Hello, I'm trying to make a Newtonian reflector telescope at home. For some reason, in my country, I cannot find pitch that's used for polishing the mirror. I don't know why, but there isn't even a clear translation of this term to my language and hence, I cannot purchase it. What alternatives can you suggest? ChatGPT suggested a Carnauba wax (https://en.wikipedia.org/wiki/Carnauba_wax), which is apparently very hard and is used for polishing. Can anyone advise whether it's a good option?

Hello, I am thinking about engaging in a new hobby - amateur telescope making. I was inspired by the story of William Herschel who managed to become a Royal Astronomer without any education, purely by self-study and his own "homemade" telescopes, in the 18th century btw.

So, I recently began to wonder, if all of the homemade telescopes that I read and watched videos about, use glass mirrors, but first reflector telescopes (like Newton's and Herschel's) use metal mirrors, so how difficult it is to actually manufacture a metal mirror for a telescope at home? There can be a umber of different metals and alloys used for this, but regardless of a specific material, what are the actual prospects of doing this at home?

I tried Gordon Waite method on 12" and got some issues because it's my first time.

Now my lap has a large hole with no contact about 1mm deep. I see several options, kindly let me know what would work best.

• I could use warm water and do a hot press
• I could cut what's too large on the lap and fill the hole with this once remelted.
• I have a used 6" lap that I could melt but I fear potential impurities when removing the lap from dental stone.

Few months ago, I set out to build an equatorial platform for my 8" Dobsonian telescope. Before I was finished, I decided to upgrade my telescope to a 12" Dobsonian. So,then I had to build a bigger one. Meantime some guys showed up literally at my doorstep and wanted to buy them from me.

So, I ended up building four in total, sold three for a 500$ profit and kept one for myself. Then I decided to call it quits for the time being and just enjoy the stars. It does take time and effort to build one of these so the price of a commercial one at around 500$ is justified IMO. But you don't have to buy one if you are willing to put up the work!

Since building one of these, I have used it every single night of observation. It is so nice to be able to crank up the magnification all the way to 500x and enjoy something like the Ring Nebula or Cat's Eye Nebula without worrying about the drifting image. Or simply looking at Saturn for many minutes at a time.

When I set out to build one, the first thing I really didn't like was everybody's reliance on aluminum segments. As some of the commercial solutions like Omegon have shown, aluminum is not necessary at all. Fancy cutting with lasers of the segments is also not necessary. The only thing you need is a cheap jigsaw! So, I took the existing solutions and designed one myself that went with the simplest/cheapest way that anybody can do in their garage or even living room for literally like 100$.

The road there was not as easy as I originally thought and definitely there was some trial and error.

First, I documented the building of the 8" version here:

https://youtu.be/Q6oVmOdKPmg

As I needed also to upgrade to 12", I went and documented the 12" version here

https://youtu.be/8NtrHkfYcRs

To make things really simple for everybody else I also created some step-by-step plans to be used in combo with the video guides here:

https://drive.google.com/file/d/1vaq1xYoLOoWMC4bgHCmyJTn5w97NLlUx/view

This was 5 months ago.

Since then, over 10 000 people have seen the videos and 100s of people have downloaded the plans with many successful builds. Some have already shared their plans with me, and I have included some of the nice builds in the plans to encourage others that this is something they can also build.

Initially it was not clear what was the latitude limit to the plans but some of you have recently confirmed that they work all the way down to 34! so, I have updated the plans to include those segments.

Another small modification was also needed for the voltmeters, in the video it was not accurately connected to ensure enough voltage for powering of the display.

Have a look, give it a go and if you need an additional segment do let me know either in this thread or in one of the videos and I will add it.

Hi All -

I have a very old 10 inch mirror blank - probably from the 1970s, The box says "Code 634100 1 PC 10" x 1 3/4" Telescope Blank." I would love to get this into the hands of someone that will actually make something out of it. Pretty darn heavy, so shipping will be an issue, but I am in the San Diego area if anyone is interested. (Not looking to sell, just give it to someone that will make good use of it.)

Any ideas or interest?

Hi guys!

I'm a beginner with telescopes, currently I have a Svbony MK105 - I like it, it's small, light and practical. But there comes a time when you start thinking about a new telescope to see more. When I look at Saturn (I will use it as a reference), I can see the rings but without much detail, with a very bright image of the planet (see the photo). I can barely see the deep sky, and I associate it partly with light pollution, but also because I have a telescope with F/D = 13.

