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Highburymark

Another observation about night vision

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I've held back posting reports on night vision this year as Gavin and Alan have done so comprehensively, and I've had limited opportunities to get out, but I've had ten decent sessions in the past few weeks, and now seems like a good time to share a few thoughts, particularly after the lively exchange of views on NV in other threads....

On that issue, I think it's important to consider the different observing situations we all find ourselves in. My north London skies are about as challenging as it gets. Most nights, it's very difficult seeing even two clear stars in the areas of exposed sky to get my go-to mount aligned in the first place. Even once my eyes have adapted to the 'dark', I can only see 8-9 stars through the murk - that's how bad things are. I decided to invest in NV because it transforms everything for me. I have a back injury, no car or regular access to dark skies. The idea of having a large telescope to take to dark sites is an unachievable dream. But that doesn't stop me enjoying reports from those who have those options. This hobby is about sharing our passion for the night sky, and anything that helps us do that is to be encouraged, I think. 

Of course NV is not cheap, but at around £3.5k for a PVS-14 with a Photonis Echo tube (haven't tried one but should be plenty good enough for astronomy), it's about the same price as an entry level double stacked 60mm Lunt solar scope, or an Orion 16" dob (1/10pv). Many on this forum have a case of eyepieces which cost more. Though, to be fair, the best NV devices are more expensive than this - around £6k for a spotless Photonis 4G. 

What night vision offers urban stargazers like me is the opportunity to see deep sky objects previously only visible from dark sites. Benefits many times greater than the incremental gains from simply trading up to a larger telescope.  From my back garden, I've seen the Heart and Soul, North America, California and many other nebulae for the first time - sometimes with a near full moon, and floodlights beaming from a school at the end of my garden. Mostly they are fully formed images without averted vision and with minimal 'scintillation', and the experience is little different to looking through glass - though I don't always see the level of nebulae detail shown in Gavstar's awesome phone shots. Objects around the zenith are obviously far more distinct. Cygnus especially memorable a few months ago. 

The views of M42 through a 4" refractor are always astonishing - so bright that it's possible to pump up the magnification. Without doubt the most impressive thing I've ever experienced in astronomy, even though my location means Orion is always placed over the centre of London. M31 is brighter and more detailed with NV through a 3" frac in London than through a 6" scope I took to a dark site in Spain.

But there is a limit to what NV can do. Some nights, I can only just pick up the faintest signs of nebulosity in objects like the Rosette or Heart and Soul. The key factor I think is transparency, rather than just light pollution. On these evenings, the narrowband filters are packed away, and I go after star targets with an IR-pass filter- Messiers 35, 36, 37, 38, 41, 44, 52, 67, 103 all showed nicely the other night. Clusters are lovely. Stars so numerous that star hopping becomes very difficult - so I bought a little AZGTi mount which works beautifully.

I'm still experimenting with the set up. I don't think I'm getting anything like the best from the device yet. I need to speed up the system further to tease out more details of nebulae. So will try a decent focal reducer soon. And I can go narrower than my 7nm ha filter. I'd like a faster scope than my F7.4 and F6.25 fracs. Perhaps an F3.3 Epsilon - we shall see. All more money. But am able to sell off a lot of eyepieces which I just don't use much any more.

I think it's also worth noting that no matter how significant the improvement with NV, there are small halos around the brightest stars - you can see them on photos or YouTube videos - so at the end of a session it's nice to remove the monocular, slip a Panoptic 24 into the Tak, and spend a few minutes drinking in the tack sharp stars of M45. Even in London, there's nothing to match the Plaeides through a nice frac. 

I don't think NV threatens any other form of astronomy in any way. Because it's possible to see the Horsehead from light polluted sites (I've never seen it by the way) doesn't diminish the achievement of anyone who's seen it with no powered assistance at all. Though they will have had different types of assistance - either a large telescope, pristine skies, or a great deal of experience in astronomy - or all three. And I remain very envious of them.

