John

I always felt that Messier 81 and 82 were more interesting through a scope than Messier 31 is. I guess I'm biased, though because those were the first galaxies that I ever saw with a scope. I found M31 later with binoculars.

1 minute ago, bosun21 said:

..... Does anyone else appear to have this streak?

I seem to 🙄

I really enjoy searching out faint targets with rather small aperture scopes. Stuff that is at the edge of what the aperture / conditions / observer can see. Usually it's that last component that is the weak one !

Next clear and dark night I'll be trying to spot the quasar 3C 273 in Virgo with 130mm or smaller apertures 🙂

I agree with the comments regarding the visibility of M31 above. 

Taking a different type of deep sky object, with the brighter globular clusters, these aperture increases will show noticeable differences in the resolution of stars within the cluster and the depth towards the core that is resolved. With a 10 inch and upwards aperture, M13 starts to look like some of the images you see of it. Quite splendid 🙂 

The Askar 140mm triplet does look very appealing for it's cost. I'm a little wary about being an "early adopter" though. I'm going to wait for a larger body of considered feedback from owners covering a number of examples of the scope before considering it myself.

There have been low cost triplets that have actually shown more CA than ED doublets in the past. I'm not saying the Askar is one of those but I'm just cautious.

1 hour ago, Telescope40 said:

.... Big but nice.....

Yep, the ED150 is quite big. This is it compared with my ED120:

1 hour ago, Flame Nebula said:

So, I read the Roger Vine article. Interestingly, the 100DC came out well. I checked the DZ version on FLO, and it's a grand more! I really do like sharp images, but not prepared to pay 50% more. I also  wonder how much more the SW 150ED would give me for the same price as the 100DC. In theory I'd get 250-300 x on jupiter with good image quality, compared to 200ish for the 4". 

Jupiter rarely responds well to really high magnifications, whatever the capabilities of the scope.

In all the scopes that I've owned (up to 12 inch in aperture) around 200x is about the highest magnification that I've found really useful when observing Jupiter. 

Saturn, Mars, Venus etc are a different proposition. You seem to be able to throw more magnification at them and get decent results. Not Jupiter though.

1 hour ago, Flame Nebula said:

How about 'APO - like' or 'APO-light' I'd go for that. 🤪

For what I think you are interested in, the levels of accuracy of optical figure, polishing and coating are just as important as control of CA, IMHO, maybe even more so 🙂

32 minutes ago, Flame Nebula said:

Thanks Deadlake, 

Interesting point on the mtf. When you say Apo, do you include SW 120ed, which I understand is not a full Apo? The C11 and C9.25 are primarily AP scopes, where lower apertures can't compete, as I understand (and supported by astrobin) 

Mark 

Can any doublet be a "full apo" ?

Thats the subject of many long threads on another forum I can think of !

There have been a few newtonians where the secondary mirror was positioned away from the optical axis of the primary mirror, on the side of the tube. Off-axis newtonians. No secondary support vanes of course. Here is a review of a DGM 5.5 inch off-axis dob by Ed Ting:

Telescope Reviews, Page 7

It impressed the reviewer but there are a number of drawbacks with the design (cost being one of them).

Orion (USA) even had one in their catalogue for a while but the design was not popular so it didn't last.

I imagine that collimation is an interesting process 🤔

1 hour ago, Stu said:

.... I recall there were some packaging issues which led to review scopes being out of collimation. That was all rectified, not sure if any changes were made to the scope, I think it was mostly better packaging.

Yes, the packaging was improved substantially by Skywatcher. 

In the USA the Skywatcher rep on CN also claimed that the objective lens retaining ring was made more substantial which makes sense because that ring (which did seem rather thin) had shifted in the 2nd example that I was sent, allowing the objective elements to get out of alignment.  

I've never been able to get any confirmation on whether a similar change was implemented on scopes destined for the UK / EU.

Despite my 2 unfortunate experiences I always felt that the ED150 had a lot of potential and from reading reports since from those who now own and use them, that optimism seems to have been borne out 🙂

We saw a Space-X launch from Kennedy Space Centre back in 2017. We were positioned a couple of miles away from the pad and had a good view. The whole thing seemed quite calm and uneventful really. The rocket just moved smoothly upwards from the pad eventually disappearing into the cloud base. The sound took a surprising amount of time to reach us and that crackle (like tearing calico as it has been described !) was very noticeable. A few minutes later we heard a sonic boom as the bottom part of the rocket came back down to earth - it was the first time that the lower section had landed on terra firma I recall and from later footage that was successful.

I wish I had seen a shuttle go up but maybe I'll get a chance to see one of the heavy lifters go up one day.

13 minutes ago, Flame Nebula said:

Hi John, 

I'm surprised more people weren't interested in that design - seems perfect, and as you said, it may have made the difference between splitting sirius or not. That's the kind of design I'd go for, if I went for a large newt. 

Well, many are not convinced by it and that's fine as well of course. I have owned newtonians with conventional secondary support vanes and been happy with those as well, despite the diffraction spikes. Orion Optics obviously stopped doing the curved ones for a reason and I guess lack of demand was a part of that.

