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Heading towards budget mono imaging...


Demon

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Hi All,

 

This may be slightly disappointing as I've just received them and I am waiting for a clear night - so sorry no images yet.

 

I've bought a ZWO ASI178MM from FLO and Astromania 9x1.25" manual filter wheel with LRGB and Ha filters over Amazon.

I cant afford a bigger sensor or higher quality filters or motorised wheel so will see how it goes.

It will initially be used with a SW 80ED doublet that I got second hand.

 

I'm just motorising the manual filter wheel with a cheap stepper motor and GT2 belt which looks like it should be pretty easy as the belt fits in without any mod and already got an Ascom Arduino driver working for it and tested with APT already and a stepper ready. Also likely going to fit a peltier and fan to back of camera.

Its pushing the pixel scale but am going to try lucky imaging with shorter exposures to hopefully get the quality up with selective stacking.

I'm really looking forward to trying a more sensitive system and having access to Ha etc. as my previous was an unmodified Canon D50.

 

I'll hopefully update this before the end of this year with more relating to the actual cameras performance (likely starting with M81 & M82) - heres hoping for some nice clear night.

 

p.s. I was going to try it with my light bucket but I've had no end of collimating and atmospheric issues, so taking the easier option for now and staying wider field - especially with the small sensor - usually used for planetary or solar but seen great results, even overcoming the amp glow - yes will also try some longer exposures also but really sick of the atmosphere and want to eventually go big for small targets with lots of shorter exposures.

p.s. I got my mount tracking better recently by simply tightening up the clutches, but also got plate solving working beautifully so I can now easily get on any target with APT linked to Stellarium - which is so fantastic and has given me the biggest boost I've been needing - especially for those better straight up targets.

 

Best wishes & clear skies,

Nick

Edited by Demon
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This bit should probably be on the DIY section (although its been done by many before me), however its leading to the important camera results so kept it here.

 

It definitely needs more work and refinement which I can do but at least I know it works and can use for testing the camera.

 

However, after reading more about filters it also sounds like I'm going to have to knock up an ascom to stepper focuser due to the cheap filters - shouldn't be to bad and on the list anyway so thats next.

 

p.s. I hope the end results are less shaky than the video...

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Well the clouds finally parted tonight.

What I'm actually most pleased about is getting my none goto mount and this very small sensor onto M81 fairly nicely as well as first light with the ASI178MM.

Its my first time on a proper straight up target hopefully with less atmospheric issues - I used plate solving to get on it which thankfully is working beautifully.

I sadly screwed up all the calibration files and I was trying lucky imaging with lots of short exposures.

I took 360x3sec and while its stretched to hell I'm actually really pleased I got anything.

The tracking was working great so I wish I'd just got some decent length exposures also...

The second image is a single 120sec that I did take for framing before fully tracking and simply stretched - you can see the amp glow - no stacking or biases...

It was a pretty warm night at 12C - need to stick a peltier and fan on the back.

Plenty to continue with (actually quite enthused even though the images are very basic) and if I get a chance I may refit my 12" F5 newt and have a go with that for lucky imaging with a bigger light bucket, as opposed to the very nice but little ED80.

 

Autosave002STRETCHED.jpg

Single__0152_Bin1x1_120s__12CStretched.jpg

Edited by Demon
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That first image is looking very promising👍. The second looked very good too - almost better.

 

If you are looking for another project you might want to think about adding a Peltier to the 178 to tame the noise a bit - that would help your lucky imaging. (I added one to my first camera (a webcam) - just keeping it around 0 deg improved my pictures massively).

 

Your guiding looks pretty good even at 120s. If the amp glow can be removed using darks then I suggest lots of 60+ second stacks to keep the core of the galaxy not saturated. 

 

Also dithering aggressively if you can will help tame the fixed pattern noise.

 

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Thanks very much paul,

as you suggest I'll defo add the Peltier and fan as it's pretty easy to do and should help with noise and keeping temp stable for cal frames.

I'm not at the level where the amp flow at the corners is worrying me to much. But it's good to see what I've read about and how to overcome it.

Then as you say a stack of 60s could be very interesting.

Then with a few filters now that's working, also got the ascom Adriano focus motor working so just need a shaft coupler for that.

While they don't look like anything too special I think the detail is there as you say and the system is working so with time and fewer mistakes - fingers crossed.

Edited by Demon
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You won't regret getting into Mono imaging.  A lot more detail than a DSLR especially if you now have Ha.  I started with a DSLR and became frustrated with the noise and bought mono - never looked back even though it took me a little while to figure out how to combine the filters without misalignment.  

 

I think I gather from the posts above that your camera is not cooled and you plan to get this sorted, which will be another big improvement.

 

Looking forward to seeing your images and well done on motorising the filterwheel.  I started with a manual Fw and it served for a little while but soon found the costantly changing of the filters a bind. 

 

Carole 

Edited by Carastro
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Thanks Carole,

I'm hoping so also, with the added complexity of trying to do it on the cheap...

But hopefully I can counteract that with some fun projects...

Actually all gearing up for full automation as I can't do late nights but need to get the imaging hours up - key to everything.

 

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