John

Thanks David.

Very clear skies here and my dob is out cooling

8 hours ago, Dantooine said:

John, from those simple calculations it should be easy to work out the in travel for ethos in the Antares 🤔

Piece of cake

All way over the original posters intended budget of £280, unfortunately.

If you can't find it in the eyepiece without a barlow lens, having one is not going to help.

You seem to have a diagonal of some sort - the eyepiece is inserted into it in your photo.

The most important thing is to get your finder scope really accurately aligned with the view in the main scope. If that is not done then finding anything is going to be very hard work even if you can see it clearly with your eyes.

Nice sketch !

I enjoyed the better seeing as well when observing Mars with my ED120 tonight.

Mars is looking good tonight.

Nice and steady with quite a lot of contrast in the surface features at 300x with my ED120 refractor.

20 arc second disk as well !

Forecast was cloudy tonight so a bonus session

50 minutes ago, ibraidwo said:

Thanks for posting, I recently picked up the same mount, with an old 6" reflector at an auction a month or so ago for £45 and am just starting to see how it works and whether it does everything it should. It came with the same tripod as yours as well; I note your tripod cross-support also has rust on it - I was wondering what I should do with that.

Until seeing your post, I wasn't exactly sure what model mine is, however it looks exactly the same as yours, so i assume its a Vixen SP GEM also.

I have stripped the telescope down and cleaned it - it was very dusty (probably sat in a barn/garage for some time. I have also partially disassembled the mount, but won't go too far with it. The RA worm screw shaft is a little bent, so I need to do something with that and it has an RA drive, however I don't have a controller so can't test it.

The mount appears to move well on both axis. Hopefully it will work okay once I reassemble.

 

 

 

In case it is of use to you, here is the original Vixen manual for the Super Polaris mount:

super_polaris.pdf

They are very good scopes. It is probably worth a reasonable additional investment to get rid of the fungus between the lens elements as well.

I understand the point that you are making Don and the optical principles that underlie it but I'm rather baffled all the same.

I've read many reports of the Antares 1.6x barlow being used with the Ethos in 2 inch mode on the CN forum (Lawrence Sayre was a great exponent of this approach, among others) and yet I have not read that these combinations result in more than very small variations, if any, from the 1.6x amplification. My own experience of using the barlow with the 8mm and 6mm Ethos, in 2 inch mode, and comparing the resulting combination with eyepieces with a native focal length of 5mm and 3.7mm is that there was no noticeable difference in the image scale that was achieved.

Maybe I've missed something though, either from my own experience or the reports from others

I guess it's fairly academic now because I don't use this barlow or any others with my principle eyepiece sets but I'm puzzled all the same !

14 minutes ago, Robindonne said:

I wasnt sure if this topic was about the possible giving up of a member. And the fear for scams while searching for a good set.    Sorry if it is not that post.   Last week this post looked mixed up but that could also be my browser.   

A last try to get the o.p. in this hobby

Last week this thread was mixed up - by me when I tried to merge two threads and actually merged three !

I spent some time yesterday sorting it out back into two, unrelated threads.

On the topic of this thread, if the OP is unsure about getting a scope its probably best if he / she holds off purchasing anything just now. Supplies and choice are limited currently and used prices seem to be escalating.

The good thing is that the Universe will still be waiting if and when the interest is re-kindled

Some of my best views of the planets have come when observing them against a sky which still had quite a lot of light in it. Dark adaptation is just not needed and actually hinders seeing the more subtle detail.

Currently there are a lot of issues conspiring against getting good views of the planets because they lie low in the sky from the UK and these are not really related to the scope.

With Jupiter I'm finding that 100x - 150x is delivering the crispest views and sometimes even those are not that sharp. With Saturn and Mars you can push things on to 200x or perhaps a bit more (Mars being higher in the sky helps).

I have to say that my smaller aperture refractors are making a better job of handling the adverse positioning of the planets than my 12 inch dobsonian is.

38 minutes ago, Robindonne said:

A c11 on avx for 1750,- on abs.  Scam?

