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

[Gina]

Better now.  Gibbous moon at the bottom.

[Gina]

The clouds come and go...  Some stars showing now though not dark yet.

[Gina]

More stars, less sun but still have the moon...

[ChrisLX200]

I hope it stays clear for you Gina, wall-to-wall cloud here of course.

ChrisH

[gentlebear76]

On 8/10/2016 at 12:21, ChrisLX200 said:

I used my 178MM for a 5hr run on the 8th, not trying to go deep as I was just after meteors so 20sec exposures with a gain of just 200.

 

ChrisH

 

edit: and YouTube seem to have broken the vid as it sticks early on - just jump over the sticky point!

Hi Chris.

Are you using your new 1.4 lens for this? It seems that you've got a good setup here. Reading Gina's comment on the 178MM I was wondering what your experience with it has been? Do you have any active cooling on it? 

Clear skies :-)

Michael

[gentlebear76]

On 8/12/2016 at 11:59, 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.

That's a bit discouraging :-/ However, I'm glad I caught your comment before placing an order. When I saw the video from Chris I was quite positive. I'm looking forward to more experiences and images from you :-)

[ChrisLX200]

5 minutes ago, gentlebear76 said:

Hi Chris.

Are you using your new 1.4 lens for this? It seems that you've got a good setup here. Reading Gina's comment on the 178MM I was wondering what your experience with it has been? Do you have any active cooling on it? 

Clear skies :-)

Michael

No this is the stock 2.1 lens, the 1.4 is on the GPCAM2C at the moment. Personally I find the 178 good for this job, I'm not even trying with the gain setting at the moment (just 200 and 20sec exposures). I also have the 174MM but prefer the higher resolution provided by the 178MM, so the 174 has been relegated to my Solar rig at the moment. Noise is not a problem when using SharpCap with its dark subtraction capability but as I said I haven't tried higher gain settings which I will do when we get deeper into the Winter season. I do have a Peltier cooler sat on the bench but it is untried as yet, just worried about what the effects of frosting around the back end of the camera will be.

ChrisH

[gentlebear76]

1 minute ago, ChrisLX200 said:

No this is the stock 2.1 lens, the 1.4 is on the GPCAM2C at the moment. Personally I find the 178 good for this job, I'm not even trying with the gain setting at the moment (just 200 and 20sec exposures). I also have the 174MM but prefer the higher resolution provided by the 178MM, so the 174 has been relegated to my Solar rig at the moment. Noise is not a problem when using SharpCap with its dark subtraction capability but as I said I haven't tried higher gain settings which I will do when we get deeper into the Winter season. I do have a Peltier cooler sat on the bench but it is untried as yet, just worried about what the effects of frosting around the back end of the camera will be.

ChrisH

Sounds great, Chris. I'll do some more thinking and I'm hoping for more experiences and pictures from you both :-)

Michael

[ChrisLX200]

14 hours ago, Gina said:

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.

 

Yes, you can only fit C-Mount lenses and not CS-Mount, makes sense really because of the large size of the 174MM sensor - CS-Mount lenses are designed for much smaller chips.

ChrisH

[Gina]

Yes, I remember now that you said that before.  Seems that the majority prefer not to waste pixels rather than including all the sky all the way round.  Mind you, I guess most people don't have the fantastic views that I have here.  I think this site would take some beating and I feel lucky to have it though I have seen other posts showing great views (but not many).

Today I'm planning to set up cooling for my ASI178MM using the 12v Peltier TEC I bought recently.  I'll probably try running it from 5v as I don't want a lot of cooling.  For testing I have bench PSUs that will provide a variable voltage (or current).  I expect I shall want control over the cooling eventually and have set-point cooling control.  I have an Arduino sketch to do just that already.

[Gina]

Cooling now added to camera and testing   Dismantled ASC and removed SS screws from camera to ali block then drilled deeper holes for the heads of the nylon screws.  Took the Peltier TEC, applied thermal compound to the two faces and put it on the camera base.  Then took the ali block and attached it to the camera and TEC with the nylon screws, tightening down lightly to avoid breaking the screws or applying too much pressure to the TEC.

For testing I connected the TEC wires to my smallest bench PSU - 0-5v or 0-15v @ up to 1A.  Increased voltage up to 5v while watching the current.  With no temperature difference the TEC drew 0.6A @ 5v but decreased to around 0.5A as the cooling started working and there was a temperature difference between the two sides.  It looks like the temperature difference achieved at this setting will be quite sufficient - it might want reducing in cold weather.  I hope to take some dark frames later to see what the difference is - I need to make up a light block to screw into the camera.

[Gina]

BTW - If anyone is wondering why there's a black band round the aluminium, it's because this was the test piece I used for testing anodising and the black is black anodised aluminium.

[Gina]

What I though was thermal noise in the sensor isn't showing in a dark.  Here's a screenshot of captured frame with 60s exposure,  Gain at 350 and gamma at 50 (normal).  There are hot pixels but not the random noise I was seeing in the sky images.

[Gina]

Cooling switched on and drawing 0.7A.  I'll take another screenshot when the camera has cooled down a bit.

[Gina]

Camera is now cool but well above freezing and TEC current 520mA.  Same camera settings as before.

[SilverAstro]

You've lost nearly all your stars ! Have you tried it in astrometry.net    sorry > hat&coat

[ChrisLX200]

That looks significantly less noisy

ChrisH

[Gina]

Yes, a nice improvement I think

I guess it's about time I started a new thread.  Now using a different camera and case and now have cooling.  Just have the RPi to sort out and add AVR chip etc. to control cooling and focus (unless these functions can be handled by the RPi).

[Gina]

Camera is a bit cooler now (TEC Current just below 500mA) and I've taken another screenshot.

[Gina]

ASC reassembled, attached to mast and hung outside on gutter.  I'm using an ex PC ATX PSU which I converted by adding an XLR socket with Gnd, +5v and +12v.  Also the cable I used for an earlier ASC which plugs into this with the Gnd and +5v connected to the Peltier TEC.

[Gina]

I don't know what to make of this.  Here are two captures first without cooling second with but over half an hour later.

[Gina]

Found the problem - dew.  So I shall need to add the dome, probably a heater and, because of the dome, remote focussing.

[Shand359]

I just stumbled upon this thread. I would love to get something like this up and running myself but I have neither the equipment (3d printer) or the apparent knowledge to accomplish.... Closest I can get is my home made dome from an old security camera and my QHY5L-II Mono.......

 

[Gina]

I'm planning to see if I can produce a design that doesn't rely on 3D printing or alternatively produce a set of plastic parts with assembly instructions.  But mine also uses a lathe turned fitting for mounting the camera on an aluminium tube used for a mast.  I think there could be a problem producing a design that uses neither 3D printing nor a lathe though there are designs out there that don't as I recall.