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Highburymark

Night vision in Yorkshire Dales

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On Christmas Eve my wife and I were visiting family and friends in a tiny village in Swaledale, North Yorkshire, and I'd taken my Tak FC-100 scope and PVS-14/Photonis 4G night vision monocular along in the hope that the skies would be clear after dinner. There were 11 of us in total (including a physicist who is currently studying distant quasars for her PhD - no pressure on me to put on a good show then.....), so I was pleased to see we were cloud free at 10:30pm, although the Moon was exceptionally bright. I wanted a varied selection of targets, but as time was limited, I decided on three bankers: M42, M45 and M31. I chose to use 27mm Panoptic and 36mm Baader asph eyepieces to achieve reasonably large images as most of the guests had never looked through a telescope before. First up was M42 - bright enough to justify a magnification of 29x with the Panoptic and 7nm H-alpha filter. It was mesmerising - though interestingly not significantly more detail than I achieve with the same set up from London, which really brought home to me how well NV delivers under extreme light pollution. I'm sure that without such a prominent Moon nearby the views of M42 would have been even more compelling, but the rest of the party were not complaining - the Orion Nebula brought regular gasps. Next, the Plaeides - with the 36mm eyepiece and 685nm IR pass filter. Whether such a majestic open cluster is improved by night vision is a matter of personal taste. The stars are not quite as tight as they are through a native refractor, the brighter ones showing small haloes, though this is a minor quibble - the Photonis tube has a reputation for controlling haloes very effectively. Another factor is the sheer number of stars in the fov - which as others have reported completely changes the perception of familiar clusters like M45. For me, the brightest open clusters are best seen natively. Where NV technology really helps is finding and observing fainter clusters. Last of all, we turned to M31, very nicely framed in the 36mm, with companion M110 easily discernible. Just starting to see a little bit of structure to the galaxy instead of a mere milky blur. Most popular target of the night with dinner guests. All in all, the session was 90 minutes - 3 minutes per target per person. Not the most challenging of dsos, and not really stretching the night vision device either - didn't have time to go for other nebulae with the 55mm Plossl - but it was a wonderful evening, and a joy seeing everyone appreciate some of the showpiece objects in the night sky. 

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Nice one Mark.

Dont be afraid to use the 55mm plossl with the NV. Focal speed and exit pupil are key to get great results, your TAK is pretty slow at f7.4 (when used with 27mm EP).

Then there is the exit pupil, with the 27mm, you are putting 27/7.4 = 3.6mm of light (exit pupil) into the NV (which can take 20mm entry pupil) therefore you need the plossl to get more light into the NV.

55/7.4 = 7.5mm that’s a lot more light up into the NV!

Try to forget about the magnification and concentrate on speed. The 55mm will also turn the slow TAK into effective f3.7. 

NV works great under dark skies, if not then consider if you are doing something wrong or rather are focusing on the wrong variables?

I say “Stretch the legs of that 55mm plossl“ :) 

Alan

Edited by alanjgreen
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Lovely report Mark. I agree with Alan, get using that 55mm plossl. And also get scanning the skies at just 1x with an h alpha filter. It’s great fun...

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Thanks both. The 55mm is getting good use, but night vision enhanced observing has turned out to be much more varied and flexible than I was expecting - not just limited to low power nebulae - so I'm getting good use out of all the eyepieces - really pleased I bought the 27mm Panoptic. 

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29 minutes ago, Highburymark said:

Thanks both. The 55mm is getting good use, but night vision enhanced observing has turned out to be much more varied and flexible than I was expecting - not just limited to low power nebulae - so I'm getting good use out of all the eyepieces - really pleased I bought the 27mm Panoptic. 

That’s interesting Mark. Generally I’ve found running slower setups a bit disappointing. I will try my 32mm plossl and compare with the 55mm next time I look at open clusters or globulars.

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Good to see your sayt delivering the goods. There’s a lot more up there to see. 1x with 685nm is always entertaining!

PEterW

 

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It can be real nice on the dales without a moon and with a clear sky when it happens (rarely- usually the other way around).   

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On 01/01/2019 at 11:20, kev said:

It can be real nice on the dales without a moon and with a clear sky when it happens (rarely- usually the other way around).   

It can. From a little campsite in Muker two years ago I had some lovely views with M42 giving up its turquoise and purple hues which made it really nice and some of the best views I've had of it. 

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4 hours ago, mapstar said:

It can. From a little campsite in Muker two years ago I had some lovely views with M42 giving up its turquoise and purple hues which made it really nice and some of the best views I've had of it. 

I love the colors in this object too- the other night we were observing a deeply mottled green in the core and fairly bright pink under the wings, intermixed with faint green/gray hues.

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Posted (edited)
On 29/12/2018 at 19:55, Highburymark said:

tiny village in Swaledale

I wonder which village that was?  ;)

We also had an early Xmas Eve evening session before moonrise :)  TMB 92mm f5.5 APO.  Comet 46P, M31, Milky Way etc.  The relatives were entertained!

NV is not a usual accessory for our SQM 21.4 sky  :)  pity about the moon...glad you were successful!

Happy New Year

Paul

Edited by clarkpm4242
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3 hours ago, clarkpm4242 said:

I wonder which village that was?  ;)

We also had an early Xmas Eve evening session before moonrise :)  TMB 92mm f5.5 APO.  Comet 46P, M31, Milky Way etc.  The relatives were entertained!

NV is not a usual accessory for our SQM 21.4 sky  :)  pity about the moon...glad you were successful!

Happy New Year

Paul

And a happy new year to you Paul! Always love my visits to Low Row. 

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