The scope is looking good and I'm impressed by your workmanship and attention to detail, looking forward to a first light report.
Thanks Jeff!
Quote:
Originally Posted by toc
The rabbit is impressed and so am I
Kind of a left field question, but how hard are SCT corrector plates to make? I dont think they can be hand ground can they?
The Netherlands Dwarf rabbit is my supervisor.
The SCT corrector plates are practical to make only in a series production scenario because of the fancy/expensive tooling required.
The plate usually gets sucked onto concentric supports by vacuum, so that the top side is deformed in such a way as to allow grinding and polishing to a flat surface. One the vacuum is released the surface will spring back to form the complex curve required to correct spherical aberation.
Last edited by Stefan Buda; 08-02-2025 at 05:42 PM.
They look like good quality fans Stefan?
Cheap things never synchronise and set up harmonics and introduce a lot of unwanted vibration, I've seen it too many times in computer systems.
Overall it's looking amazing, I bet you're excited to try it all out.
Leo,
They are not the cheapest fans, but not top of the range either.
I hope to tune out the resonances with the speed controller.
Yes, I'm keen to try it although there are no planets now that are high enough in the sky to be worth looking at. I might have to test it on double stars.
Is the design better for planetary Stefan?
Yes, not top of the range fans but certainly not the cheapest will often put you in a sweet spot where you get the performance without the vibration or price. I've tried explaining this to people in the past who swear by their cheap eBay stuff. Though top dollar doesn't always win as the best either but you soon learn which brands to trust.
Sorry for my ignorance Planetary is in the title!
I must learn to read one day..........
I don't have a planetary telescope as such, I just naturally assume I can see everything with my telescopes, probably accounts for some of my lousy results at times.
One thing I learnt early on, doing planetary imaging, is that a good finder scope, well aligned with the main OTA, is necessary, otherwise planet hopping with the camera mounted is difficult due to the very small field of view.
So I made a decent finder mount and knocked together a finder scope, using a 1.5" diameter achromat from my junk box, that will allow me to do the initial testing. The achromat has a brass housing and it is engraved Waterworth - Hobart. I did a bit of digging on the internet and discovered an interesting story about optics manufacturing in Tasmania: https://www.asap.unimelb.edu.au/bspa...waterworth.htm
Also, I think I finished figuring the secondary mirror today.
Last edited by Stefan Buda; 27-02-2025 at 08:54 AM.
The OTA went together yesterday, ready for testing, but it's going to be cloudy in Melbourne for a while.
I intend to take it up to Heathcote tomorrow or on Saturday to the Messier star party. It will be very embarrassing if it turns out that I made a design or manufacturing error and the thing won't even come to focus. I always wonder whenever I finish a new prototype.
I'm sure, with your attention to detail, that the scope will perform excellently but regardless, the telescope looks fantastic and well engineered.[
QUOTE=Stefan Buda;1625625 It will be very embarrassing if it turns out that I made a design or manufacturing error and the thing won't even come to focus. I always wonder whenever I finish a new prototype.[/QUOTE]
Looks fantastic Stefan, well done!
What is the overall weight of the full rig as shown?
Friday could be clear in melb, according to my sources.
Thanks Rod, the overall weight as shown is exactly 11Kg. The OTA alone, without the finder scope and camera/filter wheel, is probably close to 10Kg.
Quote:
Originally Posted by Rod
Congratulations Stefan.
Looks terrific! That came together really quickly. I hope to have a look through it one day.
Rod
Thanks Rod, I'm off to the Messier star party and if you are attending too, then you will be able to look through it, providing that I can make it work. Not much to look at though, with the planets so low.
Quote:
Originally Posted by Saturnine
I'm sure, with your attention to detail, that the scope will perform excellently but regardless, the telescope looks fantastic and well engineered.[
QUOTE=Stefan Buda;1625625 It will be very embarrassing if it turns out that I made a design or manufacturing error and the thing won't even come to focus. I always wonder whenever I finish a new prototype.
