Many of you may have missed the wood telescope from a recent MSWG instant gallery. Let us take a closer look.
A refractor telescope is really just a tube to hold the primary lens and the eyepiece optics. Most of that support structure can be made of many types of materials including wood!
The scope was made from all locally harvestable wood. Only a couple of the small knobs are made from any imported materials.
The process started with a primary lens from the Lens Surplus store. It's actually a recycled projector optic. The key criteria for the design was the base diameter and the focal length of the lens. This on is 100mm in diameter and has a focal length of 450 mm. That translates to an f/4.5 telescope for those that want to know. The photo to the right is a test of lens to be sure of the actual focal length. All the tube and focus unit lengths are based on the distance from the primary lens to the focal plane (focal length).
The next piece is the focuser. A typical focus unit is a Crayford style unit. Essentially, a tube with a rod under it to roll it in an out. I did add bearings to make it more solid and roll easier.
Adding the tensioner to pull the focus knob rod onto the tube is the next part. That part was dovetailed together and a dovetail was cut into the body of the focus unit to allow this piece to be tightened by the top knob.
Add the knobs on the end of the tube to hold the
eyepieces and tada, a focuser.
So now we need to attach the primary to the focus unit to have a telescope. The tube is made from poplar and birds mouth jointed together. The temporary piece at the bottom has an inside disk to help hold the pieces for fitting and gluing.
Once the glue dried, a simple mandrel was used to mount and turn the recess for the lens cell. Note the band clamps. They were used to insure that the tube did not come apart during turning. The clamps were moved around to allow access to the tube in sections for turning.
Next a small plate was made to hold the focuser tenon and tube together securely.
The primary lens cell is ready to insert into the tube and is held with in place with a ring and screws. The same ring will be used to attach the dew shield. Segmented turning anyone? Poplar and Black Walnut were cut and glued to make the dew shield.
Here's a pic after turning the dew shield.
All that's left is to add a rail on the bottom to connect the scope to the mount. Adding a simple lens cap to keep dust out.
This scope has already been out for use at several Memphis Astronomical Society events here in Memphis. Surprisingly the view are comparable to commercially made scopes!
The design allows for a camera to be attached in-place of the eyepiece. I'll add some images below.
I hope this inspires you to create a project of your own like this or something totally different. Get out there and go for it!
Actual photos with a Canon 60D. No tracking and no special settings.
Here's the moon a few nights before the full eclipse.
Here's Jupiter and it's moons. The lens is intended for wide field observing so no surprise the photos is grainy.
More to come when we get to a darker sky sight...not the front driveway in Bartlett ;)