John

17 minutes ago, Soligor Rob said:

Thanks for that, could you give me any advice, I have a Sky Watcher 200p Dobsonian, and also a 120mm x 1000mm Refractor.

I started this thread late last year which may be of use:

5 minutes ago, Soligor Rob said:

I feel so much better with myself now after reading these posts. I have been looking at Sirius thinking what am I doing wrong I just haven't managed to observe the split.

I must try harder, mind you a clear sky would help haven't had one here for over a week now.

It's far from easy Rob. There are many experienced observers around who have not managed it yet.

Like so many astronomical observing challenges, when you have done it once, it gets somewhat easier the next time because you know what to look out for

I have a scope with a focuser just like that and I have just the same problem. Those little screws are not good at holding weight / gripping and are so small that applying any real tension to them is difficult, plus the screws mark up the diagonal barrel.

Ideally the visual back  (the black part that the diagonal fits into) would be replaced by one with a compression ring fitting. but I'm not sure that these are made for these smaller focusers 

A simpler alternative would be to replace the two tiny set screws with larger ones that have more for the fingers to grip and which have more contact with the diagonal barrel. This would entail re-drilling and re-threading the two holes in the visual back and fitting larger and more robust set screws.

It is an annoying problem. Perhaps someone else with a Skywatcher 1.25 inch focuser has managed to find a way to improve it ?. I'd be interested myself if they have.

Sorry that I don't have a handy solution but I can empathize !

Great piece on Theta Aurigae here by John Nansen:

https://bestdoubles.wordpress.com/2012/04/20/theta-aurigae-and-the-light-of-its-passage-is-night-on-the-face-of-the-world/

3 minutes ago, Zermelo said:

Thanks John.

And no, I've failed with Sirius at least a dozen times!

Took me a long time and, eventually, a 12 inch scope to split Sirius

It's a little easier now (the separation is more or less at it's max) but still a very tough challenge.

Well done on Theta Aurigae though - it's a bit of a "classic"

I've just been looking at Theta Aurigae (prompted by your post). It does sound as if you have got it.

I got it at 170x with my 100mm refractor.

Doing the mental conversion between the refractor and the newtonian view, 300 degrees sounds about right and it corresponds with the Stella Doppie database data which says 302 degrees.

I think you got it

It is quite challenging because of the brightness difference between the A and B stars which makes otherwise straightforward separations much harder, eg: Sirius for the most extreme example.

That looks quite typical for a Synta scope. Their internal blackening is OK but nothing special in my experience.

I hear what you say regarding the optics but I have to confess that I've owned two or three scopes over the years that I never managed to get a really satisfactory star test from

I'm not suggesting that yours is like that I hasten to add.

My 90mm F/11.1 produces pretty decent performance visually in terms of splitting double stars, detail on the moon and planets etc even if it's star test is not that great.

There may be a limit to how good you can get the collimation and star test with these F/5 achromats. A lot of them have an optical issue called spherical aberration (SA) in the form of either under or over correction to some degree. Many of the slower achromats from the same source have the same.

It's worth keeping at it to get it as good as it can be but I feel there is likely to be a limit beyond which you would need to experiment with rotating one of the objective elements or even more drastic work to gain improvements.

I have a 90mm F/11.1 achromat from the same manufacturer (Synta) and I've been fiddling with that for about 4 months now but it is still showing a little flaring of the star test despite my efforts. The next stage, when I have time, will be to experiment with the relative rotation of the lens elements to see if there is some "wedge" in one of them. It's a time consuming process though and we have not had enough clear nights to justify spending time on that.

1 hour ago, michael.h.f.wilkinson said:

With something like this, you hold on for dear life

 

Carry it with both hands, like the Terminagler

55 minutes ago, SuburbanMak said:

Great report thank you!

 After I stripped my ST80 down last week I noticed some up/down play in the focuser - I was able to eradicate this by tightening the two tiny hex screws on the outside of the barrel. 
they push down in on a little plastic bush about 2 1/2 inches long housed in the casing above the silvery barrel. Seems this gives some control of the level of friction & play, I guess if you tightened them differentially they would fine adjust the tilt of the focus tube. Worth a go maybe. 

Good advice

Its worth checking that before doing the stuff that I mentioned earlier in the thread. A floppy focuser is not going to help the star test !

With a bit of adjustment and maybe a re-grease these Skywatcher rack and pinion focusers can be made to work quite well.

Nice report !

One trick that can help the star image quality with these scopes can be done indoors in daylight. Point the scope upwards and keep it that way though this process. Remove the lens cap and dew shield. Loosen the lens retaining ring a couple of turns so that the lens elements are loose. Gently "slap" the objective cell all around it's sides. This gives the lens elements a chance to settle into their positions. Then very gently tighten the lens retaining ring again just enough to hold them in position.

