Gina's DIY All Sky Camera - Mark 4 - with ZWO ASI185MC

[Gina]

I think I'll start the new thread for the ASI178MM when I get the RPi working.  I may produce a separate daytime ASC later on.  A lower resolution and less sensitivity would be adequate for this and I'd like to cover the whole sky with no missing bits so I'll probably go back to the Fujinon zoom lens.  Not sure which camera but I might keep the ASI185MC for planetary imaging which was what I originally bought it for and use the QHY5-IIC which shows bad noise at low light levels but is alright at higher levels.

[Gina]

Lots of cloud tonight but could get a bit of clear sky later according to the forecast.  Maybe some stars peeping through.

[Gina]

Could be lucky tonight.

[ChrisLX200]

Lucky you! Still hoping for a break in the clouds here but it's not good at the moment.

ChrisH

[Gina]

Latest image.  Been fiddling with camera controls and had to go over to SharpCap with it's zoom feature to get a half-decent picture when binned 2x2.  This image is 20s.  The moon is still a bit of a nuisance but gradually sinking in the SW.  North is at the top.  I'm hoping to catch some Persieds later.

[SilverAstro]

2 minutes ago, Gina said:

catch some Persieds later.

I was just about to post a 'thank you' for your earlier pic of a clear sky, alerting me to 'maybe' for tonight, cos yes ! outside I now see a 1/2 clear sky ( was 0/0 a few hrs ago ) so fingers and everything xxed

and was just about to ask if your system could ( had) see meteors at what mag. but you are telepathic and already on the job ! Good luck

goes back outside >>>

 

[Gina]

Gradually losing the moon.  Exposure 20s bin 2x2 Gain 256 Gamma 20.

[ChrisLX200]

Well good luck Gina, bringing my cameras in here as it's just not going to happen tonight.

ChrisH

[Gina]

Was watching the live image from the ASC and just seen a Persied   Very bright with a comet like shape.  I was increasing the max auto-exposure to 30s to show the Milky way better but since the trace was so bright I'll reduce it again to catch more - maybe.

[Gina]

Exposure reduced to 15s  Gamma increased to 35.

[Gina]

The dreaded cloud is coming in now from the south.

[Gina]

Clouded over completely now   Anyway, I've left video recording on in case the sky clears again but I'm off to bed.

[Gina]

Watched the video from last night.  Unfortunately, the video recording I thought was running when I saw that one Persied, actually wasn't   But the video was recording for the rest of the night but no Persieds and it soon clouded over completely.  One short gap between clouds but no meteors.

The only way I seem to be able to use 2x2 binning is to reduce the resolution and then the captured image covers even less of the full sky.  With the Milky Way showing well almost right down to the horizon it seems a pity not to be able to capture that bottom bit.  For best star capture I shall need the maximum exposure the software/camera can provide of 60s with 2x2 binning.

[Gina]

The ASI178MM is not performing as well as I thought it might.  I think the reason is the small pixel size of 2.4 microns maybe the ASI174MM with 5.86 micron pixels would have been better with more than twice the size.  The sensor is bigger too and the FOV would fit on the sensor.  I'll have to give this some serious thought. 

The ASI178MM with it's small pixels might be good for planetary if I'm prepared to accept mono images.  OTOH a higher resolution mono image might have some appeal over a lower resolution colour one.

[Gina]

Showing possible promise for tonight in spite of the forecast for thick cloud.  The dark areas are clear blue sky.

[Gina]

Sky is almost completely clear now.  The moon is showing middle bottom of the image - nearly due south.

[Gina]

Several contrails but otherwise clear.  Not dark yet and the moon is still up (just outside the image area).

[Gina]

More stars showing.

[Gina]

Milky Way showing.  Exposure 15s max.  Gain up to 300  Gamma 20.

[Gina]

With short exposures and higher gain I think some extra cooling might be beneficial with the ASI178MM.

[Gina]

Think it's about dark now - just waiting for the moon to set.  Exposure 15s  Gain 320  Gamma 15  Unbinned.

[Gina]

Having a clock that shows the phase of the moon is nice but I think I want a dial that shows moonrise and moonset times as well.  OH NO Not another project

[Gina]

On 12/08/2016 at 10:59, Gina said:

The ASI178MM is not performing as well as I thought it might.  I think the reason is the small pixel size of 2.4 microns maybe the ASI174MM with 5.86 micron pixels would have been better with more than twice the size.  The sensor is bigger too and the FOV would fit on the sensor.  I'll have to give this some serious thought. 

The ASI178MM with it's small pixels might be good for planetary if I'm prepared to accept mono images.  OTOH a higher resolution mono image might have some appeal over a lower resolution colour one.

Further to this, the ASI174MM will not do, it has different dimensions (for some strange reason best known to ZWO!!).  It is quite unlike ZWO's other offerings.  The back focus is increased by 5mm and the main housing won't allow a fisheye lens to be placed close enough to get focus.  What a pity - otherwise this would have been a great camera.

[Gina]

Seems the ASI178MM may be the best choice after all but the high noise level at high gain means I shall want to cool it.  Currently the box just fits perfectly with the bottom against the mast attachment and the top against the top of the camera.  I shall need to gain 4.8mm for the thickness of the Peltier TEC. 

I could turn that amount off the mast attachment but that's a very long-winded operation with my rather inadequate lathe so I plan to enlarge the hole in the top of the case to allow the camera to poke out a bit.  A few other alterations such as raising the dome a bit will also be needed.

This diagram shows the current arrangement with the hole in the case top clearing the lens.  I shall cut it bigger so that the camera body can poke through.  The Peltier TEC will go between the camera base and the aluminium mast attachment (of course).

[Gina]

After several hours of totally clear sky, some wispy clouds have come into view!