I'm studying how to build an OTA using my 3D printer, and I found some famous projects, such as Hadley ( https://www.printables.com/model/638436-hadley-telescope-designbydave-mod ) and Leavitt. The latter, in particular, has a very interesting modification to make it lighter, and can even be used on my current mount, which supports 5kg (Skywatcher Eq Gti), and which is the same mount as the author of the modification ( https://www.printables.com/model/355997-8-newtonian-telescope-leavitt-lite-metric ).

My question is: what will I gain from a new telescope? So I tried to compare them with my current one and based on my 6mm eyepiece (using metric system):

Svbony MK105

F/D = 1365/105 = 13 (best for planets)

Magnification = 1365/6 = 227x

Hadley

F/D = 900/115 = 7.9

Magnification = 900/6 = 150x

Leavitt

F/D = 1000/203 = 5 (best for deep sky)

Magnification = 1000/6 = 166x

(203mm = 8")

Then I had some questions, which I would like help with:

1. with my current MK105, would I have gained significant detail using only a Barlow? Reasoning: I currently see Saturn as small and very bright, so I would be able to enlarge and reduce the brightness of the image. Could I? Even so, I probably would not be able to see deep sky.

2. Would the Leavitt be a good telescope for deep sky with the eye? I mean: not for astrophotography, but for observing the deep sky with the eye and the telescope only. Or is observing the deep sky with just the eye not good (I really don't know)? Is it maybe good just for astrophotography, increased exposure, stacking, etc?

3. The Leavitt, despite doubling the diameter, has an even lower magnification than the MK105 and tends to make the image even brighter due to the lower F/D. Ok, it would be a good telescope for deep sky, but what would the experience of seeing Saturn be like? Would it actually be worse (lower magnification and brighter image) than MK105? If I use a Barlow, would it solve this problem and have a multi-purpose telescope (planets and deep sky)? The reasoning here is also that you could magnify more with the Barlow and reducing the intensity of the light and seeing more details, when used for planets.

4. If I decide to slightly modify the Leavitt design to a longer focal length, it would only mean using longer rods in the design. With a 1000mm focal length mirror, from the original design, the OTA is approximately 1m long. Increasing the focal length would have a more or less proportional increase. If this increase does not imply a greater weight than my mount can tolerate, could I have a problem due to the length of the OTA? I am wondering if, because it is longer, even with the center of gravity fixed to the mount, the moment of the force of the weight at the ends could impose any extra challenge on the motors, or not.

Thanks everyone!

Saturn taken from my MK105 and Samsung Galaxy S24 Ultra, using Svbony Phone holder:

https://preview.redd.it/xuyvze3ohcvd1.jpg?width=1520&format=pjpg&auto=webp&s=53fd1b8e472026239715618d1d8af91ff0f07f08

Hello, I wanted to ask about the issue that arise with using say a 3/4 inch thick mirror for a 12.5 inch F4 telescope. Mel Bartels’ sagitta calculator say the sagitta is 0.2 inches, is that too thin in the center?

Thanks!

Hey guys, I'm trying to build an EQ platform as a way to improve my astrophotography with my 8 inch dobsonian. I'm not the best at math, and would really like to build it myself in order to save money, and also because they aren't really sold in my area. I have looked over plans, and a lot of them are based in the northern hemisphere, which confuse me even more (I live in NSW, Australia). Does anyone know of any guides in building them? I watched Astral Fields video on how to, and it helped quite a bit, but im still quite confused on orientation with poles due to me being in the southern hemisphere, and i dont understand where north and south goes in regards to the polar axis and stuff like that (i barely understand what polar axis means). If anyone could help me out in understanding how to go about this, it would be much appreciated.

I'm currently fine grinding a 300mm (12"). I'm thinking about building a fixed post grinding/polishing machine from a washing machine.

I could reuse the motor, reduction and tank so there is not much to do in the end.

Would this work ? What are some thoughts?

Hi I have an explorer 200p with a single speed focuser, I'm looking to machine my own crayford 2 speed focuser with a rack and pinion and a 2 speed planetary reducer. Has anyone in here got some tasty pictures of one they've made or a really high quality one they bought that they took apart for some inspiration

http://jimshomeplanet.com/CrayFocus/CrayFocus.html https://bedair.org/Focus/focusproject.html

I work at a glass factory and we have glass that is 10x10 feet and 1/4 inch thick just laying around collecting dust. Would it be realistically possible to make a giant mirror out of them.

It's not optical glass it's just plan clear glass

Here is my telescope materials and plan: Costs for the parts: 

1. **Primary Mirror**:

   - The primary mirror is one of the most critical components of the telescope and can vary significantly in price depending on its quality and specifications.

