that are fused together (with a clever series of shrink wrap tubes), and just leave the phone on the whole time during the job - it even can deal with incoming calls (which go to voicemail), returning to the forefront automatically.
I had purchased an iPhone based tuner some time back, but (despite the ease of use) I didn't use it all that much when playing. Aside from keeping me from tuning to the group standard (which can vary if your piano or string section tends sharp), it ran the phone's battery down too much.
And, I'm not one for playing a job with the tuner running on the stand in front of me. If you need a tuner to tell you where you rest within a group's intonation, then there's something wrong with your ears, or your "audible picture" (to coin a phrase). Spending more time playing as a section will help this far more than any mechanical or electronic device.
However, at gigs I do use a iPhone timing application called Chronology, which allows me two custom timers for our fifty minute hours. One count down to zero from 50:00, while the other counts up to 50:00 from zero, making it easy to make the amount of music played fit the time allotted.
If I see, because of extended patter by the vocalists, or because of slight delays caused by audience interaction, that we are going to run a bit long if we do the whole programmed set, I can pick an appropriate tune to drop (I even have three of these preselected and "grayed out" on the set list.) Conversely, if I decide to change out tunes as we go and plug in some from our Reserve set, I can compute the approximate additional running time needed and make decisions from there.
I have a iPhone charger and custom six foot cable (with a locking attachment plug for the phone) that are fused together (with a clever series of shrink wrap tubes), and just leave the phone on the whole time during the job - it even can deal with incoming calls (which go to voicemail), returning to the forefront automatically.