13 replies to this topic

[Aerions]

Hey everyone, so I've had an autogated milspec pvs 7 for a few months now and I currently own the prime focus c mount adapter for telescope adaption. I've used it with a 9.25" sct reduced and a friends 8" F/6 dob. Views with Ha filter were cool on bright targets, but I wasn't fully making out the pillars in M16 etc.. even hooked up to a friends 12" F/5 at a star party was needing long exp with my phone to reveal the bubble nebula. I barely made out the spire within the bubble using prime focus f/5 with my eye , but a 29" F/4 with a 55 to 67mm plossl with a pvs 14 showed everything bright and clear as **** day. 

 

After that, I did some research and found the advantages of an eyepiece effectively acting as a reducer for NV.  my Pvs 7 with fuji lens has the same threads as a pvs 14 so I can buy the TNVC eyepiece adapter. I had to sell off the 9.25" for a couple reasons so I'm just left with a 120mm F/7 triplet refractor at the moment. I see that 55mm and 67mm EP's in an afocal train would take me down to F/3.3 and F/2.7 respectively with my F/7 scope. I asked the owners of the 29" what the effective f/ was with their 67mm plossl + pvs 14, and they said around f/1.5. There's quite a big difference between f/2.7 and f/1.5 so is it even worth it to pursue stuff with my F/7 refractor? Or should I just go buy a generic 8" F/4 imaging newtonian for nv astronomy. 

 

Thanks 

Edited by Aerions, 02 December 2024 - 05:12 PM.

[Jethro7]

Hello Arions,

 An NVD will enhance any scope. Some better than others. Give it a try and see how you feel about it. I use my Tak TSA 120 F/7.5 with and without a focal reducer with my  PVS14 afocally with the TV 55/67 Plossl also my 26 Nagler for probably 90% of my NVA endeavors and this arrangement works wonderfully. However, the old rules still prevail even for night vision astronomy. You know the ones. Aperture wins and viewing under dark skies will always be better. Even though I am using My TSA 120, I never feel like I've somehow cheated my self by not using a large Dob, fast Newt or packing everything up and traveling to dark skies.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Edited by Jethro7, 02 December 2024 - 06:07 PM.

[Aerions]

Hello Arions,

 An NVD will enhance any scope. Some better than others. Give it a try and see how you feel about it. I use my Tak TSA 120 F/7.5 with and without a focal reducer with my  PVS14 afocally with the TV 55/67 Plossl also my 26 Nagler for probably 90% of my NVA endeavors and this arrangement works wonderfully. However, the old rules still prevail even for night vision astronomy. You know the ones. Aperture wins and viewing under dark skies will always be better. Even though I am using My TSA 120, I never feel like I've somehow cheated my self by not using a large Dob, fast Newt or packing everything up and traveling to dark skies.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Absolutely, even in prime focus the longtime visual guy that owned the 12" F/5 was saying he was seeing noticeably fainter stars around familiar objects. The first run with my SCT had me stunned, lagoon was just so cool... I'll definitely give it a go and see what happens, I currently have my scope fully  configured for imaging with a matched .8 reducer that ends in m48 threads. Im curious on what you needed to get in order for a diagonal and eyepiece to be connected to the reducer and getting proper spacing. Glad to hear a similar sized scope is doing just fine for NV, thanks for your input and clear skies. 

Nick 

Edited by Aerions, 02 December 2024 - 06:28 PM.

[Jethro7]

Absolutely, even in prime focus the longtime visual guy that owned the 12" F/5 was saying he was seeing noticeably fainter stars around familiar objects. The first run with my SCT had me stunned, lagoon was just so cool... I'll definitely give it a go and see what happens, I currently have my scope fully  configured for imaging with a matched .8 reducer that ends in m48 threads. Im curious on what you needed to get in order for a diagonal and eyepiece to be connected to the reducer and getting proper spacing. Glad to hear a similar sized scope is doing just fine for NV, thanks for your input and clear skies. 

