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Night Sky Photography - An Equatorial Mount: My lucky day!  Rate Topic 
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Posted by Robert: Wed Apr 3rd, 2019 22:49 51st Post
Thank you Chris!

Yesterday I had an idea... I checked out the Go-Pro controls, they are accessed via an app on my iPhone or iPad, I seemed to recollect there was some means of controlling the exposure manually.  I fiddled with the controls at home and managed to increase the sensitivity a bit, two stops I think, so I redoubled my efforts and made a small clamp to properly secure the tiny Go-Pro camera to the eyepiece of the scope.  It worked fine in daylight and even poor light in my bedroom with the lights off and curtain closed, so I got some fish and chips, then headed for the local viewpoint, to await darkness.


While I was exploring the track I attracted the attention of the local gamekeeper, who stopped and watched me for some time while I enjoyed my fish and chips!  Eventually the parking spot near the  bench came free and I moved down to set up before darkness fell, ready to test the Go-Pro camera.  Gamekeeper still back and forth keeping an eye on me! lol

Eventually it was almost fully dark, just about to test the Go-Pro the gamekeeper came past again so I stopped him and assured him I was just a mad photographer waiting for it to go really dark before I could take some photo's. :lol: He seemed a bit puzzled, I explained you can't see the stars in daylight!!! He laughed, so I took the opportunity to ask him where the best viewpoint would be where I could get a full view of the Duddon sand-bar and the estuary.  He was very helpful and showed me where I could go to get a the best view of the entire estuary.  I am going up there this afternoon to check it out.  I am hoping I can make a time-lapse video of an entire incoming tide on a very low to very high spring tide.

Finally... It was dark.  I powered up the Go-Pro and no dice.  Just a black image, no sign of Polaris or any other stars.  By shining my red lamp into the polar scope I could see the etchings to locate Polaris, so the camera was working.  One thought was perhaps in the darkness the Go-Pro autofocus wasn't able to latch onto the tiny dot in the sky?  Whatever the reason it's a No-Go-Pro!  Turning my thoughts to an angle finder, will see what my buddy has...



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Posted by Robert: Mon Apr 8th, 2019 23:24 52nd Post
OK so I have acquired a damaged DR-3 right angle finder for a pittance.

I made the mount for the DR-3 over the weekend but cloud prevented testing.  This evening with totally clear skies I took it out and was able to test the finder, the threads which attach the finder to the camera eyepiece were damaged, that doesn't matter for me because I have made a slip on adaptor to fit it to the polar scope.  I still need to fine tune the fit but essentially it works.  I have now made an adaptor to allow me to hold a red LED in front of the Polar scope to light up the etched markings in the Polar scope to assist aligning the stars.

The forecast is for tomorrow and Wednesday nights to be clear skies, so with luck I will try to get some images tomorrow night.  I will try the Nikkor 300mm f/2.8 too.  If I can I will try to capture an image of the Orion nebula, the only possible issue may be the Moon because it's in the same area of sky as Orion at the moment.  I might even be able to combine them in the same image.



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Posted by jk: Tue Apr 9th, 2019 07:41 53rd Post
Well done.
Seems like you are getting a really nice setup for a song!



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Posted by Robert: Tue Apr 9th, 2019 20:26 54th Post
There seems to be a very slight mismatch between the Vixen Polar scope and the DR-3 right angle eyepiece which reduces the field of view but I still have enough to aim at Polaris and get three of the stars of Ursa Minor, which I am hoping to be able to lock onto tonight.  Getting Polaris locked on is only half the story, the rotation alignment of the Polar scope has to be correct too.  I am gradually gaining an understanding.  The manual I have is for a newer model which has different markings and the various tutorials online seem to be aimed at people with 'Go To' mounts.  This is an old fashioned, manually aligned mount which is a very different kettle of fish.

Hoping to get some images tonight... ;-)  Taking the 300mm f/2.8 and the fisheye.

The wind seems to have abated some, it was blowing hard last night, my eyes were watering because of the wind, which made it even harder to aim the scope.



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Posted by jk: Tue Apr 9th, 2019 20:43 55th Post
Bon chance, mon ami.
Look forward to seeing the results.



