Grab and go advice...

[Ricochet]

If the only thing stopping you from buying one of the mini dob telescopes is the mini dob mount, it is worth noting that almost all of them (i.e Skywatcher/Orion/Bresser) have a standard Vixen dovetail and so can be mounted on any standard mount with a Vixen clamp (unfortunately not your current mount). Given that all of the other suggestions so far in this thread will also require the purchase of a new mount, I don't think that is really a negative to worry about. 

How "transportable" do you also need the new mount to be? Do the legs of your current mount cause you issues with transport in the car like the telescope does? There are several mounts (e.g. Skywatcher AZ5, GTi) that have 3/8" mounting points that allow them to be fitted onto a good photo tripod which can then collapse down into a very small package for transport/storage.

[Marc1964]

18 hours ago, Cosmic Geoff said:

If you want a widefield 'scope with which to learn the sky, you could do worse than get the Sky-watcher Startravel 102 (102mm aperture, 500mm focal length).  It is inexpensive, quite well made, similar to the Evostars, and easy to handle (I normally carry mine in one hand).  It also works surprisingly well for dabbling in EEVA and astro-imaging.

On the downside, it has some chromatic aberration and field distortion, and is not much good for high power work (e.g. planets) but you can't have everything unless you want to spend 896 Euros + shipping. (see above).

The Startravel should mount on your existing tripod.

Hi

Thanks for the advice. I do wonder about SW quality sometimes... The lenses that came with mine were poor, the diagonal is poor (I used a relatively cheap one a friend had one night and was unpleasantly surprised at how much better it was). How have you found quality of the components overall? 

[Cosmic Geoff]

2 minutes ago, Marc1964 said:

Thanks for the advice. I do wonder about SW quality sometimes... The lenses that came with mine were poor, the diagonal is poor (I used a relatively cheap one a friend had one night and was unpleasantly surprised at how much better it was). How have you found quality of the components overall? 

I have no particular criticisms. The eyepieces that came with it were not that great but that applies to any lower priced outfit you might buy. The Barlow that came with it somewhat improves the performance on planets, and this Barlow seemed to work just as well as a Celestron Omni x2 Barlow I bought recently, originally priced at £50.  My Startravel OTA came with a terrestial 45 deg diagonal, but fortunately I had a a spare star diagonal.    Major parts of the OTA and focuser are all metal.

The terrestial diagonal is actually useful if you want a RACI image to avoid swapping your brain L/R, but does not give as sharp an image as a star diagonal.

[Marc1964]

2 hours ago, Ricochet said:

If the only thing stopping you from buying one of the mini dob telescopes is the mini dob mount, it is worth noting that almost all of them (i.e Skywatcher/Orion/Bresser) have a standard Vixen dovetail and so can be mounted on any standard mount with a Vixen clamp (unfortunately not your current mount). Given that all of the other suggestions so far in this thread will also require the purchase of a new mount, I don't think that is really a negative to worry about. 

How "transportable" do you also need the new mount to be? Do the legs of your current mount cause you issues with transport in the car like the telescope does? There are several mounts (e.g. Skywatcher AZ5, GTi) that have 3/8" mounting points that allow them to be fitted onto a good photo tripod which can then collapse down into a very small package for transport/storage.

Hi, thanks for the points you are making. Ideally I would like to comfortably be able to carry the mounted telescope comfortably for upto 20 minutes on foot. I have done that with the 90/900 mounted and it is surprisingly heavy after awhile!  It also ideally should be able to fit in my mini in the back without needing me to put back seats down  and move passenger seat forward 😂

I have not ruled out the mini dobs yet. They offer a lot of bang for the buck and I am actively looking at ways in which I could use one up on the Downs or in the local fields... 

Thanks! 

[Marc1964]

19 hours ago, johninderby said:

90mm isn’t a common size for ED or APOs and hence seem to be a bit expensive.

There are some fine triplet 90mm APOs but £££

https://www.teleskop-express.de/shop/product_info.php/info/p5964_TS-Optics-CF-APO-90-mm-f-6-FPL55-Triplet-with-Certificate.html

Ouch! 

