bobro

Having recently purchased an Altair Hypercam 183M with a simple fan cooler rather than a TEC cooler, I wondered what effect the fan would have on sensor temperature as it's really an anti-warming fan rather than an active cooler.

So a simple test was to let the camera operate without the fan running to see what stable temperature it reached, followed by turning on the fan at full speed to see how this affected the sensor temperature.

The (indoor) test without the fan running stabilised the sensor at over 28 deg C (actually the temp was still climbing but very slowly). This took about 25 minutes.

With the fan then turned on, the sensor temperature dropped by over 5 deg C in a further 25 minutes - showing the fan does provide a useful cooling effect which will help with the (already low) sensor noise.

With the fan running the sensor temperature looks to be about 2-3 deg C above ambient.

Sometimes I think about relaxing in a sky viewing chair looking at the night sky through a pair of imaging specs that would show me real-time what only cameras can today capture. A great mixture of visual and imaging - what a sight that would be looking around the sky e.g. just imagine the size of the Rosette nebula!

3 hours ago, Adam J said:

What coma corrector are you using?

My 650/130 reflector started out life as a Meade Polaris 130 before various mods (including fitting a SkyWatcher mirror) but it still has the Meade 1.25" focuser (teflon strips inside to eliminate slop). As 1.25" coma correctors are hard to come by (and expensive!) I made one from stock parts based on a design in an old magazine. https://stargazerslounge.com/topic/288608-diy-125-coma-corrector

For such a simple design it works pretty well with the f#5 scope as can be seen in the attached M42 taken with the 1000D and CC. A 1.25" filter can be screwed on to the bottom of the CC, so I can even do a bit of LRGB or Ha before deciding on which filter wheel to purchase.

3 hours ago, Adam J said:

Did you calibrate with darks?

Yes - just 15 to test with. Taken at the same time as imaging. Lots of sky noise around from the near full Moon. First time for me using darks as I depended on dithering to reduce noise with the DSLR. Longer exposures did result in some amp glow though.

3 hours ago, Adam J said:

2x2 Binning on CMOS does not have to be done during capture. You get the exact same benefit if you down sample them image in photo shop once stacked.

Certainly an alternative Adam. I think that's Super Pixel mode in DSS (have tried it once some time ago with success).

Bob

Thanks for the info @jjosefsen and @david_taurus83.

The replacement guide camera module and hub arrived, so I've been able to make a start on testing and learning about the new setup - takes time as I didn't become familiar with my DSLR overnight (using APT for capture and PHD2 for dithered guiding)!

Due to the imaging and guiding resolution of my setup I plan to use 2x2 binning. As confirmed on the APT forum, APT has an issue with binning with the Hypercam 183M, so I won't use if for now until the issue is fixed.

SharpCap seems to take quite a lot of memory and my little netbook has trouble running SharpCap together with all of the other necessary programs, so I'm using Altair Capture at the moment as this runs without problem and is easy to use. At some point I will likely need to control a filter wheel and also run dithering so a change of program will be necessary - but I'm not there yet. Before that there are still flats to get right (didn't work first time) and installation of the coma corrector. 

Although the Moon was up last night, I did a couple of quick test images (attached) using my 650/130 reflector. Both 60 off 30 sec subs at gain 4 (I think that is unity gain with Altair Capture - please correct me if not) plus darks, no flats. At 13 degrees C darks seem free of noise with just hot pixels evident. Aligning targets and focusing using a mask is quick and easy with the 183M camera in video mode - a nice improvement.

I'd like to do an Ha test image with an (old) Astronomik 1.25" filter (especially with the Moon up) - just need to work out how to mount it! If you have any ideas on a suitable target please say.

So far seems a great camera. The simple cooling fan helps stop the sensor warming - It doesn't look like sensor thermal noise will make much difference to LRGB imaging for my conditions. Ha imaging is likely to be different of course.

NINA looks interesting. I will give it a go.

Bob

Nice one - I like the smoothness and detail in the galaxies.

A bit of blue around the stars - something to do with the filters? Perhaps a bit of star reduction would improve the image.

I'm just starting out with an IMX183 sensor camera and will be very happy if I can do as well.

Bob

Like yourself, I was out last night testing my new Altair Hypercam 183M on the Moon. For comparison, here is a single sub at minimum gain (good for max dynamic range) and 12msec exposure.

39 minutes ago, Adam J said:

The chap who produces APT is very good at helping out if you post a topic on the APT forum I am sure he will get you sorted.

Is there a reason you would not want to have the fan running at full speed?

Thanks Adam - I will post on the APT forum.

No real reason to slow the fan down other than SharpCap and Altair Capture provide this and (very brief) testing suggested half speed kept the sensor at a similar temperature. The fan is very quiet so full speed isn't an issue and the fan certainly helps with limiting sensor warming.

Bob

19 hours ago, Adam J said:

I thought that APT had native drivers for the Hypercam 183m? Are you still using the ASCOM driver? Is it the latest version of APT?

