Jump to content

Narrowband

Thoughts on which imaging rigs to concentrate on


Gina

Recommended Posts

One thing I didn't mention before - there is provision for dew heater control should it be wanted.  This runs off the Astroberry Board driver which connects to a GPIO pin with a resistor driving an NPN transistor and P-channel power MOSFET and connector (3 pin on the right).  The MOSFET is the black TO220 cased component in the middle of the HAT.  Dew heater power is derived from the 13.8v supply (switched by the MOSFET) and has common Gnd.  The Astroberry Board driver only provides ON/OFF control rather than PWM.

Here's a zoom in on one of the photos above

Electronics 04.JPG

Heater Control Circuit 01.JPG

  • Like 1
Link to comment
Share on other sites

Put fuses in the fuse-holders and connected the unit to 13.8v from bench PSU.  Firstly, just focuser motor connected, not camera, EFW or mount.  Ekos showed Astroberry Focuser and Board as expected.  Set focus "Ticks" to a few thousand and watched for motor rotation - rotated fairly fast in one direction.  Set back to zero and rotated in the other direction.  So the focuser is working fine :)

  • Like 2
Link to comment
Share on other sites

Connected other stuff and everything appeared in Ekos as before.  I shall need something to point the telescope at to capture a sensible image.  If we get any reasonably clear weather tomorrow I can put the rig on the NEQ6 mount and point the scope out of the east facing window.  Then I can try focussing on the usual tree on the far hill that I use from the observatory.

Link to comment
Share on other sites

That's looking good :)

I've also made progress. The final adaptor I need to (hopefully) get my spacing right arrives tomorrow. I also managed to move my scope from the Mac and I also managed to vitualise my Windows installation so I can run SGPro from the Mac too. I now need to test the alignment process but I need clear skies for that. If it works, it means I no longer need to step outside other than to set up and take down the kit. Once set up, I can do the alignment, focusing and framing all indoors from either the kitchen where the Mac will live or remotely from the much warmer office PC.

At some stage I will have to investigate doing something similar to your own setup with a mini-PC attached to the mount though I will have to solve the whole connecting and controlling the mount from Windows first. Every combination of connection/setup sequence has failed so far.

  • Like 2
Link to comment
Share on other sites

Everything required to capture images seems to be included in KStars/Ekos including astrometry, auto-focussing, auto meridian flip, sequencer, etc.  And all free :)  I have quite a lot to learn about KStars but I'm sure it'll be fun.  Must say, it's nice having everything in the one package and not have to mess about with a whole raft of applications as in Windows.

Screenshot from 2017-02-01 22-25-19.png

  • Like 1
Link to comment
Share on other sites

Heavy rain here :clouds2: Same forecast for days and days though might ease off a bit now and then.

Running the focus motor takes about 300mA, the RPi about 200mA.  I'm using a 1A fuse for the RPi and focuser (and dew heater if connected) and a 3A fuse for the camera and EFW.  Cooling current depends on voltage - higher voltage takes lower current.  At 13.8v 40% cooling took 800mA - cooling to -18°C with 20°C ambient.  Didn't test it at full cooling as I'm testing with a 1A PSU ATM.  When I test it tomorrow with mount etc. I'll use my 5A PSU

Edited by Gina
Link to comment
Share on other sites

48 minutes ago, Gina said:

Everything required to capture images seems to be included in KStars/Ekos including astrometry, auto-focussing, auto meridian flip, sequencer, etc.  And all free :)  I have quite a lot to learn about KStars but I'm sure it'll be fun.  Must say, it's nice having everything in the one package and not have to mess about with a whole raft of applications as in Windows.

Screenshot from 2017-02-01 22-25-19.png

Kstars apparently also does the guiding, but it seems to use lin_guider on the client as its native guider. That must put a heavy load on the network, I think. According to the docs/forum, it's possible to do the guiding in the driver on the server side, but I wonder how that works. Do you have any idea?

Atm, I use lin_guider on a RPi strapped to my mount. (Actually, not at THIS moment, since it's solid clouds for the next week, and has been for the last two weeks.) Seems to work ok, but lin_guider is very basic, more "just push here dummy" than PHD.

Link to comment
Share on other sites

The only guider app I've used is PHD and hoping to get away without guiding with the ASI1600MM-Cool with its short exposures.  Maybe someone else knows or ask on the INDI forum.  I'm still very much a novice with INDI etc.