[Marc1964]

10 hours ago, Davesellars said:

Ah, that's a shame.....  Get a bigger car????

I used to walk with gear from my apartment about 15 mins walk to an allotment where at least I kept my mount in a shed.  I can relate to the need to keep it lightweight though!  TBH, the mount is the most problematic to find something sturdy enough (especially for planetary obsevation) that you can physically walk with the any length of time so perhaps stick with using the car.    If the tripod at least goes in without having to lay down the seats you may have more options?

Yes the mount will be the biggest issue. They are not cheap and cheap ones are probably not very good! 😁 John gave a recommendation for me for an AZ5 mount and legs which I will probably follow... 

Actually the biggest problem is the 900mm tube in the mini, the mount less so! The mini boot and the width of the car mitigates against a 900 tube. A bigger car is probably on the cards in the next 12 months but for reasons other than astronomy (shockingly enough!). 

[vlaiv]

11 hours ago, Marc1964 said:

I have not seen much in the way of reviews. They seem to be a reputable brand and the optics, whilst not full ED seem to be pretty well received. Anyone got experience of this at all??? 

Check this out:

http://interferometrie.blogspot.com/2017/06/3-short-achromats-bresser-ar102xs.html

[johninderby]

Pretty much what I found with the Bresser 102xs.

[Marc1964]

14 minutes ago, vlaiv said:

Check this out:

http://interferometrie.blogspot.com/2017/06/3-short-achromats-bresser-ar102xs.html

OK thanks. Very technical review! So if I follow this correctly, the CA on the AR 102 xs is poor compared to the known ED glass of competitors, therefore the claims of using an ED type glass should be taken with a pinch of salt... This could be a good reason not to consider the shorter Bresser then... 

[Marc1964]

4 minutes ago, johninderby said:

Pretty much what I found with the Bresser 102xs.

Doesn't sound like a good long term scope. I wonder if the larger AR-102S is better in this regard? More reading to be done... 

[Tiny Clanger]

2 hours ago, Marc1964 said:

Hi

Thanks for the advice. I do wonder about SW quality sometimes... The lenses that came with mine were poor, the diagonal is poor (I used a relatively cheap one a friend had one night and was unpleasantly surprised at how much better it was). How have you found quality of the components overall? 

What I failed to completely grasp before actually buying and using a 'proper' telescope is that some of the accessories are just there as a 'get you started' measure, I liken them to those special, low capacity ink tanks some inkjet printer manufacturers supply with new printers . Enough to prove the thing works, but you will soon be spending some more money ...

Every skywatcher 'scope I've looked at seems to come with the same 10 and 25mm eyepieces, the 10mm is horrible, the 25mm is OK The cheapest upgrades would be standard plossls ( around £20-£30 each) which are a small but noticeable step up , but the current favourite recommended 'cheap' eyepieces are BST Starguiders, which are at the moment close to £50 each including P&P.

Ditto the finder on most scopes is a very basic model, I put up with the RDF  for a few months, but performing contortions to get my eye in line , and problems with averted vision visible objects being impossible to see looking straight at via the RDF sent me buying a RACI ...

Then on my shiny new mak I can use the RACI, but ... there is only one finder shoe, and an RDF would be useful for some brighter objects, and I'm too cowardly to dismantle it to drill holes for a second shoe ... So I end up buying a rigel quickfinder which has a small footprint, stick-on base .

So, I've spent around £80 in total on better finders (which can be swapped between the two 'scopes ) and at least double that on eyepieces. Nearly forgot, there's the original kit diagonal on the mak, it was plasticky and not very lovely. I got lucky and bought a second hand skywatcher dielectric star diagonal second hand from a seller on here , new it would have been £69.

[vlaiv]

Just now, Marc1964 said:

OK thanks. Very technical review! So if I follow this correctly, the CA on the AR 102 xs is poor compared to the known ED glass of competitors, therefore the claims of using an ED type glass should be taken with a pinch of salt... This could be a good reason not to consider the shorter Bresser then... 

