John

It was the Baader UHC-S filter that 1st showed me the Veil Nebula with my 100mm refractor. Since then I've realised that the UHC-S has it's limitations but it still made the difference between seeing something and not seeing anything. I find that it's worth observing nebulae with the UHC, the O-III and without a filter. Each option gives different results and, in the case of targets such as Messier 42, each option seems to enhance different parts of the nebula. I even try a H-Beta filter on M42 occasionally ! (that is usually a more specialised filter for observing targets such as the Horsehead Nebula). It's good to experiment and explore what these tools can do. Quite often I prefer no filter but in some cases the differences are really worth seeing.

That's a great result Mark This is one of my targets when I next have my 12 inch dobsonian out. I managed to see the huge nebula NGC 604 in Messier 33 a couple of nights back which re-ignited my interest in these extra-galactic DSO's

I have not used an Explore Scientific O-III so I can't comment on that one. I did have the ES UHC for a while and found it OK but not as effective as the Astronomik UHC that I now have.

A good quality O-III filter delivers quite a bit more enhancement than a UHC on some notable nebulae including the Veil Nebula and the Owl Nebula.

One thing I've sometimes wondered about refractors with thinnish diameter long drawtubes is, with a diagonal in use and the drawtube therefore racked inwards to take account of the diagonals light path length, is there any possibility that either the inner end of the drawtube or the baffles within it could clip the light cone from the objective ?

The scope actually weighs in at 9.5kg so it was well within the capacity of the mount from that point of view. The length of the tube put the mount under more strain than it's weight. After trying a Celestron AVX, the HEQ5 and a Vixen GP-DX, none of which were really totally satisfactory with the scope (the AVX was actually the best of those 3) I decided to go for a heavy duty alt-azimuth mount and was very lucky that a T-Rex mount came on the market around that time. That does the job beautifully well

M 42 is spectacular for us but it looks rather puny compared with NGC 604 in the Triangulum Galaxy M 33. If that nebula was within our galaxy just think what that might look like !

NASA put this movie together from Hubble and Spitzer imaging:

My dream scope for years was something like Sir Patrick Moore's 5 inch F/12 Cooke refractor: And a few years ago I was lucky enough to be able to buy something similar Except that mine is .1 of an inch larger in aperture than Sir Patrick's

I've just come back from a great evening observing with Bristol AS buddies at the society observatory south of Bristol. 4 of us took scopes along ranging from a 102mm Maksutov-Cassegrain to an 11 inch SCT. We just toured some well known late Summer / early Autumn sights. Nice to see all 4 gas giant planets through a variety of scopes. What was really nice though was to be out under a dark sky again with others who share the interest and enthusiasm. I now realise just how much I've missed that over the past 18 months.

What an interesting discussion I've no idea what the answer to the original question is I'm sure glad that I have my 12 inch dob as well as my refractors though

I use the excellent Baader T2 Zeiss prism with my Tak 100 but that is F/9. Not sure that prisms are quite such a good option for faster refractors Personally I stick to mirror diagonals for my faster refractors. The Stellamira 1.25" looks the same as the diagonals sold under a number of brandings including William Optics. They are nicely made and work very well. The only exception is that the design uses a rather thick ring internally where the eyepiece holder joins the body. This can vignette the field of view when used with eyepieces approaching the maximum field stop size for the 1.25" fitting eg: 32mm plossls, 24mm 68's etc.

I use a clone of the Hyperflex 7.2mm - 21.5mm quite often despite my other eyepieces being Pentax and Tele Vue's. Accepting the restricted AFoV at the 21.5mm end, it's optical performance is rather good for what it cost. It works very well with the Baader Q-Turret 2.25x barlow lens as well giving a useful high power zoom range of 9.55mm - 3.2mm. The zoom is also great for outreach / star parties.

Lovely sketches !

I've noticed, when doing outreach events with my astro society, that it is often the younger eyes that can pick up colour tints more readily than older folks can. Maybe younger eyes are more receptive to colour ?

At least, through your questions and threads, you are getting a good idea of the various strengths and weaknesses of the different scope options The slight irony is that, if you didn't have a scope at all, the 200P dobsonian (that you have already) would probably be recommended by many as a very good all round scope for visual observing !

Another out of production eyepiece that might be worth looking out for would be the Tele Vue Nagler 2mm-4mm zoom. In your 60mm F/6 refractor that eyepiece would give you 90x - 180x. A very useful range and a high quality eyepiece.

I think I caused this confusion by picking the wrong name for the material used in commercial dobs. Sorry about that Thinking back to the last one that I owned (Meade Lightbridge 12 inch) I recall that the mount was made from chipboard with a white laminate coating. The Skywatcher and GSO dobs that I've owned in the past have mounts made of the same material. I think MDF (Medium Density Fibreboard as I now know it to be) might have been used by Coulter Optical for the dobsonians that they marketed back in the 1980's but I'm not 100% sure.

Still here. Good to hear some reports from those who have clear skies though

My mistake - I thought that material was MDF. I now realise that MDF is fibreboard, rather than chipboard. The material that the commercial dobs use is heavy though.

I wouldn't worry about it - I made exactly the same categorization a few years ago

Great stuff !!!! Filters sometimes really do earn their keep Don't want to spoil the thread title but I think the Veil is a supernova remnant and the Crescent an emission nebula

Raining now here Glad somebody's getting some views though

Oops !!! I meant M31 Stu. I've corrected it now - thanks for the sharp eyes

I tried my 13mm Ethos (not quite a 2 inch eyepiece but the size of one !) with a C5 once. The views were spectacular even if the combination looks a little comical