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Are binoviewers just as great on DSO's?

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#151 bgi

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Posted 14 October 2014 - 11:27 AM

 

 

A 6" does not really show much.

Hmmm. Don't tell that to my 6" refractor... One of the finest views I've seen of M13 was with a 6" f/8 achromat and binoviewer with 20mm widefield eyepieces, working at 60x. It was not the view with the most stars resolved, but it was of an exquisite beauty I've not seen in any other scope since. 

 

 

Clear skies!
Thomas, Denmark

 

 

Not doubting that it was beautiful, but IME, globs look MUCH better with large aperture and high power.



#152 REC

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Posted 17 October 2014 - 08:08 AM

I finally got a clear night with great transparency and had my 8" SCT out.  Checked out M92 and M13 with the BV in place.  The best view I had with the BV was the butterfly cluster, almost 3D look.


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#153 Eddgie

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Posted 17 October 2014 - 10:22 AM

oou

 

 

 

A 6" does not really show much.

Hmmm. Don't tell that to my 6" refractor... One of the finest views I've seen of M13 was with a 6" f/8 achromat and binoviewer with 20mm widefield eyepieces, working at 60x. It was not the view with the most stars resolved, but it was of an exquisite beauty I've not seen in any other scope since. 

 

 

Clear skies!
Thomas, Denmark

 

 

Not doubting that it was beautiful, but IME, globs look MUCH better with large aperture and high power.

 

 

I share this sentiment.  M13 is lovely in my 6" APO, but far better in my 12" dob.      Just as in everything else, it is hard to dismiss the advantage that aperture offers and for binoviewing, I think that the Newt/Dob is the best possible platform, especially when coupled with a powerswitch type system.


Edited by Eddgie, 17 October 2014 - 12:49 PM.

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#154 Vondragonnoggin

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Posted 12 November 2014 - 08:53 AM

Kind of sad to see jdbastro's suggestion mocked here. Binoviewing with intensifiers is pretty amazing. One can equate a properly filtered night vision device with c-mount adapter and 1.25" or 2" nosepiece to using a short focus achro on bright objects.

 

they are very similar in this respect. In a short focus achro, the color fringing from CA is seen in only the brightest objects and is not detected on most DSO's. In regards to star brightness, this is the same kind of dynamics with the green hue. It appears white mostly and on very bright objects, the green will become more apparent as a fringing effect. Brightest nebula will exhibit green cast as well, but it is definitely not sickly looking and definitely not a "fail". The improved gain, and detail seen by that gain is, to me, well worth the hue on brightest objects. Proper filtering really is key to making things look more normal in the intensifier. 

 

Incidentally - they make white phosphor tubes if you absolutely hate green. PVS-7 WPT. There are several options in resolution depending on price. They can be as low as 45 lp/mm all the way up to 72 lp/mm (lp/mm = line pairs per mm on the Air Force resolution chart) the best commercially sold ones will have a range like 60-72 lp/mm but you can get a custom ordered tube that tests high if you're willing to pay enough.

 

the green phosphor tubes that are gen 3 thin film autogated are 64-72 lp/mm.

 

you would not use any narrowband filtering when looking for globs, but a 640nm Longpass filter is great for globs.

 

I use one with my PVS-7 when looking at GC's and OC's or dense Milky Way regions. That particular filter will also bring out HII regions very well in white zone LP.

 

for nebulae, I like a 3nm Ha filter. Most stars and nebula appear grey/whitish with a 3nm Ha in place, but the brightest like M42, M8, M20 still have greenish hue on brightest regions.

 

No OCS required for PVS-7 and in fact, I frequently use a .5x reducer on my ST120 and AT72ED when the PVS-7 is in. It's native eyepiece is equivalent to a 26mm but the PVS-7 has an AFOV of around 40 degrees that actually takes on an appearance like it was wider. Similar to using Plossl's in a BV. So you still can get very large TFOV's particularly using a reducer with it. Of course for globs, you would not use a reducer.



