DaveL59

doing my bit to keep the clouds hanging around...

A star diagonal and finder shoe courtesy of Svbony. No idea how you tell if it really is dielectrically coated but hopefully it'll be as good as the TAL one. Good news is the OV polarizer filters fit the nosepiece just fine 🙂 Intention with this one is so the little Celestron LT70 has a proper diagonal to use rather than the plastic erecting one it came with. The finder shoe I may fit later on to the vintage scope so it'll be easy to swap an RDF or regular finder onto it.

not 100% that the prism I'm using is coated but might be. Are you seeing reflections between camera lens and the prism then? Could be the light level, at night it may not cause any issue unless aiming at a bright target. As you can see I flocked the edge facing the camera as well as the long edge, cut a hole wider than the camera and flocked the area under the phone. Idea was to quash as much stray light as possible and to give the prism as optimal a housing as I could. Seemed to work quite well. A bit of vignetting doesn't seem to affect the ability to get a star fix so I've gone ahead with building it. 

I do see a section at the lower part of the image that has a darker area as per your pic but it didn't seem to affect it at night so could just be stray internal reflections in brighter light. Saw similar with a prism diagonal of older japanese vintage when looking through the prism while cleaning it and when back in the diagonal looking down the barrel. But in the scope day or night I didn't note the effect at all. I did black the ground edges on the prism I'm using just to try to dull off any potential effects, kinda mute really tho being it is now fully clad in a flocked housing 🙂 

1 hour ago, AlexK said:

 

Re 3D printer: The tech is super-mainstream by now. You can have a decent tool in your man's cave for just $200 shipped. Given the well known UK/EU prices on trivial astro gear "issue" that cost will be recovered in no time.

thanks, hopefully will get a chance to test sometime in the next months 🙂 Interesting re the accelerometer  I guess that could become a problem, I guess we'll know soon enough.

As to the printer, yes I have thought about it but where I currently am, space and curious kitties are the issue. One day perhaps...

The loss of FoV with a bino prism isn't too bad really, a squared prism like Mark showed would be better but I didn't have one of those laying around so tested with what was to hand. The rig I fabricated should work well enough given the first mockup was some acetate film and flocking and that located under the stars very well sat on a photo tripod. Not having a 3D printer, hacksaw and acetyl sheet was the easy route, not to mention something to do to pass the time!

I plan to use it on EQ mounts as most of mine are that way 🙂 Not had a chance to test it out like that tho as weather here has been typically cloudy/wet of late but hopefully it will be usable. Always a chance that Celestron will release it as a stand-alone one day with a finder shoe mount, but the base model scope isn't exactly expensive for a play and other than the mount it performs pretty ok as it happens.

Hi Alex

yes it does seem tolerant as in my testing so far the prism and plain mirror solved faster than the starsense OEM rig which surprised me. I was aiming the camera high to NW at the time and that way is the London light dome tho my back garden is reasonably dark. Others on CN have tried with plain mirrors, shaving and the like and reported it works just fine. The mirror I used was very thin glass and fell off a hairbrush so I figured why not see if it works. Losing some of the FoV doesn't seem the be a big issue so long as there's enough sky for it to solve, more a problem is cloud or brightness in the sky. It warns of a bright moon and suggests to look at other regions of the sky as accuracy can't be assured in the region of the devil's floodlight.

4 minutes ago, markse68 said:

this prism is doing this weird thing of partially seeing through the long face- this image is camera looking through short side and the curved bit of decking and fingers is seen through long side which it shouldn’t. I reckon it’s a semi silvered because splitter or something- not the right thing. Shame as it doesn’t vignette otherwise. I liked the idea of a prism as it’d be easy to wipe condensation off in the field. 

hmmm I get that if the prism is in free air, but if you hold dark/flocked card against the long edge the the image correct to be only what is in front 🙂 When there's plenty of light you get the interference of light entering via both exposed surfaces unless they are silvered or blocked in some way.

For me I didn't see the point buying a diagonal even cheap when I have a couple spares binos just kicking around waiting for a good use to come along 😉 

3 hours ago, markse68 said:

couple of questions- does it really need the funny looking funnel light shield at the front do you think?

And anyone know about prisms? I found this in our junk optical box- it’s from an old industrial laser printer iirc. I suspect it may be a beam splitter with partially reflective coatings but not sure, but if the camera looks through a short side it sees out the other short side but also partially (the curved part in image with my fingers in it) out the long side 🤔 That’s not normal is it? It’s a bit on the big side anyway

I’m just playing around thinking about it for possible future purchase

Mark

 

 

 

If the prism will give an inverted view with the camera looking in one short side and therefore of what is in front of the other short side, assuming you have good internal reflection off the long face then you'd be good to go. An old 10x50 bino prism is what I'm using in the rig I made, but a plain regular mirror also works, doesn't need to be first surface from a test I did the other night. As John says a cheap plastic diagonal might be easier as that already has the box you can glue to a phone holder etc.

