DIY all-sky cam?

[Gina]

I have succeeded in undoing my QHY5   Just put the mounting flange in my little table vice and was able to unscrew the body by hand  

There certainly seems to be enough room to get a shutter between the lens and the image sensor

I have had confirmation of my Fujinon lens order

[Horwig]

Brut

I have succeeded in undoing my QHY5   Just put the mounting flange in my little table vice and was able to unscrew the body by hand

There certainly seems to be enough room to get a shutter between the lens and the image sensor

I have had confirmation of my Fujinon lens order

Brute force is a wonderful thing Gina, Agree with you that there is more than enough space to put a shutter behind the lens, I'd miss measured the required spacing, here it is with a correct back focus distance.

Huw

[Horwig]

We're not the only ones playing with this:

http://www.iceinspace.com.au/forum/showthread.php?t=107919

[Gina]

The Fujinon fisheye lens has arrived - now to sort out mounting it

[Horwig]

Glad to hear the lens arrived, I bought an adaptor from Bern at Modern Astronomy, couldn't be bothered to make a c to t  adaptor

Just found this on CN, very interesting with respect to what we are trying to achieve. If you give up on the qhy5, it could be that the Lodestar is not the best camera for all sky applications, ie very short focal length.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5969048/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1

Huw

[Gina]

Hmmm...  Looks like the QHY5L II would be a good camera - not cheap though   Anyway I'm going to try the QHY5 original and see what it gives.  It's surplus to my requirements as a guide camera so nothing to lose by trying.  I'm about to print a casing to connect the Fujinon lens to the QHY5 PCB.  Here's the current design I'm going to try.

[pete_l]

I've already used the qhy5 in anger for an imaging session, and it worked fine as a tool to warn of incoming cloud. It will never give pristine images of the night sky, but within its limitations, and with darks, it was usable.

Here's a shot I took with my QHY5-ii a couple of nights ago.

IIRC: 10 seconds, full resolution, north is up, east is left (the light there is my laptop). outside temperature at the time was 28°.

As you can see from the banding, this was pushing the camera about as far as it would go. However you can see Arcturus at "3 o'clock" and Deneb just left of centre. The summer triangle goes off to the left. The sum total of my LP is to the south (bottom) and if you squint and use your imagination, you can make out the Milky Way curving up from there. Scorpio is just above the trees at "5 o'clock', too.

The lens used was the fisheye from the QHY5 accessories pack. I calculated that this gives an image circle of about 3.45mm. it does seem to me that a proper All-sky camera will need a cooled CCD and a longer exposure time than the temperature will permit.

But it was a promising start.

[Gina]

I'm not expecting very much from the QHY5 but at least I'm starting with a decent lens which should give it a better chance.  The noise is going to be bad with these warm summer nights.  Unfortunately the sensor and PCB do not lend themselves to be cold finger cooled though it might be possible to provide it with a cool environment.

I agree that a cooled CCD camera is what is required but it will need to have a relatively short back focus.  The cooled CCD cameras I already have won't do because of the large back focus distance.  eg, the Atik 314L+ has a back focus of 13.5mm whereas the Fujinon lens has a 12.5mm back focus (and it won't quite fit inside the Atik mounting).  The 314L+ also has rather large pixels, though not as big as the Lodestar.

I wonder if the relatively new Atik GP Guider/Planetary Camera would be suitable, though it isn't cooled.  Back focus at 7mm would be fine.  I has a good Sony CCD sensor and looks like it could be a contender.

[Gina]

I have found an old meter that I've been looking at as a shutter motor but I don't think it'll be any good.  It's large for the purpose being about 58mm diameter by 43mm.  And even without its case it has a large permanent magnet that would take up a lot of space.  The "works" measures 47mm across   It'll need dismantling and cleaning too though it would probably need dismantling to attach the shutter.

I think a better approach will be to make a new shutter motor from scratch using one of the latest rare earth "super" magnets.  I'll do some experiments.  At least there's a nice little gap between the lens and the QHY5 image sensor so I won't be needing anything like that large shutter mechanism I posted above

[pete_l]

I agree that a cooled CCD camera is what is required but it will need to have a relatively short back focus.  The cooled CCD cameras I already have won't do because of the large back focus distance.  eg, the Atik 314L+ has a back focus of 13.5mm whereas the Fujinon lens has a 12.5mm back focus (and it won't quite fit inside the Atik mounting).  The 314L+ also has rather large pixels, though not as big as the Lodestar.

