John

I've been using refractors for the past 40 years - what do you want to know ?

Joking apart, this is a good resource:

http://www.astronomynow.com/books/Choosing and Using a Refracting Telescope.html

I think you would find the planetary views with an F/9 ED 100 refractor (eg: Skywatcher ED100) somewhat of an improvement over your current achomat. I moved from a good achromat (100mm F/10 TAL) to the ED100 and noticed that the ED scope was sharper, more contrasty and supported higher magnifications.

No disrespect to the TAL 100 which is a very good achromat but the ED doublets are a step up in my opinion.

I've owned the 30mm and 40mm Aero ED's and found they worked fine with my Lumicon and Astronomik filters

I've found that my refractors are punching above their weight on the planets because of their low altitude currently. On the deeper sky, the refractors (100mm - 130mm) do very well for their aperture but my 12 inch dob pushes substantially deeper and fainter and resolves globular clusters much more impressively.  

My skies are Bortle 5, generally.

The signs that you might need to pay attention to collimation are if you often read reports on forums from folks who have the same equipment as you do but seem to be able to regularly see more detail / tighter resolution on the moon / double stars / planets or if you look through a similar scope to yours at a star party or similar and the views seem noticeably better than your scope is delivering.

I've looked through 8 inch SCT's that have been struggling to split the "double double" epsilon lyrae, for example. Some collimation adjustment and this showpiece binary pair becomes a clear and easy split.

Excellent report Stu

I'm on holiday enjoying some good weather on the Isle of Wight but with no scope but it was nice to be reminded about whats going on up there !

I'll be looking forward to observing again when I get back home.

On holiday with no scope here so hope those who can, get some good views !

I have used the UK Astro Buy & Sell website many, many times to buy & sell equipment over the past 15 years and it has worked out extremely well 

https://www.astrobuysell.com/uk/

Buying new items (which I rarely do) has invariably cost me money over the years when I've decided to part with the item. The used items I've bought and later sold have generally not cost me much apart from the postage costs.

I could probably have made a profit on some sales because I've had some great buys but I don't feel that's a good thing to do so I've just recovered my outlay and given someone else the benefit of a great value buy as well

I have seen Zeiss ZAO orthos being sold at substantially more than they were retailed and sometimes also TMB Supermonocentrics and the Pentax XO's at but I think they are exceptions.

I really don't think astronomy equipment is a good place to invest if you hope to make a profit of any sort from it. It's a great thing to invest in to have some fun with though

Nice report of an interesting feature 

The Propeller looks great with my 12 inch dob at 265x on a dark night.

Through my smaller aperture scopes it's not very distinctive at all.

11 minutes ago, Kon said:

Just saw the shadow coming through, very nice. Waiting for another 45 min for Europa to come through.

Yes, I've waited to see that. Quite nice seeing now although Jupiter is now getting lower in altitude. Some "clumpiness" in the S Temperate Belt but nothing that looks specifically "oval-like" with my 100mm scope tonight. I was using the 130mm last time I saw them though.

Hope it keeps good for you

I'm probably going to pack in soon regardless of the conditions. I've got quite a bit of driving to do tomorrow. Hope it stays good for those who stay out  

1 minute ago, Kon said:

The breeze has cleared the clouds and seeing has vastly improved with nice details all along now. I can spot 2 clear barges and possibly a third one. Quite a lot of distinct banding as well.

Similar here.

I was wondering if any of those pale oval features in the S hemisphere would be showing as the GRS rotates out of sight. Just waiting for Europa's shadow now.

I agree 100%

18 minutes ago, Ian McCallum said:

Would you say my Sky-Watcher 200P is a medium aperture scope? 

Yes - that's just the sort of scope that I meant.

Personally I'd go for a 100mm refractor (or more) over an 80mm or a 90mm. I've owned nice 80's and 90's but found that they did not quite show enough to hold my interest for long. Something like an ED 102mm F/7 for versatility as I think was suggested earlier in this thread.

That's just my preferences though. Yours are what matter much more in this thread

I'm sure that these 80mm refractors are lovely things but the original posters scope should show all that they do and more besides and catch challenging stuff like Neptune's moon Triton which is simply beyond a 4 inch refractor no matter how good it's optics are.

Having a small refractor AND a medium aperture scope is a great way to go though

The seeing is good here with lots of intricate detail but there is a large back of cloud that keeps swallowing up Jupiter so I'm getting small excerpts rather than a continuous show.

I've bought and sold many items there over the years and with no issues that I can recall.

Use a common sense approach and clear communications with the seller as John suggests above.

While some items might be on SGL as well, many are not.

7 minutes ago, IB20 said:

I’ve just watched Io appear from Jupiter’s shadow and observed Europa ingress onto the planetary face. Amazingly I could still see Europa in front of Jupiter even after it was entirely on the disc, I can’t quite believe it, that’s the first time I have been able to observe such an event, in a little 80mm too!

The seeing was good at times and I could also see the nice colour in the GRS at 62x and 80x. 

The clouds have rolled in now unfortunately so I think that’s me done.

 

Europa stayed visible against the disk for quite a while. It's very hard to spot now though and the sporadic cloud cover is not helping.

I think the moons are visible during the early part of their crossing of the Jovian disk because of the effect limb darkening which allows the moon to stand out better against the limb areas of the planet than it does as it moves more onto the disk.

Whether I get much more observing is in the lap of the cloud gods just now. Some is a lot better than none though

Europa has just started it's transit of Jupiter's disk.

With the GRS nearing the central meridian and a small dark barge on the top of the NEB plus decent seeing for a change, it's all looking rather nice

Europa's shadow starts it's transit at around 23:40 hrs I think.

Might not stay clear so I'd better enjoy it while I can !

20 minutes ago, Ian McCallum said:

I've just seen the price of the mount that I've been recommended by FLO!😮 Well, I guess that knocks that plan into the bushes...🙄

https://www.firstlightoptics.com/skywatcher-mounts/skywatcher-eq5-deluxe.html

Long scopes need sturdier mounts than short ones of the same aperture even if the weight of the scope is easily within the mounts capacity. Long tubes exert a lot of force on the mount and tripod.

Assuming that all is in working order and the optics are in good condition that is a real bargain for $500 plus some gas.

Assuming that it is the 8 inch, even the optical tube alone is well worth that.

It looks like the Nexstar 8i model with an upgraded tripod.

Lots of information on these here:

https://www.nexstarsite.com/

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

22 minutes ago, Dave scutt said:

Would explore scientific OIII filter be of good quality it's not cheap but not as expensive as some other brands

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.