As for the big wings in front, they baffle the stray light from the mirror so I guess if there's total darkness you won't need them, but not hard to add as needed if you find it necessary. I thought it worthwhile as I've no control of neighbours turning bright upstairs lights on etc.

always the way Ade, here it's not too bad tho cloud is drifting across now from the NW, but tired eyes and needing to be up and out early, need to go unload tools etc from the car before I head off to zzzz so won't be playing tonight. Would like the epoxy to have a chance to cure off properly too before I try using that home-made prism rig 🙂 

do bear in mind Mark that you'd need to buy a starsense explorer scope so you can get the unlock code, else the starsense app won't let you use the camera to platesolve. The LT70AZ is the cheapest one at £135 but stock is low like with most scopes at the moment. Performance wise it's ok but the mount is real shaky, if patient with it tho it does pretty well I found. Was able to give it a short try out w while back with the SV171 zoom but I expect it'll perform better with a proper star diagonal rather than the erecting one supplied.

Yet to have a chance to test this on an EQ mount but can't see any reason it won't work albeit the directions may get confusing being geared for alt-az but will report back when I get a chance to test it out.

7 hours ago, markse68 said:

What are you going to use to glue acetal Dave? it doesn’t seem to stick very well to anything?

Has anyone had any luck using this thing? is it accurate and reliable? It is very tempting

Mark

using epoxy which should work, roughened up the contact areas first with emery cloth.

Here it is assembled and flocked (well where it matters at the moment at least)
 

Tapped for 2x M3x16mm thumbscrews which will secure the prism, the top one nudges into the ground off corner that Bino prisms tend to have. Will make it easier to remove the prism for future cleaning. The nib at the front (arrowed) should be a close fit to the lip of the case on the phone and stop the prism holder sagging, I noticed that it did a little so added this and a rib underneath so things stay reasonably stable in use.

comme ça

View vignettes because of the prism but earlier testing when I had some clear skies showed it worked just fine and quickly found the location and offered directions to target. Prism needs a clean as I can see I got sharpie pen onto the long surface, oops

Worst case if I find this doesn't cut it I can easily swap in a piece of plain mirror which also works 😉 

hmm ok so I guess the webcam doesn't generate much heat compared to the CCTV module

Guess I may need to fit a dew heater inside the dome. Wonder if I can do that off the USB tho I expect the Network-USB hub isn't going to like supplying high current, will have to check but IIRC it limits to 500mA/port.

I was tempted to use a spare case to glue the prism carrier part onto, but then swapping cases each time I wanted to use this sounded too much hassle. Not to mention the hard back and soft sides of the case would then split apart after a while and it'd be back to doing another build. This way just seemed simpler in the long run.

1 minute ago, johninderby said:

Ah.........elf and safety and all that. 😀

yep those Elf's are a right PITA lol

5 minutes ago, johninderby said:

Here’s your Blue Peter badge for that. 😁

I'll only earn that if I round off all those sharp edges and angles I think 😉 

as the 2mm thick acetyl sheet has arrived I thought I'd start looking at making a prism carrier for this, aim being I'd use the Joby adjustable phone holder for my phone and re-fit the OEM mount back onto the LT70. The Joby on a camera bar is an easy transfer across to my other main scopes but the LT70 less so, plus hopefully I can pass that on to my daughter later on so the OEM holder would be real useful at that stage.

So I made a mock-up using card so I can confirm the idea might work and that the 100x300mm sheet is big enough. On the right is the acrylic sheet test rig I knocked up earlier for comparison.
 

Next take the mock-up apart and check it'll be workable

Then get the Acetyl all marked up ready to cut

Now assemble the cut pieces with masking tape so I can test for fit. Reason for picking 2mm is that the phone will still be held secure with this sheet under it in the Joby clamp.

