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Gina

Thoughts on which imaging rigs to concentrate on

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With occasional sunshine during the daytime but almost perpetual cloud or rain at night I'm wondering about a spot of white solar imaging - I have DIY solar filters for my scopes.  I haven't yet tried solar imaging with the ASI1600mm-Cool.  Resolution is nearly twice as good as the Atik 460EX mono that I've used before.  Problem might be the bandwidth of my connection between observatory and indoors or even between imaging computer and local storage in the case of the Raspberry Pi.

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No no, still too cold to mess about in the observatory for more than a few minutes at a time.  I shall leave any thoughts of solar imaging until the warmer weather.  I shall also leave any thoughts of planetary imaging until next time there are any planets I'm interested in where I can see them.  So with the widefield rig and scope systems virtually finished and waiting for the weather for final testing my thoughts are moving on to other projects. 

Still astro is the observatory automation which I'm looking into.  I can do more planning and thinking about the control electronics - plenty to do that doesn't involve extended periods out in the observatory.  Also, vaguely connected with this is my weather station which needs parts making before it is ready for installing outdoors.

While I'm waiting for the weather I'm also thinking of finishing off some of my smaller or almost complete projects so that I can add to the DONE list :D

 

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And still no imaging! :(  It's now galaxy season so once we get a few clear nights I expect to sort out an imaging rig for that.  Meanwhile I'm concentrating on other projects so not terribly bothered :D

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I think I've had four or five clear nights this year. I've had almost clear nights but the high haze ruined any ability to image. Still, every night is still special :) Hope you get some soon. 

With the extra hour, the Milky Way through Cygnus starts to rise to a reasonable altitude from about 2am, giving three hours of potential nebula hunting. 

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I've put the Esprit on the EQ8 mount ready for when I get sorted out.  The widefield imaging season is over until the autumn so I shall be imaging galaxies with much narrower FOV.  Later I might be using the EQ8 for solar Ha imaging...

A mini observatory might be on the books again this summer to accommodate the widefield imaging rig ready for the nebula season.

Edited by Gina

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The size and design of a mini observatory will depend on the mount used.  I had hoped to build a fork mount for the widefield imaging rig but this has turned out to be rather heavier than originally thought and I have my doubts about the engineering of a strong and stable enough mount.  OTOH I have a perfectly good GEM type mount in the form of an NEQ6 but this format requires a much greater space to rotate in.  A fork is much more efficient in this respect.  I guess the very wide FOV reduces the accuracy required of a mount and maybe I could make my own.

I have had a couple of designs for a mini observatory in the past - a roll off roof type and a cylindrical version.  I would very much like to make a dome as this would have several advantages.  I have ideas for controlling a dome with INDI.

Another possibility I have in mind is planetary imaging.  This would involve my MN190 scope mounted on the EQ8 (probably) with a Barlow magnifier.  This means several different telescopes to use on the EQ8 mount though the Esprit rig could probably use the NEQ6.  At this rate I could end up with three observatories :D  The original with EQ8 mount a mini one with NEQ6 mount and a micro observatory with the widefield rig on a home made fork mount.

Edited by Gina
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This thread has become relevant again as I hope to get my enthusiasm for astro imaging back following treatment for a health problem.  The problem that arises though is that I seem to be short of observatory facilities for all the different imaging rigs I have and which I would like to use.  I'm now trying to find where I had got to with my various imaging rig projects and see which might be viable.  I have just added another in the form of a rather large Ha solar telescope which has similar dimensions and weight to my MN190 Mak-Newt and will need the EQ8.

I currently have my Esprit imaging rig on the EQ8 and the solar scope sitting on the arms of my warm room chair.  Of course, I want to set up for solar so the Esprit will need moving.  I have a micro observatory on the books which will take my widefield rig using vintage SLR camera lenses but isn't big enough to accommodate the Esprit.  So what I really want is another observatory (or something) to take the Esprit imaging rig probably mounted on an NEQ6.  Having two piers in my main observatory would have been ideal but unfortunately I didn't design it that way!