   - A high-quality 200 mm (8-inch) primary mirror suitable for a Dobsonian telescope could cost anywhere from $200 to $600 or more, depending on factors such as optical quality, coating, and brand.

2. **Secondary Mirror**:

   - The secondary mirror is typically smaller and less expensive than the primary mirror.

   - A secondary mirror for a Dobsonian telescope of this size may cost around $50 to $100.

3. **Telescope Tube**:

   - The telescope tube can be constructed from various materials such as plywood, PVC pipe, or composite materials.

   - The cost of materials for building the telescope tube, including the main structure, focuser, and other components, may range from $50 to $200, depending on the materials used and availability of tools.

4. **Alt-Azimuth Base**:

   - The alt-azimuth base is another essential component of the Dobsonian telescope, providing stability and allowing for smooth movement.

   - Depending on whether you purchase a pre-made Dobsonian mount or build one yourself, the cost can range from $100 to $500 or more, including materials and hardware.

5. **Focuser**:

   - A sturdy and reliable focuser is essential for achieving precise focusing and maintaining stability during observations.

   - A basic rack-and-pinion focuser suitable for a Dobsonian telescope may cost around $50 to $100.

6. **Miscellaneous Components**:

   - Additional components such as eyepieces, finderscopes, collimation tools, and other accessories will add to the overall cost of the telescope.

   - Budgeting an additional $100 to $300 for these miscellaneous components would be reasonable, depending on your specific needs and preferences.

7. **Labor and Tools**:

   - If you're building the telescope yourself, consider the cost of any tools or equipment you may need, as well as the value of your time and labor.

   - Budgeting for tools and supplies such as woodworking tools, adhesives, paints, and protective equipment could add another $50 to $200 to the total cost.

Based on these estimates, the total cost of building a Dobsonian telescope with a 200 mm aperture size, 400 mm focal length, and alt-azimuth base could range from approximately $550 to $1850 or more, depending on the quality of components and whether you're purchasing new or used parts. Keep in mind that these are rough estimates, and actual costs may vary based on your specific circumstances and choices.

1. **Telescope Structure**:

   - The cost of materials for constructing the telescope structure, including the telescope tube, truss rods (if applicable), mirror cell, and secondary mirror holder, is included in the estimates provided.

   - Depending on the materials used (e.g., plywood, PVC pipe, aluminum tubing) and the complexity of the design, additional costs for hardware, fasteners, adhesives, and finishing materials may be required.

   - Budgeting an additional $50 to $200 for hardware and structural components would be reasonable, depending on the specific design and materials chosen.

2. **Secondary Mirror Holder**:

   - The secondary mirror holder, also known as the spider, holds the secondary mirror in place and aligns it with the optical axis of the telescope.

   - Depending on the design and materials used (e.g., metal vane spider, carbon fiber spider), the cost of the secondary mirror holder could range from $20 to $100 or more.

   - This cost should be included in the estimates provided for the secondary mirror and miscellaneous components.

3. **Nuts, Bolts, Gears, and Hardware**:

   - The estimates provided account for the main structural components and hardware needed for the telescope's construction, but they may not include every single nut, bolt, gear, or small hardware item.

   - Budgeting an additional amount for miscellaneous hardware, fasteners, and small components is advisable to ensure that you have everything you need for assembly.

   - Depending on the complexity of the design and the availability of hardware, budgeting an extra $20 to $100 for miscellaneous hardware items would be reasonable.

Optical Components:

• Primary Mirror: 200 mm diameter, concave mirror.
• Secondary Mirror: Appropriately sized to reflect light into the eyepiece.
• Secondary Mirror Holder (Spider): Holds the secondary mirror in the optical path.

Telescope Tube:

• Tube Material: Can be made from plywood, PVC pipe, or a similar material.
• Focuser: Rack-and-pinion or Crayford focuser.
• Mirror Cell: Holds the primary mirror securely and allows for collimation adjustments.
• Baffling: To prevent stray light and improve image contrast.

Mount:

• Alt-Azimuth Base: A stable base that allows the telescope to move in both altitude (up and down) and azimuth (left and right).

• Altitude Bearings: Smooth bearings that support the telescope tube and allow it to move vertically.

• Azimuth Bearings: Bearings that allow the base to rotate horizontally.

What feedback can I get from this?

I built a 203 Leavitt (https://sites.google.com/view/203-leavitt-telescope).

But I went cheap on the mirror and end up with a D203F1600, meaning a really long tube.

This makes the telescope unstable, shaky.

