Davesellars

You're definitely good to go! I did all the Messier 110 list with a combination of my (then) Celestron C8 and 80ED refractor. The filters definitely help in some cases but I can't think of any Messier objects that I had to use them on in order to actually see the object.

Bit windy... but clear and the transparency was really quite good! Got in a 2 hour session (first light) with my Starfield 102 ED f/7 which arrived today! Did a whistle-stop tour of Messiers - report to come!

Yes, the 100mm f/9 Skywatcher is the same amount which would for me be really bad value for money now compared to this. Having said that The SW 80ED was definitely great value many years ago - I'm glad I bought it when I did and would not sell it although it could use an upgrade to the focuser I've serviced it so it's pretty strong now. I agree with the twist-lock fitting having played with it and also the fact that the force to do that rotates the focuser unless you have it really tight or grab on the focuser at the same time.

... and the new scope has landed! Absolutely love the focuser... it puts the one on the 80ED to shame.

Low clouds aren't so much of a problem if they are intermittent.. I would in this case just get out my refractor on the alt/az mount for easy moving from one location in the sky to another. High clouds are a bane as they are normally covering most of the sky and in this case transparency will normally be awful anyway for deep sky objects. I've become much more interested in observing the Moon lately so have been able to take advantage of a few nights when it's been quite cloudy to still view in the "windows" of opportunity.

The sky has been terrible all this month. All the "clear" nights have been low or very low transparency here - absolutely nothing like wonderous sky we were getting in January. Ensure that you wait for Ursa Major to be high enough before attempting M97 (later on in the night works much better at the moment) otherwise you'll be hitting much more LP which will easily wash out the nebula. M97 is one of those nebulaes though that reacts very well to use of an OIII filter - it can actually make it visible when it's not without the filter.

Yes, M7 will be nigh on impossible from up here. I managed it in Oxford after over years waiting for the perfect moment. and that's a couple of degrees difference. Still, some of the really low Messiers are at least bright enough to get a with small aperture if you vacation somewhere further down south at any time! Your 6" newt will be more that enough though to bag the rest that are far enough up though (the majority!) Like as has been mentioned it will depend completely on the darkness of your observing site and sky (where are you in Derbyshire?) as well as the transparency of the air on the night... M108 is quite easily drowned out by bad transparency and light pollution. Can you see M97 (Owl nebula) without a filter? If so, then M108 should also be visible.

Just bought the Starfield 102 ED f/7 from FLO for less than the Altair f11 I was looking at originally - I couldn't say no to that offer! Thanks FLO!

Thanks John for your invaluable input!!!

Urrgh... another frustrating one. It looked really promising at 7.30 ish with transparency looking OK - I could just about make out M31 naked eye. By the time I managed to get out at 9 after the kids were in bed it had got significantly worse and the sky seemed milky and bright. With the cold wind I decided against getting a scope out. Went out a few times until 1am and it had only got even worse....

Thanks @johninderby . I've also started considering the Bresser Messier MC-127 mak which seems a good price at around £360 - I noticed from some searching that you had this scope as well as the 6" CC - and have sold them both? Why did you sell them? and thinking back would you still recommend the 6" CC over the mak? The mak I think is quite a bit lighter although that's not too much of an issue if the CC really outperforms the mak on contrast and resolution and taking it higher magnification particularly for lunar observation.

Yep, just clouded here as well... so packed up. 🥴 At least, as mentioned there are a few promising looking nights this week.

It cleared quite well so had an hour with the 120ST until 9:30 but frustrating as hell with neighbours' lights on in various directions which is why I do most of my DSO observing after 10 or 11... Well venture out again in bit.

Glad to see it's a bit better elsewhere.. It's clear here but terrible transparency so will wait a while to get a scope out.. Hopefully it will improve!!!

If i'm going to get the 12" dob out then for me I need reasonably good indication of transparency for observing DSOs. You can normally get a feel for this in the afternoon while the sun is going down and if the sky looks a nice deep clear blue instead of whitish haze then I'll get the dob out early. Later on if it's cleared and I can see down to mag 5 stars clearly then it's going to be OK. Anything other than that i'll probably stick with a shorter session with the refractor. BTW, there are many NGC objects that are way brighter than those in the Messier list. I wouldn't see it another level of difficulty...

Just received the 21st Century Atlas of the Moon (Charles Wood). It's exactly what I was looking for and a nice compliment to Rukls' illustrations that are in the Collins Night Sky book. Also, with it being ringbound I can easily take a photocopy of a page or two of interest to use at the scope / notes.

