Altair Astro 6” Ritchey Chretien review

[halli]

More food for thought in your responses !  

I guess there  is a little twisted logic to getting a scope for a longer focal length and then using a FR - I guess the RC is probably  worth it for its compact nature and coma free optics anyway !    I guess I will try it at its native F8 and see how it behaves before fitting a FR.  

I believe the AA one has all the spacers required.  I dont see much point in going for the CF tube for just weight alone as it is an extra £300  or so and this can help fund  a better focuser.  

Lovely galaxy images John - there appears to be a whole new world of DSOs on offer with this scope !

[johnrt]

Interesting thoughts to consider ideed Olly, you've just left me wondering where to mount my 2" IDAS if I remove the CCDT67 (it currently screws in to the front of it). I do see where you are coming from, but I also admit that I do like the slightly wider framing in the shots above, there's a background fuzzy just creeping in to the edge of the frame in nearly all of them  

BUT! I would be fibbing if I said I hadn't checked out numerous targets and rejected them as I didn't quite have the focal length to do them justice, these are the ones that got through!

[ollypenrice]

More food for thought in your responses !  

I guess there  is a little twisted logic to getting a scope for a longer focal length and then using a FR - I guess the RC is probably  worth it for its compact nature and coma free optics anyway !    I guess I will try it at its native F8 and see how it behaves before fitting a FR.  

I believe the AA one has all the spacers required.  I dont see much point in going for the CF tube for just weight alone as it is an extra £300  or so and this can help fund  a better focuser.  

Lovely galaxy images John - there appears to be a whole new world of DSOs on offer with this scope !

The carbon is not really about weight, it's about stiffness and freedom from thermal expansion/contraction and its effects upon focus. On the other hand the carbon is maybe more likely to retain heat in the tube. How does this really play? Does anybody really know? I know I don't. I wouldn't listen to anybody who hadn't imaged with both, that's for sure.

Olly

[halli]

Agreed Olly experience is the key - it seems from Sara's and John's experience above that CF seems to introduce focussing issues due to temp change and not the metal tube  - if I have interpreted correctly !

[swag72]

Agreed Olly experience is the key - it seems from Sara's and John's experience above that CF seems to introduce focussing issues due to temp change and not the metal tube  - if I have interpreted correctly !

An auto focuser has revolutionised my imaging for sure and if there was one thing I had to get rid of, I'm not sure what it would be, but it wouldn't be the auto focuser! So while I have zero idea of what causes my focus shift (be it carbon v's metal tube) this nifty piece of equipment makes it a non starter issue from the off I knew that every sub would be well focused...... not something I could say before I used it.

[kirkster501]

Another thing to consider about the AA RC8 Carbon version - the one that I have.  The tube might very well be carbon fibre.  But on the top and bottom of it are steel dovetails screwed into the tube.  And they CAN expand in changing temperature....!!!!

[halli]

ok guys  - I have pressed the button and ordered an AA 8inch RC with metal tube from Rother Valley Optics today !

Let you know how I get on.

cheers  Ian

[johnrt]

Good luck Ian, looking forward to seeing some images from the RC.

[halli]

Failed at he first hurdle - out of stock with AA currently - 6 weeks anticipated for new delivery................... very frustrating ! 

[halli]

Latest update  -  found a source of the AA RC8  in Europe - AST Optics -  so i've pressed the button and ordered it !    

They despatched it on 22/7 and according to the tracking status it is now on route in 'Gran Bretagna' after travelling through 'Germania' having started its journey in Alessandria.    So it may be here very soon !    

The excitement mounts...............

[damnut]

@johnrt,

Just seen this thread, those shots are amazing. Thanks for sharing.

[halli]

Hi Everyone

Well it finally arrived !   Although when unpacked it was branded TecnoSky not Altair Astro.  However it was a GSO RC8 with exactly the same spec including the Losmandy plates and 3 extension rings.  The first collimation with a Cheshire showed it was only slightly out and needed a little adjustment to the secondary only.  A further slight adjustment to the secondary was made with a star test.  Not sure how well I have done this so would welcome comments on the attached image.

So to the first real light with a camera !

I had a go at open cluster M103 to give it an easy first try  but without any guiding set up I had to reduce the exposure length to about 60s - and took 30 subs.

The result is attached after a quick and dirty processing in PI to get something out.   I am quite pleased with the star shapes as far as I can make out  - although some slight coma deep in the corners under high magnification only - which doesn't bother me !  

I would appreciate  any comments particularly at this early stage.

I have also obtained an OAG and focal reducer but want to do some work without the FR first so I can compare befoere and after.  I also  need to set up the OAG!   I presume this just goes in between the focusser and the camera.  It has a 2 inch nose piece supplied with it and I hope to use my ASI 120MC as the guide camera.  

Any tips on setting the OAG up would be most welcome !

So onward and upward to bagging some galaxies !

Best wishes

Ian

[damnut]

Hi Halli,

Great first result with the new scope. Look forward to seeing more of your images.

[r3i]

The main challenge with getting the OAG up and running is to get the imaging and guide cameras in focus at the same time. This is best achieved during the day when you have plenty of time to spare, by pointing your rig at a distant target such as an electricity pylon. This should get you pretty close and you should only need a small adjustment during your first imaging session.

[halli]

Thanks for the comment Damian and for the OAG tip Mike.  

I can see from the way the OAG is constructed that the focus is going to be fiddly !  

Unfortunately I dont have an object visible from my garden far enough away to represent the kind of focus necessary to represent a star so I may have to wait for a clear sky to work on it  which is a shame.    I have found that focus is achieved with my DSLR with the three extension rings on and the focusser just wound out about 5mm, so I have taken one of the rings off to put the OAG in so I guess I may be able to figure out where the rough focus needs to be with the DSLR beforehand.   I am hoping there may be a bit of a clearance early on tonight to have a fiddle.  Looking forward to it !