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Posted by Robert: Tue Apr 9th, 2019 20:55 56th Post
Likewise! LOL



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Posted by chrisbet: Tue Apr 9th, 2019 22:22 57th Post
Me too ... :smilesmall:



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Posted by Robert: Wed Apr 10th, 2019 02:48 58th Post
Well, I'm home and cold.  Had to wait for the moon to set, I exposed a batch with the fisheye 16mm.  I failed to lock onto Polaris properly but I now have a clear understanding of the issue.  It's known that the earth's axis is wavering slightly which effectively means my scope from about 1986 is incorrectly  calibrated.  I have asked on several forums by what degree the relative location of Polaris has changed but nobody has given me a clear or definitive answer.  However tonight I think I have cracked that one.  While the camera was clicking away making exposures with the fisheye lens, I was thinking about the problem, it occurred to me that to swivel the Right Ascension movement around the Polaris axis 360º should reveal where it describes an imaginary circle with the hairline cross sight which denotes the celestial North pole.  It *seems* that the little aiming circle which Polaris should be central in is about twice as far from the Celestial North as a it should be, however I gave up due to the cold wind. Pleased because I feel I am a step nearer.  I will resume again tomorrow night if conditions allow, with additional clothing.  The right angle finder makes it much easier to see what's going on.  Pity the Go-Pro didn't work.

I can see why people like these 'Go To' mounts but I ain't for spending a grand, or ten of them...  Just to save a bit of head scratching.  What's the fun in that?



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Posted by chrisbet: Wed Apr 10th, 2019 06:43 59th Post
No fun at all and they are the poorer for not understanding how it works. That's one of the reasons I like old cars rarher rhan the comurers in wheels - I can fix them when they go wrong😁



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Posted by jk: Wed Apr 10th, 2019 07:20 60th Post
Well it seems that you can fix computers as well Chris.
The buttons on the Splash screen and the green down arrow seem to be working perfectly.
Very well done.



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Posted by chrisbet: Wed Apr 10th, 2019 07:54 61st Post
Thanks - any view on the Unread posts button?

I find that the easiest way to check for new posts.



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Posted by Robert: Wed Apr 10th, 2019 15:01 62nd Post
This morning afternoon I have processed the images from last night.

Nothing spectacular, I had hoped to try the 300mm but until I get a real handle on the Polar alignment there is no point.

I took these pics with the 16mm f/2.8 fisheye.  The mount is rock solid, well on top of it's job, the adjustments are nice, the right angle finder is good enough. I have established that Polaris is closer to the celestial North than it was in 1985 by about 50%.  I now think I know how to set the Right Ascension (RA) to the celestial 'clock' by aligning Ursa Major with the etched markings in the Polar scope.  Now that I know Polaris is only about 2 degrees from celestial North, that makes the RA adjustment less critical in a sense, although for long exposures with a long lens it does matter, especially if the subject is well away from the pole.

The Milky Way is close to the horizon.

All images taken with Nikon D800 and Nikkor 16mm f/2.8 fisheye @ ISO1600, 30 seconds at f/4.0, taken at 35 second intervals.



This is 20 exposures taken with the polar mount running, stacked in StarstaX. Almost no trailing, the motor is doing the business but it's only a 16mm lens.



And 100% crop...



The next is with the Polar mount turned off.  37 exposures.  And a meteor!



And 100% crop...  Also showing the crop area.



With the 100% crop, you can clearly see that Polaris is nowhere near the celestial pole at that magnification with the D800 resolution.

It's coming together.



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Posted by chrisbet: Thu Apr 11th, 2019 08:45 63rd Post
Looking at those photos brings to mind a couple of Douglas Adams quotes :

"Space is big, really big."

and

"The last thing you need is a sense of perspective."

:smilesmall:



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Posted by jk: Thu Apr 11th, 2019 08:58 64th Post
Well the latest black hole pictures are interesting. 

https://www.bbc.co.uk/news/science-environment-47873592



Robert, your next project is.......



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Posted by chrisbet: Thu Apr 11th, 2019 09:08 65th Post
Yes - I watched BBC4 last night - very interesting - couldn't help thinking about Robert while they were trying to align 8 telescopes all over  the world to focus on such a tiny target - an orange on the moon I think they said!



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Posted by jk: Thu Apr 11th, 2019 13:44 66th Post
Robert, Please can you post a picture of your current setup preferably with the 300mm on the camera so I can see the setup.
I have looked at the manual briefly but everything seems to be driven from the telescope being in place.



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Posted by Robert: Thu Apr 11th, 2019 14:08 67th Post
Yes, no probs, I have it set up outside  now, fine tuning the Polar scope.



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Posted by Robert: Thu Apr 11th, 2019 22:37 68th Post
Doh!  :doh:

Sorry, I clean forgot to take picture of setup, will try tomorrow.  I took the D3300 out specially to make some pix for posting but I was so focused on adjusting the mount that I clean forgot to take pix of it.