There was a US company called Destiny I think - don't know if they are still in business ?:

1800 Destiny On Line Store for Curved Vane Spiders (destinycomp.com)

Another approach is to use an optical glass window to support a minimal size secondary, rather like the meniscus that the  maksutov-newtonian design uses. Now those things really do perform well on the planets, double stars and other high-res targets 🙂

38 minutes ago, F15Rules said:

To be honest, I found the spreadsheet referenced  above totally confusing and user unfriendly, especially on my Smartphone.

What really bemused me were the claims that the Hyperion Zoom and Pentax XL 8-24mm zooms both had had "terrible image quality". That assertion is completely at odds with my experience with both these zoom eyepieces..

I have owned both of these and still have the Pentax Zoom. Both showed very good image quality: you might not like the narrower field at the lower power settings versus fixed length eyepieces, but the actual image quality (which by the way I judge by the pleasure I derive from what the eyepiece shows me, NOT this "spot" or that "aberration"), and the build quality of the units are excellent.

I can say with certainty that the Pentax zoom build quality is exemplary, and the images it delivers in terms of sharpness and contrast are very good indeed..very close to the fixed length XL and XW ranges.

Dave

I'm glad that you have shared some experience with the Pentax Dave. Thats a zoom that I have not had the pleasure of trying out 🙂

My OO 12" F/5.3 had these secondary vanes:

I didn't see diffraction spikes with this scope. The diffraction was still there but spread evenly across the image and, to my eye, did not degrade it. The CO in this case was 21% the diameter of the aperture.

Personally I was very happy with this arrangement. Orion Optics stopped offering it many years ago though so I guess uptake was low amongst customers. I didn't specify this - the scope had 2 owners before me.

The scope showed excellent planetary and lunar details, conditions allowing, and was the first scope that I managed to split Sirius with. 

Martin Mobberley went for a similar approach with his OO 10 inch F/6.3:

At some point in the future I would consider a scope such as the above with OO's top quality mirror in it. I'd try and find one pre-owned though, to avoid having to deal with OO 🙄

Other folks have different opinions of course - I can only relate my experience 🙂

Maybe you should tell us a little more about what you are looking for Mark and what your criteria are ?

For example, in terms of portability, an ED150 is not going to be preferrable to a Tak 100 or an ED120 even if it's ultimate performance on a wide range of targets does exceed the smaller aperture scopes.

Do you see what I'm getting at ? 🙂

This will be interesting - I have owned a Tak 100 (a DL) for 7 years now and an ED120 for over a decade. I have briefly used a couple of the ED150's (loaned to me) but neither was in good shape optically due to shipping issues (early examples - Skywatcher improved the packaging soon after) so I can't judge those.

I'll give some thought to my views on the 100 - 120 comparison, rather than give a knee jerk reaction so I'll post again in due course.

I have seen the Horsehead Nebula visually a couple of times when I had my 12 inch dobsonian. I made this report on SGL the first time I did it - I was rather chuffed 🙂

Barnard 33: The Horsehead Nebula - At last ! - Observing - Deep Sky - Stargazers Lounge

4 hours ago, Mr Spock said:

Not seen Antares yet. It's just too low here 

When it's at it's best here I get about 30 minutes to observe it as it passes from behind my neighbours house to hiding behind the branches of a large chestnut tree. When I used to use the dob to get a glimpse it was practically horizontal !

2 hours ago, wookie1965 said:

I wonder if I could get new glass for this if anyone sees any please let me know.

A "wanted" advert in the SGL classifieds and on UK Astro Buy & Sell can throw up some interesting offers. It's worth a try. 

1 minute ago, lunator said:

The frustrating thing about Sirius B is the ease with which Southern Hemisphere observers can split. I remember reading about someone spliting it in a 3" scope back in 2010. They had the luxury of a dark sky in Namibia.

 

Ditto with Antares. 

I've not seen Mars as a white disk as far as I'm aware. Even when a long way off and very tiny or when viewed with my ancient Tasco 60mm refractor, the disk has always had a pink / pale orange / pale rust tone. When it's far away making out any surface details, ie: the darker areas can be very challenging. Syrtis Major is the most obvious one but even that can be difficult to spot when the martian disk is very small.

That is a chinese made one IMHO. Probably one of the later Celestron ones. The lens cell design is the give away for me as well as the focuser and smaller diameter tube. 

It's a pretty decent 4 inch refractor of course, but IMHO, made by Synta in China rather than by Vixen in Japan.

Just my opinion of course.

I'm a suspicious so and so and I am wondering that sticker has been applied to a chinese made Celestron 102 F/9.8 ?

The focuser (or at least what I can see of it) does not look quite right for a Japan / Vixen made 102 either - it looks like the chinese one that the 102 F/9.8's branded Helios, Skywatcher, Konus, Saxon etc used. 

Hope I'm wrong of course 😕

If it is a chinese made Celestron 102 the tube rings from the Skywatcher Evostar 102 should fit it.

Sorry to spread more confusion 

I probably would put something in between the two but I prefer to have more options rather than less.

It might not get as much use as the 32 or the 13 though 🙄

I assume that your Celestron C-102 F/9.8 is one of the more recent, chinese made ones ?

Back in the 1980's / 1990's Vixen used to make them for Celestron and they were exactly the same as the 102M Vixen's, apart from the gloss black colour scheme.