How does that relate to the topic of this thread

24 minutes ago, DaveL59 said:

I noticed this one on the bay today
https://www.ebay.co.uk/itm/Bresser-messier-telescope-AR127L-1200mm/333714596134?hash=item4db2f0a126:g:bW8AAOSwMYRfV3O3

Not sure how it'd balance compared to the F15 John pictured but in case it's of interest...

I used to own one of those. An earlier version with a different colour scheme. It was a very good scope I felt. Minimal CA, well corrected and really gave a "big refractor" feel. They are long scopes that need a sturdy mount but the HEQ5 that Neil has would handle it well enough.

That one is over priced though, as has been said.

As a slightly alternative point of view, I've owned a couple of the GSO / Revelation diagonals and the Skywatcher ones and the William Optics ones and found their performance pretty much the same. I currently have one of the 1.25" Skywatcher 1.25" dielectrics and have compared it directly with a Tele Vue Everbright 1.25" and my Baader T2 Zeiss prism in my Tak refractor and found the Skywatcher performed quite nicely. I paid £35 delivered for it so I'm quite happy with it.

Just another "data point" of course

The objective cell on the ED100 should unscrew from the tube allowing you access to the inner face of the objective lens for cleaning.

Hopefully the fungus has not occurred between the lens elements (it is an air spaced doublet) because that will require the objective to be removed from the cell and split to access those lens faces. I've done a few of those and they can be a fiddly operation. 

I would not do a triplet objective - that is a much more specialist operation.

On some targets you will notice quite a difference - globular clusters are an example.

On others, not so much and what you actually see depends on a whole lot of factors other than the scope aperture as @vlaiv says above.

Personally I find the 4 extra inches well worth having but the scope size and weight has increased markedly to get this and this needs to be considered as well:

32 minutes ago, kotitonttu said:

On sorry. Im new here. What is FLO. Some retailer? Im from Finland and we don't have so many telescope retailers here. I already send email to opticalvision UK wich IS sky-watcher retailer on europe. They have not answered yet. 

OVL are the importer but it is usually more effective to contact vendors such as First Light Optics (FLO). Here is there website:

https://www.firstlightoptics.com/

Amazing what is possible with simple tech !

I tried to get the ISS crossing the moon with my DSLR mounted on an undriven scope and got it in a couple of frames which I have made into an animated GIF. The whole crossing took just a second or two and the moons was partially behind tree branches so I was pleased to even get it in 2 frames:

The diagonal on the Bresser's is their weakest point IMHO. All plastic apart from the mirror. I would budget for a replacement from the off.

Meade used to supply the same diagonal with their AR5 and AR6 refractors

12 minutes ago, omo said:

I was thinking about what @Don Pensack was saying about the 8mm Ethos putting the focal plane much closer to the barlow glass so lengthen the barlow to get nearer to the 1.6x. The connection between the nosepiece and twistlock is T2

Well, I used it with the 8mm Ethos in 2 inch mode and it provided the same image scale as the 5mm eyepieces that I was comparing it with at the time.

Just now, omo said:

If i am understanding this correctly, with the Antares having a T2 fitting it would be quite easy to add a T2 spacer to extend its length and get nearer the full magnification  with the Ethos in 2 inch mode

I think it works at 1.6x in 2 inch mode anyway. The one that I used to have did.

I find 21mm - 13mm - 8mm - 6mm deliver 80% of my observing with my 12 inc F/5.3 dobsonian. They are my core set with this scope.

I have shorter and longer focal length eyepieces but they don't get as much use as the above.

Either of the could be good - there are happy and satisfied owners of both types on this forum.

They both have strengths and weaknesses though so I guess its a case of deciding what you are hoping for from this new scope and the extent to which the two you have initially selected might match those aspirations or if there is a better option out there within your budget.

You are more likely to see optical issues with the F/5 but they are not designed for high power observing so it might not matter too much.

The F/8.3's are generally optically sound but you can still get some spherical aberration - it's very common with the chinese achromat refractors.

Both will show some chromatic aberration, the F/5 quite a bit more than the F/8.3.

If you are looking for optical perfection in these low cost scopes you may have to reject a lot of samples.