2 May - Big Dob enjoys first light with Photonis INTENS Night Vision

[alanjgreen]

Date: Wed 2^nd May 2215-0200am       

Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1). Night Vision: PVS14 with Photonis 4g INTENS.

Eyepieces: 55mm (f2 x38), 35mm (f3 x60), 27mm (f4 x77), 18.2mm (f5.8 x115). Filters: Astronomik CLS, Baader 610nm Red.

 

The Trial of New Kit

As always, the first night out with new kit is a bit of a “trial and error” scenario. Plenty of time lost to faffing about and needless swapping of eyepieces and filters.

I set out early (2145pm) expecting to spend more time than usual setting up my scope (and that turned out to be the case!) and wanting to get some time with the PVS-14 before the “devils orb” (the Moon) made its appearance…

I started to collimate the scope, put in the Paracorr2 then realised “What are the paracorr settings for all the new eyepieces?” [trip back to the house and internet!]

I completed the collimation (Glatter laser & TuBlug) then screwed the TNVC adapter into the PVS-14. I switched the light off and pulled back the shed roof… It was still light, especially in the west!

 

“Oh well, I can see the major stars”

I stuffed in the Ethos10 (my usual alignment eyepiece @x200) and set about aligning my AstroDevices Nexus using Arcturus and Algieba. After a quick test of the alignment on another bright star (confirmed) I stood back and wondered whether it was “too light for night vision?”. I stood and looked at the sky for a while then decided I would be fine…

I swapped the Ethos for the Panoptic 27mm (after debating with myself whether I could use the x40 55mm – x40 seems such low power compared to my regular x200-x250 that I am used to! The 27mm seemed a good compromise.) I attached the PVS-14 to the Panoptic and was pleased how easy it was to locate the TNVC connector and tighten it down. I placed the lanyard of the PVS-14 of the Baader SkySurferV red dot finder (just in case of any accidents or drops).

Nervously I turned the ON switch on the PVS-14 and moved my eye towards the glowing white phosphor of the “eyepiece”… Stars!

I adjusted the focus of the scope, all seemed to be working!

Checking Nexus I decided to head for the Whale galaxy nearby. Would I be able to see it yet? It’s not even dark.

Sure enough, the Whale came into view along with its small companion sitting just to the side. This was a result as the sky was not even dark yet, it was still light over in the west. I was pretty stunned at this point I have to say.

Onto the Needle galaxy, Yep, there it is with a lovely round core and a clear dark lane running underneath. I had to step back and check the sky again (and yes, it’s still not dark!)

Next, the Black Eye galaxy. Another good result, the shape of the black eye was lovely with well-defined edges. The best I have seen it.

 

“The Whirlpool, What about the Whirlpool”

Something whispered in my ear, “Whirlpool, Whirlpool” and I obeyed. The arms of M51 where very sharp and in plain vision. They were not merging into each other as they tend to do naked eye. The central bar was clear around the core (the hardest bit to see naked eye) and there were varying brighter patches within the arms. I tried to see the black dust lanes but did not. The whole of the bridge was not visible. With some averted I teased out some more.

 

"What about a Pin Wheel?"

M101 proved to be as elusive as ever. The vast array of NGCs in the arms were fewer than I have seen in the past with the 20" at x200. The arms were harder to discern than with the 20" at x200. After spending time at the eyepiece the arm up over the top started to appear and a larger general shape was coming into view. The 95% Moon is a pain in the backside! Need to spend more time to uncover the way to get more from M101 but last night it was my least successful target with worse results than previous naked eye. I did not try naked eye last night to compare so no direct comparison was done.

 

“What a Faff”

Now I decided to start changing eyepieces. With the 35mm inserted I was starting to take in more of the vista and I noticed that the bigger stars looked crap (sort of like 3 tight blobs rather than a nice round star). I faffed with the scope focuser, then the PVS-14 focuser, all to no avail. Eventually, I turned the Diopter adjustment on the PVS-14 and the star shapes changed – GREAT! I fiddled about with the Diopter adjuster and eventually got the round star shapes that I was looking for. [Valuable time lost and the Moon was now on its way up from the horizon]

 

Now I decided to start messing with filters. In with the Astronomik CLS, then in with the Baader 610nm then back to unfiltered. [More valuable time lost and the Moon continues its rise]. Neither improved the whirlpool to my eye.

[Why do “I have to” faff about like this when I should have just stuck to my game, only faffing when I actually needed too! Grrrr]

 

Globulars Like You Never Saw Them Before

Now I had passing clouds to contend with as well as the moon! I happened on a clear patch of sky, checked with Nexus and M3 Globular was nearby, I centred it up. Wow, resolved right to the core! The magnification being used was miniscule but it resolved to the core. The view was different to an eyepiece view as the stars were just there and sharp. There was no “coming and going” or “variations of view as it passed across the fov”. The view was the view and it just stayed the same as it wondered from right to left across my view.

M13 Hercules – Now I had to try M13. It was a view unlike any I had before, just “different”. The propeller was obvious straight off. It looked like a little “space invader” and it just did not change. Sharp and lovely. Resolved to the core even at this tiny magnification!

