Thoughts on which imaging rigs to concentrate on

[Gina]

The gigabit Ethernet switch has arrived and I've connected it up hoping the transfer rate between my two desktops now connected to it would be much better but it isn't   The data link is showing 1000Mbps but I'm only getting 80Mbps.  viz. 3GB is taking 5m to transfer across.  Could it be a slow HD?  Or is there some other explanation?  One is sata 2 the other sata 3 - don't know anything else about them except one is 500GB and the other 1TB.

[Gina]

In future I can just transfer files from my observatory laptop (or RPi) directly to my new desktop for use in PixInsight which I'm liking more and more as I use it and watch tutorials.  I'm fast becoming a convert I might even use PixInsight as client to INDI when I get the RPi setup working.  Haven't looked into that yet.  I'm thinking also of using the new PC to control the Win7 desktop as a server for remaining software that doesn't have a Linux version, using TeamViewer.  I've already been doing this in a small way.

[Gina]

I seem to have rather strayed off-topic in this thread but I guess the hardware and software involved is quite appropriate

I now have two SSDs - one of 250GB and one of 500GB together with mounting hardware and sata cables.  My original idea was to use the 250GB in my new desktop with Linux Mint and PixInsight etc. and the 500GB in my Win7 desktop which is using a 500GB HD as drive C: and which could simply be migrated to the SSD.  However, it now seems to me that the bigger SSD would be more benefit for use with PixInsight etc. 

I think I can use Linux to reduce the C: partition on the boot drive from nearly 500GB to under 250GB as I'm only using 200GB ATM.  Then the C: "drive" partition could be migrated to the SSD.  Any thoughts on this would be much appreciated

Edited September 4, 2016 by Gina

[wimvb]

Gina, in your original post you mentioned that you have 3 ASI cameras, how do these compare quality wise, other than the obvious chip size? I'd be especially interested in the 185 vs 174.

[Gina]

Yes, I have 3 ASI cameras but they are very different.  I first bought an ASI185MC for planetary imaging which I tried in my all sky camera. Then I decided to go mono for higher sensitivity for the ASC and bought an ASI178MM camera.  Finally, having sold a little piece of land giving me some extra funds I bought the ASI1600MM-Cool for DSO imaging.  They all seem very sensitive.  On the ASC both ZWO cameras were much more sensitive than the QHY5II-C I was using and with very little noise - the QHY was very noisy in comparison. 

I imagine the sensors would be very similar in sensitivity per square micron of pixel size.  Cooling helps enormously with noise for longer exposures eg. I use 60s for the ASC and have added my own Peltier TEC cooling which makes quite a difference.  Of course this is not a patch on the proper cooled cameras as they can take the temperature much lower and have desiccant tablets in the sensor chamber to stop misting up. 

A cooled camera would be nice on the ASC but with the exposed position I don't think the damp would be very good for it.  The non-cooled version I'm using is in a sealed enclosure to keep moisture out and the cooling uses thermal conduction to the aluminium mast rather than air blown fins.

Edited September 4, 2016 by Gina

[wimvb]

 

Thanks. I'm very interested in these cameras to replace my aging Pentax. I'm very much aware of the much smaller chip size of the 185 and 178, but lack the funds for the 1600.

[Gina]

The ZWO cameras are far more sensitive than a DSLR but the one that closest matches the pixel count of a DSLR is the 1600 with 16Mpx but yes it's their flagship camera and expansive - less so than CCD cameras though.  I'll check up on the specs of their other cameras - a comparison table would be useful.

[Gina]

Well, most of their cameras are designed for planetary or lunar imaging with only around 2.3Mpx.  The next down from the 1600 in pixel count is the 178 with 6.4Mpx, 3096x2080, 2.4μm and sensor size of 7.4mm x 5mm.  The mono version of this is the one I'm using in my ASC.  Cooled version ASI178MM-Cool is just over half the price of the ASI1600MM-Cool.

[Demonperformer]

Gina, hope you will forgive me using your thread for a 'headsup', but it is relevant ... 365Astonomy are currently selling the ASI1600MM Cooled for 10% off, i.e. £1184.00 including delivery (that's a saving of £132 on RRP). Stated to be "available now from uk stock", although checking the thread on the supplier reviews board, such statements can be a little inaccurate on occasion. Even so, I thought the saving would be worth having to wait for a week or two if I have to.