  • Like 1
Link to comment
Share on other sites

On 1/28/2017 at 15:46, Filroden said:

So I'm now wondering if I can get away with the following:

11.0mm Skywatcher spacer ring (included with FF)

9.0mm FLO M48 to M42 adaptor (https://www.firstlightoptics.com/adapters/flo-m48-to-t2-adapter.html)

10mm Modern Astronomy spacer (http://www.modernastronomy.com/shop/accessories/adapters/10mm-t-spacer/)

7.5mm Baader T2 extension tube (https://www.firstlightoptics.com/adapters/baader-t2-extension-tube.html)

20.0mm ZWO EFW

1.0mm Astrodon filter

6.5mm ZWO ASI1600MM sensor distance inside body

====

65mm

Maybe add a delrin spacer to make up the missing 1mm?

Having exchanged emails with Bern at Modern Astronomy he's pointed out that the addition of the filter adds to the back spacing requirement. So the distance needed is 67mm, not 66mm, when using any Astrodon filter (they are all 3mm, so add 1mm).

So I think:

11.0mm Skywatcher spacer ring (included with FF)

9.0mm FLO M48 to M42 adaptor (https://www.firstlightoptics.com/adapters/flo-m48-to-t2-adapter.html)

1.0mm delrin spacer

7.5mm Baader T2 extension tube (https://www.firstlightoptics.com/adapters/baader-t2-extension-tube.html)

10mm spacer supplied with ZWO camera

2mm male to male connector supplied with ZWO camera

20.0mm ZWO EFW

6.5mm ZWO ASI1600MM sensor distance inside body

====

67mm!

  • Like 1
Link to comment
Share on other sites

The rain has stopped here but still very windy and the visibility is rather poor.  I think I'll have a go at putting the rig on the NEQ6 mount.  At least I could see how the controls work.

Link to comment
Share on other sites

Powered up and ready to test :)  EFW works.  Captured with 1ms exposure and Ha 3nm filter and got blank screen - changed to L filter and got image, currently out of focus.

Screenshot from 2017-02-02 13-26-59.png

  • Like 2
Link to comment
Share on other sites

I had similar issues - had to introduce a 4.5 multiplier into the code, so when driver sends 10000, the stepper moves 45000, which is required for full range of travel in my case.

  • Like 1
Link to comment
Share on other sites

Thanks Marci :)  But I think I'm more able to alter the mechanics than the code ATM.

Manually roughly focused on the trees and re-engaged the gears then worked out how to use the mount controls and put the tree line in the middle of the frame.  Now I can select just a small part of the image to (hopefully) reduce the download time because even with 8bit data selected it takes 4s to download and strains the ol' patience :D

Screenshot from 2017-02-02 14-26-57.png

Link to comment
Share on other sites

Yes, that works :)  Chose a smaller area from the centre of the image and put the binning back to 1.  Then went over to the focuser and adjusted the focus in hundreds of ticks.  That about represents one focus count in my Arduino based focuser.  Having manually set the focus for 5,000 ticks (centre of the range) the Astroberry ticks for best focus turned out to be 4600.  Here is an image, not just of the central area but further zoomed in to show individual twigs of the tree, about a mile away.

Screenshot from 2017-02-02 14-49-24.png

Link to comment
Share on other sites

Having focused with the Luminance Baader filter I will now change to the Ha 3nm Astrodon filter and increase the exposure to get a picture then refocus and see what the difference is.  Theoretically it should be ⅓mm different as the Baader filters are 2mm thick and the Astrodon 3mm.

Link to comment
Share on other sites

Here's the result.  Focus seemed best at 4250 changing 50 ticks at a time but the atmosphere caused variation in focus so I averaged (in my head) over several exposures.

Screenshot from 2017-02-02 15-11-21.png

Link to comment
Share on other sites

Finally, here's the full frame screenshot of the KStars FITS Viewer.  This is a much clearer view than I get by eye as the trees are almost invisible in the mist.  The narrow bandwidth in the red end of the spectrum helps cut through the mist.  Incidentally, I had to increase the exposure from 1ms in L to 1s in Ha 3nm.

Screenshot from 2017-02-02 15-16-58.png

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.