DIY all-sky cam?

[Gina]

Well, after designing and making a mounting for my little MFA DC motor I had an idea for a much smaller motor and wondered why I hadn't thought of it before.  It's the shutter motor for a DSLR - I have one with a broken and unrepairable shutter so the motor is surplus.  I wanted a motor for a shutter and never thought of a shutter motor - amazing     I also realised that the DSLRs are a good source of rotary springs too   The pop-up flash and flip mirror, for instance.

[Gina]

I have now mounted the tiny shutter motor onto the QHY5 PCB using the microscopic screws that held the motor in the DSLR.  I drilled 2 1.5mm holes in the PCB for the screws.  I took a return spring from the mirror of the DSLR and adjusted it to us as a return spring for the shutter.  The photos also show a test shutter without the spring or solar film attached - the idea was to check the end limits for the shutter.

[ncjunk]

How's the noise on the pictures? I have been reluctant to use my camera as I tried it last year and it was very noisy, qhy5 btw.

I may dig it out again but I'm starting to think I may need a second pc in the observatory as the usb ports on the laptop are already overloaded, you have to connect the devices to certain ports of lines start appearing during image downliad and stuff starts glitching!

Dome or flat glass/plastic?

Sent from my GT-N5110 using Tapatalk

[pete_l]

Dome or flat glass/plastic?

Rainwater won't run off a flat aperture (and will leave dust/gunge behind when it dries in-situ)

[Gina]

How's the noise on the pictures? I have been reluctant to use my camera as I tried it last year and it was very noisy, qhy5 btw.

I may dig it out again but I'm starting to think I may need a second pc in the observatory as the usb ports on the laptop are already overloaded, you have to connect the devices to certain ports of lines start appearing during image downliad and stuff starts glitching!

Dome or flat glass/plastic?

Sent from my GT-N5110 using Tapatalk

The noise is much less than I expected - 15s exposure at up to 75% gain - see post #345 above.  And that's without darks.  I should be able to get to 100% gain with darks and coax a bit more sensitivity out of it.

I'm considering getting another PC too - a laptop.

I have a clear plastic dome from a cheap CCTV camera (that I might use in a shed or maybe the obsy, where it would need less protection).  The dome is of far more value for the all sky camera

I'll take and post some photos shortly.

[Gina]

Here are more photos of my design of all sky camera.  Modified shutter with solar film attached with Selotape - don't know if this is a good method or whether it'll fall off.  Maybe glue would be better - suggestions welcome   The round black part forms the light proof box between the lens and the camera.  The shutter motion limits are provided by this as well.  The two red parts hold the main unit in place and provide an outer cover.  The control unit for the shutter has yet to be designed, built and put in the casing   I expect to add a dew heater too.

[pete_l]

I'd suggest having the top of the lens as close as possible to the perspex dome, to reduce internal reflections getting on to the image. There might be some trade-off with dewing, depending what measures you are intending to deal with that prospect.

[ChrisLX200]

I'd suggest having the top of the lens as close as possible to the perspex dome, to reduce internal reflections getting on to the image. There might be some trade-off with dewing, depending what measures you are intending to deal with that prospect.

I think you're better having it at the centre of the sphere to avoid distortions in the periphery of the FOV. That's where mine is anyway.

ChrisH

[Gina]

I think you're better having it at the centre of the sphere to avoid distortions in the periphery of the FOV. That's where mine is anyway.

ChrisH

Yes, that was what I thought.  The original CCTV camera was roughly at the centre of the sphere.

[Gina]

I have my all sky cam perched on my warm room roof feeding the laptop inside.  There's strong sunshine ATM and the sun is the only thing showing in the image - running at 0.001s exposure.  Don't have the shutter control done yet so it's currently daylight only but hoping to do the shutter control soon.  Roughly east is up in the image.

[Gina]

Seeing such a lot of light spread from the sun, I thought I'd try it without the dome.  This is the result.  Note that I didn't put it back in the same orientation.  Seems the dome is causing some image degredation

[Gina]

Here is the result of using auto exposure, with the range set to maximum viz. 0.001s to 15s.  With the camera on a long USB cable and laptop on mains power in/on the warm room, I seem to be getting a lot more noise.  This needs investigating.  Previous tests were with the laptop at ground level and on battery with the camera on a short (about 2ft) USB cable also on the ground.

I'll be interested in seeing what happens when the sun goes down behind the trees to the west.

[Gina]

Found the reason for the noise.  The lens aperture control lever had closed it down!  The controlis quite loose so I've Sellotaped it in the wide open position.  The power/cable/position had nothing to do with it and I now have camera on roof and laptop inside on mains power.  Here's the latest image.  The clouds are coming in now ready to stop any AP tonight!

I think a remote focus control would be a good addition.

[Gina]

Sun has gone down and here is the latest image together with a photo looking west showing the cloud formation for comparison.

[Gina]

Another image.

[Gina]

Taken about 2200hrs - exposure 2.5s binned 2x2 - north is up.  Mast to the east is for my weather station wind sensors.  Light at SE is garage security lights on far hill.  Aircraft vapour trail can be clearly seen - also a couple of stars in the clear area.

[Gina]

2212hrs  Exposure on Auto - unbinned.

[JamesF]

Looking very nice, Gina

James

[Gina]

Thanks James   Very promising, I agree

[Horwig]

Right I'm back after a 110 hour working week away, and straight back to play with this. The LDRs have arrived, I don't think I even need any transistors to switch the meter, a 2k2 series resistor in the 5v supply gives full scale deflection on the meter, and two LDRs in parallel across the meter drops the meter to nearly zero in bright light, and back to fsd in darkness. 

Using two LDRs will afford some protection if one of them fails, or if the lens were to cast a shadow.

Huw

[Gina]

Right I'm back after a 110 hour working week away, and straight back to play with this. The LDRs have arrived, I don't think I even need any transistors to switch the meter, a 2k2 series resistor in the 5v supply gives full scale deflection on the meter, and two LDRs in parallel across the meter drops the meter to nearly zero in bright light, and back to fsd in darkness. 

Using two LDRs will afford some protection if one of them fails, or if the lens were to cast a shadow.

Huw

Good point Huw

[Gina]

I've ordered some LDRs (pack of 5) expected tomorrow   So I hope to get the day/night shutter control working then.  Meanwhile, I'm 3D printing the support parts to mount it on a piece of ali pipe on the side of the obsy.

[ChrisLX200]

Caught a few meteors on mine last night, the software is being a PITA though, missed more than I caught.

http://youtu.be/CWl3jBgy6LQ

ChrisH

[Gina]

At least you caught some   I've yet to get my cam set up.

Which software are you using Chris?

[Gina]

Been doing a bit of testing.  The return spring for the shutter is too strong, which is strange because I thought I tested it before   So I need to sort out a different spring.  I would like to use 5v as I think 12 would be too much as the camera the shutter motor came out of uses a max voltage of 8.5v and 5v is certainly enough with a weak enough spring.