Incoming storm!!! I remember when my 12" dob arrived we had to worst storm for quite some time that night while I set it up... Good luck with the secondary... at least it's not your first dob for setting it up! I bought the Moonlite focuser to replace the stock one directly (first newt as well) and foolishly replaced it before checking the original was collimated even.. Spent the next few days getting the collimation of the secondary dead on...

So the CC would be sharper than the Mak? I suppose this is because of the need for the glass corrector... ?

I hadn't thought about that. A fine helical focuser at the diagonal could alleviate the issue... What advantage does the 6" mak have over the 6" CC (with them both being f/12) ?

I've not tried a Mak however I really didn't like the mirror shift in my 8" SCT when I had it which i believe is also present in Maks as well.

Wait.. what??? the focuser is not straight?

Thanks Ricochet. Yes it's exit pupil is the issue as I start to get some floaters with my 80ED and the 4mm. which gives an exit pupil of 0.53. While it's not overly bad. I certainly wouldn't want to go any lower and find using the 5mm Pentax much more comfortable for prolonged periods (exit pupil 0.67). John: after some research I'm sure you're right that this calculation for loss of contrast (not talking about loss of resolution) is overstated and to me would seem an over-simplification anyway not taking other factors into account.

Many thanks Mike. I'd not considered before going down the binoviewer route.... I can see how that would increase the comfort quite a bit. I don't think I can budget a £900 refractor for this though especially with other extras so may have to re-think. I do like that idea with the binoviewers though! I've read that the contrast is basically calculated by deducting the central obstruction diameter from the aperture - since the CC6 has a 58mm obsruction this would essentially give it less contrast than the 102mm refractor. While resolution would be better in the 6" CC... the low contrast details for Jupiter and finer lunar features may well not be as good in the CC 6" as the 4" refractor...

Thanks guys. F/7 is not really sufficiently long for a 4" to get enough magnification at times without a very small eyepiece focal length which then is uncomfortable and reduces the exit pupil too much for my liking. I use a 4mm (cheap TMB planetary II clone) with the 80mm ED which is just about OK but that's giving 150x which is not really sufficient. I certainly wouldn't want to go start using a small focal length eyepiece than that. I didn't have any stability issues with my 120ED on the EQ5 (probably similar weight and length to the 4" f/11) although noted it would be uncomfortable on the mount because of the length when the Moon is high up so that's a good call. OK, probably erring towards the 6" CC but in no hurry to decide at the moment!

I think I may be in the market for a large(ish) focal ratio scope specific for lunar observation as I'm getting more interested in the Moon and would also like to participate in this program at the Department of Physics at Aberystwyth University when possible: https://users.aber.ac.uk/atc/LS_present/Birmingham.htm I have the 12" dob which I use for DSOs and with spot on collimation has produced very good results when the seeing is very good for lunar observation. Certainly, for some observations I would (have to) use this. However, for the majority of the time I would prefer using a a scope that I get out relatively quickly when the oppotunity arises and sit on the EQ5 mount (manual) which I orginially bought when I had my 8" SCT (which was very stable) Also, when the planets become more available later this year this scope would be used more for this as the dob rather has more restricted location (I can take my EQ5 or AZ4 perhaps with another scope and view from the park next to us - something I definitely wouldnt lug the dob out to. I've been looking at these two: a. 6" Stellalyra Classical Cassegrain F/12 - £460 b. 4" Altair Astro F/11 ED - £670 Collimation doesn't particularly phase me but I gather it would have to extremely precise in the CC... I'm a little more concerned about the effect of contrast from the central obstruction particularly for planetary observation but if this brings it "down" to more like a 4.5" to 5" APO refractor performance then I'd be sufficiently satisfied. The other concern for me would be if the figuring of the mirror is sufficiently good to perform as well or better than the 4" refractor. A major pro for the 6" CC would it would provide 183x with a 10mm Delos and 131x with the 14mm Delos - both very comfortable eyepieces. I also have a 5mm and 7mm Pentax XW which would have to be used to reach approximately the same power in the 4" refractor or for when the seeing is truly excellent with the CC. My doubt is if a mirror in the CC would be able to go much higher in the CC without going mushy though. Difficult decision... Will the 6" CC give more than the 4" refractor? I'd see the refractor as lasting longer as mirrors degrade and are a pain to clean... lots of other pros and cons! But then the CC is pretty cheap... Any advice or from other members that perhaps have both as a comparison. I've read through the extensive long thread started by FLO when the Stellalyra CCs were made available...