View Full Version : How do I make a focal reducer?


Xevious
09-13-03, 02:28 AM
I've finally had suscess with my Orion CCD Camera, but the chatch is it magnifies too much. Do any of the other Astronomers here have experience making focal reducers?

Crushing Belial
09-21-03, 03:24 AM
You can make your own focal reducer (macro filter) for your lens. This will of course loose quality but if you are only going to use 6x4 prints. It's probably a good way to try out macro photography before you can afford to buy quality equipment
for serious professional results a consumer focal reducer is advised.
All you need is a 40mm objective lens. The one I use is out of a Tasco #54T I had given to me as a kid, I can’t guarantee that all 40mm objective lenses will work though as I have only tested this one. I have come across a web site that used the 40mm objective lens to make a focal reducer to take pictures of stars. So if you have a broken pair of 40x binoculars handy, it might be worth a try.
This focal reducer has both worked on my Canon 50mm/f1.8 and my 80-200mm/f4.5-5.6 lenses and both of them have successfully auto focused with the focal reducer on. It has taken the minimum focus distance on my 50mm from 1.5ft to under a foot which is very handy in
what i use
1 Tasco 40mm objective lens (a bit smaller in size than lens)
1 piece of solid cardboard cut into the shape of the lens with the center cut out
Sticky tape to hold it into place and so you can get it out
Steps…
Get the lens from the telescope. For my telescope you had to jiggle the end until the seal snapped.
Cut out the cardboard to just a bit smaller than the camera lens so it will fit in.
Cut out a hole in the center of the cardboard just enough to fit in the telescope lens.
Put a folded over piece of sticky tape at 90 degrees of the lens then put sticky tape over 4 sides on each side for both sides (see diagram) and cut around edge of cardboard so that it is round.
Done…place it inside the lens when the focus is fully back into the lens (for external focus).

Xevious
09-22-03, 03:44 PM
Hmmmm, okay.