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Nice to have you back here, Gina.

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I tried the Ha solar scope for observing on the Skywatcher Pillar Mount with NEQ6 yesterday and did actually manage a brief view of the sun in Ha including a couple of very small prominences and some sunspots but the support was far too wobbly.  Also, I soon lost the sun's image from the eyepiece so tracking is needed at this focal length and magnification (1200mm FL plus 2x Barlow).  To have a real chance of success at Ha solar imaging it will have to go on the EQ8 on concrete pier.  In any case there's all the facilities in the observatory already there (except a laptop).

Not sure if this is the best place to discuss this but I've been having a few thoughts about cameras for solar Ha.  I've read that a wide dynamic range would be an advantage and the widest dynamic range is obtained with CCD sensors rather than CMOS.  OTOH I think CMOS sensors are better for short exposures.  It will probably turn out to be a trial and error situation :D  Clearly, a mono camera with good Ha sensitivity is indicated.  I currently have the Atik 460EX mono CCD and ZWO ASI1600MM-Cool plus a couple of smaller ZWO CMOS cameras.

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Yes great to have you back again Gina and I hope you are sorted health wise. I want to see you imaging again, so I can see more results from the ASI1600M.

Steve

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Thank you Steve :)  Gradually getting there health wise I believe :)

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The EQ8 and observatory is not really suitable for the Ha solar telescope after all - the roof obstructs the view to the west even when fully open.  Also, I want to use the EQ8 for dark side imaging - it's overkill for solar.  I shall be putting the solar scope on the NEQ6 mount with a new mounting of some sort nearer the house.  I'll probably start with the NEQ6 tripod, which is a very substantial one and certainly more sturdy and rigid than the Sky-Watcher Pillar Mount.  I shall use the latter for very widefield dark side imaging when I have the DIY mount and micro dome observatory built.

I have ordered another ZWO ASI1600MM-Cool camera and now plan to build a dual NB widefield DSO imaging rig which will be put on the EQ8 initially so that I can soon start DSO imaging again.  My experience of DSO imaging has been that there is very little SII in most of the sky and capturing SII is hardly worthwhile.  So my idea is to use one camera with a 3nm Ha filter and a vintage SLR lens and no filter wheel with the second camera having a 3nm OIII filter and another matching SLR camera lens.  The 3D printed dew shield could be designed to cover both lenses.

I haven't yet decided whether to have the whole rig in a turret to rotate the camera sensors' FOV to frame the DSOs better.  In any event I shall want two stepper motors to drive the focus rings on the lenses.  The electronics control box from the turret type single rig can be used with the stepper driver that was used to rotate the turret, to drive the second focus motor.  I think I shall start without turret for simplicity and get that working - it will be quicker to produce than having a turret, of course.

Edited by Gina
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I think I shall just assemble a single imaging rig for now, probably tomorrow as I won't have the second ASI1600MM-Cool for a couple of days and the probability of some clear night sky seems to be improving.  It appears clear tonight though the moon is quite bright and next door have their flood light on.  I may remove the Ha solar scope from the EQ8 tomorrow and put the WF NB imaging rig on it.  Depends on the weather.

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Well the sky looked clear a little while ago but now cloud is coming in.

59a730e79f137_Screenshotfrom2017-08-3022-22-29.thumb.png.912329af450df9f36fc6093337bd6657.png

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A night that started out looking promising turned out not to be - more and more cloud.

59a738ed291ac_Screenshotfrom2017-08-3023-09-23.thumb.png.edbe4442bf1f3fdf3e31f9023f76ba6a.png

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:eek:Good heavens Gina, at first glance I thought it was your first solar imaging attempt!  :eek:

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36 minutes ago, Peter Drew said:

:eek:Good heavens Gina, at first glance I thought it was your first solar imaging attempt!  :eek:

If it was I think it would be time to move planet!

Good to see you back to imaging Gina. You're taking on another great project and I can't wait to follow your progress.