Nick 

Hello Nick,

I have a C8EHD but not a big fan of SCT's in general however these scopes work very well for NVA and is probably the only reason I have not sold it. I use it for small Globulars and Planetary Nebulae where narrow FOV don't matter and the 2032mm focal length comes in handy. The focal reducer will need to be placed 55mm from the end of the 55/67 plossl. I use a series of spacers left over from the Imaging days, the ones you use to achieve back focus with the camera screwed into the eyepiece barrel. but a simple eyepiece or focuser tube extention will also work. 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

[Aerions]

Ahh okay, by the way I shoulda specified refractor reducer. I’d need an m48 to 2” barrel but haven’t ever heard of that… ty for specifying how the spacing would be though. Can’t wait to really take my observing to the next level and not be as frustrated as I can get with astrophotography 😂

[sixela]

A 2" extension tube has M48x0.75 '2 inch filter' threads (obviously you can't have threads of 50.8 mm on something with an external diameter of 50.8 mm).

Edited by sixela, 04 December 2024 - 06:31 AM.

[bobhen]

I use a Takahashi TSA 120 in prime mode reduced to around F5.2 and it's a wonderful NV telescope. For small objects (globulars or galaxies) that need image scale, you can use a Barlow, if you feel the need. My TSA 120 is a great general NV telescope.  

 

Of course, you can go bigger and you can go faster. I use the below for NV observing as well... 

 

For small objects I also use a C8 and it works extremely well.

 

I also use use an inexpensive, 102mm F5 achromatic refractor, like the Sky Watcher Startravel. I can get this refractor down to F3.5 in prime mode and it really delivers excellent, wide, rich-field views. 

 

Bob

[Aerions]

I use a Takahashi TSA 120 in prime mode reduced to around F5.2 and it's a wonderful NV telescope. For small objects (globulars or galaxies) that need image scale, you can use a Barlow, if you feel the need. My TSA 120 is a great general NV telescope.  

 

Of course, you can go bigger and you can go faster. I use the below for NV observing as well... 

 

For small objects I also use a C8 and it works extremely well.

 

I also use use an inexpensive, 102mm F5 achromatic refractor, like the Sky Watcher Startravel. I can get this refractor down to F3.5 in prime mode and it really delivers excellent, wide, rich-field views. 

 

Bob

neat neat glad to hear people have fun with smaller apertures too 

[Jethro7]

neat neat glad to hear people have fun with smaller apertures too 

Hello Aerions,

With a light intensifier, you can see more with a small 60mm refractor than you can with a large Dob. 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

This baby AT60 ED F/6 refractor is really amazing for large targets. like the Cygnus Nebulae Complex. 

Edited by Jethro7, 07 December 2024 - 10:35 PM.

[Aerions]

Hello Aerions,

With a light intensifier, you can see more with a small 60mm refractor than you can with a large Dob. 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

This baby AT60 ED F/6 refractor is really amazing for large targets. like the Cygnus Nebulae Complex. 

So i got a 55mm plossl from here and my .8x reducer doesn't work but it focuses at f/7 with a 50mm extension, had a first light last night and orion was incredible. wish I actually got a 40mm or something to start but orion is def brighter than when I tried in prime. used a 5nm Ha filter from svbony too . can't wait to do this more! 

[ButterFly]

I have had my SW 120ED at f/7.5 for quite a while before getting NV.  I still have it and I'm definitely keeping it.  I did also get an 8" f/4 (SW Quattro 200p), with about the same focal length, about two years ago.  I rarely use the 120 for NV anymore.  It's faster for better nebulae, and bigger for brighter stars.

 

Both mirrors are aluminized, so in a patch around 850nm, it's only getting about 72% of its aperture's area's worth of light in that band (85% ^ 2), but it's not a huge band taking that hit.  The refractor's loss in that band is completely unknown because I have no idea what the anti-reflective coatings are doing in that band.  Despite all that, the improvement is clear cut for non-h-alpha viewing of fasteroids and what not.  In h-alpha, the reflectivity is close to 95%, as is the transmissivity of the refractor.  For h-alpha, the winner is clear cut, no questions asked, the 8" f/4.

