Thalestris24

Hi Neil I don't know why SharpCap would be stuck but what frame rate are you trying to run at - lower might be better. I remember I had problems trying to run my qhy183m but using the Ascom driver worked (even though SharpCap moaned). Have you got the latest version of SharpCap installed? Louise ps isn't ASICAP for Android? Maybe you have a usb problem?

Well, that sounds encouraging! There's a wide mix of Glasgow lighting types contributing to the skyglow. Even with Ha I'm limited. I usually don't bother trying to do anything until the nearby all-weather pitch switches of it floodlights after 10pm. I'll just have to see what I can do. Louise

Yes, SharpCap can control cooling and do long exposures ok. However, the length of my subs is generally limited by the city skyglow . With the Atik383l+ I can probably do 360s with a normal sub but then I'd be using a lp filter or Ha filter. Not sure how long I'll be able to get in pure luminance. That looks a nice Eta Carinae spectrum! That is about mag 6? So quite bright and the Atik314 has quite a high qe. My Atik383l+ isn't so sensitive so presumably would need longer exposures. My snr would be a lot poorer. I can only see to the East and not much higher than alt=35 deg. Nothing involving astro imaging is simple or straightforward for me! Louise

Oh, ISIS not IRIS! I have some image processing software called IRIS... SharpCap pro does live stacking with optional darks, flats and auto alignment (or can just guide with PHD2). I can't see any way to take flats, though. Not sure about image measurement. Louise

Hiya I'd not really thought about specialist imaging software - I kind of assumed I'd be able to do it with SharpCap as I did with the Star Analyser? Is Christian's IRIS a possible? Possibly AstroArt, especially as you recommend it , but I wouldn't want to fork out for something unless I already know all the kit is working ok. I don't get the best guiding here, not helped by having to do my imaging through an open window... So I might put everything together only to find my results are rather poor . Thanks Louise

Hi Ken @Merlin66 Useful info in your last post on Rockmover's thread Paul changed his design slightly - he made the camera fl = 100mm and dia 30mm so fr = 3.3. However, I currently have one which is fl=87mm and dia=26mm (fr=3.34). It should allow attaching my Atik without too big an extension. My collimator lens is fl=121mm. So with a slit gap of 20 um it would appear as 14.4um. With my Atik383l+ that means it should cover 2.7 pix when focused. I suppose that means 3 pix in practice? When I've tried to test focus the collimator it's proved quite difficult since illuminating my diy practice slit from the 'scope' side tends to generate diffraction though I did get some ok images via Sharpcap. However, I'll be testing it more properly with all the right components in place - hopefully within the next week. Um, I have been assuming that, on its own, the imaging camera is focused on infinity/a distant object? Hope that's correct... I was using a second test mirror to see outside through a window with a Touptek camera in place of the proper imaging camera. I was able to get an image of distant objects ok. I'll repeat with the Atik attached next. I understand that an attached scope will focus it's image (normally of a star) on the slit? The photons which exit from the slit are collimated by the collimating lens which transmits the beam to the grating and the spectrum is then (hopefully!) seen by the imaging camera. Hope I've got that right! Thanks Louise

Thanks for the suggestion re Tinkercad. I can do it in Fusion 360 and the original lowspec stl files already had T2 threads. At the end of the day it's trial and error to try and get the print to work properly however you generate threads. I have the magnetic bed also and it does make it fairly easy to remove most things. Louise

I think I'm really enjoying this projector! It frees up my PC monitor and lets me lay back and watch from a distance. Must be better for my eyes too. Why didn't I think of doing this before? Louise

The struggle is half the fun! If it was made too easy it wouldn't be so interesting. Overcoming hurdles is how you learn about something

Ah yes, I recognise it now - not used to viewing it like that! I just took a 1" round mirror and cut a short line in the backing with a scalpel. Then just taped it in place. Not good enough for a proper slit (though maybe with a new blade and a bit of practice...)

I don't recognise that diagram - where is it from? It's the non-shiny side that's used. I found it a bit confusing and counter-intuitive too. However, having tried it out I believe it will work ok. The guide camera is focused on the slit. The telescope is also focused on the slit. The guide camera can then see the star and can guide on it. I think it might be quite challenging to get a particular star lined up with the slit.

Yes, it's a reflective slit though, as I understand it, the shiny/mirror side points in the other direction. The side with the numerals in mirror image is the one that points to the scope. ps as you see I made a slit from one of the round craft mirrors I bought. Used the non shiny side for the reflective side.

Well I used a diy slit - https://stargazerslounge.com/topic/343342-the-lowspec-spectrometer/?do=findComment&comment=3746287

Because it's reflecting light from the slit to the guide camera - via the guide lens

Oh, sorry, I was confused - thought you were referring to my 45 deg mirror tool! That's what I gave you the dimensions for above! The guide mirror holder should print out fine with no changes. Apologies for my confusion! Louise

That looks rather like the guide mirror holder?

Oh, I was only referring to the 45 deg mirror holder.....