I wonder if buying an astro-camera has the same effect on the weather as buying a telescope ...

[Gina]

Interesting but I can see no mention of the built-in USB2 hub that the latest version of this camera has and is the version sold by FLO.  Maybe the 365Astronomy one doesn't have the USB Hub and that's why there's 10% off!

Edited September 4, 2016 by Gina

[Demonperformer]

Mmm ... well ... The specifications list the Interface as USB3.0/USB2.0 and looking at the two versions here, I don't see how it provides a USB2.0 connection if it is the older version. But then, it does talk about "guiding" and the newer version does not have a specific guide port (although that can be done through USB). In addition, I don't think they have helped themselves by saying " This product listing is for the COOLED MONOCHROME version of the ASI1600." and then further down talking about " Features of the NEW ZWO ASI1600MC-COOLED "!

All-in-all I will adapt to whichever comes. It is, afterall, the sensitivity of the chip/electronics that is the main appeal and, based on the link above, that certainly seems to be identical in both versions.

Thanks.

[Alien 13]

I think FLO priced matched the ASI1600MM Cooled.

Alan

[Gina]

The connection to the camera is USB3 but will also take a USB2 plug.  The built in hub is USB2 only.  The camera works perfectly well with USB2.  USB3 is only needed for the maximum frame rate as used for planetary imaging - USB2 is perfectly adequate for frame exposures of a second or  more (up to 2000s = 33⅓m).

[Gina]

Here is the master flat obtained from PixInsight using biases and darks for calibration, reduced in size to 1200px wide.  This was with the 3nm Ha filter.

[wimvb]

No dust bunnies?

Btw, I doubt if you need darks for flat calibration.

[Gina]

And this is the same image histogram stretched to show the variation and slight vignetting in the corners which is easily calibrated out.  Must say, I'm pleased with the cleanliness of my optics - I did clean everything before assembly

[Gina]

Since all the filters are the same size and distance from the camera, I think this master flat could be used with other filters as well as the Ha.  Any comments. please?

[wimvb]

Vignetting seemed almost nonexistent anyway. DBE will clean that up nicely, so as far as vignetting is concerned, you're good.

But how about dust bunnies, eventually? Your master flat is very clean at the moment, but that may change.

[Gina]

I'm not proposing to open the rig so the optics is pretty much sealed.  Actually I thing it's perfectly sealed because I was taking darks around midday today with the roof open and in broad daylight, with the lens cap on and there was no light getting in.  The only surface open to dust is the lens front element and I'm sure any dust on that will be well out of focus but I'll keep it clean anyway.

[Gina]

Now running the PixInsight script to calibrate the NAN & Pelican 3nm Ha subs using sets of bias and dark subs and the master flat.  Then going on to register and stack the lights.

[Gina]

Still working...  Further speeding up would be good   I'll probably add the 500GB SSD tomorrow and reinstall everything on that.  The data is all in a separate partition on the HD designated /home starting at about 250GB.  I've read that reinstalling on the new SSD is much better than migrating from HD to SSD in Linux.  Once I have the system and software installed on SSD I can reuse the root partition and assign it as a data partition.

[Gina]

Here's the NAN & Pelican from PixInsight with a bit of histogram stretching and resize in Ps

.

 

[Demonperformer]

13 hours ago, Alien 13 said:

I think FLO priced matched the ASI1600MM Cooled.

I enquired, but got no response.

[Gina]

Sorry,  FLO price is £1316 and is for the latest version with the USB hub.

[Gina]

Did a defrag on my Win 7 desktop in preparation for shrinking the boot drive with Linux Mint with a view to migrating to a smaller SSD.  That went fine but when I tried to boot from USB it got to the MB start-up screen with options to change boot order etc. but nothing worked.  Without the USB boot stick plugged in it booted as usual but straight into Windows.  Maybe I won't bother to upgrade to SSD - shan't be using it much anyway and I have the new Linux desktop to upgrade to SSD so I'll do that first.  I might add a second 250GB SSD to add to the first one of 500GB.