That is to be expected. Level of CA depends on both glass type and speed and aperture of the telescope.

AR102xs is 4" F/4.5 scope - you simply can't get that sort of speed at 4" with good correction unless you throw like 5-6 optical elements. I'm sure that it indeed uses some sort of ED glass as simple achromat at F/4.5 and 4" would be much more colorful.

It is good scope - if you need that sort of speed and you want to limit yourself to wide field viewing. Similarly - if you get ST102 - you'll get wide field scope that has CA and is light weight.

If you want 4" ED scope that is good for visual and won't break the bank (it's not cheap but it is not as expensive as some models out there) - get this one:

https://www.teleskop-express.de/shop/product_info.php/info/p4964_TS-Optics-ED-102-mm-f-7-Refractor-Telescope-with-2-5--R-P-focuser.html

That scope is still not color free - you'll be able to see some CA at high power views and bright targets like Venus or bright stars. It is not quite grab'n'go either - it has 4kg and at least 60cm with dew shield retracted (I'm hoping it has retractable dew shield - it looks like it).

[vlaiv]

5 minutes ago, Marc1964 said:

Doesn't sound like a good long term scope. I wonder if the larger AR-102S is better in this regard? More reading to be done... 

Here is good scope in that category (but it is expensive):

https://www.bresser.de/en/Astronomy/Telescopes/EXPLORE-SCIENTIFIC-AR102-Air-Spaced-Doublet.html

I would consider adding some more money and going for that TS 4" ED scope that I linked above instead of this achromat.

[Marc1964]

4 hours ago, Tiny Clanger said:

What I failed to completely grasp before actually buying and using a 'proper' telescope is that some of the accessories are just there as a 'get you started' measure, I liken them to those special, low capacity ink tanks some inkjet printer manufacturers supply with new printers . Enough to prove the thing works, but you will soon be spending some more money ...

Every skywatcher 'scope I've looked at seems to come with the same 10 and 25mm eyepieces, the 10mm is horrible, the 25mm is OK The cheapest upgrades would be standard plossls ( around £20-£30 each) which are a small but noticeable step up , but the current favourite recommended 'cheap' eyepieces are BST Starguiders, which are at the moment close to £50 each including P&P.

Ditto the finder on most scopes is a very basic model, I put up with the RDF  for a few months, but performing contortions to get my eye in line , and problems with averted vision visible objects being impossible to see looking straight at via the RDF sent me buying a RACI ...

Then on my shiny new mak I can use the RACI, but ... there is only one finder shoe, and an RDF would be useful for some brighter objects, and I'm too cowardly to dismantle it to drill holes for a second shoe ... So I end up buying a rigel quickfinder which has a small footprint, stick-on base .

So, I've spent around £80 in total on better finders (which can be swapped between the two 'scopes ) and at least double that on eyepieces. Nearly forgot, there's the original kit diagonal on the mak, it was plasticky and not very lovely. I got lucky and bought a second hand skywatcher dielectric star diagonal second hand from a seller on here , new it would have been £69.

Hi, yes I have come to realise this... I quickly bought two new Celestron omni plossl lenses (15mm & 32mm)off ebay for around £40 new total. I have no idea how they compare to other brands but a major improvement on the SW ones that came with the scope... Need to replace the Barlow next, and then the diagonal.... 

I was out for a walk on the South Downs this afternoon and about 10 minutes walk from my car park where I do majority of my viewing, there is a concrete water tank about table height. Could be used for a mini dobson... Maybe the Orion Starburst 4.5 or the SW Heritage could come into my life... 

Scouring ebay and used sites to see what the art of the possible is now! 

[Marc1964]

15 hours ago, Nyctimene said:

The Heritage 130 P Flextube in the trunk of my tiny Seat Mii,

together with a folding stool and the PSA in the left corner. Still enough space for some eyepieces...

Stephan

Your Mii has a nice deep boot which ironically is better than the Mini boot... 😁 

Seriously though, was good to see a picture with the scope in! Thanks! 

