GavStar

10 minutes ago, vlaiv said:

Well, at first it was just called EAA and at that time I would agree with you, but subsequently it was renamed to EEVA - precisely to include night vision devices which are electronic in nature and in the same way you are watching computer screen - and small display in devices like evScope - you are looking at phosphorous screen and not actual target with night vision device.

Does it require electricity to be able to observe (but not for tracking - for actual observation)? Then it is EEVA

So is using a Quark for solar visual observing EEVA since it needs electricity? Defining an approach purely based on use or not of electricity is a poor definition imo since the various methods are just so different.

What it’s not for me is night vision - night vision is just another eyepiece in my eyepiece case that can be used in the same way as my Televue, explore scientific eyepieces etc.

Virtually all the discussion in this section is about EAA which uses cameras and computers.

17 minutes ago, Deadlake said:

What about 700 nm range (red)? 

Agree for larger aperture SCT looks the way to go, EdgeHD series looks like less maintenance than other mirror based systems. At lot of RC scopes have quartz mirrors which aids with cool down, but for  NV less sensitive to acclimation.

Diagram direct from celestron document 

4 minutes ago, Deadlake said:

Googling for mirror transmission for reflectors comes up with limited hits, for instance I wondered if an Epsilon would have a higher transmission. 

NV I believe is not so sensitive to the green/blue frequency bands, do we have transmission values for the red band that NV is sensitive too?
 

The figure I quoted for Celestron is at the 656 halpha band that is critical for nv nebulae observing. I haven’t seen anything specific regarding the Epsilon transmission but would think it would be similar to the other scopes.

As Peter says the key advantage of reflectors is the ability to have large aperture to get the necessary image scale for smaller objects with nv, which is what I use my c11 edge and 16 inch dob for.

10 hours ago, PeterW said:

Depends on the mirro coating, can go >95%, easier to get bigger and faster... lots of options.

Peter

Eddgie on CN estimates his Boren Simon has transmission in the order of 85% which is the figure Celestron gives for its latest coated scts.

I still think refractors give a crispness of view with night vision that reflectors can’t match 😀

Also I believe that mirrors have some light transmission loss that refractors don’t have. The two mirrors in an imaging Newtonian f4 can lead to a light transmission loss of 80 percent meaning it’s actually operating at f5ish rather than f4...

Although I really enjoy the views through my Pegasus Binoscope, recently I've either been using my grab and go refractors for quick and easy observing or my C11 or 16 inch dob for more serious sessions. Since the WO binoscope is not grab and go (requiring my Panther TTS-160 mount) and also has relatively small aperture, I haven't had a proper outing with it since April. Weather conditions have been poor in the UK for the last month or so, but the forecast the other night was for clear skies from 2am, and with Orion nicely visible at that time from my London back garden, I decided it was about time to dust off the binoscope for a proper large nebulae session.
 
I've also acquired 2x 67mm televue nv plossl adapters so it was a good opportunity to test these out for binoscope usage. With the 67mm, the setup has a nice fast f2.6 effective speed, 11x mag and 3.5 degrees fov, perfect for those famous large nebulae that grace the sky at this time of year. Due to the severe light pollution in my back garden (sqm 18.6 as measured), I use a very narrow 3nm chroma ha filter with each monocular.
 
According to specialist nv binocular users I commit a cardinal sin by using very mismatched monoculars, in the left I use a Photonis 4G PVS-14 (actually gen 2 tech but top end) and in the right a Harder gen 3 PVS-14. The harder tube has nearly double the luminance gain of the photonis (the key drawback of gen 2 tech) but also has a materially higher sn. Having the monoculars side by side its extremely easy to do direct comparisons of the different tubes by switching from one to the other in mono mode. The lower gain coupled with the narrow 3nm ha filter resulted in the photonis being obviously visibly less good, the nebulae fine detail was noticeably less clear and distinct compared to the Harder. However, the brain is a fantastic thing and in bino mode even with the drawbacks of the Photonis tube, the views were a big jump better than the Harder mono mode (again easy to see, just by switching the photonis tube off and on!). I mentioned in my previous thread a number of advantages of bino nv observing, but the key one apparent to me was just how clear fine detail was in the nebulae compared to the mono mode. The brain really does some awesome stuff. I've decided that the next time I visit a dark site, I will be taking my binoscope with me - I've only used it in LP London and am itching to see the results at a dark site.
 