Thanks again

Ian

[astrosathya]

I was surfing for reviews of the GSO 6" RC, and this happens to be right from the heart. Also the quality of the images are simply superb, but that mostly would boil down to the skills of John, who is an amazing Astrophotographer. I sold my Sky-Watcher Explorer 200, F/5 Newt  yesterday and now in the market for a less bulky scope. My primary interest are small galaxies, so I as leaning towards the 6" RC. Brilliant review I must say, and I am convinced that it is the scope of my choice. Thanks once again John for the wonderful writing.

[Sp@ce_d]

John's fantastic results & this review inspired me to move away from the SCT as my long FL weapon of choice & embrace star spikes. Although I'm still trying to work out how to get rid of those large stars showing the shape of the central obstruction!

I went for the 8" AA CF tube and been very happy with it so far. It was smaller than I expected & certainly lighter after having the SCT on the mount. Of course the one thing I overlooked when I ordered mine were the "Masters Hands". John obviously already had his... I'm not sure if they do them in my size.. or even what my size is as I'm still trying to work out how to get these Boxing Gloves off!! 

[swag72]

These are great scopes for sure and John is an example to us all

[ChrisLX200]

I would agree these are excellent scopes for the money, and are a much better option (IMHO) than an equivalent SCT for DSO AP. I would say though that the 8" and larger OTAs are to be preferred - not just because they _are_ bigger but because even the 8" is easy to mount/guide and the price difference is modest. I have the metal tube 8" version and it shows much promise. Sadly, what with other new gear to get working together with horrible weather for the past 2 months I've hardly had chance to use it at all. I spent more time playing with the collimation than taking images. Below is one of only two actual 'fitst light' images I've captured using it, and what impresses me is the useful image scale I get with the 490EX camera, and the good definition. This is only 4 x 900s luminance subs but I wish I could collect a full LRGB set (preferably without aircraft trails...)

ChrisH

I meant to add - the optics are well secured in the tube and I found I could generate a model using my 10-Micron mount of 5" RMS, which means I can use the scope unguided (as indeed it was for the above image). I don't think I could have got away with doing that with an SCT.

Edit: Oh poo. That was the wrong image... I wondered where the diffraction spikes had gone! I'll leave it there though (it's a cropped image from the 5" refractor but more subs than with the 8" RC). So. Ahem. The AA 8" RC image is below:

Edited November 30, 2015 by ChrisLX200

[johnrt]

Thank you for all the comments!

The truly amazing thing about thing about the 6"RC is that it doesn't get more exposure as an imaging scope and not more people have caught on, perhaps Chris is right and the 8" version is preferred. I have thought about upgrading to the 8" RC but then what would be the point, especially after the weather since the end of May in the UK has been terrible ???

I have the latter part of last year and all of this year so far honing my LRGB skills, which is a dark art all in itself, but as they say with capturing the data - rubbish in, rubbish out!

PS. I last collimated this scope in Summer 2014 and it's still bang on!

Edited November 30, 2015 by johnrt

[Thalestris24]

I'm quite tempted by a 6" version especially as I frequently feel the lure of galaxies TS have a bit of a discount on the GSO version at the moment. Any differences between the AA and GSO versions? I'm a bit concerned by the f9 though, yet I'd need the fl for galaxies. Any thoughts? How challenging are they to collimate compared to an f5 newt?

Thanks

Louise

Edited December 10, 2015 by Thalestris24

[ChrisLX200]

I'm quite tempted by a 6" version especially as I frequently feel the lure of galaxies TS have a bit of a discount on the GSO version at the moment. Any differences between the AA and GSO versions? I'm a bit concerned by the f9 though, yet I'd need the fl for galaxies. Any thoughts? How challenging are they to collimate compared to an f5 newt?

Thanks

Louise

It is more complicated to collimate than a Newt, you need a decent laser (like a Glatter) and follow the various tutorials - there's a YouTube one linked from the AA website. The problem with RCs is that there is only one position where both primary and secondary mirrors are both in correct alignment with each other - unlike a Newt or SCT where the secondary can be collimated independantly and good collimation achieved.

ChrisH

[Thalestris24]

It is more complicated to collimate than a Newt, you need a decent laser (like a Glatter) and follow the various tutorials - there's a YouTube one linked from the AA website. The problem with RCs is that there is only one position where both primary and secondary mirrors are both in correct alignment with each other - unlike a Newt or SCT where the secondary can be collimated independantly and good collimation achieved.

ChrisH

Hi Chris

It sounds quite stable, though (re johnrt above)? Looks like I'd need one of these too?

Anyway, I'm thinking about it!

Thanks

Louise

[prusling]

Hi Louis,

I have an RC6 and found that locking the focuser would tilt it a little. I did get an adjustment ring but that was not ideal.

Instead I bought a monorail focuser from TS which have been reduced and seem great value.

It's early days yet but they do seem more stable than the stock item and could be a better option than the adjustment ring for not much more cost.

Cheers

Peter

[Thalestris24]

Hi Louis,

I have an RC6 and found that locking the focuser would tilt it a little. I did get an adjustment ring but that was not ideal.

Instead I bought a monorail focuser from TS which have been reduced and seem great value.

It's early days yet but they do seem more stable than the stock item and could be a better option than the adjustment ring for not much more cost.

Cheers

Peter

Hi Peter

Ok - thanks for the tip! I think I might experiment with my 150pds + a ed barlow before splashing out on yet another scope. That way I can get 1500mm albeit at f10 (rather than f9) but at least I can see how I might get on with long fl guiding and imaging. Mind you, the currently discounted RC from TS I linked to does seem a bargain and I also like the idea of a shorter tube..

Louise