jetstream

I'll mention something- I use my 90mm frac over a 120mm because for terrestrial viewing the smaller scope is less sensitive to local seeing, I couldn't believe it actually. I do view over water though which is nasty. But, the 90mm, straight through will show insects flying over the water 800 meters away (as measured on a Zeiss rangefinder, near island). Not sure how an aperture mask will perform, in theory it should work but Id want to try it before giving an answer on this one. @vlaiv is helping me with lunar imaging, once I'm ready, and preliminary views through the camera suggest that 120mm scope is sensitive to that local seeing, big time- for various reasons.

Yeah, fires are all over the place. Got 9 within 40 miles of me, in Quetico. https://www.lioapplications.lrc.gov.on.ca/ForestFireInformationMap/index.html?viewer=FFIM.FFIM

Thats what the fertile soil of the Brazilian rainforest is built on ...IMHO It can definitely hit the USA.

I can tell you for a certainty that the scope youre bringing will give mind blowing views, if the conditions co operate. You will see Barnards Loop easily, with and without an Hb, go for the shade edge next to M78. Keeping in mind that dark adaptation is a must as is zero alcohol

All these eyepieces are vg, but sometimes, to some individuals certain ones stand out. For me the 17/14 mm Nikon HW is one of them. The view of the Swan neb with this eyepiece in the 24" f4.1 is burned in to my brain forever. The 17 Ethos is an extremely good eyepiece and another top tier hyperwide choice. For ease of use the 17 Ethos gets the nod. The Nikon has some "niggles"- eyecup design, collar for focus and not being able to be used with the PCII. However, the views... ps conditions must allow the possibility to maximize what all these eyepieces have to offer, or theres not much difference.IMHO

The 17.3mm Delos is another favourite of mine, deeper than the Nikon, extremely tight stars and used for different things than the 17mm/14mm HW Nikon. The 17.3mm,10mm Delos are super eyepieces. Put the 17.3mm on the core of M42 under dark skies and be prepared to look for your jaw on the ground....IMHO.

You guys take old crippled up Canucks?

My SW120ED has excellent transmission and contrast on DSO. The list is long for targets in truly dark skies. The H130 is my perfect companion for ultra quick views and holds mag really well, up to 270x on the moon. SW ED scopes really perform on DSO IMHO. Under truly dark transparent skies its shocking what most any scope can do. I wish I had the Tasco refractor I had as a kid to try now with more knowledge. I'm excited to hear your reports!

The new Televue is made by Astronomik and is my favourite OIII filter, out doing an older, excellent Lumicon. Either one will be top notch but I'm partial to the TV. You will see the veil no filter as well, you taking the 80ED?

I would only buy a new Astronomik or the new Televue. Check out the North American neb... with and without the filter.

I'd be taking as much aperture as you can and a top quality OIII filter.

Your welcome, I'm north of you up in north west Ontario where we have over 100 forest fires burning, not including the ones in eastern Manitoba. Right now as I look across the lake a thick haze is present and there is an air quality warning. T storms tomorrow and I hope no more are started from the lightning.

Right now forest fire have the sky here filled with haze, really bad viewing conditions, including scatter. I use really low scatter equipment, but it doesn't matter at the moment. Particles in the air scatter light, made worse by planets low elevation. The 82ES ep's have more scatter than your (vg) orthos. A 12.5mm Circle T is a mainstay in my TSA120, for some reason I really like this eyepiece. To minimize effects use your great 100mm f9 with orthos- one thing what diagonal do you use? I had an expensive poor one that cause massive scatter in a 90mm APO years ago. The SW mirror diag I have is vg- but maybe check "straight" through?

30% obstruction is getting up there IMHO.My truss dobs are 21% or less.

Did you split up HCG 55 yet Mark? getting kind of low now though

Thing is Heather, the 10mm BCO is a top tier eyepiece... it goes deeper than my 10mm Delos, 12.5mm Docter UWA and provides sharpness on par (at least) with those 2, and others. The 18mm is a fine EP but my 6mm bloats stars and is not used. When I'm using the 24"f4.1 the 10BCO is used to confirm sightings in other eyepieces and used with/ without the VIP. I'll not be without one. Ive heard the Baader Q barlow is vg as well.

The Baader Classic 10mm ortho is a vg eyepiece, with a plossl like AFOV.

Yes exactly. Also, from experience with filters it seems that smallish transmission differences can make big differences visually- such as a 5% difference. Many will say that the eye wont detect this...my eyes do. I have the old, wide Astronomik OIII, an excellent tight older Lumicon OIII and my best, the new TV OIII, made by Astronomik. In addition I have an excellent Lumicon UHC and the TV equivalent (by Astronomik). The new TV's transmission is higher than the Lumicons- and it shows. IMHO a 10% difference is massive with these filters. BTW, an astro colleague/vendor measured the bandwith and transmission of my new TV's and they were bang on.

Its best to get both OIII lines and imaging filters are typically (not always) lower in transmission. Do you have the graph that came with it?

You have an extremely well thought out scope/eyepiece/filter selection John and the views through this scope will not be lacking compared to any. The f 5ish 12" dob is perhaps the best all round scope going. Low central obstruction, great lunar/planetary resolution and very effective on nebula and galaxies.

Yes I find 5mm exit pupil very good for dark skies and 4mm the best all round exit pupil for filters use. Less than 4mm impacts the filtered views "brightness" to my eyes.One thing that can severely affect nebula views is a poor transmission OIII/UHC and or one thats bandpass is too large or in the wrong spot. IMHO.

Excellent, this is the eyepiece I should have instead of the 30 ES 82.

APM 30mm UFF?