Thalestris24

If you have a 6 x 30 finder (as supplied with a ST80), the objective is 125mm fl. I got the slightly shorter fl achromats from Surplus Shed because I thought the collimator-slit distance might be less than 125ml though it looks like 125mm will do (but need to double check when my back allows). Printing the T2 threads might be straightforward - it might depend on the particular filament. Even a small amount out might make it hard to screw a T2 metal male part into the printed part. It's probably luck of the draw! Louise

Yes, takes a long time to print the main body/case. When I did mine I actually only meant to print the base so I could check the layout. If you try to use camera and collimator lenses that are too big, they may not fit. Anyway, in the end I just let it print to the end The lenses I got from Surplus Shed seemed a good match though I've yet to test them properly. The collimator fl is quoted as 125mm in the design but when I measured it (albeit just with a ruler) it looked like that might be a wee bit too long but I've yet to definitely confirm that. From Surplus Shed I got 2 x L13930 which are 26 x 121mm, 1 L x 13857 which is 25.4 x 87mm, 1 x L10914 which is 25.7 x 120mm, and 1 x L14253 which is 13 x 31mm (Total cost $37.50 + $8.60 for shipping). At the moment, I'm using the L14253 for the guide camera. I altered the size of the holder to accommodate the slightly bigger lens (actually, I just redid the design). I'm using the L13857 for the camera lens. The collimator lens is currently an objective lens from a SW 6 x 30 finder - I had to make a bigger holder for it as it's 31.2mm dia and I haven't as yet incorporated a stop ring (which is in the design). The lenses that will be used aren't finalised yet. Earlier today I made a little stand to hold a small mirror at 45 deg (I got some small square and round 1" craft mirrors off Ebay). The mirror was to temporarily go in place of the grating holder so I could check that the collimator lens could be focused on the back of the slit. At a glance, I think the 125mm lens can focus on it (I need to bend over to check it but my back is killing me today ). I'm not sure if it would be better to have a larger lens for the imaging camera. But if what I have in place works ok then I'll leave it as it is - at the moment the camera lens centre might be a little low. I can also use the 45 deg mirror to check where the camera lens focus will be, so a useful tool. Oh, the micrometer I got off Ebay for £20 - lucky bargain! I'm not sure that there isn't a way around using a micrometer - perhaps just a screw would do if you have an imaging camera with a large sensor. The 6mm aluminium rod for the camera lens focus mechanism I got from Screwfix quite cheap but had to saw the required lengths. I couldn't fin a source for the 25mm round coupling so got a 20mm one instead. Seems ok but I'm not overly fond of the camera lens focusing mechanism but it just about works. Hope that's helpful Louise

Oh, sorry - I can but empathise! I didn't see an option without the mount when I ordered mine. They charge quite a lot for shipping/exporting from France. You've seen my Lowspec thread, haven't you? I got lenses from Surplus Shed and saved a lot. But had to get the reflection grating from Thorlabs. Also got the optical mirrors from Thorlabs - not too expensive. Louise ps oh yes, I see it now. Only about 4 Euros cheaper

There's a scraping tool supplied with the Ender 3 Pro - the one time I didn't use it.... I deserve all I get Louise

It was just one of those things doing something in a hurry without thinking. Glad it's not just me though! Lesson learned also - finger is quite sore 😢 Louise

I was a 3d novice when I started. Printing the Lowspec components isn't trivial (for a beginner) and things don't necessarily quite fit together as expected, but has been a good way to learn! I've had to learn how to use Fusion 360 CAD software in order to make changes to some parts. I got the ender 3d pro via Amazon at the end of October so it's taken a month. I'm doing the final optical setup and almost ready to connect an imaging camera for preliminary testing. If all seems ok, I'll then fit the proper slit and grating. It's taken some effort, had some ups and downs, and I'm not there yet, but it's been a useful experience. If you already have an Alpy 600 and guide module, I'm not sure you'd gain anything with the Lowspec. I did it to, hopefully, get better Spectra than the Star Analyser 100 without spending a lot. I had to buy the Ender 3 Pro but expect to use that for other projects. The slit, grating and lenses are the most expensive parts. Fortunately, I got the lenses cheaply from Surplus Shed. The design uses a micrometer which I was lucky to get off Ebay for £20. The reflective slit cost Euros 59 and the 600 l/mm grating was £87+vat. So basically a substantial saving on a purchased spectrometer - but only if I can get it working ok! I did consider making the Uvex3 but the design doesn't actually include a guide module but I think it does interface to the Alpy guide module, so if you already have that, it might be the way to go. I don't think there are any stl files available though - just basic optical measurements (as far as I know). Louise

I do wonder if the Universe is out to get me - it will in the end, of course! I successfully designed and printed a 45 deg mirror support to aid lining things up on the Lowspec spectrometer, so not all bad. My finger's sore though 😢 Louise

You know those little strips that the printer lays down on the left hand start at the beginning... I was removing a small bit and, instead of using the supplied tool, I used my finger. Unfortunately, instead of simply coming away, it decided to behave like a splinter and went in under my nail, diagonally, by over a cm. After one of my front teeth breaking off yesterday, I wonder what mishap is next to befall me... #bewareofsharppla Louise

Ok, thanks. I'm struggling a bit today as it's cloudy and dark - can't see . I remembered I have a F6.3, 500mm Mirror lens with the option of a 2x teleconverter so could use that as a 'scope' - if I can get the backfocus right. After fiddling a bit, I can just about see a daytime image on the slit at F6.3, so that's a start. I'll put the proper guide cam in next. Louise