The nebulae views I was getting were the best I've had from London (the 67mm televue eyepieces making a difference here also, working really well albeit with some vignetting due to the ~38mm image circle of the binoscope. The vignetting wasn't a particular issue for me as the vast majority of the fov wasn't impacted visually.
 
M42 was the obvious first port of call given Orion was blazing bright in the southern sky and the full extent of the extended nebulosity was clearly visible. Then onto the horsehead and flame which were bright and the horsehead had a nice shape even at this low magnification. But the first wow moment really was the Rosette in which lots of intricate detail was visible which isn't the case usually from London. The bino mode really "smoothed" out the nebulosity and the fainter bits became much clearer, but it was the sheer fine detail shown that blew me away given the observing conditions. The fox fur nebula and cone were easy to see, something that hasn't happened for me from London before. The wide band of Barnard's Loop was very contrasty.
 
Then I scanned around enjoying all the other nebulae highlights including seagull, monkeyhead, lowers (very nice when often it disappoints me at a LP site), monkeyhead (that's a bright one!), jellyfish, sharpless 254/255/257 (a bit small but all three clearly visible, first time I've observed these from home, I stumbled upon these by accident in Gran Canaria in a 16 inch dob in February), spider and fly nebula, and flaming star.
 
To finish off a very enjoyable session, I scanned over to the California which provided another "wow" moment, the top and bottom bands were very distinct but also the fine nebulae detail within was fantastic. I did a quick comparison with mono mode and this object unambiguously showed how much of a difference two eyes makes on nv nebulae observing. A similar thing happened on the final objects of the night, the heart and soul, looking much like the views and phone images I have taken from dark (21+ sqm) sites, wonderful.
 
Now I must getting planning that dark sky trip for the next new moon...

At the start of this year I purchased a Williams Optics Pegasus 103mm Binoscope as discussed here

I’ve been delighted by the views given by this Binoscope and in particular the ability to use 2 inch eyepieces. This enables wider fields of view but, importantly for me, enables me to use my 67mm Televue plossls (55mm plossl with Televue 67mm adapter attached) with my two night vision monoculars. Using two eyes is transformation for me for night vision observing in that the two separate images merged give significantly improved views of fine emission nebulae.

However, when using the 67mm (40 degree fov) eyepieces I noticed that the bottom left and right of the fov was clipped off. I contacted Tatsuro Matsumoto directly by email and he promptly replied that he could do a bespoke modification to replace the mirrors with a bigger set to remove this clipping.

I shipped the ems set to Japan and Tatsuro completed the modification this week. The ems mirrors are now on the way back to me and I’m looking forward to trying them out soon. Truly excellent service.

Tatsuro has documented the modification on his website and I’ve attached some translated screen shots below.

15 minutes ago, PeterW said:

I  do still wonder what level of tube coupled with a fast low power lens and a long pass filter could be used for outreach to show people the Milky Way… Wouldn’t need such high specs as we need for nebulae…. The public (even astro imagers) don’t get impressed by nebulae that much but get shocked by the abundance of stars that appear. Could be an Echo could work for this?? Of course if you want to dig up really diffuse nebulae you need all the gain and contrast you can get, which still costs more.

 

Peter

That’s a very good point - yes I think an echo would be very good for this task

37 minutes ago, David J H said:

Thanks very much for all the responses.