 

After a couple of hours spent with 55mm, 35mm & 27mm plus the CLS and 610nm filters I concluded the following.

Eyepieces

35mm = I like the 35mm, it gave a great view of pretty much anything I looked at.

27mm = Need to use this more as when I did, I liked it.

55mm = Least impressed with this one. Just something about the edges of the view was distracting. Again, hard to make a judgement on one night but those are my thoughts this morning.

18.2mm = Hardly used. Verdict not possible.

14mm = Unused.

 

Filters

610nm = good, worked well once the moon came up. I was able to keep on with galaxies.

CLS = slightly worse than the 610nm maybe. Might get a different result under a smaller moon?

 

Other kit

TNVC connector – very pleased with it. Had no issues holding the PVS-14 tight to the eyepiece Dioptrx. Easy to remove & fit in the dark.

PVS-14 – Very pleased after the first night out. The Diopter faff was a bit of a distraction. The “manual gain” was another battle - its wonderfully easy to use but hard to decided just how much gain is the right amount (Maybe just until the first hints of “scintillation” (sparklies in the view due to photon starvation at the sensor) appear. More time at the eyepiece needed...

 

 

Other thoughts

1. Why do targets seem bigger than the actual magnification being used?

This was a strange one, I am used to x200-x250, last night I was using x40-x77 yet the objects appeared big and bright? Puzzling but a relief as I am not a low magnification man. Was it the 40 degree view compared to the 100 degree I am used to?

2. Manual nudging of a dob with only a 40 degree fov

This was really my main concern before last night. The focuser stack is pretty lengthy (Paracorr, eyepiece & PVS-14). I had wondered whether I would be able to even reach the scope! But it was no problem. The glow of the PVS-14 eyepiece makes it easy to locate with your eye so head-butting of the stack is unlikely to be an issue.

As the magnifications are so low. Even the 18.2 DeLite was no issue with the nudging.

 

Clear Skies,

Alan

[Littleguy80]

Very successful first light with the NV, Alan! Am looking forward to future reports and ultimately to see if you end up preferring NV to traditional observing. I'm kinda expecting that they're complimentary rather than one besting the other but I have no personal experience to go on! 

[GavStar]

Very interesting report Alan, I’ve been very interested to hear how the views are in a big dob. I think you will see much more impact on emission nebulae such as North American nebula with the Ha filter - I guess you didn’t try this filter last night? On emission nebulae I think you will find the 55mm plossl will come into its own much more. I love mine on these objects.

Galaxies are probably the trickiest objects for NV (apart from planets and double stars which are in the don’t bother category). Getting high mag views of galaxies whilst still retaining a fast system is tricky. To get 200x mag with NV and a fast f4 ratio you’d need a 50 inch scope!!!

[GavStar]

9 minutes ago, Littleguy80 said:

Very successful first light with the NV, Alan! Am looking forward to future reports and ultimately to see if you end up preferring NV to traditional observing. I'm kinda expecting that they're complimentary rather than one besting the other but I have no personal experience to go on! 

Alan has got the fantastic advantage of a really dark site. So I agree NV may well be complementary for him rather replace the ‘pure’ (and lovely) conventional eyepiece views he gets. 

From my light polluted back garden in SW London, for DSOs it’s more a case of NV enables me to see stuff that I just can’t with conventional eyepieces - so it has really changed and massively enhanced my observing.

[alanjgreen]

13 minutes ago, GavStar said:

Very interesting report Alan, I’ve been very interested to hear how the views are in a big dob. I think you will see much more impact on emission nebulae such as North American nebula with the Ha filter - I guess you didn’t try this filter last night? On emission nebulae I think you will find the 55mm plossl will come into its own much more. I love mine on these objects.

Galaxies are probably the trickiest objects for NV (apart from planets and double stars which are in the don’t bother category). Getting high mag views of galaxies whilst still retaining a fast system is tricky. To get 200x mag with NV and a fast f4 ratio you’d need a 50 inch scope!!!

Yep, I agree.

I was really pleased with the performance of the Photonis INTENS, stars were small and sharp (once I sorted the Diopter on the PVS-14) and star halo's were pretty much none existent!

 

[alanjgreen]

22 minutes ago, GavStar said:

Alan has got the fantastic advantage of a really dark site. So I agree NV may well be complementary for him rather replace the ‘pure’ (and lovely) conventional eyepiece views he gets. 

From my light polluted back garden in SW London, for DSOs it’s more a case of NV enables me to see stuff that I just can’t with conventional eyepieces - so it has really changed and massively enhanced my observing.

Seeing small galaxies when its not even dark was a stunner!

I managed to locate the very tiny "mice" galaxies with the 27mm Panoptic before it was dark! These are hard targets that can be hit and miss in big dob naked eye

[GavStar]

Alan,

I’d suggest having a go with your 89mm Borg soon as well. The widefield NV views are great. The forecast is good this weekend so I’m aiming to have some early 3am starts for North American. Veil and maybe even lagoon, swan etc...

Plus just using the NV on its own for unity views (but I confess I haven’t had a much fun with this as the US NV posters rave about). Barnards Loop should be great for you at You dark site in the winter!