I spent all last night outside with the mount, determined to overcome my lack of understanding of the adjustments and practice setting it up.  Part of the problem has been that the Polar scope reticule wasn't adjusted properly.  It's impossible to set the altitude and azimuth if the Polar scope itself isn't set right in the first place.  I had been trying and no matter how hard I tried, I got nowhere.  Going back to basics today I spent time adjusting the reticule in daylight, I now have it set up very close to an optimum setting. It isn't easy because it requires adjustment in two axis with three screws, possible but for very fine adjustments it's not easy, the Allen key is 0.9mm (tiny), I have fitted the Allen key into a small screwdriver handle to make it possible to hold with my arthritic fingers. Four adjustment screws would have been much easier.

I still need to fully understand the time element since it can cause an error from zero to twice the distance between the celestial North pole and Polaris.  As Polaris appears to describe a circle around the celestial North pole, one has to know *where* around that circle Polaris actually needs to be, because that is what determines where the centre of the circle is, it needs to be exactly centred on celestial North, an incorrect time causes an eccentric rotation, it would be exactly right once in 24 hrs.  Difficult to describe, this adjustment is achieved by rotating the Polar scope to the correct angle, like setting a clock, which is correctly determined from periodic tables, by the date and time of day, a bit like tide tables, in fact probably uses the same base calcs.  It can also be determined from the position of Ursa Major but in reality using Ursa Major is only a very rough guide.

The more I use the EQ mount the more I realise how exacting the settings need to be.  Even with modern and very expensive EQ mounts they are only as good as the alignment and support allows.  For really accurate alignment massive foundations and an incredibly solid structure are needed.  A tripod mounted setup is way too flimsy and then add the distortions caused by air movements.

With the practice I have had, I can now get the mount roughly aligned in a few minutes.  For most purposes that's probably good enough to reduce star-trailing to acceptable levels but for what I want I think I will also adopt another technique, rather than making very long exposures, which risk showing star-trail elongation of the image, I will take many relatively short exposures using the EQ mount to maximise the exposures and minimise the elongation.  Because drift is likely over long sessions, using image alignment software will align the images exactly.

My eventual hope is to be able to make pictures of planets, star clusters and nebula, I might eventually get a modest telescope if I find one at the right price.



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Posted by Robert: Fri Apr 12th, 2019 13:54 69th Post
11 Pictures!  Of the mount...
#1


#2


#3


#4


#5


#6


#7


The original flimsy mount against my solid heavy duty mount.
#8


The DR-3 right angled eyepiece with my adaptor, a bit of plastic plumbing fitting and three thumb screws out of an old Mac.
#9


A somewhat out of focus eyepiece.
#10


#11



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Posted by jk: Fri Apr 12th, 2019 14:27 70th Post
Thanks Robert.

I think that I see what is the problem and the issue with some of your difficulties with sighting.

If you want to call me this evening then we can chat it through.
PMed you my mobile number.



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Posted by Robert: Fri Apr 12th, 2019 14:56 71st Post
Thanks JK, I have numbered the images for ease of reference.

In image 7 (and others), the silver dial around the Polar scope is numbered 1-24 effectively, that relates to hours, when locked to the running motor, the arm rotates at 24 hours per revolution.  That dial can be turned independently of anything else and can be set to time of day.

The graduations on the original mount which is green Hammerite are used to set the rotary adjustment of the polar scope, in combination with the hours on the movable disk AND a mark etched on the polar scope itself.

This is a screenshot of the Vixen Manual, page#12.  It explains the procedure in detail.

[/url]

My brain is going into meltdown with that description.  I think that this also requires star charts as well as the hardware.  The movement of Polaris is also indicated in the final figure, #10 at bottom right.  It's not as much as I thought.

The applicable procedure starts at item 6 I think but I very quickly get lost in the nonsensical text/reality.

My EQ mount is not exactly the same as the one illustrated but in essence near enough.  The one below is 1986, the one in the manual is 1995, nine years newer.  Mine is older than both.



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Posted by Robert: Sat Apr 13th, 2019 09:04 72nd Post
OK, I have success! ^_^

Last night I went out again set up at Stickle Pike and took three series of images, firstly the Moon, just to test a theory, then I selected a bright object to the North West, not too high in the sky, then another bright object to the South East.

I set the Polar scope as best I could then rotated the mount arm around 360º which caused the polar star to appear to describe a circle around celestial North, by eye it seems pretty well centred on the celestial North marking.  After I took the Moon exposures I again checked alignment, there was slight Polar drift so I corrected that and went for the first set of a star, may have been a Planet, I don't know...