 

That's a nice focal length for fitting things in the view.  The 8" f/4 also does very well visually, so it lives on my mount at most times.  The mirror quality is nowhere near the optical quality of the 120, so its view on the planets isn't much better, despite the 8" (7.4" effective with secondary included) vs. 4.7" boost.  Lower power views of clusters and nebulae, especially with NV, are far, far better than with the 120mm.

 

Your EQ6 will handle the added weight just fine, but EQ viewing with a newt is horrendous.  You can get rings to rotate the scope on the dovetail, but the giant torque arm will throw off the balance.  The mount won't complain too much, but it is a serious comfort issue.  I went with the AZEQ6, just so I can keep the giant stack pointing inward in altaz mode.  There are no balance issues, and even at zenith, I can comfortably look into the device over the mount.  An XBox controller moving that thing around is just a joy to use in nebula alley between Cep and Cas.  No way would I tolerate rings on an EQ mount for that.

[Jethro7]

So i got a 55mm plossl from here and my .8x reducer doesn't work but it focuses at f/7 with a 50mm extension, had a first light last night and orion was incredible. wish I actually got a 40mm or something to start but orion is def brighter than when I tried in prime. used a 5nm Ha filter from svbony too . can't wait to do this more! 

Hello Aerions,

To get the most of a reducer for full reduction,it needs to be placed 55mm in front of the eyepiece. 50mm will do. Eyepiece choice are a personal one. I mainly use the TV 55 plossl with the 67mm converter and my 26 Nagler. I agree it is hard to beat M42. Next time you are out, spend more time with Orion. This constellation has alot more points of interest besides M42. Such as the Horse head and Running man Nebulae that are located at the star to the far left on Orions belt called Alnitak. You can also see the brightest parts of Bernard's Loop. Really cool. Not too far to the left of Orion, you have the Monoceros, constellation and there you will find one of my favorites, the Rosette Nebula as well as several other Nebulae. The Rosette Nebula is located not too far to the left of Betelgues. You will need the 55 plossl to fully frame this huge Nebula in the eyepiece. I think on first light with a night vision device, the first thing that I became very aware of was, just how unbelievably big many Nebulae are. One book that I have found that is very useful for finding Nebulae and Galaxies is Charles Brackens book " The Astrophotography Sky Atlas" This night vision Astronomy thing is addicting, being able to actually see so many celestial artifacts that are other wise invisible. This is just the beginning my friend. There is so many wonderful celestial objects and Nebulae to view. One fitting cliche comes to mind here. "You ain't seen nothing yet" 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

https://www.amazon.c...927235844&psc=1

 

The Rosette Nebulae. Image captured with my phone, using TV 55/67 plossl, 6nm Ha filter and Tak TSA 120 F/7.5

 

 

 

Edited by Jethro7, 11 December 2024 - 10:44 PM.

[ButterFly]

Pictures don't really help with the difference in the live views one gets.  Here's a Rosette picture from my 120 f/7.5:

 

 

The live view through the 8" f/4 looks better than that, and it's at about the same image scale.

[ButterFly]

Here's the same settings on the camera and the device, but at 6nm rather than 3nm.  Added: on the same 120 f/7.5.

 

 

What either of these pictures fails to show is the scintillation.  That's where the f/ratio will have the biggest impact on the view.  Even with these single 7sec exposures, rather than a stack, the image is glossing the scintillation one gets with a live view.

 

These were both parts of a test series on an oddity of one of my filters: Antlia 3nm Pro Edge Performance, so the only thing that changed between the shots is the filter wheel position.  Very different looking, and not representative of what the 3 can do over the 6, but it was good enough to show the oddity of the 3nm.

Edited by ButterFly, 11 December 2024 - 11:12 PM.