If the comatic stars continue to be an issue, you will need to think about the collimation of the scope. Having a laser collimator is helpful to check if the focuser is aligned with the central axis of the objective. With the diagonal off, shine the laser down the tube and note where the laser exits the objective - it should be pretty much bang in the centre. If it is not, tilting the focuser to get the laser central is required and then some form of shims to hold that tilt when the 3 screws that hold the focuser to the tube are tightened. Once you are confindent that the focuser optical axis is aligned with the objective optical axis, you can use a cheshire collimator (again without a diagonal in place) to see if there is objective tilt:

The challenge with these simple refractors is that there is no focuser or objective tilt adjustment facility built in which is why shims are needed to apply any necessary tilt.

Aplologies if you know all this !

19 minutes ago, jetstream said:

Seriously?!

 

Seems a good point to me

I suppose a legitimate question that can / should be asked is what will all these marvellous eyepieces that have been proposed show with the Tak 76 that the OP's current BST's and Baader zoom won't show ?

In  a number of cases (including my own suggestion) the proposals could involve spending £1000 plus. So just what does that buy in terms of tangible / specific performance gains over the eyepieces that Nicola currently has ?

(I'm asking for a friend )

9 minutes ago, Spier24 said:

If I didn't have a GoTo scope then I'd buy a copy, seems to get good feedback.

Does your GOTO tell you which targets your scope is likely to show well and those where you might recognize something in the eyepiece ?

One of the great things about the book is that the targets are carefully chosen to be those which small instruments and new observers can both find easily and that will be interesting to observer.

GOTO's, when set up properly, are great at pointing the scope at object X or Y but many objects may simply be either incredibly vague or invisible when you actually look though the eyepiece at them.

Some great sales people on here !

You pop in to ask about a couple of eyepieces and exit with a couple of sets of eyepieces, two additional scopes and a mount or two

If Arkwright ran an astro shop .......

I'm very impressed at the efforts that folks will go to to get decent skies

Cracking eyepiece Michael

5 minutes ago, jetstream said:

I think that when we get into this quality of equipment were splitting hairs for differences.

I agree. It keeps the forums rolling when it's cloudy though

Grabbed half an hour with a 100mm scope and the herschel wedge to view the Sun this afternoon. Rather hazy conditions. The 7.2mm - 21.5mm zoom eyepiece did a good job. Quite sharp views even at the upper end (125x).

Apparently there are 3 active regions on the solar disk just now, AR12807, AR12808 and AR12809. Only AR12808 was showing anything visible to me today. A small spot with a roughly triangular umbra and close to that a tiny group of 3 spots that form a triangle. So something to view at least. Quite wide areas of faculae showing around AR12808 and in patches elsewhere. I could not see any sunspots associated with the other two active regions.

Must remember to view the sun a bit more often as it becomes more active

Images below of the Sun are from the Solar Monitor website.

2 hours ago, JeremyS said:

Tim Gregory came to speak at the Bristol AS in 2019. Excellent speaker, every engaging and entertaining

It's going to be a tough one to spot from northern Europe I think !

I observed one of these a few years back - quite eerie to see this tiny dot of light creeping along against the backdrop of stars !

That's a good image for a mobile phone !

M82 has a couple of dust lanes across it which you can see with a larger scope at higher magnification and your image shows those.

They were the 1st galaxies I ever spotted with a scope - my old 60mm Tasco refractor !

M82 might have been outside the field of view with your scope - you need a reasonably wide field and low magnification to get them both in.

Good that your daughter is showing an interest as well

28 minutes ago, Nicola Fletcher said:

Do you really have to pay for membership on that site?

That looks fab - the case it comes with is amazing.

Yes, you do pay to use the classifieds and the forums.

The Cloudynights forum is free to join and often the classifieds there carry the same adverts as Astromart.

The problem with both for us is that they are predominately USA based sales and many sellers stipulate USA / Canada sales only and if they do sell over here, import duty and handling charges add a fair chunk to the price for the buyer.

I do 99% of my observing from a small patio which is about 3 metres away. The skies are around Bortle 5 / NELM 5 and a bit so not too bad.

When times are normal I can go to my local astro society observatory site which is about 5 miles away. It is not much darker than my back yard but it does have a lower horizon to the South, which can be useful.

7 hours ago, A McEwan said:

A new-to-me but obviously used Skytee-2 mount which incuded the ADM upgraded saddles and the heavy duty tripod! It was all a bit..."lived in"...but an hour or two with WD40, Cif degreaser and some microfiber clothes worked wonders. I need to get some longer slo-mo controls (see wanted ad) but otherwise it's really, really good!

Ant

I'll have to get the toothbrush and Cif out for my Skytee II - It's looking rather "well used" too !

Great mounts though, real workhorses. Mine is very heavily used

I guess you want longer slow motion cables to suit your long refractors ?. My Skytee II still has the original knobs on it but they can be quite a stretch to reach 

I got some lovely long ones with my T-Rex mount - I'll have to pop them on the Skytee II and give them a whirl on there.