I took about 70 exposures, 30 second intervals, checked alignment again, the Polar drift was so slight I left it alone.  Then I made a second star set, same settings.  Going through the sets the results are variable, some exposures are crisp and clean, others are mush.  At the end of the session I again checked the Polar alignment and drift was very slight, Polaris had drifted from the centre of the tiny locating circle to the edge, which is measurable but insignificant for my purposes, in fact Starry Sky Stacker suggests a little drift is beneficial because it helps to cancel any noise.  I have processed star 1 images and they are below.  I have used Lightroom and Starry Sky Stacker free trial.

https://drive.google.com/file/d/18CE7amExArYwIvF5h0K0SBaEwjKrXSGb/view

Initially I tried to use Starry Landscape Stacker, by the same developer but it recognised that I was using an astro mount and warned by using the wrong version it could freeze the software because the algorithms are not intended to deal with that type of image. Amazing!

The composite image produced by SSS was made with ten selected 'best' images from 72, the images used spanned a period of 18 minutes of exposures, the first few exposures were not very good, I assume the mount needed to settle down.

Firstly the worst individual image from the set.  These are at 100% crop.



The best individual image from the set.



The best individual image uncropped.



This is the final, cropped image made by Starry Sky Stacker from my ten selected best images.



As you may imagine I am delighted.  I still need to more clearly understand how to get Polar alignment without groping in the dark! I will now go forward and finish the machining of the mount and refine some little niggles but essentially I have cracked it.

Will process Star 2 images later and post the results.



____________________
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Posted by chrisbet: Sat Apr 13th, 2019 10:47 73rd Post
Absolutely great photos, well done!



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Posted by jk: Sat Apr 13th, 2019 10:52 74th Post
Well done Robert.
Looks like you are almost there.



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Posted by Robert: Sun Apr 14th, 2019 18:14 75th Post
Thanks, I am very pleased.  I went through the second set of images but they are somewhat mundane, the same image quality is there but they are just boring plain star pix.

However, just for fun this morning I stacked them in photoshop and blended them that way.  I aligned them manually although they were very close, the error was well less than half a small star between any of them.  The 11 images I selected for star 2 were chosen from about 70 exposures, The 11 images were taken over 22 minutes, so any error could have been much greater.

This is my setup 'in the field'. Note the kneeling pad, just the right height to view through the DR-3 fitted to the Polar scope.




This is the combined 11 exposures stacked in Ps CC.  Taken towards the South East, lowish in the sky, a bright star.  The light pollution to the south is worst aspect at that site,  Lancaster, Morecambe, Ulverston and Barrow all contribute to making a low contrast sky.



This is a 100% crop from the above full frame image, there are no noticeable signs of elongation of the stars due to Earth rotation.



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Posted by Robert: Fri Apr 19th, 2019 16:34 76th Post
The final piece in the jigsaw...

https://itunes.apple.com/gb/app/polar-scope-align/id970157965#?platform=iphone

I came across this by a rather circuitous route of exploring a lot of dead end avenues, which mainly ended in obsolete PC software.

The particularly appealing factor with this 'app' is it knows about my Vixen equatorial mount and more especially the peculiarities of the Vixen Polar scope.  The app makers suggest my scope isn't the best, most accurate design for a Polar scope but by using their app properly it can in fact bring it up to excellent accuracy.

I am off out again tonight, good forecast for clear skies.  Hopefully I will mount the 300mm f/2.8 lens on the D800 and run off some test exposures.  If the full Moon allows I will try to get some of the Orion nebula.



____________________
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Posted by Robert: Sat Apr 20th, 2019 10:12 77th Post
Well I didn't get to try it last night, too much cloud.

This is what I saw: Pennington reservoir.



This is what the camera saw:



This was at full focal length, 120mm with the 24-120 on the D800

Morecambe across the bay.



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Posted by jk: Sat Apr 20th, 2019 10:42 78th Post
Like the darker version Robert.
Lots of light pollution for your sky shots!



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Posted by Robert: Sat Apr 20th, 2019 11:26 79th Post
It was like a sort of misty haze, the light pollution is from Ulverston and Barrow to the South East, I forgot to mention it was a full Moon, a Pink Moon no less.  To the North it's much darker.



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Posted by Robert: Sun Apr 21st, 2019 13:39 80th Post
I have finally been able use the Equatorial (EQ) Mount with my Nikkor 300mm f2.8 lens.  Last night was reasonably clear but the 'pink' Moon was almost full, only having waned very slightly.