I'm really struck by Mike's comments that EEVA can exceed a 20" scope, and I think that is what I have been realising as I've been reading through the various EEVA reports. Nevertheless, I will probably stick with what I have, and see what how visual observing goes over the next few months - there is already a lot for me to discover, and I have already blown my budget. Hopefully we will have some dark, clear nights over the winter months. 

That said, is there an NV monocular at a reasonable price (say up to £1K?) that would enhance what I can already see with my 12" dobsonian? £5.5K is way beyond my price range!

 

 

Regarding nv monoculars, unfortunately not. Even second hand you would need to pay £2-3k to get one good enough for the strenuous demands of astronomy.

25 minutes ago, Deadlake said:

Any idea on weight? Thanks

Pvs-14 is 300 grams and Televue 55mm plossl is 500 grams so 800 grams in total, materially lighter than a 21mm Televue ethos (which is about 1kg)

4 hours ago, PeterW said:

With a fixed lens you can still use a 3x lens though no ultrawide or slightly higher power options that camera lenses would enable. It is easy to make or buy (depending on threads) a 2”filter to the 1x or 3x options. For maximal focal reduction afocal is probably the best option, though it does lead to rather a long unit in the focusser.

Many commercial tubes have occasional black spots, there are specs that limit the size, location and number. I have a little spot off to one side, doesn’t bother me. I agree that the photonis gen2 are behind the Gen3 even for the best specs.

 

Peter

 

Yes I’ve noticed a gradual switch in the USA, promoted by Televue introducing some innovative adapters for afocal night vision observing, from prime to afocal nv. Afocal enables extremely fast (ie bright) systems to be used (eg my preference for nebulae with ha filters is to get below f2 - not too many f2 reflectors or refractors!). For live visual observation with a telescope I think afocal beats prime. 
 

As you say there is a nice 3x afocal lens for the pvs-14 which can take filters (with some vignetting), so these systems are not limited to 1x or afocal telescope use.

I have a photonis 4g intens (which is still gen 2 tech but better quality than photonis echo) nv monocular and it at least equals my harder tube for standard (not too black) nighttime use - very smooth detailed views of terrestrial observation (great for nocturnal animal observing). The photonis also has a noticeably smaller halo on brighter stars so for scanning the Milky Way, looking at star clusters, it provides a more attractive view than the harder.

But where night vision really kicks is for ha nebulae observation which requires heavy ha filters and this really starves the photons getting to the nv tube. In this mode you need as much sensitivity and luminance gain as possible as that’s where gen 3 really trumps gen 2 tech. With heavy ha filtering my harder gen 3 comfortably beats my photonis.

Regarding dark spots, I completely agree. My harder tube is completely clean but my photonis tube has two small dark spots towards the edge of the field of view. However, in astro use you just can’t see these at all and they have absolutely no impact. 
 

See these threads where I’ve taken some phone shots through my photonis nv monocular, I don’t think the two little spots have any noticeable impact on the views

3 hours ago, Jonk said:

Well, a bit of good fortune and a large heavy box was delivered today!

I’m now a very pleased owner of a TEC140ed!

Congratulations. You will love it!! I love my TEC scope, amazing on planets and lunar

1 hour ago, Trentend said:

Some great responses here (but a lot to take in!). Looks like different scopes depending on viewing objectives.

a) Have big dob in back garden for DSO with/without NV goggles (and great with binoviewer for lunar and planets when in view) 

b) Have Mak127 for grab and go for lunar and planets (but not NV). Great views but small FOV so may have to add some fine tuning knobs or tracking (not fun nudging around).

c) Perhaps a lightweight refractor for grab and go NV. I’ve seen a lightweight apo (4kg) in the 102mm F7 range.  Is that the wrong speed for NV even if I’m using the 67mm Televue adapter? Guess this would be ok for lunar/planets but I’d need more magnification from the eyepiece (24mm in Binotron even at high power would be less than I’m used to in the dob and Mak).

Any thoughts on c?