Yes, I'm using the latest version of APT (just downloaded) with native Altair support. I'm selecting the Hypercam in the camera setup rather than Ascom. I've tried it again with another more powerful Core i5 laptop - same results with no fan control and binning resulting in no image. The APT instructions say to download the latest drivers from Altair (http://cameras.altairastro.com/), though these seem to be Ascom drivers. I'm confused - perhaps I'm doing something incorrectly?

New guide camera module is on its way - can't wait for another imaging try with the 183M.

Bob

9 minutes ago, Adam J said:

For your scopes remember to bin 2x2 or you will be over sampled on emission nebula, maybe 1x1 for galaxy hunting mind you. I would start at unity gain and 30 or 60 second exposures.

Which filters did you go with?

Yes, that was (is) my initial starting plan : 2x2 binning at 30/60 sec and then, with a possible bit of future fun, to try 1x1 with short exposures just to see what happens (may never get there though).

Understanding gain setting for the 183M camera with the 3 programs I have briefly tried required a little research.  For example unity gain seems to be for SharpCap : 400, Altair Capture : 4,  APT : 400.

APT doesn't like binning, reporting that it is waiting for the camera after 30 seconds (shame as that is my normal imaging program). In addition it only runs the fan at full speed without control. (My brief testing of the simple fan shows it being good at reducing the sensor temperature by something like 5-6 degrees compared to without fan as the sensor heats up.) The program runs very slowly on my netbook and does seem to have only partial functionality for this camera.

Altair Capture works well at a good speed on my netbook and is simple to use, but doesn't support dithering.

SharpCap runs capturing, binning and real time display on my netbook in a flexible config and at a good pace - impressive. In addition it supports real time stacking complete with darks, flats and dithering. I've yet to test this due to my cooked guiding camera. Lots of profiling to check out too - you can see the designer understands what imaging is all about. It will be a new way of working for me, so lots to stuff to get to grips with.

As to filters - not there yet as I'm using an extension tube in place of the filters. Hopefully a B&W image will be achieved before too long (mount seemed surprisingly jerky without a guiding camera to help it). Is this progress? 😀😀

Bob

Thanks to great advice from the forum (thanks @Adam J), my new Altair Astro 183M arrived. I was well prepared for an initial test (well at least I though so) as I had marked out the various cables with where to connect them (first time I had did this but thought it worthwhile as imaging had been infrequent recently). During the day I had a play with a couple of imaging programs and felt ready for a test of the new camera during the evening. The forecast was pretty good, so I assembled everything outside in advance, connecting the cables as marked. Final step was to connect a power supply - into a hub instead of the AstroEQ unit! Result - smoke!!!

Today I ordered a new hub and guiding camera module....it could have been a lot worse 🙄 At least the new camera wasn't connected and the notebook and AstroEQ unit survived!

Wish there was a standard cable for voltage at least. 😅

17 hours ago, Adam J said:

Personally if I was going to get a 183 mono without cooling then it would be the Altair Hypercam 183m as it has some advantages over the ASI

Thanks for the great pointers and advice Adam. Decision made - Altair 183M it is! (Going to be quite a change from the 1000D.)

Bob

Very interesting thread as I, like the op, am currently looking at zwo cameras for use with my eq5, 650/130 and 1200/150 reflectors. The aim is for quicker capture of photons from DSOs to help reduce noise with fainter targets.

As a step up from my Canon 1000D DSLR I first considered the ASI294MC as its low noise and high QE seemed appropriate. However, after watching Dr Robin Glover's excellent video https://www.youtube.com/watch?v=3RH93UvP358&feature=youtu.be (a few times for understanding!) I came to the conclusion that the overall photon capturing capability wasn't that much better than my 1000D due to the DSLR's larger pixels.

With a bit more consideration the ASI183MM is my current (!) favourite. Why? Because it's low thermal low noise seems to make cooling unnecessary for luminance imaging at my Bortle 4-5 location (noise at approx 10% of sky).  It's a 20M pixel camera and 2X binning would increase the signal level 4X (less for SNR) and still provide a good resolution image (I typically bin 2X with my 1000D for noise reduction). Binning is also a bit more appropriate for the imaging scale and guiding I achieve with my setup.

For RGB filter imaging I understand detail isn't so important and therefore the increased noise due to RGB filters can be reduced by sacrificing detail (more binning?) as luminance will provide the necessary detail.

The ASI183MM still looks to provide a reasonable fov, although a bit less than my 1000D.

I hadn't planned to get into mono imaging, but it seems to make sense as the best way forward. Have I missed something important? Thanks.

Well, this scope is marketed as being good for observing details on the lunar surface, Venus and its phases, polar caps on Mars, Jupiter and its four moons, Saturn with its rings and much more! I.e. its key use is viewing (and possibly imaging) our solar system. Deep Sky generally means outside our solar system. When beginning with with Deep Sky photography a reasonably fast scope (e.g. f#5) and not too long a focal length (e.g. 400-700mm) help with keeping exposures to a manageable length and also with equipment stability issues. You have realised that an equatorial mount is also necessary to allow longer exposures.

With its long focal length (1500mm) and slow aperture (high f#11.8) this scope isn't very suitable for DSO imaging. The alt/az mount, even with a wedge, won't be very stable or accurate. It will be difficult to produce DSO images with this setup.