My newly acquired app for making the rotation setting of the Polar scope to obtain better accuracy of tracking worked well, I still have to perfect it but that's down to refining my technique, I now have the tools I need and an understanding of what's needed to get very close tracking of the night sky.

While waiting for the sky to get darker I tried some Moon pix.

This is Knottallow tarn above Ulverston, with Morecambe Bay in the background, the GSK factory can just be seen to the left, together with the Sir John Barrow monument, a replica of the Eddystone Lighthouse, caught in a blue moment.

http://www.ulverstoncouncil.org.uk/education/john-barrow-monument

D800 and Nikkor 24-120 f/4.0 - 2.5 sec @ f/5.6



This was made with the Nikkor 16mm f/2.8 fisheye - 2.5sec @ f/4.0




This is Pennington reservoir, not far from Knottallow tarn. This is where the Ospreys have been seen fishing.  Taken about an hour after the previous images, the Moon having risen above the mist and become less pink.



Next is the EQ Mount image no idea what star it was, location to the North West. Made with the best 11 images of 15, taken at 30 second intervals.

Nikon D800, Nikkor 300mm f/2.8 ED Ai lens (MF) - 25sec @ f8, ISO 400.  Processed in Starry Sky Stacker.



This is a star trails image using the same frames as the stacked image above, showing the movement from slight tracking error.  I did not balance the weight of the heavy f/2.8 lens and camera for this test, partly because I need to make a better balancing arrangement and also because I wanted to see how badly the lack of balancing affected the tracking.  It seems to have given an error of about one star diameter over 7 minutes.  There wasn't as much air turbulence last night, almost all the exposures were pretty well perfect once the EQ Mount had settled down after a couple of minutes.



It's been quite a long journey but I have learnt a lot, I need to refine the mount and my technique but I am confident I have an outstanding combination with the D800 - 300mm f/2.8 and the EQ Mount.  Roll on the autumn and darker skies.

EDIT: Looking at these last two images there appears to be some banding effect visible, I don't have that on my processed images at my end, need to investigate that



____________________
Robert.

 


Posted by jk: Sun Apr 21st, 2019 20:39 81st Post
Well how about this for temptation?
https://nikonrumors.com/2019/04/19/new-eagle-core-device-for-astrophotography-with-the-nikon-z6-and-z7-and-dslr-cameras.aspx/



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Posted by Robert: Sun Apr 21st, 2019 22:45 82nd Post
Wow!

What a rig...

Looks expensive.  :needsahug:



____________________
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Posted by Robert: Mon Aug 26th, 2019 17:37 83rd Post
Well, with feet back on the ground after that amazing link JK provided, I went out last night, first time this season.  A slim waning Moon and a warm night was pretty promising.  Armed with coffee and some munchies Christopher and I went up to my favourite local vantage point to see what we could get.  I left the astro mount at home, just hoping for a few simple shots of the Milky Way.  As we pulled up at the top of the hill I was dismayed to find a very large camper-van, awning and tents taking up most of the parking area, the rest of the locality was taken up by hundreds of sheep.  They were the laziest, most stubborn sheep I have ever seen.  I had to bump into them to get them to move, they were completely blocking the road, usually they scamper off but not this lot.  I decided to move on to an alternative location, I didn't want them knocking the tripod over.  Birker fell wasn't too far away so we made our way there.

No sheep but lots of cars driving by, at least for the first 10 minutes after I started taking pictures, Birker fell seems an OK place, about the same travel distance from home as Stickle Pike with possibility of less light pollution, despite being slightly closer to Sellafield.  After about 20 minutes the sky started clouding in, at 30 minutes it was total cover so I wrapped up and we headed home.

I used the D800 and 16mm f/2.8 fisheye, pointed straight up at the Milky Way which was overhead and visually very clear.  I have looked at the results, there were only about 15 usable exposures but they have quite long trails, the exposures were for 30 seconds, ISO1600, f/4.  They didn't stack well and so I haven't done anything with them. I think this is about the first time I have used the 16mm on the D800 so I wasn't sure what to expect.

Another clear and almost Moon free night is forecast for tonight so I am planning to go out again, this time on my own.  Charging the astro mount battery as I type...



____________________
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Posted by jk: Mon Aug 26th, 2019 18:05 84th Post
Looking forward to seeing some more results from your mount.  Longer nights are coming and hopefully less  numbers of holidaymakers in the high places.