 

 

 

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Mark

Tks for that

Down under , where I am, do not have a major issue with light pollution

I leave home around 4-30 every morning, for a 5-10 minute drive to my local rain station, to commute to Brisbane for work

Most morning, if cloud free, look up and see the milky way above me

When get to the station carpark, a different situation, due to LED lightening in the carpark

Snapped the attached the other morning, conjunction of quarter moon, with Venus

Jupiter was just above Venus

Used my mobile Android phone to image, and Samsung Android phones do not like poor lighting conditions

Moon did not turn out way I wanted, and not sure due to handshake, or just a longer exposure due to light conditions

Hope you enjoy

John

 

 

Conjunction Venus and Moon.jpg

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Mark,

A great read - I’m very happy to hear that NV has added an extra dimension to your observing. Its going to be interesting to see how you decide to tweak your system to get even better results in the future.

I’ve had very good results with my 0.75x AP photo visual reducer in my larger refractors but so far haven’t managed to get a suitable solution for my smaller ones. I’ve got a couple of experiments coming up regarding this and will let you know if I have any success. As you say getting as fast a system as possible is so important and even more important in severely light polluted skies. I always like to get to about f2 (including the 55mm plossl) with my scopes - that’s when I find  things like the horsehead start to pop out...so I think the Epsilon is a great option (albeit the star shapes at the edge go rather elongated due to the plossl struggling at the faster speeds)

And yes a nice 5nm Ha chroma (or suchlike 😉) will take out more of the light pollution.

Ive also had great results with the NV monocular on its own or with a 3x afocal lens since these run at a super fast f1.2. I often use these as a quick way to assess the transparency of the skies at the start of a session. In my SW London back garden (which does seem to be a bit better than your London observing site) if I can’t see for example Barnard’s Loop obviously then I know it’s not very good and I’m likely to concentrate on star fields, globs and galaxies instead...

Hopefully you’ll also get some opportunities to visit a dark site soon - you are very welcome to come along to one of our clubs dark site trips - I’m happy to give you a lift 😀

 

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Very informative and measured post. It is good to know what it can/can't do ... not that I am ever going to be in a position to seriously  consider in investing in this route ...

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transparency is key as mentioned. That harder-chroma must be working well if you set the “loop” as a quality test... need to work harder to reduce the impact of my local light pollution?

Peter

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Mark,

A very thought provoking post.

Astronomy is different things to different people. A member of my society never observes. His astronomy is the science. I observe and image but have little understanding of the numbers behind what I am seeing. We both consider ourselves astronomers.

If it works for you and increases your enjoyment of what you love, go for it.

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15 minutes ago, Swoop1 said:

Mark,

A very thought provoking post.

Astronomy is different things to different people. A member of my society never observes. His astronomy is the science. I observe and image but have little understanding of the numbers behind what I am seeing. We both consider ourselves astronomers.

If it works for you and increases your enjoyment of what you love, go for it.

Most members of my society don't observe or image. They like listening to the speakers we get in though. Those of us who get out there with scopes are thought of as a bit odd I think :rolleyes2:

 

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15 hours ago, John said:

Most members of my society don't observe or image. They like listening to the speakers we get in though. Those of us who get out there with scopes are thought of as a bit odd I think :rolleyes2:

 

My club is very hands on

Club nights are saturday night closest to full moon, due to moon brightness

Even then, we have 10-15 scopes set up outside the club rooms

Check club URL, member pics taken due the previous month

Click on Event Horizon, which is monthly newsletter

WE are also out a couple times per month, around quarter moon, doing presentation in primary schools, scout/guide groups

I had to cancel a cubs group weekend before last due to overcast weather

Kids were doing an overnight camp, and was going to do solar viewing in the afternoon, and deep sky objects that night

John

http://sas.org.au/

 

 

 

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Most of the societies I have been a member of do have observing sessions, when the weather cooperates, but I agree many are there for the talks only. Each to their own.

Peter

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22 hours ago, John said:

Most members of my society don't observe or image. They like listening to the speakers we get in though. Those of us who get out there with scopes are thought of as a bit odd I think :rolleyes2:

 

I really don't get that. Same happened in my astro club back in the late nineties. There were even people who loved the moon, but never actually observed it.

At that time that was the main reason why I left the club. Of course people are free to do what they like in this hobby, but as a teenager at the time, I found this quite frustrating. 

 

Anyway, sorry for my side comment. Please, gentlemen, let's carry on with the OP's NV thread. Amazing technology, really. I wish the cost will decrease in the next few years so that more and more people will benefit from them.

Edited by Piero

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