[Tiny Clanger]

1 hour ago, Marc1964 said:

Hi, yes I have come to realise this... I quickly bought two new Celestron omni plossl lenses (15mm & 32mm)off ebay for around £40 new total. I have no idea how they compare to other brands but a major improvement on the SW ones that came with the scope... Need to replace the Barlow next, and then the diagonal.... 

I was out for a walk on the South Downs this afternoon and about 10 minutes walk from my car park where I do majority of my viewing, there is a concrete water tank about table height. Could be used for a mini dobson... Maybe the Orion Starburst 4.5 or the SW Heritage could come into my life... 

Scouring ebay and used sites to see what the art of the possible is now! 

Yep, my first tentative EP purchase was a skywatcher 17mm 'super' plossl , because I wanted to see for myself if better EPs really would give my eyes,  in my garden, through my 'scope a better view worth £20 ... I went for the 17mm as it was part way between the 10 and 25mm , so even if it wasn't any better, I'd at least have an extra magnification step. It was so much better I added a 32mm from the same series. Reading about the drawbacks of plossls at greater magnification, I went mad and splashed the cash on an 8mm BST starguider (from Alan at 'The sky's the Limit' , a few £ cheaper than other sellers , and he is a very nice guy , responding to my daft questions politely. ) . 

Happy to report that the BST starguider is as far ahead of the SW super plossls as they are of the bundled 10mm . A few BSTs came up secondhand on here, and were snapped up in minutes, finances meant I could only realistically choose one of them, so I got a 25mm and have retired the bundled one.

If/when any become available second hand, get in fast ... I'll race you (as will many others !)

Heather

[RobertI]

I'd also heartily recommend the Heritage Flexitube 130P or 150P.  Very lightweight, so doesn't need a super heavy mount. Has standard vixen rail, so can be mounted on anything. Collapsible so doesn't take up much room. Decent focal length and aperture. Very versatile and excellent quality optics. Because the eyepiece is at the top, the tripod can be set low, adding to the stability. A lot of experienced observers use them for convenience. The helical focuser is the only downside, but it is perfectly adequate, although zoom eyepieces are a bit of a pain to use.

When I spent a couple of days at a dark sky site recently, I wasn't sure what to take - eventually I took pretty much everything, but when I got there I ended up using the Heritage 130P as it's so easy to set up!

Here is the 130P on a Giro-WR mount on a Horizon photo tripod, and a 66mm apo the other side. The whole thing can be easily lifted with one hand.

 

Edited December 31, 2020 by RobertI

[Spile]

On 30/12/2020 at 13:37, Tiny Clanger said:

Every skywatcher 'scope I've looked at seems to come with the same 10 and 25mm eyepieces, the 10mm is horrible, the 25mm is OK The cheapest upgrades would be standard plossls ( around £20-£30 each) which are a small but noticeable step up , but the current favourite recommended 'cheap' eyepieces are BST Starguiders, which are at the moment close to £50 each including P&P.

I understand why cheaper EPs are included - it keeps down the cost but they 'get you going' without compromising on the quality of the rest of the instrument. That said, I purchased a Hyperion Mark IV Zoom less than a week after getting the 200P!

[Marc1964]

OK quick, probably dumb (!) question:  Is an 'air spaced' doublet a thing or just marketing speak?

[vlaiv]

30 minutes ago, Marc1964 said:

OK quick, probably dumb (!) question:  Is an 'air spaced' doublet a thing or just marketing speak?

Real thing - type of lens, you can have air spaced, oil spaced or cemented doublet (probably even other kinds depending on material used between lens).

Air has refractive index that needs to be matched to glass when designing optical characteristics.

Air spaced is usually better than cemented (more surfaces that can be independently curved) and is light enough as construction does not require additional weight.

[Marc1964]

3 minutes ago, vlaiv said:

Real thing - type of lens, you can have air spaced, oil spaced or cemented doublet (probably even other kinds depending on material used between lens).

Air has refractive index that needs to be matched to glass when designing optical characteristics.

Air spaced is usually better than cemented (more surfaces that can be independently curved) and is light enough as construction does not require additional weight.