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Posted by Robert: Mon Aug 26th, 2019 20:22 85th Post
Yes indeed and fewer dumbhead sheep! LOL

I am using 'Clear outside'...

https://clearoutside.com/forecast/

It seems pretty good, takes a little getting used to, the app allows you to store locations, the Mac software doesn't seem to allow that.  Not always 100% right all the time but the weather is a rather inexact science.

If I get anything worth sharing I will post it.

I'm now running Mojave on the iMac and the Mac Pro, just now Google Earth locked my iMac up, reporting incompatibilities with the OS and also a notice saying that future updates of the OS will render Google Earth inoperative.  That's a minor disaster, I use Google Earth a lot.  Presumably I will still be able to run it on the Mac Pro but I use it for so many things besides photography.

Is there any (viable) alternative?



____________________
Robert.

 


Posted by Robert: Tue Aug 27th, 2019 02:08 86th Post
Much better this time.  I found setting the astro mount up a bit daunting but once set up the world stopped turning, for my camera at least.

Nothing spectacular by way of images, I took about 16 I think but I have been experimenting with the MC-36 and longer exposures.  It works very well.  The Astro mount worked well stoping star trails, the MC-36 worked well providing long exposures.

Will post some later this morning, it's a bit late now.



____________________
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Posted by Robert: Tue Aug 27th, 2019 15:59 87th Post
OK, gradually getting this together.  Here are the images.

This was taken setting up the Equatorial Mount, need to level it and align with Polaris.  The only item of gear I forgot was my little level.  The iPhone did that perfectly well.

As I was doing my first test exposures a car came from the South, behind me.  At that point any cars approaching from the South light up my position for quite a long time, at least a couple of minutes.

All these images were taken with the D800 on my Equatorial Mount using the 16mm f/2.8 ais fisheye.

This was @ f/4.0 for 30 seconds, ISO1600.  you can see the shadow of the tripod and a slightly ghostly shadow of me on the weatherbeaten grass.



This was taken @ f/5.6, 120 seconds, ISO1250.  Graham may be interested because the signpost is directing the traveller to Eskdale 3 Miles away.



Longer exposure of 240 seconds, a flash of my head lamp on the signpost reveals the text better, again f/5.6 and ISO1250.



Ambient lighting here, f/5.6, 240 seconds, ISO 1250



The next image was caught by my red head lamp, 180 seconds, f/5.6, ISO1250.



Finally, 480 seconds @ f5.6 ISO 1250 but with the Astro Mount motor turned off.



I took one exposure at f/8.0 but it wasn't much good because it was contaminated by my torch and a passing cars headlamps, but it was pretty sharp @ f/8.0 so I may try that again.

This is the location, I was in the Southern corner of the crossroads, the Lat-Long are of my camera position.



____________________
Robert.

 


Posted by Robert: Wed Aug 28th, 2019 12:22 88th Post
jk wrote:
Nice mount.
The motor will drive well off the powerpack that you made for use for your Nichai UV light.  Double utility. :-)  :applause:

You can use an LED [illuminator] off that powerpack as well but you will need a dropper circuit to reduce to 3v for the LED.

Just reviewing the thread, I had clean forgotten this post.  Many thanks JK, that is a perfect solution.

One of the snags I have encountered has been that I have been using a 12 Volt lead acid golf trolley battery which is heavy, somewhat fragile and not particularly easy to connect onto, requiring spanner and screwdriver to connect the wires.  I don't like the idea of having a powerful battery with loose trailing wires which are live.  A recipe for fire.

I will make up a lead for the purpose.  It's an XLR plug which avoids the possibility of connecting anything other than suitable into the power pack.

As for the illuminator I found a cheap copy Chinese illuminator off of eBay which fits perfectly and does the job nicely.  It's only needed at set-up so then it's put away in the box.  The button battery last for ages, provided I remember to turn it off, it's one of those devices which would benefit with an auto off circuit.



____________________
Robert.

 


Posted by Graham Whistler: Wed Aug 28th, 2019 22:45 89th Post
Very dramatic Robert, you have good clear sky with little light polution compared with our part of the country.



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Posted by Robert: Thu Aug 29th, 2019 00:17 90th Post
Thanks Graham.  So densely populated it can't avoid the light pollution, it's reasonable here but could be better.  I think Haverigg prison must have gone for LED floodlights because there doesn't seem as much glare from that quarter now.  Sellafield, to the North West is probably the worst offender.

To get really dark skies Kielder is probably our nearest but that's at least 135 miles, each way...

I really want to get up into the North West of Scotland but the weather up there is so unpredictable and it's such a long haul that the chances are slim.

I have just returned from a fruitless outing, the clouds closed in so quickly that I only had a fleeting glance of a clear sky, probably the last chance for a few days.



