The big question when someone is looking to buy a fisheye is "IS THIS GOING TO FIT MY CAMERA????" We'll clear that problem up right here. First things first...
-DOES YOUR CAMERA HAVE THREADS ON IT? You should be able to feel the threads with your finger and see them with your eyes. On the inside lip on the ring in front of your lens, there should be threads... if your camera has them. If you figured that out move on.
-Lets find out what size they are. Check out this picture here and notice the O with the slash through it, then an 85 next to it
This camera here has a filter size of 85mm. So in theory, this person needs a ring that will either step up or down to 85mm depending on the lens. (85 is HUGE BTW). Your camera is most likely going to be 43mm or lower for compact consumer cameras. Larger 3CCD cameras range from 58-73ish. If your camera does not have this symbol on it, theres a good chance that it does not have threads.
-Once you have that number, you need to look at the thread size of the lens you are buying. Most compact camera lenses are 37mm. So lets do the math here. You are buying a baby death, its 37mm, your camera has 30mm threads. To connect this lens to your camera you are going to need a 30 to 37 STEP UP RING since you need your cameras threads to STEP UP to the lens threads.
Its really simple. Just take the lens size and your cameras thread size and do the math to figure out if you need to STEP UP to the lens or STEP DOWN to the lens.
There is one worry about stepping down. Vignetting. If you are stepping down, your camera lens might see some of the fisheye that isn't glass which is going to end up being vignetting in your shot. Sometimes you can zoom through it, but I don't recommended it. If you are going to be doing this, I would research online to see if anyone has stepped down to the lens before and claimed it looked OK with an example.
Lastly, if your cameras does not have threads and you really wanna stick a fisheye on the front of it you can resort to hot gluing or JB welding a step up ring to the front of the camera. I don't recommend it but it can work if done properly.
Hopefully this clears up any confusion with attaching lenses.
Subject: Step Up and Step Down Rings 
Fri Jan 14, 2011 10:45 pm
