As a practicing Traditional Catholic and a photographer, I have photographed the Mass during the liturgy several times. And frankly, I always feel awkward and badly about doing it. But the truth is that Traditional priests want the outside world to see the majesty of the Mass and it is the preservation of a historical practice to photograph it. So what's the best way to get it done? Here are a few do's and don't's:
DO: If at all possible, ask the priest ahead of time if he would mind you taking some discrete photos during the Mass. If you cannot find the priest, you can still take some shots but be respectful above all else. If you see the priest turning around during the liturgy or trying to tell you not to, just stop. Nothing is more important than the worship itself, not even a photograph.
DON'T: Don't get out of our pew and walk around to get a good angle. It is inappropriate to walk around while the Mass is going on, especially during the Consecration (see picture above). This is the most sacred part of the Holy Mass.
DO: Find a good seat in a front row pew if possible. This will leave your view relatively unobstructed.
DON'T: Straight on shots from behind require standing or kneeling in the middle of the aisle. While this might seem like the best angle, it is very disruptive to the liturgy. Side angles or diagonals make for great shots and you won't have to embarrass yourself by being ushered out of the sanctuary.
DO: If you need a straight on angle from directly behind the priest, check ahead of time to see if you can shoot from the choir loft. It's in the rear and out of the way, but you'll need a good zoom lens.
DON'T: DON'T USE A FLASH!! EVER!!!!! This is the most annoying, distracting things a photographer can do. If you know how to use a camera, you don't need the flash anyway. You may need to put your ISO on "auto" and set it at a decent shutter speed, but a little bit of "noise" (referring to the graininess of the image) is superior to disrupting the Mass. And frankly the images won't be as attractive with a flash.. you'll want as much natural lighting as possible.
DO: Always kneel during the Consecration. Period. This is the most holy part of the Sacred Mass and it's completely inappropriate to stand at this point.
DO: When not shooting, put the camera down and follow the liturgy! Never make the entire Mass a photo session.
BEST CASE SCENARIO: If it is at all possible, ask the priest if he and the altar servers would be willing to have a Mass during the week when there will be few people there OR to celebrate a Mass for the purpose of you documenting it. In this case you may have the freedom to move about (always kneel during the Consecration!), but you should still be respectful of the Lord's presence and the Lord's house. If this cannot be arranged, a priest may be willing to let you have a side seat in an inconspicuous location during the Mass so you can get good angles, and he may be willing to make an announcement before Mass that you are there to document the Mass, not disrupt it.