If your aim is solar system imaging then a webcam is better than a DSLR (video rather than still images are taken) and this setup should be suitable.

See this thread for more info: https://stargazerslounge.com/topic/225638-can-i-use-a-celestron-nexstar-127slt-for-astrophotography/

It would be interesting to hear other experiences with this camera, especially as it is marketed as an 'alternative to a DSLR'.

It has relatively small pixels at 2.4um, which makes for good planetary imaging. Yet high Mpixels aren't needed for planetary as objects are small.

If, for example, DSO imaging is required with a 200mm aperture 1000mm fl scope, the resulting imaging would be at 0.5 arcsec per pixel, which may be a bit too precise for some setups. Larger pixels could make more sense for DSO imaging.

It is a colour camera - not so good if shorter exposure or narrowband work is the aim.

No cooling either, so no benefit of low temp noise reduction.

My interest is DSO and an ASI174 cooled mono camera seems to me to be better for DSO imaging, though filters would be required for colour.

So is the ASI183MC just a jack of all trades or is there a sweet spot for it?

Hi Nige,

Just made my first Ha image : https://stargazerslounge.com/topic/304350-first-ha-image-california-nebula-as-hargb/

I understand what you mean about focusing. The easiest way for me to achieve this was to put the Bahtinov mask in place and take 20 sec subs, tweaking the focus between subs until it was ok. Not fast but works.

Bob

8 hours ago, Nigel G said:

And both images together.

Lovely pairing Nige!

54 minutes ago, Stub Mandrel said:

I looked up the cost for 38mm to and the price rockets.

I assume you went uncoated?

The EKSMA lenses I used were uncoated BK7, part#s 112-0227E and 111-0222E (17 Euro each plus charges). Putting together a 1.25" CC isn't going to be low cost, but is certainly lower cost than swopping out a scope or focuser in order to be able to purchase a 2" CC if the original scope has a 1.25" focuser.

Bob

In an effort to have goto I've been playing with a CG5 (sacrilege I hear you say!) using AstroEQ and found the same sawtooth using single direction guiding a couple of nights ago. You can see from the graph the mount wants to go in the same direction as guiding, which is wrong as the mount should be pushing against guiding and the slack taken up before guiding starts. In any case I wouldn't use single direction guiding as dithering is such a useful feature (used with my EQ2) and requires bi-directional guiding. So I've done my best to remove the slack in DEC waiting for a retest.

What I would rather do is put the stepper motors on the EQ2 as its guiding performance isn't much different to the CG5 and much more pleasant to carry around (I'm learning more about guiding and can make the EQ2 guide better as it wasn't being controlled enough). Putting a motor on RA is straightforward but DEC only has a limited range of movement. 

Can anyone offer a suggestion of how to modify the EQ2 DEC to allow 360 degree control with a stepper motor?

Although the 6 min version has a slightly different resolution, I find it to have the smoothest colour transitions . Not a lot in it though! How many subs in this version Nige?

Bob

Thanks Wim, though you could be corrrect in that checking the tightness of the worm gears would be worthwhile in case binding is taking place. Much quicker than a stripdown!

1 hour ago, wimvb said:

I would advise to first take care of backlash in ra and dec, before stripping the mount.

Hi Wim,

As the setup in question isn't guiding but just tracking in RA (hence DEC not driven and RA always driven in one direction), could you explain why reducing backlash in RA and DEC would help?

Thanks

3 hours ago, Stub Mandrel said:

afraid I hit the bottle of laphroaig

See any little green men?  (My favourite whisky!)

A little green man going past last night in his flying saucer would have seen lots of scopes pointed up at him - a super night for AP! So time to revisit IC1396A, the Elephants's Trunk nebula, lit up by the nearby massive star. 18subs @ 480secs (approx 2.5 hours).

Thanks for the super fast reprocess Nige! 

I agree - the image that includes the 600s subs looks better. No sign of increased noise. My understanding of combining comes from a page on DSS theory (http://deepskystacker.free.fr/english/theory.htm) which states :

------------------------

Can I combine two (or more) resulting images?
Absolutely, the square root rule applies with a small twist.

When combining two images the SNR increases by 1.414 (square root of 2).
If both images have the same SNR then this is the same as doing a single stack. That does not mean that the combination is giving the same image, just that the SNR will be the same.

However if one stack contains more light frames than the other, the SNR of the two stacks will be different and the SNR of the combination will be lower than the SNR of a single stack containing all the light frames.

Thus by combining the result of a 10x1 minute stack with a single 1 minute frame the SNR is roughly the same as the one obtained by combining 2 light frames. This is due to the fact that when combining two images the noise is additive and the best image is damaged by the worse image in the process.

--------------------------

I must be missing the point (again!). 

Bob

Thanks for the info Nige. The difference in detail is obvious between the 240 and 360s. Any improvement with the 600s subs isn't so obvious and I think there can be a noise problem combining a small number of subs with a larger number (in DSS anyway) when they are in different groups - noise will be determined largely by the group with the worst noise. (Hope I've got that correct .)

I wonder how a final image using only the 360s subs would compare to the one with both 240 and 360s subs?

Bob