Viewing problems with Astromaster 130

[Alan64]

In addition, a precise collimation is paramount when attempting the higher and highest powers of which the telescope is capable, and up to 200x is possible with a 130mm aperture.  I just don't know about eyeballing the collimation, and without that primary mirror being center-spotted; which it isn't in fact, as I found out at last.  

https://www.firstlightoptics.com/other-collimation-tools/rigel-aline-collimation-cap.html

https://www.cloudynights.com/topic/570729-uh-oh-how-can-i-tell-if-i-dented-or-fractured-my-telescope/?p=7775740

[Ricochet]

1 hour ago, Alan64 said:

You can dim down Jupiter and other bright objects with a variable-polariser...

http://www.rothervalleyoptics.co.uk/antares-variable-polarising-filter-125.html

I have found, and with my 150mm f/5, that decreasing the brightness will reveal colours and details, especially during moments of good atmospheric seeing.  If Jupiter, and Venus, appear as this...

...then you may want to try the variable-polariser.

I have found my polarisers to be less than helpful on Jupiter. Putting one in the optical path leads to a noticeable drop in observable detail. As a result I would suggest increasing magnification is a better solution to reduce brightness. 

[Alan64]

A polariser will reduce brightness, and as though one is observing with a smaller aperture instead, but the full resolution of the full aperture is retained.

I, on the other hand, have witnessed a surprising level of fine detail whilst using one; shattering e'en. 

In that the magnification may only be increased so far with a 130mm aperture, I'd suggest giving the polariser a whirl, if there's even the slight prospect of improvement.  It's also useful when dimming down the Moon during its various phases and varying levels of brightness; for the Sun as well, during the day, but only with a safe  solar filter fitted onto the front of the telescope.

The polariser will also reduce and even eliminate the diffraction-effects, the flares, when viewing brighter objects, and caused by a Newtonian's secondary spider-vanes...

...win-win.

[rockystar]

I've also had some success with a #80A blue filter on Jupiter, offers up a differently contrasted view.

[Grassblade]

Hi Guys,

...and a profound Thanks To All for the continuation of commentary.

I have a modest collection of filters and did indeed slap on a 13% ND and notice a little 'improvement'. I think M'Learn'd colleagues comments regard focal length/ magnification most informative and  would agree with that analysis. Or to put it in laymans terms Cr4p gear for the purpose!

I did get a better view but found I was struggling to maintain observation among all the black beans!

Attempting to take the Morris down the Santa Pod strip....everyone's just having a 'Bubble'!

Looking at the spider, it's a thick old tool....I note with interest the supports are way thinner on higher end weaponry and I'm sorry Celestron but balancing against eye relief and the zooming focal lengths I can 'see' the damn thing, that carries on to very definitely form a 'degradation' of image quality at the center of my view.

The 'scope/zoom do not get fully along together.

I take the point regarding fixed length and better quality eyepieces ( and, as I've mentioned, question the capabilities of a zoom to do all lengths properly. At worst some combinations of optical gear can do all things rubbishly)!

I know it's a good lens. I can see it's way beyond a tin can with a magnifying lens at each end...but...does it 'seem' to want to talk to the Celestron...I'm not sure it does.

More important that my ramblings. Any further comment on the 'Rattling' within? I have emailed Baader asking for any comment or recommendation....and received a damn good ignoring! Angry Bunny now then!

Once again...thank you guys...for your continuing attentions.

[Ricochet]

Did you use the contact form on their website to contact them or email directly? A direct email could potentially be rejected by a spam filter while the contact form should get a response. 

[Grassblade]

Yo Ric,

I did indeed. Although with other company contacts I've found in the past that the reverse to be more functional. Maybe they're all asleep in Germany? Easter etc? so 'Benefit Of The Doubt' for now plus folk who are off sick and so on.....FOR NOW.

Your personal thoughts? Is there room to believe any mech' within would be or could be possible/acceptable/fully functional with a toleranced 'movement'? Or have I got a slackly wandering element or group prancing around in my zoom making the focus poor and leading me to believe that this whole Astronomy lark is a waste of.....!

It's a MarkIV btw.

[Ricochet]

I don't know when you first contacted them but I would assume that they have taken time off for Easter and so that you have to account for that. I contacted them myself at the start of the month and had a reply perhaps the next working day. Follow up emails were also replied to promptly so I don't know why you wouldn't have received a reply. It is probably worth checking your junk mail in case the reply was lost on your end. If you don't receive a reply soon I would suggest that something has gone wrong and it would be worth trying again. 

With regards to the rattle in the eyepiece, I don't think that sounds right, although I've not owned a Baader zoom to know for sure. If Baader don't respond I would go back to your supplier, I'm sure they would replace the eyepiece. 