I have the impression the primary and secondary mirror are relatively stable and fault is the mounting.

Right now it's a DOB. The tube weights around 4.5kg, I could convert it to an EQ mount.

The mid term plan it to motorise it. Waiting on parts to be delivered.

That said, what would you recommend?

A custom designed truss-tub dobsonian telescope. I decided to make it as light as possible so that I could mount it on a small EQ mount, so the truss is made of 600mm carbon fibre tubes, and the rest (minus the focuser) is 3d printed. It uses an 8" f/8 spherical mirror off of eBay, and works surprisingly well

Planning to build very first reflective telescope from scratch and I have no idea where to get the mirror. I'm assuming a regular magnifying mirror is concave, but I'm not sure if it's a parabola. Please share your experience.

I'm making a 300mm mirror but started from a scratched mirror already curved, not a blank. Did some K80. White area is glazing.Tool running-in will continue with K180. Is it ok to switch now ? I will redo the channels of the tool

So I was browsing Wikipedia regarding telescope types because I am filling my head with all things telescopes lately. I was also watching mirror grinding videos on the Youtubes. So here's my brains' idea, tell me if my brain has the dumb.

There apparently is such a thing as a liquid mirror for zenith astronomy, utilizing mercury or gallium in a spinning tray, below a suspended secondary. From what I gather, the motion creates a near perfect parabolic mirror, but of course its useless in anything other than perfectly horizontal positions. so, I had an idea to get a large glass or metal blank, build a mold around the edge and pour epoxy and then spin it with a controlled RPM motor. When the epoxy cures you would have a parabolic shape, maybe requiring a minimum of polishing for mirroring or aluminization. Would this work? Can epoxy accept the surface mirroring?

Hello, all. I was referred to this sub from r/telescopes. I'll ask the question here. please keep in mind have no experience with optic calculations, building scopes or grinding mirrors but it's on my list...so...

I have a cheap entry-level reflector telescope I found at a yard sale for US$20. It's a 4" dobsonian type with a cheap tripod, but the eyepieces are crap. Looks like one you would buy at a department store. So since its basically worthless, and I am an experimental type, I was wondering of I were to get a hole water-jet cut through the primary mirror for the new rear focus tube, rebuilt the secondary mirror mount for 90 degree operation and kept the original focal length by shortening the OTA, could I make a Schmidt-Cassegrain style scope? The original focuser is 1" So I was going to plan on upgrading the focuser to 1.25". even if it was useless for night sky observation it might make a good spotting scope.

Or perhaps just purchasing a new primary and secondary mirror set? Is that something you can purchase?

I would love to hear your thoughts on this modification and please tell me if I am totally out of my mind thinking it would be simple enough for a person with half a brain in his head, a wild idea, and good skill with his hands and his tools.

I already have a nice 8" Zuhmell Dob and good binoculars since I got into the hobby so I figure I've got nothing to lose.

I new to making telescopes and I was looking for advice about if the spider viens are strong enough. I may just need to test this but I though maybe somebody knows better than me where to start.

This is for an 203 mm (8") telescope with a 50mm secondary.

I dislike the method of clamping the principal mirror with fingers that are protuding onto the optical surface. I intend to glue fixations on the sides. Is there any things to know or avoid?

Hi all, so I've been trying to upgrade to a larger telescope for a while (currently use Orion StarBlast 4.5) so that I can better see deep sky objects and so that the Andromeda galaxy looks like more than a smudge, but I'm on a tight budget and can't afford to drop a grand on a telescope unfortunately. So I've been browsing Facebook Marketplace in hopes that I can find a great deal, and I did, kinda. Someone is selling a used Orion SkyQuest XT10, but without the base/mount. After an immense amount of research, I found lots of info that suggests that building one wouldn't be too hard, and people apparently do that kind of thing all the time, but I couldn't find ANY specifics regarding how to go about doing so.

You see, I'm not handy at all, but I'm an expert at following instructions, so I've turned to Reddit desperately hoping that there might be someone out there that could help me and would know where to look to find detailed instructions for how to go about building a base for this telescope, including materials, dimensions, and step-by-step directions, if such a thing were to even exist out there on the internet. This seemed like the right place to ask such a question, so any help that anyone here can provide will have my deepest gratitude! :)

Hi,

My son and I created an open source project based on a BTT EBB36 board originally intended for use with 3D printers. We created the case, firmware and driver needed to turn one into an auto focuser for a telescope.

https://github.com/RealtaScopeTech/Realta-EBBfocuser

https://hackaday.com/2024/07/23/need-a-tube-reach-for-plywood/