Looking at the (Japanese language) drawings for the old QHY6 http://qhyccd.com/ccdbbs/index.php?PHPSESSID=a1ec1aad6dd84485e158f2a7355c5e68&action=dlattach;topic=2809.0;id=2829 the distance from the CCD to the front of the flange is 14.5mm and the flange is 8mm proud of the case. It's got an M42 0.75mm thread, so with an adapter that's not too thick it might do the job.

[JamesF]

I'm not expecting very much from the QHY5 but at least I'm starting with a decent lens which should give it a better chance.  The noise is going to be bad with these warm summer nights.  Unfortunately the sensor and PCB do not lend themselves to be cold finger cooled though it might be possible to provide it with a cool environment.

My recollection is that the QHY5 PCB is very similarly laid out to the ASI120.  If so, the pictures here might be of interest:

http://www.astronomy.com.cn/bbs/thread-242988-1-1.html

James

[Horwig]

James, I think there might have been two versions of the qhy5 pcb, I remember reading somewhere about a cooling mod which involved a cold finger through a hole in the pcb. The pcb in my qhy5 is sold, and has components in the area behind the sensor.

Huw

[Gina]

Same here Huw - solid PCB with components behind the sensor

[Gina]

Having waited all evening for the ASCOM platform to download onto my desktop I now have a working setup.  Went on the QHY site and downloaded the ASCOM QHY5 driver and PHD2, installed everything, rebooted and got it all going. 

Here is the result - 15s exposure time.  The USB2 cables are not quite long enough to get the camera assembly right outside.  It is purched on a table vice attached to the windowb ledge and pointing mainly upwards.  I'm pleased with the result I have to say. And this is just with the back focus set up by measurement - I haven't tried focussing yet.

The laptop I use for astro is in use grabbing the Cygnus Loop mosaic panels.

[Gina]

Here are a few photos of my unit.  The first shows the layout of the QHY5 circuit board and components - no hole for a cold finger unfortunately.  The others show the printed ABS case holding the lens and skeleton QHY5.

[Gina]

Re. Shutter operation.

This is the sort of meter that I think would lend itself to adding the shutter but not cheap.  I used to have a couple of similar ones a while ago but no idea where they are

Meanwhile, I've ordered one of these.

Been searching Google for actuators but not found anything suitable as yet.  I'm sure there ought to be something suitable amongst the mini robot stuff.

[tekkydave]

Try technobots. They do allsorts of mini robot stuff.

[Alien 13]

Might also be worth looking on the RC sites or just rip the bits out of a cheap RC car.

Alan

[pete_l]

All a meter is, is a small (milliamp or micro-amp) electric motor with a spring attached and a stop at either end.

To rotate a shutter across a camera sensor, all you need is a small, low-power motor with a stop when the shade  covers the sensor. Would not a small vibration motor ith the shade glued to the vibration weight, run at low current do the trick?

[Gina]

Try technobots. They do allsorts of mini robot stuff.

Yes, I've tried Technobots, thanks   First place I thought of as I've dealt with them plenty of times in the past.

[Gina]

All a meter is, is a small (milliamp or micro-amp) electric motor with a spring attached and a stop at either end.

To rotate a shutter across a camera sensor, all you need is a small, low-power motor with a stop when the shade  covers the sensor. Would not a small vibration motor ith the shade glued to the vibration weight, run at low current do the trick?

DC motors are not very good run in stall mode - the commutator contacts tend to corrode.  I guess I could take one apart (I have several) and connect flexible wires direct to the rotor coils.  Then use a heavy duty hair spring to return when power is removed.

[Gina]

Had another thought...  A small stepper motor without gearbox will return with a hair spring.  Lots of scrap items contain little stepper motors.

[Gina]

I've decided to use a small DC motor as suggested   I've got several spare from my original CCTV panning motor/gearboxes.

It would be nice if I could find a neutral density filter to use as a shutter so that it could be used as a daytime all sky camera.  I'll try solar film but I think that will be too dense.

[pete_l]

It would be nice if I could find a neutral density filter to use as a shutter so that it could be used as a daytime all sky camera.

Isn't that the only excuse needed to buy a tin of Quality Street?

Apart, that is, from needing a tin.

[Gina]

I've tried the Baader solar film and it works - with an exposure of 0.2s.  BUT with it in between lens and sensor there's too much stray light, which floods the image.  Sealed to the top of the lens it's fine.  So to make a practical night/day camera will need some thought but I think it could be done