____________________
Robert.

 


Posted by jk: Thu Aug 29th, 2019 07:49 91st Post
Robert wrote:
OK, gradually getting this together.  Here are the images.

This was taken setting up the Equatorial Mount, need to level it and align with Polaris.  The only item of gear I forgot was my little level.  The iPhone did that perfectly well.

As I was doing my first test exposures a car came from the South, behind me.  At that point any cars approaching from the South light up my position for quite a long time, at least a couple of minutes.

All these images were taken with the D800 on my Equatorial Mount using the 16mm f/2.8 ais fisheye.

This was taken @ f/5.6, 120 seconds, ISO1250.  Graham may be interested because the signpost is directing the traveller to Eskdale 3 Miles away.



Longer exposure of 240 seconds, a flash of my head lamp on the signpost reveals the text better, again f/5.6 and ISO1250.



Ambient lighting here, f/5.6, 240 seconds, ISO 1250



Like these three best.
Well done looks like you are well setup now.



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Posted by chrisbet: Thu Aug 29th, 2019 08:25 92nd Post
Great photos but not convinced about including the signpost!

Any idea what the curved dotted trail in the 2nd pic is?  Plane? Meteor?



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Posted by Robert: Thu Aug 29th, 2019 08:36 93rd Post
Thanks JK, my setup is maturing, I will take a look a the UV power Pack later that will make the setup tool-free, quicker, easier and safer, I'm not keen on taking lead acid batteries into the field, in the dark, clambering over gates and suchlike.  Also it would make it easier (lighter) to take the rig to less accessible locations, although the astro head is by far the heaviest and most cumbersome bit.

I went out last night but as soon as I parked up the clouds came rolling in.  We have windmills in the hills nearby, I had intended to use a couple as a feature with the Milky Way behind but it was not to be.  I want to get a feel for the exposure using the MC-36, it's a totally different technique because it allows me to close the lens down some and reduce the ISO to much lower levels.  I still need to assess that compared with wide open lens and high ISO but shorter exposures. I suppose it's a bit like birders and TC's or longer lenses.  The 16mm seems to improve about f/8.0, wide open the stars towards the outer edges of the image seem to take on a triangular appearance with severe CA.  The triangles seem to point towards the centre of the image.  I haven't noticed this with the D3 but the higher resolution of the D800 reveals it clearly, so that is another reason to stop down some.  The lower resolution of the D3 largely masks the effect.

There are no clear skies forecast for the next week or 10 days, beyond that it's anybodies guess, by then the moon will be bright again. o.O



____________________
Robert.

 


Posted by Robert: Thu Aug 29th, 2019 09:42 94th Post
chrisbet wrote:
Great photos but not convinced about including the signpost!

Any idea what the curved dotted trail in the 2nd pic is?  Plane? Meteor?
Thanks Chris, these shots are only me trying to get a handle on the D800, 16mm fisheye and the MC-36 combo.  I try to include a land based structure or feature like a tree, church or maybe a viaduct in my night sky images.  To me plain pictures of the starry sky lack a subject, they make a nice background.  Unless of course you can get close in to nebula or other spectacular night sky features but that really requires a telescope, which ramps up the cost, astronomically... 

Once I get a good feel for the combo and have refined my technique a bit, I plan to take some starry background photos of some of my favourite locations, Coniston Water - East side, the Ribblehead Viaduct, an old rail bridge near Sedburgh, various churches, etc.  As I drive around I am constantly looking for suitable subjects, sometimes they have snags, like security lights which only manifest themselves on the night... Which was the case when I made a planned shoot at Ravenglass railway station, permissions obtained, all set up perfectly, once it was properly dark and I started taking the photos, security lights started coming on in one of the building every few minutes, totally ruined my picture. I did eventually get there, I grafted in a sky from one I had taken at nearby Wastwater the week before, same sky, different day!




After (more than) a bit of work with photoshop...



This is Ribblehead Viaduct with a little added extra from Eric.  Viaduct and star-trails were mine, Eric added the train!



Might not be a wonderful example from my trip to Scotland in May, but it's different...



Another...

The Skye Bridge.




The reason I included the signpost was to give me some idea of how the ambient light works with the starry sky background.

Dotted line = plane. Curved track is due the curvature of field caused by fisheye lens.  To be honest I hadn't noticed it! LOL  My current glasses are rubbish, mind you, what can you expect @ 98 pence for TWO pairs of glasses! Now that is specsavers!  One day when I can afford it I plan to get another two pairs of a different spec, that might be better, I don't think these are powerful enough.