? Isn't it your design? ps you can probably round up the above dimensions e.g. 36.98 = 37, 17.96 = 18, and 18.98 = 19

Yes, should be at 45 deg. Here are my dimensions: I just fixed a 1" mirror to the angled part with a small drop of glue. The angle actually came out at 44.94 deg, I think, but it's fine! Louise

A quick update! I had a bit of a moment last Friday night and ordered a projector from Amazon on a 'Black Friday' spot deal. I'm sure Amazon and co know just what I'm thinking! It's a cheap Chinese job but supposedly projects 1080p though I'm not sure if it quite does, but I'll have to double check the settings. Here's a brief clip taken with an old mobile phone. The sound is actually from speakers rather than the projector itself. Anyway, seems not too bad considering. It's bigger (about 30cm x 28cm x 11cm) and heavier (around a couple of kg) than I expected. I reckon the main lens could make a half decent scope ha ha - it is in fact about 80mm in diameter! The image size in the clip is about 112cm horizontally and that's about as big as it can go on that bit of wall. On another wall it could go several times larger - I'll have a play when I get time. If it actually keeps going it should be quite good for watching some Christmas movies on . I like to watch the Muppet Christmas Carol on C4 every year . It disappears under bright room light and probably wouldn't be much cop on a sunny day with the blinds open... But in low room light (40W bulb) it's fine. The fan is noticeable but not too bad and the issuing warm air will probably help to warm the room a bit. Louise

Update time! I had a bit of a struggle with the imaging camera focus mechanism the other day. It went quite happily one way but refused to go the other. So I had to undo it all and fiddle with it. Eventually got it going ok though it never seems quite as smooth as you might hope for! Anyway, I have been fiddling with the collimator lens and choosing a different one to what I'd planned. The ex-finder 125mm is a really good lens but is a tad too big. Instead, I'm now using a Surplus Shed lens which has a fl of 121mm and Dia of 26mm. I had to make another holder for it but it fits better in the light path. I decided I just couldn't rely on my poor eyesight to decide whether or not it was in focus. So I set up a web cam (MS LifeCam Cinema) to look down on the 45 deg mirror and through the lens back to the slit. I still couldn't decide on focus with certainty! The lens seems to have a reasonable depth of field and the precise positioning didn't seem to make a lot of difference. I did find that if you move back towards the main mirror too much then it encroaches on the light path. Anyway, it's currently positioned about midway along its 'groove'. I took some pics: This is the dummy slit backlit (from a torch at an angle). The slit illuminator has been removed so that the slit position is fairly clear: And this a Thorlabs post-it on a piece of card and in place of the slit: Moving the card backwards and forwards in the slit holder space didn't seem to make much difference to the focus. Perhaps with the grating and other proper components in place, the focus point might be more or less better at slightly different positions of the lens. As you can see on the 'Thorlabs' pic, the edge of the lens is slightly encroaching from the south east. Anyway, I'm going to try attaching the camera next. I'll try and use the 45 deg mirror again to look back at the camera sensor and see if the lowspec focus mechanism can adjust the camera lens to be in focus. Louise

Hi The collimation lens is focused on the slit and passes a collimated beam to the grating. It's just that at the position of the grating you can see, via the mirror tool, the back of the slit in focus. I don't find it easy to do cos I wear glasses and can't always tell when something is in focus! I've found it easier to do it with something in place of the slit but at the same position/distance. I'm not convinced a lens with a fl of 125mm is able to focus on the back of the slit but it might do. I've made a new lens holder to take a 26mm dia lens of focal length 121mm and with a shorter 'foot' so I can move it more in its slot. Hopefully, I'll be able to properly check it out tomorrow. It's 2:30 am now and I'm off to bed! Louise

Hi Rockmover Just to butt in I'm just assembling mine also and also faffing around with lenses. The set up is as defined by the design of a classical reflection grating slit spectrometer (with reflective slit). I 3D printed an item to hold a small 1" craft mirror at 45 deg. I put it in place of the grating mechanism and the centre of the mirror is in line with the centres of the lenses and mirror. I can look down and check that the collimator lens can focus on the back of the slit. I'll also use it to check the camera lens focal plane. It's a surprisingly useful little tool! As I say I've been trying different lenses which have required me to print new lens holders. Hopefully, tomorrow I'll be able to check the imaging camera focus. At the moment, I only have the guide lens in place. I've not touched the grating at all yet (very delicate!) and will probably put that in last of all. In the meantime I have a dummy grating (another piece of 3d printing with a mirror on it). I haven't put the actual slit in yet either but again made a practice one by scratching the back of another craft mirror with a scalpel. It's good enough to test with. I don't exactly know for sure how to set up the grating but Christian Buil has some useful info here and here. He includes calculations for the grating angles of incidence and angles of refraction (alpha and beta). I think basically you do your own calculations for whatever components and scope you have. That should let you approximately set the angle of the grating and you can do fine adjustments using the micrometer with everything in situ. Oh, there is a handy Excel spreadsheet here to make some of the calculations easier although Paul Gerlach (the Lowspec designer) has obviously already fixed some things in the design. Hope that's helpful - I'm no expert, just finding my way Louise

I got one included with the Ender 3 Pro.... Louise

Sounds like 3D printers should come with a health warning!