jetstream

I absolutely believe that an OIII will prevent the Horse Head from being seen, unless its so wide that it is not really an OIII.

Thats where I had the issues, the hook overs

Magnus, years ago I purchased an 8" f3.8 OOUK and it arrived in the same way with respect to the mirror cell and had massive astigmatism. It gets better- after removing the silicone the mirror was too thick to be properly supported with the nylon tips... if supported properly the mirror was pushed up into the "L" clips that retain the mirror. This also added big restraint on the glass. Make sure you have enough room to support the mirror properly while maintaining a bit of room to the clips. I posted this years ago with pictures.

Me too.

Perfect, thank you.

@vlaiv What would be the meaning of entanglement in this context? I presume that when more "room" is created between galaxies that the galaxies themselves remain as is? ie no more space in them or "stretching"

Thanks Mark.

Yeah, I'm looking at the cheaper ones mentioned in the thread- be good enough for the H130 and the 90mm Raptor. Its the length of the scope, more than the weight that causes issues IMHO. I cannot justify a new Gitzo. With a bit of playing around I'm sure these ones will be ok with the 120mm fracs.

These are so expensive...

Me too lol! Early on I went on a mission to see as many DSO as I could, but now I visit favorite objects, including the strange Arp's and Hicksons- HCG 55 is an absolute favourite of mine.

Thank you Mark.

The thing is objects that would be poor under lighter skies become showcase under excellent skies, the Flame neb is one of them. M101 will show spirals in an 8"+ scope, M33 same thing and so many nebula open right up with a proper filter. M42 takes on a whole new, stunning look with its lower loop showing and M43 will show its lane cutting it. The Running Man will show its shape easily etc. What I do is a nice sky cruise on bright objects and then have a few DSO goals for the evening. I rarely only chase very faint objects.

So most any mount with a 3/8" bolt and flat will attach?

This one ^^, and with decent aperture, 8" and up. The showcase objects take on a whole new level of greatness under truly dark skies. After all, DSO smudges will always be DSO smudges with differences in most of them only showing up with big aperture increases.

Looks excellent Mark, how does the mount attach to the Gitzo? Is there an adapter we can buy? Thanks

Another thing- in my large scopes, very minimal to no dark adaptation is needed to see the Veil but it obviously gets much better as I adapt.

I'm like a bat when I'm dark adapted, the sky, through the eyepiece is not black, its grey and I see mottled structure in places that I believe could be galactic dust, very faint nebs etc. For reference we'll say my sky is 21.6 mag or darker- which it is most of the time. This depends on the object but my eyes "see the background" as a constant once adapted and under stable conditions. So for the objects- we'll use the Veil to start. A bunch of things happen here with large aperture, one of them is pulling out features because the mag at the exit pupil pulls them out, invisible in smaller scopes. And then existing features are seen as "brighter", not just bigger. All this is in reference to viewing the object itself and not looking at the edges (sky). However to pull out very faint nebula I do use the sky edge to notice a different shade or shape. The sky looks the same to me, once adapted using any telescope.

Ive never seen an object drift into view getting larger as it goes and then get brighter. If this worked a threshold object should "just appear" as it gets larger. I have no idea about how this all works but I firmly think that the eye and brain play a role. I also dont understand how an ortho will best a more complex eyepiece when transmissions are very close- we are told that even 5% difference in transmission should not be noticeable and the differences between orthos and most widefields are smaller than this.

@vlaiv any more thoughts, conclusions or questions on this subject? I just love the fact that letting an object drift out of the FOV doesnt make it dimmer then disappear.

I like this one Also it is a complete myth that some objects will not show brighter in large aperture, espc fast telescopes, IMHO. I think the effects are multifaceted, some of which might not be understood and I do believe that the eye/brain plays a role in this. M42 is much brighter in the 15" than the TSA120 at the same exit pupil and the 24" is much brighter than them both on it.Oddly enough it is the already "bright" objects that appear to be greatly enhanced by aperture eventhough there are more threshold objects to be seen in the larger apertures.

@Nyctimene Excellent Stephan and I cant wait to observe again- piles of snow the other day and now again today so I eagerly wait for a chance to try the mentioned objects!

Great choices. I do the same with the 17.3mm Delos and 10mm Delos. The Delos line offers a near unbeatable combination of "DSO deepness", contrast and planetary/lunar sharpness.

Delos.

The Mewlon 180 is strutting its stuff! Excellent Fedele.

What a fine, versatile set up Fedele, it doesnt get better than this.