Oh, ok. I don't have anything F10. F7 is the longest I have and that would be the scope (sans reducer) I was planning to use with the spectrometer. Presumably it's also possible to tweak the collimator in use, to get the best image, or is that not advisable? There isn't a lot of movement of the collimator possible - maybe 5 or 6mm max. Measuring with a ruler, I'd say the collimator-slit distance is approx. 119 -123mm max and obviously fixed to those limits by the physical layout, though the fl of the collimator is specified as 125mm in the design. As it happens, the candidate lenses I ordered from Surplus Shed are 120 and 121mm fl so, hopefully, should fit in that range ok. The lenses I took from the old finders have a fl of 125mm (with some depth of field) but their diameter might be too big to fit. I'll just have to see how things work in situ. Thanks Louise

Ah, ok - thanks, Andrew - re the guide camera, I should have figured that out, it's too early ha ha. Need second coffee Louise

Although, normally, the guide cam would be focused on a star, not the slit itself? Yes, checking the collimator light path and focus is coming up next, together with testing the imaging camera, which I assume will also be focussed on infinity? I'm wondering how to check the collimator-slit focus? The only way I can think of is via the imaging camera - or am I missing something? Thanks Louise

Yeah, I've had some holdups, especially with trying to print the t-threads - 'mare! Also with getting things to fit together properly - that hasn't been straightforward. On the plus side, I've learnt a lot on the way. Louise

Am making progress with the assembly I've partially put it together with some test components so as not to risk damaging the critical/expensive ones. I bought some craft mirrors the other week. They only cost a couple of quid. Mind you they seem quite good! I bought some 1" square and 1" dia round. I put one of the round ones in the main mirror holder and another one where the guide mirror should go (it's supposed to be 1/2" really). Another one I cut through the back coating with a scalpel and made a diy 'slit' which I put in the slit holder. I've installed a 13mm dia lens, (bought from Surplus Shed) for the guide camera. Had to make a new holder for that. Put my Touptek microscope camera in place of a guide camera. Was able to get an image (focused on the slit itself). I was pleased with that as it showed things were lining up ok. Took this image of the slit with Sharpcap: Tomorrow I'll try it with a proper guide cam and some sort of scope so that I can get an image from infinity. Maybe I'll be able to connect a 60mm finder or something. It's coming along, bit by bit! Louise

You might be better off with an oag on a c8. The avx tends to have a lot of DEC backlash - something to bear in mind.

Hi It's not the most sensitive of cameras for guiding with (qe = 65) but it should be useable on brighter stars with a 50mm finder. The thing is first to make sure the camera is attached in way so as to enable focus on infinity. The SW finder has a fl of 180mm so you should be able to measure ~180mm between the plane of the objective and the plane of the sensor. Best checked during the day on a distant object such as a church spire or electricity pylon. Make sure you can adjust the focus to be slightly beyond that. As James mentioned, if all ok, try on the Moon and some bright stars. I don't know whether the qhy6 has any setup options such as offset and gain, but you might need to check that out. The camera is still sold so there should be up-to-date Ascom/native drivers available for it via the qhyccd web site (but don't go there without internet security / anti virus software running!). Here is 12dstring screen grab showing fov and image size of M44: Hth Louise ps what exposure lengths were you trying with phd2? You may need longish ones - 3 or 4 seconds. It's very easy to take a finder guider out of focus and you can then get a bit lost in the dark. If you can get sharp focus on a distant (~mile away) object, it should only need a very slight adjustment on the Moon/stars). Thereafter, you shouldn't need to refocus again.

Hi See p29/30 of the manual. To polar align using ASPA you have to align on 2 stars plus a third calibration star before selecting another star to do the mechanical alt/az pa adjustments on. I've never done it myself. I think it's best to just use PHD2's drift alignment tool via your autoguide scope, plus platesolving to accurately locate end centre the target instead of doing all that time-consuming star alignment. Some people use SharpCap Pro, or PoleMaster, if you're rich... Hth Louise ps SharpCap Pro uses platesolving and can be done via a finder guider

Cool!

Thanks, lol, though I don't think I'd want to go that far - (my) life's too short! Louise

Well a flat ceiling projection is no different from a wall. Maybe a 45 deg mirror attachment would make it easier. Louise

May well have been - I didn't get the chance to ask/find out at the time. IIRC it wasn't colour and seemed rather poor compared to Stellarium on my PC. I've had a quick look at 360 deg projectors and standard home projectors. They can get rather pricey and I wouldn't want to spend more than ~£150. I was also thinking it would be nice to project tv onto a wall sometimes. Maybe I'd settle for a standard projector that I could optionally just point at the ceiling or the wall . I use my pc as a tv via a 27" monitor so it would be good to have a bigger picture sometimes. 4k projectors are rather pricey too, but maybe a hd one would do. Of course, I have the Oculus Rift S to play with I need to swap it over to the new graphics card - should be a better experience on that. Louise

I'd like to project Stellarium When I was at Uni we had an old version of Stellarium projected on to the roof of the dome at our observatory. I don't know what was used to do the projection, unfortunately, though it was likely quite a few years old! If I could manage to cobble something together, I'd be happy. Louise

Ok, thanks

Oh dear... I was thinking of getting a standard LED projector which I could use as is fo projecting tv etc. and maybe adapting it to also project astro things onto the ceiling. It's just an idea, and am musing over it. Louise

Thanks for the reply! Yeah, I was thinking a fisheye would do it, but don't know if you can change the lens in a standard LED projector. Can I ask which one you have? Are you pleased with it? Cheers Louise