#155 Eddgie

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Posted 12 November 2014 - 09:28 AM

While I agree that the mocking (which i personally did not feel was intended in a mean way at all) may have distracted people from the recommendation, the big thing that probably keeps most people from adopting this kind of technology is the cost.

 

Most people would not consider spending $3500 or more on this kind of solution.

 

I have the $3500 to spend I guess, but I have gone back and forth on this before.   I am a visual observer.  I like sitting at the eyepiece because I feel like I am experienceing the sky "in person".

 

If I were to put a peice of technology between myself and the sky that processes the view and presents it to me in an altered fashion, then why not just put an image intensifier camera in the eyepeice holder and stay inside and view it on my computer monitor.

And if I am going to do that, why not simply just view the thousands upon thousands of images available on the web and dispense with my telescope viewing entirely?

 

I am not at all saying it is in any way wrong for anyone else to choose to enjoy an electronically augmented reality.  That is not at all my intention with this response.

 

Rather, my intention is to say that while using electronic augmentation may be a great way to see the sky in a different way, it is a different way, and for me personally, much of the enjoyment is the challange of seeing targets and resolving them with my own two eyes.  

 

is not "Cheating" to use an image intensifierIt is though to me, a completly different kind of activity. 

 

If I were going to do it though, I could see myself doing it with a small refractor. In fact, I think I would rather do this than use my 6" APO with binoviewers.   Why bother with a big honking telescope on a heavy mount if you can see more in a small, inexpensive telecope on a simple alt-az mount?

 

I get that.  I really really do.   For $4000, you could see more than with the best 6" APO ever made.  How could that be bad?  Not for everyone, but I absolutly totally get the appeal.  Heck, just talking about it makes me wonder sometimes if I should one day take that step...


Edited by Eddgie, 12 November 2014 - 09:37 AM.


#156 Vondragonnoggin

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Posted 12 November 2014 - 09:41 AM

You are definitely entitled to your opinion. I've seen the contempt about it though in plenty of other threads. Just as using a binocular telescope is binoviewing, so is using a PVS-7. It is a visual only experience for me. Uses the same concepts as traditional binoviewer with the added electronics part stuck in the middle. Equating it to sitting inside and looking at pictures on the Internet is quite a stretch in your condemnation of the technology.

It is the norm here on Cloudy Nights unfortunately.

#157 Vondragonnoggin

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Posted 12 November 2014 - 09:43 AM

Oops. I replied to your post before you edited. Has a different tone now.

 

I also bought used and ended up spending about $2500 including the filters needed.

 

Compared to Binotron and accompanying gear, not a whole lot of difference.

 

Make no mistake though - not to be used on the moon or planets or tube damage may occur.

Too bright.

 

So, that, besides cost, is a big detractor. The thread was about DSO's though, which these excel at. The other major detractor is export laws. These cannot be exported overseas although if looking carefully, can find variants in other countries besides the USA. 

 

Suitable variations to PVS-7:

NVG-7

NYX-7

 

PVS-7 comes in two types - older is PVS-7 A/C which has 25mm ER and newer is PVS-7 B/D which has 15mm ER. Actually 4 different models, but still only two types.

 

PVS-7 uses MX10130 tube and it's variations (MX10130C/UV, MX10130D/UV, MX10130A/UV, probably a few more depending on defense contracts at the time)

 

Other biocular variations:

 

PVS-4 with Wide Angle Eyepiece - a single eyepiece so wide you can use two eyes to view through single ocular. ER is very very long and allows you to comfortably view with both eyes. Nearly 4" of lens. Very rare to find now. I have one of these as well.

 

Russian Panoramic viewer - this is what was being sold with the Astronomy oriented BIPH and was coupled to a PVS-7 body. I think I would prefer to use the larger 25mm intensifier tubes as what is in the PVS-4. PVS-7 uses the 18mm tube and that is the reason for the approx 40° AFOV. The 25mm tubes appear more like a 60° AFOV and even more with wide angle EP on them.

 

This is all two eyed views through a single scope, although the PVS-7 type is really the closest to traditional binoviewer with beam splitter and all.


Edited by Vondragonnoggin, 12 November 2014 - 10:21 AM.







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