I recently obtained a used Quantaray for Nikon 500mm f8 f/8 Mirror lens. I have a Nikon d3000 and I am not sure how to attach it to my camera.

A 500 mm mirror lens is a fully manual lens (manual focus no aperture change) using a T mount adapter to your specific camera. The T mount costs some $15. It depends on your camera how to turn off the auto focus and go to aperture priority mode. The aperture on a mirror lens is set, usually at F8, so the shutter is the only item that can be adjusted to get a correct exposure. A digital camera (set in adjustable ASA setting) can change it's ASA to help with getting a correct exposure. Manual for digital camera are usually on the companies' web site.

If you remove the back cover, there is a flexible circuit on the bottom left that attaches to the rear circuit board. Check to make sure that there are not cuts in the lands caused by impact pressing the flex into the back board components. This is a common problem with this model.

Note: replacing this calls for removal of the mirror box. Nikon stopped selling parts on July 13, 2012. You may be able to find it on Ebay.

This lens does not have the electronics to communicate with the camera. You have to use the camera on the Manual exposure mode (turn the mode dial to M) and set the aperture and shutter speed yourself. You will not get any metering help from the camera's light meter, but you can use the histogram to fine-tune your exposure. You also have to focus the camera manually.

You'll want to use a tripod or other support, as the lens will magnify every bit of camera shake.

The Nikon lens, absolutely.

Quantaray makes their lenses with a variety of mounts. A lens with a Canon mount, for example, will not fit on the D3000. Assuming the lens has a Nikon mount, then yes, it will work with the D3000.

Quantaray lenses are available with a variety of mounts. Assuming you get one with a Nikon mount, then yes, it will work with a Nikon camera. However, unless the lens has a focusing motor, it will not autofocus on the D3000. Some Quantaray lenses have such a motor, some do not.

The Rokinon lens does not have the electronics to communicate with the camera. You must set the camera to the Manual exposure mode in order to use this lens. You control the shutter speed on the camera and the aperture by turning the ring on the lens. You also will not be able to use the camera's exposure meter; you can use the LCD display and the histogram to fine-tune the exposure.

Refer to the manual for full details on using the Manual exposure mode.

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.

You'll need to switch to M (Manual) mode. You won't get any metering through the lens, nor will you get any autofocus.

Hey SHUTTER HEAD,
Without knowing what camera you have I would set your camera's aperture to f/8. I would have your camera mode set to either aperture priority or manual, and leave the aperture on the camera set to f/8.

Sincerely,
Allan
Go Ahead. Use Us.

You can get an M42 adapter; try bhphotovideo.com.