So an 'air spaced' doublet should in theory be optically better I assume than a cemented or oil doublet?  Or is the answer 'it depends'?

[KP82]

19 minutes ago, Marc1964 said:

So an 'air spaced' doublet should in theory be optically better I assume than a cemented or oil doublet?  Or is the answer 'it depends'?

Google the terms "air spaced" and "oil spaced". You will be able to find detailed explanations on the pros and cons of them.

In short both "air spaced" and "oil spaced" lens designs are used by top tier premium refractor manufacturers. For example Takahashi and LZOS use air spaced whereas TEC and CFF use oil spaced. Astrophysics uses both.

[vlaiv]

27 minutes ago, Marc1964 said:

So an 'air spaced' doublet should in theory be optically better I assume than a cemented or oil doublet?  Or is the answer 'it depends'?

Each surface where two mediums with different refractive index meet is degree of freedom for optical designer.

With air (or oil) spaced doublet you really have 4 such surfaces:

First lens has air/glass and then glass / air surface (or glass / oil) and second lens has again air/glass (or oil/glass) and then glass/air surface. Each of these 4 surfaces (first lens front and back, second lens front and back) can have different curve to it and combination of these curves (and distance between them) defines optical properties of system.

With cemented doublet - you only have 3 surfaces - you have air / glass1, then glass1/glass2 and finally glass2/air (as glasses are touching - they must have the same curve where they meet).

Less surfaces to work with and less things you can tweak for optimum optical performance.

[Marc1964]

Just now, vlaiv said:

Each surface where two mediums with different refractive index meet is degree of freedom for optical designer.

With air (or oil) spaced doublet you really have 4 such surfaces:

First lens has air/glass and then glass / air surface (or glass / oil) and second lens has again air/glass (or oil/glass) and then glass/air surface. Each of these 4 surfaces (first lens front and back, second lens front and back) can have different curve to it and combination of these curves (and distance between them) defines optical properties of system.

With cemented doublet - you only have 3 surfaces - you have air / glass1, then glass1/glass2 and finally glass2/air (as glasses are touching - they must have the same curve where they meet).

Less surfaces to work with and less things you can tweak for optimum optical performance.

Thank you - my education in telescope technology continues....

[Marc1964]

On 30/12/2020 at 13:37, Tiny Clanger said:

What I failed to completely grasp before actually buying and using a 'proper' telescope is that some of the accessories are just there as a 'get you started' measure, I liken them to those special, low capacity ink tanks some inkjet printer manufacturers supply with new printers . Enough to prove the thing works, but you will soon be spending some more money ...

Every skywatcher 'scope I've looked at seems to come with the same 10 and 25mm eyepieces, the 10mm is horrible, the 25mm is OK The cheapest upgrades would be standard plossls ( around £20-£30 each) which are a small but noticeable step up , but the current favourite recommended 'cheap' eyepieces are BST Starguiders, which are at the moment close to £50 each including P&P.

Ditto the finder on most scopes is a very basic model, I put up with the RDF  for a few months, but performing contortions to get my eye in line , and problems with averted vision visible objects being impossible to see looking straight at via the RDF sent me buying a RACI ...

Then on my shiny new mak I can use the RACI, but ... there is only one finder shoe, and an RDF would be useful for some brighter objects, and I'm too cowardly to dismantle it to drill holes for a second shoe ... So I end up buying a rigel quickfinder which has a small footprint, stick-on base .

So, I've spent around £80 in total on better finders (which can be swapped between the two 'scopes ) and at least double that on eyepieces. Nearly forgot, there's the original kit diagonal on the mak, it was plasticky and not very lovely. I got lucky and bought a second hand skywatcher dielectric star diagonal second hand from a seller on here , new it would have been £69.

@Tiny Clanger you have put doubt in my mind. I have disappeared down the refractor vs reflector debate and agonised over dobsonian mounts... So I am now contemplating this: https://www.harrisontelescopes.co.uk/acatalog/bresser-messier-6-dobsonian.html#SID=1739