Why build a telescope? YOLO, as the kids say. Having decided that, one must decide what type of far-seer one will construct. For his 10″ reflector, [Carl Anderson] once again said “Yolo”— this time not as a slogan, but in reference to a little-known type of reflecting telescope.
The Yolo-pattern telescope was proposed by [Art Leonard] back in the 1960s, and was apparently named for a county in California. It differs from the standard Newtonian reflector in that it uses two concave spherical mirrors of very long radius to produce a light path with no obstructions. (This differs from the similar Schiefspiegler that uses a convex secondary.) The Yolo never caught on, in part because of the need to stretch the primary mirror in a warping rig to correct for coma and astigmatism.
[Carl] doesn’t bother with that, instead using modern techniques to precisely calculate and grind the required toric profile into the mirror. Grinding and polishing was done on motorized jigs [Carl] built, save for the very final polishing. (A quick demo video of the polishing machine is embedded below.)
The body of the telescope is a wooden truss, sheathed in plywood. Three-point mirror mounts alowed for the final adjustment. [Carl] seems to prefer observing by eye to astrophotography, as there are no photos through the telescope. Of course, an astrophotographer probably would not have built an F/15 (yes, fifteen) telescope to begin with. The view through the eyepiece on the rear end must be astounding.
If you’re inspired to spend your one life scratch-building a telescope, but want something more conventional, check out this comprehensive guide. You can go bit more modern with 3D printed parts, but you probably don’t want to try spin-casting resin mirrors. Or maybe you do: YOLO!
My father built several Newtonian reflector telescopes when I was a child. I remember him talking about the Yolo telescope, but I didn’t remember the name. We had a lot of fun with the telescopes. Once a neighbor reported us to the police, thinking that a 6 inch telescope was some sort of morter or something.
WTF is the world coming to.
When I was a kid, about 8, we played ‘war’ all the time.
One of our toys was an expended LAW rocket tube, likely a training round.
I had bought it at a garage sale, along with two dummy grenades.
We used to point it at cop cars as they went by.
Good times.
Oh man. Now you reminded me of our bottle rocket wars when I was 10. Intense!
F/15. is that bright? or dark for a typical telescope. i have no idea. in photography, f/15 is quite dark, but that depends on the focal length. i have no idea what the focal plane of this setup is.
questions, questions
This is essentially a Herschelian reflector, or ‘Schiefspielger’ design. Not sure why it’s now being renamed a ‘YOLO’ except for modern vibes.
The article here as well as the linked instructable tell you where the name came from, and it’s not “modern vibes” considering the name was coined in the 1960s.
“Art Leonard came up with the Yolo telescope in the 1960’s. It is quite similar to Anton Kutter’s Schiefspiegler. The main difference is Art Leonard used a concave secondary mirror instead of a convex mirror as found in the Schiefspiegler design. It appears from Art Leonard’s document “The Yolo Reflector”, “
That must act to shorten the focal length, as convex secondary mirrors increase it.
Was named for Yolo county, California.
Ok for visual and planetary work, pretty dark for DSOs.
It doesn’t depend on the focal length. That’s what’s nice about the f numbers.
A f/15 50 mm lens is as dark as a f/15 500 mm lens. What changes is the actual aperture size. 50 mm/15=3.33 mm aperture diameter, and for 500 mm it’s 33.3 mm.
But in both cases the same amount of light and ISO will have the same exposure speed.
it’s dark but it has a lot of magnification. and generally longer has less distortion but i don’t know about that lopsided mirror
It will provide a dimmer image for the aperture than a scope with a shorter focal length, yes, but with a ten inch primary this scope is gathering a lot of light.
Usually longer focal length scopes like this one are more tailored for planetary viewing than deep sky, as the long focal length lends itself to higher magnifications at the eyepiece.
It’s slow as a photographic telescope, but visually the F/15 focal ratio means Yolos are best suited to medium and high magnification observing. Photography through one would be best limited to the Sun, Moon, and planets.
it seems to me that the telescope world has split between telescopes designed for the Mk 1 eyeball, and those purely for astrophotography.
The lack of a motorised mount and that is not an equatorial mount would mean any serious astrophotography would be hard, and this is a problem with a lot of the larger DIY telescopes
Nowadays astrophotography is largely abbout taking a large number of images and stacking them, so a accurate tracking mechanism is more important than size (Although if you can do both, great )
‘Off-axis’ telescopes tend to be either very expensive, very labor intensive, ‘cranky’ in their implementation (“…the need to stretch the primary mirror in a warping rig to correct for coma and astigmatism…”), or all the above…and sometimes more.
That said, kudos to [Carl Anderson] for pursuing his dream in such an elegant fashion and all the outstanding craftsmanship he employed.
Great job!
I’ve got a 10″ f14. 6 Maksutov and it’s plenty bright. It’s a bit easier to handle than this Yolo, but I’d love to get a look through it to see how it compares!
Great, unobstructed scope means no diffraction effects and contrast reduction from the spider holding the secondary. Good planetary scope.
At the other end of the scale, amateurs are making f2.8 mirrors, 18″ and up in glass only 1/2 thick.
For those of you that haven’t experienced the joy of grinding your own mirror(s).. and trying to create automatic salt shakers.. while working with hard Tree sap LOL. I suggest you put everything aside and contemplate how random errors can lead to perfection. Who cares the damn things F15, and has a lopsided coma… Kudos.
f15 is a very slow telescope. This is not important for visual use, but is extremely important for astrophotography. For planets and the moon, f15 will not be a problem as the objects are bright. For DSO astrophotography, f15 is not recommended, as very long exposures will be required, and with the ever increasing number of satellites in low earth orbit the odds of imaging one or more of them in a long exposure are very high.
Can the YOLOMatic be repurposed to play 45’s and LP’s?
Evidence exists that YOLO is absolutely false. Just because you don’t remember living previously doesn’t mean it didn’t happen. It should be called “you likely recall only this life” or YLROTL.