 

 

I agree with Mark, c would work well with a 67mm eyepiece 

Here’s an old thread that gives some more detail on the various night vision tube specs 

Lots of good discussion here on what types of scope work well with night vision. But for astronomy you also need excellent quality night vision monoculars. Mark briefly touched on the various night vision tube specs earlier but to show a more specific example here’s the spec sheet for a gen 3 harder white phosphor monocular I’ve got arriving next week

37 minutes ago, Highburymark said:

 

Useful message that isn’t always communicated in night vision threads - it is not a panacea for all astronomy problems - particularly poor seeing. 

Mark, I think it’s poor transparency that nv struggles with rather than poor seeing?

2 minutes ago, Deadlake said:

Can you calculate the apparent F number or is it just fast enough. For instance the Sharpstar is F/5.7 and then adding the 67 mm adapter and it become an effective F/2.2 from comment above?

In my experience below f2.5 is really where I aim for nv emission nebulae observation. Once it gets to this point, I become more concerned with aesthetics of view such as edge stars etc

51 minutes ago, Deadlake said:

Reading CN threads I can see following scope being used with NV and a focal reducer

Tak 100FC
Celestron 11 Edge
TEC 140 APO 
APM 130 APO LZOS F/6.7 to F/4.4

So possible, but the lack of flat field is the issue.

 

I use a 0.7x reducer with my c11 edge very successfully and with flat field.

I also use a 0.75x revelation rc reducer with my Ap stowaway, and a 0.75x ap photo visual telecompressor with my AP130gtx and tec 160fl, all with nice results. However the introduction of the 67mm Televue has meant less need for me to use reducers with my refractors since the 67mm produces enough reduction for nv. In addition, as you say, I do like the flatter fields and faster speeds of my fsqs which do seem to work better with nv than my other refractors (although they do work well).

14 minutes ago, Deadlake said:

By the way the 121mm sharpstar you linked to is also at 365:

https://www.365astronomy.com/sharpstar-121sdq-121mm-f-5.6-quintuplet-apochromatic-refractor-telescope.html

A lot better price...

Great spot. Before I got the fsq130, I was very tempted by that 121sdq and with the 67mm plossl it would give a effective f2.2, very nice for afocal nv! With a 5 lens refractor there is a risk of miscollimation (fsqs have this issue sometimes as well) but it’s a lot lighter (and cheaper!!) than the fsq130 - I like it!

24 minutes ago, Deadlake said:

Are they on tools for calculating the modification of a focal point for a refractor when adding a reducer?

I'm presuming that the FSQ-130 is your most used, however they are now out of production and cost as much as a small car fro some people 😀.

I did see this as well,

https://www.365astronomy.com/ts-apo130q-imaging-star-130mm-f-5.0-sextuplet-6-element-flatfield-imaging-apo-refractor-telescope-42mm-field-diameter-for-full-frame-camera-sensors.html

As far as a 10" scope what about these:

https://www.firstlightoptics.com/stellalyra-telescopes/stellalyra-10-f8-m-lrc-ritchey-chrtien-carbon-truss-telescope-ota.html

in fact for the price of the FSQ-130 I could get the above two scopes and  a TOA-130 for the same price 😀
 

On your first question, sorry I’m not sure, it seems to vary from reducer to reducer.

Actually my most used scope for NV is currently my 103mm William optics Pegasus Binoscope with two nv monoculars but that’s another story 😉

In respect of the two scopes you link to, the first one won’t work work for visual nv use I think - it states in the link that it won’t work with 2 inch diagonals for visual use. 
 

Re the second one it may work but again I think you need to do some investigation regarding distances from focal plane etc to see if a 2 inch diagonal would work for visual (looks like you need a diagonal for comfortable observing)

1 hour ago, Deadlake said:

F 5.6 with a flat field corrector? I was thinking of a TOA-130 with a reducer+flatterner for NV work and then I could attach an extender-Q for visual/planetary. Or is this trying to get too much utility out of one scope and best to go with separate telescopes. Also how much does the imaging circle play in scope selection, both he above have large imaging circles.