As you can see I make that small acetyl offcut work by cheating - well I prefer to think of it as creatively cutting the base of the prism baffle into the flat section that will be under the phone in the holder and so invisible in use 😉

Side views

And view from the front/Prism side

All seems to work 🙂

Some tidying to do and then glue it all together,  fit a stiffening rib on the underside to prevent it flopping and locator lugs to align with the phone. Oh and of course make a hole so the camera gets to look out via the prism. Then flock the baffle surface and fit a removable sprig across the prism top edge so it won't try to escape. I'm thinking I'll drill and tap a couple 3mm holes one each side of the prism too, so I can lock it in place and have a little side to side adjustment if needed, much like some older Japanese prism diagonals do. A quick check looking through the prism and the baffle is outside the FoV so I reckon this DIY rig will work just fine once finished.

hmm not so good in the day tho, SharpCap set to shutter 1/8000s (fastest) and still whites out the cloud, had to fiddle with white balance to get some blue in the sky hence the weird colours as well as turn down brightness etc.

Somewhat better in the W10 Camera app tho in daytime

But still poor compared to the cctv module that shows much better in daylight

Still I guess the CCTV can be daytime duty and the webcam can do nights when I want a better sky/star view 🙂 

Might flip the bracket around on the little skycam so it's over the shed roof and less in view tho relative positions are dictated by mounting options and cable lengths. Will see what I can do later perhaps.

and after running a short while

got the extendy window cleaning stick out and gave the dome a quick swipe over to clear off the water gathered. Much better so gave SharpCap live stack a go

Pretty pleased with that result, there be stars here 😄 

result! After some fiddling and rebooting the USB server SharpCap can show a picture. Had to switch to MJPEG rather than YUY2 but that's ok 

Of course it has rained hence the water on the dome, forgot to give it some RainX when I put it all back, oh well. At least now I can control the shutter speed and get a better view of the sky than MS Camera app was giving, maybe live stack etc too 🙂 

A nosepiece barrel (thanks Johninderby) and an acetal sheet - they didn't have black in stock at this thickness but that's ok, some more nylon thumbscrews and the birthday gift from my daughter, the eyepiece bum bag. Somewhat early for the birthday but will be handy now its here 😉 

Sadly the nosepiece is a hair too large for the TAL diagonal but that's ok, will see if there's an engineering place that might re-cut the thread to match if things settle down in the near future.

hmmm so SharpCap doesn't seem to like the camera being on a virtual USB port, I just get a black screen where the W10 camera app seems quite happy to connect and show an image, just doesn't have much in the way of exposure or pro settings features. Will have to have a search around for another app I can use for handling the camera and captures then. Still it works, kinda 🙂 

Took my skycam-2 apart today to swap a webcam in for the cctv module I originally installed. The dessicant pack had certainly done its work well as you can see here

top one is the used, had been in there for some time but no sign of moisture in the casing at all after quite some time and no condensation issues with that camera/dome. Replaced with 2 new ones on reassembly which will hopefully do as good a job.

so with it being nice this morning I pulled the old SkyCam2 dome down and stripped it to fit the USB webcam. Here's the result:

Must admit it's a little glitchy connected via the USB hub across 3 network switches which is a little disappointing and distracting when it's on screen, but at least it works. Seems more stable running at 720p or 640x480 so will leave it at 720P for now (640 crops significantly) while I think about any improvements I might be able to make later on. Had some fun setting it all up as the USB network server needs to be on the same LAN as the server app trying to connect to it so a bit of vLAN reconfiguring etc was needed.

Fitting it to the dome was fun tho, the board is too long but I secured it to the frame using a couple cable ties, hopefully that'll hold it well enough 😉 Also covered with some flock to protect the SMD's on the board and to dull any internal reflections. The lens is actually a little low given the edge of the carrier so will get some loss of view but not significant as it turned out.

The camera sits lower than the old setup but not at the centre of the dome arc so might pick up some distortion which the fisheye lens likely adds to, but it'll do for now. I can see the sky quite nicely and hopefully the dark sky performance will be passable too. Here they are mounted on the shed, might have to shift the little one as it's a bit far in the FoV now.

 

At 720P the image seems a little darker but that could be the effect of more cloud lol

so further mod, a 1.7mm fisheye but not having an IRcut fitted I swapped the holder with a switchable one set to filter IR. Of course it's larger so can't reassemble but a rubber band stepped in to hold things secure for testing 🙂 

Next step up I have is a 2.1mm which is wider than the first lens I fitted but am hoping to get a wider view at this stage.

So how did it do?  Some test pics tonight at long exposures via sharpcap photo capture:

Mars decided to pop out for this one 🙂

and as the clouds moved over, some stars joined the party too

I think I can work with this as a replacement for the 5MP cctv module, would give me a good indication of the sky and whether it's clear enough to pop out for a look with the scope and maybe even supply some sky captures from indoors if I'm feeling too lazy/cold 😉 

Now I just need some dry daytime weather so I can pull the unit off the shed and refit...

reminiscent of old sight style finders on old scopes, nice work-around in a pinch 🙂