[/QUOTE]
Thanks Jeff, fingers crossed - so to speak, as I'm not superstitious.
Back from field testing.
All went well, no mistakes found.
Unfortunately the seeing was horrible for planetary imaging and I came home without any good data captures.
The seeing was nowhere near good enough for capturing data for a Roddier test so I had to rely on visual star testing and a Ronchi eyepiece to assess the optics. I detected a very small amount of spherical aberration that I will have to track down and correct.
Managed to see Sirius B at 400x and the attached images were captured through red and blue filters respectively. Each image is a stack of about 2000 unsorted frames, as Autostakkert was unable to sort them.
I really enjoyed having a look through your new scope. It looks fantastic of course. I was really impressed be the sharp images I saw visually. The Tarantula was very clear and bright. Lots of contrast. Thanks for showing us the pup. I hadn’t seen it at the eyepiece before.
Looks like it will be another great product. Hope it goes well for you.
Shame about the poor seeing though. I've hever done planetary observing from that location so I have no idea how often good planetary seeing happens there.
Just in case anyone is wondering whatever happened to this project.
Well, I had to focus on more urgent jobs but I did not completely stop working on it.
Firstly, I made a new focuser with a 26mm focusing range. The CDK focuser I used initially, had only 16mm, which is more than enough for an astrograph
but a planetary scope needs to accommodate a variety of eyepieces as well as various camera/filterwheel combinations.
I also finished the new primary mirror using the Borofloat 33 glass blank.
Plus I 3D printed a clip-on cover for the secondary.
I still have to make a dust cover for the primary.
Just in case anyone is wondering whatever happened to this project.
Well, I had to focus on more urgent jobs but I did not completely stop working on it.
Firstly, I made a new focuser with a 26mm focusing range. The CDK focuser I used initially, had only 16mm, which is more than enough for an astrograph
but a planetary scope needs to accommodate a variety of eyepieces as well as various camera/filterwheel combinations.
I also finished the new primary mirror using the Borofloat 33 glass blank.
Plus I 3D printed a clip-on cover for the secondary.
I still have to make a dust cover for the primary.
Hope to start some lunar test imaging soon.
Thanks for the update Stefan, was wondering what was happening. Look forward to seeing the lunar test results.
Thanks for the update Stefan, was wondering what was happening. Look forward to seeing the lunar test results.
Thanks Jeff, I'll post here when I get something.
Quote:
Originally Posted by Leo.G
Did you machine your own focuser?
I'm interested in doing this in the future and would love to see your build.
Leo,
My focuser is ultra simple but it can be used only in conjunction with an electronic focuser.
If you have a close look at the pictures on my website you will be able to figure it out without any extra information. https://beamtech.com.au/product/focuser-rap-7256/
That's a lovely looking focuser Stefan!
Billet aluminium, do you use a CNC milling machine?
I guess it would be a heck of a lot of work trying to do it repeatedly manually and introduce likely errors.
I have the BF20 mill I have yet to weld up a stand for and the BF30 compound table I bought and I am considering once up and running converting it to CNC. There's a lot of information on the web about doing the conversions, only time and money, I have plenty of one when I'm not too sick, the other, the lotto Gods hate me, LOL. I would have made the stand by now but I have to fold up a chip/swarf tray and didn't know how large it had to be. I have that sorted out now and the old cover from the floor to ceiling flued gas heater which used to be in the house gives me sufficient flat plate to fold and weld. It's only thin sheet but it's a good project to re-familiarise myself with the TIG welder (AC/DC 200A).
Is that an anodised finish?
I have to look into a black anodising agent for my adaptors I'm going to be machining up soon. I have read about black food dye but don't think it would give good end results.
I used to do zinc plating and anodising for a living back in the early 80s, don't remember much though and I never had to mix my own chemicals, they brought a chemist in to do that. That was back when zinc plating was done with cyanide in the primary tank and sulphuric only one to two rinse tanks away. I never skipped a rinse no matter how big a hurry I was in. Except for the dust you never swept up till you hosed it first, fumes and headaches, it wasn't a bad job.