As far as seeing the central obstruction, that isn't right and you shouldn't be able to see it within the range of focal lengths the zoom covers. Do you see the same effect with the eyepieces supplied with the scope? Being able to see it suggests that either your eye is in the wrong position with respect to the eyepiece or you have not focused the eyepiece. 

[Moonshane]

Re the rattle it might be something as simple as a slightly loose retaining ring.  something like the one in the pic below. Try tightening it with a cocktail stick or similar, pushing the little notch clockwise a little until  rattle stops.

 

 

[wookie1965]

As Moonshane has said a couple of my BST`s did this i was scratching my head why until checked the rings.

[Moonshane]

I should add though that this is unlikely to be affecting the views, it's just annoying.

[Grassblade]

Hi Guys,

Happy Easter y'all,

With all 'rings' held or removed (the 1.25 nosepiece/ retainer / folding eyecup etc ) everything gripped or accounted for ( but everything exteriorwise IS engineered nice and tightly), there is a distinct clonk 'inside'.....like a rhino charging around in your lunchbox. Is this the missing focal? Or a whoops a daisy with the (new) Mark IV? Or is it just necessary tolerance, therefore normal? The 10 I mentioned earlier is pants...like gorping through a bubble. The 20 erecting isn't the most cracking optic on the planet but works well(ish).

My 'View' of the secondary/ spider is 'noticeable' as I rack up and down the eye position/ relief/ working focus ranges so that's just me with a Newt I feel sure. What I don't like is that the, Ok there, but defocused artefact is present in the FINAL working otherwise satis' (  at the edges ) image......ghosted...but there! I tried the other eye but that can't see Jack Sh....much.

The Cheshire say's everything is where it should be and so did a Star Test, nice, concentric an' everyfink! With a whole disc Lunar image, central in the view the center detail is off against the edges. This is not the focus difference between the edges of the Moon and the nearest middle is it? ( that sounds silly )!

I did whizz of the Emule well before Easter so if they're Next Working' type adults then I'll try them once more tomorrow. Benefit Of'...perhaps their only fluent englischer sprechen may be on holiday or sick, who knows.

 

 

[Ricochet]

2 hours ago, Grassblade said:

With a whole disc Lunar image, central in the view the center detail is off against the edges. This is not the focus difference between the edges of the Moon and the nearest middle is it? ( that sounds silly )!

Possibly. While I would expect there to be enough field depth to cover the difference, the moon isn't a flat object and it is possible you might need to refocus from centre to edge. What is more likely is that the combined field curvature of the telescope and eyepiece mean that the focus points for the centre and edge are different. You can test this by focusing a star in the centre of the field and then moving it to the edge and checking if it is still focused. Alternatively, if you know where to find a large star cluster you can check the focus of stars at the edge of the field of view against those at the centre. If your scope/eyepiece combination has significant field curvature then a usual method of minimising it is to focus half way between centre and edge rather than at the centre. 

[Sky Daddy]

May Be A Case Of High Expectations, All His Equipment Should Let Him See 2 Bands On Jupiter And The 4 Galilean Satellites As Little Point's Of Light..... 

[elliot]

But maybe not right now with Jupiter so low.  I really think that's the main prob.

[Grassblade]

That's ma point, I struggled to see much at all ( at high mag' with a dubious  focus ).  All I could 'determine' was something small, vaguely spherical and.... if squinted like a Clarence, possibly ( although not with as much certainty as possibly) some VERY dim banding ( maybe two, possibly, although we're dragging it now, three colours and four dots in nice line..

If that is low expectation then fine....Anyone want a telescope?

Low it was...but two tall trees at the end of my garden means 'not that low'.

[Cornelius Varley]

Somethings to consider concerning the blurring at the edge of the image. Eyepieces are sharper at the centre of the field of view, especially the cheaper ones supplied with budget telescopes, and the quality of the primary mirror. Parabolic mirrors are designed to give sharp focus across the mirror but the sharpness will tend to be less so nearer the edge of the mirror.

[Grassblade]

Then I really am up Thing Creek.....'Cos sharpness (when viewing the Moon as a Whole view 12 ish focal length) is characterised by noticeably acceptable EDGE ....er...edgeness sharply focussed!

I accept that this is the secondary/ spider nonsense. As I enquired...am I not cut out for Newts? 'optically'? Would a refractor be more ma thang? AS indicated by (Dare I say) 'other forums...This can be an issue to some folk.

 

[elliot]

I have a background in photography and also an AstroMaster 130. At best I've only seen faint bands on Jupiter. I think that really is the limit of a scope like this and because of your history, you may have been expecting sharper contrasty images. The thing is with photography, our subject is not behind 50miles of muck (let alone zillions of miles of space.)  I don't think it's a Newt issue as such: aperture, muck and expectations of photographic sharpness might be spoiling your experience. (Apols if this has already been covered but...) have you tried using the scope with the small cover on the cover removed? You can rotate it to remove the spider from the light line. Much reduced aperture of course but you might get some sharpness/contrast back. Use a low mag and really really look with super eye powers. Would love to hear the results.