Sorry to go on and on...  Just getting carried away! :lol:



____________________
Robert.

 


Posted by jk: Thu Aug 29th, 2019 09:58 95th Post
If you want proper dark skies without light pollution then I guess you need to go to southern Chile or Hawaii.

https://www.lightpollutionmap.info/#zoom=0.8786276236983241&lat=-414578&lon=-20009004&layers=B0FFFFFTFFFFF



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Posted by Robert: Thu Aug 29th, 2019 11:17 96th Post
Thanks JK,  that's a very handy map, bookmarked already!

It confirms my expectation that North West Scotland is the closest I am likely to get to a dark sky.  It's just getting there when there are clear skies.




Kielder is affected by Glasgow and Newcastle, quite noticeable on a dark clear night It's my understanding that major cities like Glasgow can pollute the darkness for more than two hundred miles around.  In the South West Lake District National Park where I am lucky enough to live, just North of Barrow, we have green to grey rating.

As you can see from the first image in my last set, the Sellafield nuclear plant (Seascale, or Calder Hall), the whiter patch to the left, is a powerful source of light pollution, from just one plant, albeit a very large one.  The more orange patch to the right is Whitehaven and Workington.

It's interesting to see that the West coast of the Isle of Mull seems to have a good rating...  That's 'only' 320 miles from here. Mmmm..



____________________
Robert.

 


Posted by jk: Thu Aug 29th, 2019 20:23 97th Post
Teeheeeheee,  how about getting above the clouds with a trip to Scafell Pike?  Actually if you were cunning just drive to Wasdale Head hotel/pub and go into the field that is on the path to Scafell/ Scafell Pike and set up there.  Good refreshments available on tap!



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Posted by Robert: Thu Aug 29th, 2019 20:49 98th Post
jk wrote:
The motor will drive well off the powerpack that you made for use for your Nichai UV light.  Double utility. :-)  :applause: I have re-opened the UV lamp powerpack, while I could adapt it, it's main feature is the LED Driver in which which you guided me in the construction.

I would have to completely re-design the internal circuitry, it works and is reliable.  I don't want to mess with it.

However, I have had an idea...  Now the D3 is no longer my front line camera, I could use D3, EN-EL4 batteries and connect to them via the Chinese charger you sent with the D3. By removing the charging circuitry from the charger module and connecting a cable directly to the battery output terminals I could mount it on the back of the Astro Mount controller, or mount it in a small white box with the controller so I could use some of my EN-EL4 batteries to power the Astro Mount.

Perhaps include a small switchable 3 Watt instrument bulb to provide heating for the battery.  They seem to suffer badly from the cold and this rig will very likely be used in the cold more than in the warm.

If not the EN-EL4 batteries, I have another good set of three 18650 cells sitting on the shelf in front of me from my dismantled D1 batteries. :thumbs:



____________________
Robert.

 


Posted by jk: Thu Aug 29th, 2019 21:11 99th Post
I cant remember now if your 18650 batteries are tagged cells or ones like normal AA batteries with spring connections.

A single 18650 will power a LED bulb for many hours.  18650 battery is rated at 3.4-3.7volts.

To power your Astromount motor you need 12-25volts I think.  This is the equivalent of about 5 of the 18650 batteries (18v) in series.  You need three batteries only if you need 10-12volts    
Note: series, not parallel.  
So for 6 cells you can have two independent power supplies.  

However since the light will only be used occasionally then you can use 5 batteries in series but tap into the first battery only of the series for your light.



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Posted by Robert: Thu Aug 29th, 2019 21:54 100th Post
The Vixen Astro Mount motor is rated at 5 Volts.  The controller has a voltage stabiliser chip which can accept up to 36 Volts and reduce it to 5.  The excess voltage is absorbed by a primitive galvanised steel heat sink, might be better replaced with aluminium or copper.

My spare 18650 cells are tagged but one tag on one cell had broken off, the spot welds have failed.  I would not attempt to re-attach it by soldering.  The other two cells could have their tags removed so I could end up with three un-tagged cells, which could be recharged individually in an individual cell (as opposed to bundled cells) 18650 charger.

Another possibility occurs to me, I have a good supply of Makita 18 Volt professional power tool batteries, I could easily get a broken drill or other suitable tool and cannibalise the battery mount. These batteries have capacities of 3Ah and 4Ah, well more than enough to power the Astro Mount for days, weeks even!

Why, oh why, are all these batteries different.  The cells inside are largely the same, as are the voltages, yet each manufacturer has their own proprietary style of attachment and termination.  o.O



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