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I have created blogs for the individual projects and this thread will continue to be a general overview of my astro imaging rig projects.  I've also included the link to my blog about the hardware and software I'm now using for imaging.

Edited by Gina

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I've been looking at a single widefield imaging rig.  I've found the information in this thread.  I have the ASI1600MM-Cool with EFWmini filter wheel attached to a 28mm f3.5 Asahi SMC Takumar lens and dew shield.  All ready to attach to the a mount except for the focus motor and electronics box.  I can use the electronics box from the Esprit setup and the motor from my (now abandoned) rotating turret widefield rig.  (The stepper motor on the Esprit rig hasn't got a long enough cable.)  I should have a pinion for the motor but I can't find it so I'll print a new one.

The rig attaches to the mount with wedge shaped 3D printed parts one on the lens as shown in the photos below and another on the camera near the back.  One of these should be around somewhere but if I can't find it I'll print another.  The software is ready to go - INDI drivers on the RPi and KStars/Ekos on my Linux Mint desktop.  The electronics box from the Esprit rig has been tested and works fine.  (See a little way back in this thread.)

59ac4a70a3c93_WFRig01.thumb.JPG.3fac7f0a85822c815fe54a976530abcb.JPG59ac4a5bdd1c3_WFRig02.thumb.JPG.693d2400f75556baf78a6de9ba99e3c2.JPG59ac4a5081028_ElectronicsBox01.thumb.JPG.f7f261bb488c915328acad69f24c1629.JPG

Edited by Gina

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My second ASI16600MM-Cool camera arrived this morning  - a definite improvement on my other one which is the previous version and suffered from the nasty habit of the front coming unscrewed when detaching the camera.  The new one also came with many extras including a soft carrying case - nice feature but I doubt I'll use it.  But more importantly, there are many more adapters included than before and some of these seem to provide the exact distance required to satisfy the back focus required by focal reducers and field flatteners.  This would be just right for my Esprit 80ED Pro with field flattener. 

Furthermore the diagram in the booklet with the camera shows a narrower than usual OAG and on checking the FLO website I see there's a new ZWO OAG that matches the diagram. So if, as I suspect, I need guiding on my Esprit imaging rig, that's another imaging rig sorted out :)  ZWO really seem to be getting it together :)  Very impressive :)

59ad352bd3642_Adapters02.thumb.JPG.1597cf2e489bbcdcbb4532d29fbe28af.JPG

Corrected an error in this ZWO diagram - spot the different typeface :D

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The weather forecast is not good for the next few days though there might be an odd couple of hours tomorrow night.  Solar imaging or observing is out until at least next weekend so I shall concentrate on my DSO imaging rigs though I might think about PA on the NEQ6 using the Esprit rig which is ready to go.  One of the adapters that came with the new ASI1600MM-Cool will provide the spacer between EFWmini and FF on the Esprit.

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Regarding the back focus distance for the SW Esprit 80ED Pro field flattener :-

Quote

The spacing for dedicated CCD imaging cameras is 55mm from mating surface (75mm from centre of rear element).

And the back focus for the camera :-

Quote

Back Focus Distance        6.5mm

The filters are 3mm thick so add 1mm to the required FF back focus requirement giving 56mm.  Measured spacing from FF to face of camera = 49.05mm.  Adding in the 6.5mm camera back focus gives 55.55mm.  ZWO also supply thin Delrin spacers of 0.40mm and 0.15 mm so if 0.4mm one is used as well the back focus distance becomes 55.95mm.  I would say that's as close as could be expected :)  With both Delrin spacers the back focus distance would be 56.1mm.  I could try with and without the 0.15mm spacer but I doubt I'd detect any difference as the camera sensor is 21.9mm and the stated coverage of the Esprit is 33mm so I'm not using the whole image from the scope.

59adcd7ebc59d_BackFocusMeasurement01.thumb.JPG.0f214aa2f48c68d5b9d4ba77c4c85dcf.JPG

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