- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Filters must be the right size for each lens. For example the 18-105mm kit lens that comes with most D-90 kits uses a 67mm filter. They thread into the main lens. It is always safer to put a clear or UV filter on your camera lens to protect the expensive lens glass. You can thread another type of lens onto it as easily as you can your base lens. Be sure and do not force a threaded lens filter onto your lens or you will damage the expensive lens. It should thread on easily and do not over tighten it.
For the Rokinon 500mm F/6.3 lens, you can either attach 95mm filters to the front or 34mm filters to the rear of the lens.
For the Rokinon 500mm F/8 lens, you can only attach 30.5mm filters to the rear of the lens.
To attach a filter to the rear of the lens, remove the lens from the camera (or take the rear lens cap off). There's a threaded screw mount just inside of where the lens fits onto the camera. Take your filter and screw it into place. Hand tighten until it's snug and doesn't project in the way---remember, you're going to want to take it off again later.
The camera is spec'd to autofocus with lenses that are f/5.6 and faster. The conversion lens is costing you two stops, so it's a wonder you're getting any autofocusing at all with a lens slower than f/2.8.
Unfortunately, it's tough to try to get around the laws of physics. You're just going to have to focus manually.