I observer under a Bortel 4 sky, how much more will get out of say a 100 mm over a 130 mm? The other option I was considering was get a 130 mm APM f 9.2 for visual and then getting a 100 mm quad APO I could use for NV and as a grab and go.

 

I’m not completely certain since I don’t image, but reducers/flatterners generally have a very short (55mm?) distance from the reducer to the focal plane which means that 2inch diagonals and eyepieces have much too long light paths for these to work, hence I’ve gone for petzval refractors where this isn’t an issue as I’m guaranteed to be at the right distance as long as it’s in focus. 
The key eyepiece to use with nv is the 67mm Televue to keep the effective speed as fast as possible and therefore for wide 4 degree fov for California, Rosette, North America, heart and soul etc a 650mm focal length fast scope like the 130fsq works really work. I enjoy the 85mm as it’s so much more portable but then I’m getting to nearly 6 degrees fov which is maybe a little large for this big nebulae objects. For the smaller objects like the horsehead, flame, monkey head, Pac-Man, and also galaxies and globulars I think you really need an 10 inch plus scope (I use a c11 edge (flatfield again!) and 16 inch dob) to be able to use high eg 67mm eyepieces to get the bright views but also get higher mag with smaller fov for these smaller objects. So for one scope maybe 130mm only but for two a c11/dob and a 100mm or less portable easy to mount refractor would be my preference with nv.

re imaging circle, yes it’s nice to have a big one otherwise eyepieces like the 67mm May start to showing vignetting but it’s less obvious for visual only, more for imaging.

Happy to answer any specific nv questions you have by pm?

2 hours ago, Deadlake said:

You mention petzval flat field refractor. Is it the flat field part that is important, so would adding a flat field adapter and reducer work just as well? When you mention petzval I think Tak FSQ or Televue --> Ouch in the wallet. What about a Takahashi Epsilon?

Two reasons, Petzvals are typically faster than other refractors which is important for nv and also I find when using the 67mm afocally having a flatfield gives better stars at the edge (you are often really pushing these long focal length eyepieces at these speeds).

Yes I have a Takahashi fsq85 and fsq130 and they are both brilliant with nv but pricey as you say. There are other petzals eg by Sharpstar or askar that are significantly cheaper and would work well I think.
https://www.365astronomy.com/askar-fra400-f-5.6-quintuplet-astrograph-apo-apochromatic-refractor-telescope.html

https://www.teleskop-express.de/shop/product_info.php/info/p11518_TS-Optics-121SDQ-Apo-121-mm-f-5-6-Quintuplet-Flatfield-Apo.html

I did have a Takahashi Epsilon 130d and it’s a nice scope for visual nv work but didn’t give the crispness of the fsqs. Once I got the fsq85, the epsilon’s days were numbered.

For Grab and go night vision use my preference is a fast petzval flatfield refractor. What sort of budget were you thinking of?

After all the cloud and rain recently, I managed to get another opportunity with this new Lunt setup. This time I stayed in double stack mode using the two front 60mm etalons and removed the pressure tuned etalon. I also used my baader mark v binoviewers instead of mono mode (which I didn't use in my previous outing). As noted in another thread today, there is plenty to see at the moment including a massive multi stranded prom to one side, another nice prom on the top, a nice dark sun spot and several other areas of good surface activity. With my 24mm panoptics and 1.7x gpc (nice thing about the Lunt diagonal is that I can attach the binoviewer direct to it and so can use the 1.7x gpc rather than the 2.6x gpc, giving a greater range of magnifications with my eyepieces) I was at about 30x mag, but could easily go higher.

The live visual views fantastic, the best solar views I've ever had and nice and bright despite the double stack and binoviewers. The large prom is amazing with great detail shown by the lunt, I wonder if the ed doublet glass is helping here? The whole disk was in band as well due to the use of two external front etalons so I could relax and let my eyes drift around all the surface soaking in the views until unfortunately I had to pack up to do some work.