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A recent project to develop an adapter so that Webcams can be fitted with SLR lenses. There are two main issues with this project. Firstly, each brand of SLR has a different mounting (often more than one per brand) and secondly the reference distance for each mount is different. The reference distance is the distance from the lens mount to the infinity focus plane, the place where the CCD must be. To complicate the issue each webcam type has the CCD a different distance from it's mount. So you can see that there could be potentially hundreds of different adapter combinations required.
So I ended up with a range of adapters that connect SLR lens (of various mount types to either:
Why use an SLR lens on a webcam. There are many reasons, not the least of which is just to see what can be done and explore the use of webcams. Even cheap SLR lenses have very good optics. They where designed to give a very flat field image over the entire 35mm film plain. The image in the center, where a webcam CCD resides, is therefore extremely good. Telephoto lenses could be used for guide scopes and for applications where you want slightly wider Field of View (FOV) images of bright objects. Short focal length lenses like 50mm or even down to fisheye lenses can give webcams a reasonable FOV for wide field astro imaging. Note that even a 180 degree fisheye will only give a webcam a FOV of 40 to 60 degrees due to the small size of the CCD. There are also many terrestrial applications that could be explored.
Why not just use an SLR camera to T-Thread adapter and make a webcam to T-Thread adapter? It would be good however, the T-Thread ring is the wrong way around. It attaches to the camera body not the lens.
Another issue is supporting the weight of the lens. The adapter has a flat machined in the bottom with a 1/4-20 threaded hole so that it can be attached to a tripod or telescope. A 50mm lens would be OK and maybe even up to 135mm will work well on this mounting point. I have used a Nikon 70-210 zoom mounted on the tripod and it worked well. Some telephoto lenses have 1/4-20 tripod mounting attachments on them which would be good for heavier lenses. The bayonet mount will hold the weight of the lenses above.
I have also developed a Tri-Pod mount Extender which gives you more clearance between the tri pod and camera lens. These are listed under the accessories category in the shopping cart. Click here for more details.
The rotational alignment of the camera adapter and lens has been an issue. For the bayonet mounted lenses this is easier to solve, at least for the lens to adapter alignment. I have made my best attempt to get the adapter aligned correctly with the camera. It aligns with my version of the camera, but I am not sure if all the cameras are the same though so it may not align with your camera. This is not a major issue in that it just means that the may not be tight when in the vertical position. The M42 adapters are now aligned as well as the bayonet mounts. The thread starts in exactly the same place on every adapter, I love computers. (Once you get them working right)
Normally an SLR lens infinity focus is set to be at the stop of the lens focus ring. The actual infinite focus point is determined by the length of the adapter and the exact position of the CCD within the camera. Given that I don't have total control of the CCD mounting and this may vary between cameras, even of the same model, I wanted to leave a little room for error. Also I think astronomy users really want to be able to sweep the focus through infinity so that they can manually get a star in focus and confirm this visually rather than rely on the lens focus stop. So I have set the infinity focus position to occur before the stop is reached. I think this is the best solution and offers the astro imager the most flexibility. This means you will loose a foot or ten in the close in focus range.
NOTE: With the 1.25-SLR type adapters; focusing is not always possible. Some cameras with their 1.25" eyepiece tubes attached may contact the rear of the lens before they can get close enough to focus properly. So this is not a universal option that means any camera with a 1.25" focuser tube can be attached to an SLR lens. Sorry it just is not that easy. In general anything with the CCD more than 30mm from the end of the tube is going to be a potential focusing issue. (Most fall into this catagory) Not all eyepieces when placed into this adapter will focus correctly either. Some contact the SLR lens before reaching focus. So while you can use this adapter to make a telescope out of your SLR lens, not all eyepieces work. (Most seem to thought). Finally because of the short back focus distance available no diagonals or extension will work with the 1.25" SLR adapters.
You can order the adapters from my normal order page. If you need an adapter that does not appear please email and we can most likely add this adapter to the production series.
I now hold stock of these adapters for the most common combinations. In stock adapters are indicated on the order pages. I have developed a production process that cycles weekly through any adapters ordered which are not in stock. So your adapter will be produced in a week if it isn't on the shelf. Shipping takes between 4 and 14 days to arrive. On average allow about two to three weeks before your adapter will arrive.
The adapters cost as listed in the shopping cart for the various versions of this adapter
If you have any comments, suggestions or questions please email me.