[Ricochet]

14 hours ago, Grassblade said:

I accept that this is the secondary/ spider nonsense

Except that it seems to me that it isn't.

There are two things to consider that your eye can detect. The first is the image formed by the telescope/eyepiece. This is a circular image defined by the field stop of the eyepiece and the central area is not "blocked" by the shadow of the secondary mirror. Light from an object directly in the centre of the field of view passes the secondary mirror on all sides and is reflected back by the parabolic primary mirror to a point directly in the centre of the image. Light from a point offset from the centre also passes the secondary on all sides and is reflected back to a point offset from the centre of the image. All points in the field of view are affected equally by the secondary/spider in two ways:

1. The central obstruction causes extra diffraction compared to the unobstructed view of a refractor. This extra diffraction reduces contrast across the entire image, not just in the centre. 
2. The spider veins cause diffraction spikes on bright objects perpendicular to the directions of the veins. Again this effect is seen across the entire image.

The second thing that you can potentially detect is the shape of the exit pupil. This is the exact same shape as the aperture entrance and will appear like a circular ring in a telescope with a central obstruction. However, to detect this size of the obstruction has to be more significant with respect to the circle of light entering your eye which requires the exit pupil produced by the eyepiece to be larger than the dilation of your pupil. When you describe "viewing the moon as a whole" with a 12mm setting on the zoom I assume that you mean that the moon fills the entire view and that you also have the barlow lens fixed to the zoom? With this combination the exit pupil will only be 1mm, and there is no way that your pupil will be smaller than this. If you are not using the barlow then the exit pupil will be 2.4mm, which is a typical daytime pupil size and so I would think unlikely to be larger than your pupil. 

The other thing that makes me doubt that you are seeing the shadow of the central obstruction is that you describe the central degradation in terms of sharpness. If you were seeing the shadow superimposed over the image then I would expect the centre to be darker but still just as sharply focused as the edge.It still sounds to me like your issue is either that you haven't quite got your eye the right distance from the eyepiece or that the telescope/eyepiece combination has significant field curvature in which case you should be able to refocus to get the centre sharp and the edge blurry.

Also, as a last thing can you confirm that the end cap supplied with the 130mm Astromaster still looks like this:

and not this:

 

If they have changed things and the end cap now looks like the one in the second picture make sure that you are removing the entire end cap, not just the central part. If you remove just the central part then the obstruction would certainly be significant with respect to the much reduced aperture the telescope will be working at.

[Alfian]

I'm  a bit late to this discussion but my initial experience with my 130EQ (first 'scope) was not such a happy one.  Yes, the RDF is rubbish and the CG3 (EQ2) is pretty much on the limit with 130, but I really struggled to get it collimated even after centre spotting the primary. Eventually I discovered that the focuser was not as it should be. Upon dismantling I found that one of the three focuser guide strips was completely missing and another was way out of place at an odd angle inside the tube. I fabricated my own guide strips and reassembled it all and at at managed to get everything lined up. Celestron make some good telescopes but I've concluded that at the budget end of things, quality control is not so clever. I'm not saying the focuser is the cause of your problems but its worth checking that everything is as it should be and not assume it was A1 from the factory.

I did manage some fairly decent views with it and although I found that chasing a scopes max magnification is a bit of a fools errand, I think from memory 185x was about the most I could achieve with a just about acceptable image.  I have to say that cutting my teeth on the  130EQ  was useful and taught me quite a lot and I'm grateful for that, but on the whole it was a frustrating experience.  I bought a second hand Tal1 and even with its smaller aperture it was and is still is a much nicer scope to use.

[Grassblade]

Hi Guys,

I confirm that the Bin Lid is indeed the two smaller 'bung' type ( I assumed the removable one was in some fashion a climate equalisation thingy, leaving the main aperture protected....to stop flies, small children and camels getting in there while it cools) ? The Objective Cover is also a point of irritation ( although trivial). The damn thing doesn't stay on at all well, so yes... it's all removed for peeking (if only it would stay in place.....EVER )!

Overall the Astromaster is a passable excursion into The Dark Arts but personally I would say 'forget it and spend more' (it's not that great). Having tried it now for a while the higher end of the food chain makes a lot more sense....some things ( as I hinted earlier ) cost what they cost. Or to Mix Me Metafas...a Sinclair C5 is not a Vauxhall Fiesta, or a even a Ford Clio ( it isn't even a car, you ask Uncle Clarkson, he knows)!

 

.

[Grassblade]

Yes Ric,

I beg your pardon. I missed responding to your point regarding focus.

Yes that  is exactly what is happening...moving my eye to any and all distances the central area of view and the edges alternate between sharpness.

I really have to 'climb into' the Baader. It's...shall we say...Immersive! There isn't much eye relief?