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05/10/2021. Short Tube 80 revelations in Cassiopeia and surrounds. I need to buy more kit...




After a frankly disappointing session with my ST80 a couple of days ago I put the question to the SGL hivemind:

I received a LOT of helpful advice (lose the contrast booster filter!) and some suggested targets to try and gain some appreciation for the poor maligned thing. As last night was promising to be mostly clear I scribbled a target list down from the suggestions and grabbed the 'scope and went outside about 2130. I synced the AZGti with SkySafari for ease of use and began straight away - no cooldown time at all (a novelty!) I only took one eyepiece with me initially - my 24mm UFF.

Stock 2: 

Straight away I could see the difference that removing the filter had made. St2 was a scatter of tiny pinpricks of stars, interspersed by larger brighter ones.   Also in the same view was Struve 26 (Skysafari identified it as HD14172 and a bit of web cross referencing showed the Struve catalog ref) a lovely and obvious widely split double.  

I observed the vista for quite some time getting my head around the tiny, tiny sharp stars being shown by the ST80. Many more than in any binocular view (and my arms weren't shaking) and all so sharp... More stars popped out as my eyes acclimatised and the impression of depth grew.

Kemble's Cascade:

This was just a name to me when I typed it into the seach bar on SkySafari (I didn't look up any of the targets in advance)  and my notes read "Near vertical line of bright stars leading to NGC1502 (thanks SkySafari for the id.), with a dusting of dimmer stars visible to the LHS of the asterism. Wish I had darker skies".  


Tiny pretty open cluster. Two closely located bright stars visible instantly with a scattering of dimmer stars getting more numerous the longer you look.  Wiki says there are 45 - I'll have to have a count next time!

This next one wasn't on the list of advised targets but should have been - it did it for me. Wow!

Double Cluster:

This looked at first glance like a very large single circular open cluster bisected diagonally by a dark line of lower star density.  As I looked longer the two clusters kind of resolved themselves as separate - difficult to explain! A truly amazing sight with hundreds of tiny pinprick stars visible and the two clusters together nearly filling the view at 17x magnification.

I decided to revisit Andromeda without the contrast booster and could easily see M32 - still haven't located M110 even with goto assistance.


Gatekeeper stars 56 And and HR556 show the way to this delicate roughly circular open cluster. Again a feeling of depth started to occur as more stars were resolved as I observed longer...


I revisited this target again now I'd removed the contrast booster. Navi was visible in the same view and the cluster was very small, but different star colours were visible... Excellent!

At this point I thought I'd test the kit a bit and pointed at Capella - a nice bright star. At 17x magnification I could see a horizontal diffraction spike I'd not noticed before. I tried to compare the view without the diagonal but I don't have sufficient focus travel. 

At 50x magnification (42-8mm zoom) I could see vertical and horizontal diffraction spikes along with a smattering of CA and what I think was atmospheric refraction (blue on one side and red the other)- or maybe colour wedge? Maybe I need to settle the objectives as suggested. Capella was 32 degrees above the horizon at the time.

I thought I'd try and split Polaris and this time found the secondary - I think it was hiding before in a diffraction spike. Tilting the diagonal brought it out but it was very faint.


I've completely failed to find this a number of times star hopping with the dob. While I was here in the region of the sky with Goto I thought I'd have a look. I matched up the marker stars against SkySafari and I could see a very few of the brighter stars in the cluster. I'll have to return with the dob now the position is clearer...


While I was waiting for the Pleiades to clear the trees I did a goto to Uranus - just to tick it off my list really - I observed Neptune a few weeks ago. I wasn't expecting much, and didn't get much! Just a star in the right place in the view in relation to the background stars...


Now this is more like what I expected from the ST80! Filling the field of view, large bold obviously related stars. Looking white rather than blue but totally captivating. I didn't detect any nebulosity but I don't think I can expect any at this aperture. I'm not sure the neb I've seen with the dob is anything more than the powerful beam of light from the eyepiece lighting up the murk in my eyeball!

I took a last look at the double cluster before packing up at midnight. Wow! I think I need to get a mirror diagonal...



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Double Cluster and Pleiades, if either or both are around I always have a look at them if I'm using a widefield refractor, never tire of their beauty.

So, is that another convert to the cult of the humble , simple, unpretentious (and above all, cheap ) ST80 then ? 🙂 Welcome !


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20 hours ago, Tiny Clanger said:

Double Cluster and Pleiades, if either or both are around I always have a look at them if I'm using a widefield refractor, never tire of their beauty.

So, is that another convert to the cult of the humble , simple, unpretentious (and above all, cheap ) ST80 then ? 🙂 Welcome !


Yes! I appear to be part of the collective - mirror diagonal arrives today hopefully!

Thanks again for the help and advice!

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