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 04:42 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 07:54 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.
