Altair Astro 6” Ritchey Chretien review

[johnrt]

To be honest I haven't found dew to be an issue with my RC. I have used it on some pretty damp and cold evenings, and while my ST80 is fogged up the RC stays nice and clear. I would suggest a quick blast from a hair drier if you don't want to install the secondary mirror heater (which looks rather nifty btw) would be good enough to keep it all clear.

John

By the way where abouts in Kent are you Magnum?

[johnrt]

One of these might help too, but I can't seem to find anywhere that sells them in the UK

https://www.astronomics.com/astrozap-flexible-black-plastic-6-inch-astro-tech-at6rc_p19266.aspx

[johnrt]

I've emailed FLO to ask if they will consider adding them as they already stock Astrozap dew shields.

[Magnum]

Thanks, sounds ok then.

I made the dew shield for my 8" SCT from one of those foam camping mats, and it works perfect and is weightless :-)

Lee

[frjaraur]

Hi All,

Nice review!!!, It made me buy a GS RC6"

I bought a secondhand GSO RC6" but I can't reach focus with my DSLR or even using it for visual. I knew I have to buy some extenders but I will like to know exactly which ones for visual and for imaging use??

It comes with a 80mm extender but I can't focus¿?? (I haven't tried with T2 inside this extender because I only have a flattener T2 from my ED80...).

I think I have to buy following extenders:

_ for DSLR imaging: 50mm RC extension( to be placed between focuser and telescope) + 40mm T2 extension

_ for visual use: I found this "If you want to make visual observing, you will need a 35mm extension tube for a 2" Diagonal and a 50mm Extension tube for a 1,25" diagonal." I have a 2" diagonal with 1,25" adapter (I only have 1,25" eyepieces..), so what to buy?¿?

Could someone advice my what to buy for imaging and casual visual usage??

Many Thanks in Advance,

Regards,

Javier R.

[astrogardener]

Interesting thread guy's.

Gotta say, if anyones contemplating photometry, these 'scopes are superb.

A dew shield is essential and care should be taken on the ballance on the mount.

Clear skies.

[johnrt]

Doug, I agree the 6"RC is a great scope, if you're prepared to get stuck in to it. My latest upgrade for it is in the post from that America - a Losmandy dovetail for mounting the OTA to my AZEQ6. http://www.deepspaceproducts.com/d-series-dovetail-plate-astro-tech-orion-rc-6-quot-_8_4234_8580.html

There have been many images with this scope since I last updated this thread, and rather than re-post them all here as many were posted individually in DSO imaging section, you can find them all on my webpage if your interested  https://cloudedout.squarespace.com/blog/

Edited December 18, 2014 by johnrt

[T997]

very interesting thread.

John - I see on your website that you're currently using an IDAS LP2 filter. Have you placed this in your filter wheel? (or is it placed ahead of the filter wheel and therefore used in all images?)

Thanks,

joe

[johnrt]

very interesting thread.

John - I see on your website that you're currently using an IDAS LP2 filter. Have you placed this in your filter wheel? (or is it placed ahead of the filter wheel and therefore used in all images?)

Thanks,

joe

I have the 2" IDAS which sits infront of the filter wheel and I leave in place permanently - even for narrowband. The IDAS has over 95% transmission for Ha so I'm only missing out on an insignificant amount of photons by leaving it on all the time.

[kirkster501]

I have the 2" IDAS which sits infront of the filter wheel and I leave in place permanently - even for narrowband. The IDAS has over 95% transmission for Ha so I'm only missing out on an insignificant amount of photons by leaving it on all the time.

+1

I'm not at John's level of expertise but I do similar. I leave mine on the front of the CCDT67 reducer.

Sent from my iPhone using Tapatalk

Edited February 16, 2015 by kirkster501

[T997]

ok, thanks for clarifying

[T997]

johnrt & kirkster501 - I see that you're both using the Atik 460. Aside from the 2" IDAS filter, are your other filters 1.25"?

Do you find any issues with vignetting on the CCD image using the 1.25" filters?

I have a similar setup, but I use a DSLR at the moment; I'm seriously considering upgrading to the Atik. With the DSLR, all filters are 2" to avoid vignetting, but it is my understanding this is less of an issue with the smaller chips of CCDs such as the 460.

Thanks,

joe

[kirkster501]

I use 1.25 filters other than the IDAS. A bit of vignetting but flats take care of it.

Sent from my iPhone using Tapatalk

[johnrt]

johnrt & kirkster501 - I see that you're both using the Atik 460. Aside from the 2" IDAS filter, are your other filters 1.25"?

Do you find any issues with vignetting on the CCD image using the 1.25" filters?

I have a similar setup, but I use a DSLR at the moment; I'm seriously considering upgrading to the Atik. With the DSLR, all filters are 2" to avoid vignetting, but it is my understanding this is less of an issue with the smaller chips of CCDs such as the 460.

Thanks,

joe

The 460ex is fine with 1.25" filters. You can even get away with them on the larger 383l if they are kept close to the camera chip. Edited February 16, 2015 by johnrt

[ollypenrice]

There is nothing inexpensive about Deep Sky astrophotography regrettably. I shelled out over £2500 - my performance bonus paid in June - for my CCD and filter wheel/filters. I have nigh on £5k worth of gear now. And still not got all what I need. You can easily double or triple that sum for top range gear like a Takahashi scope and Mesu mount with a Atik 11000 - all stuff Olly has btw !

Don't give up on a DSLR. You can get fabulous results with one. Best beginner combination to get good resultsfor DSO AP is a ED80/HEQ5 and a modded DSLR. You can pick that lot up for a grand or so and will get you going.

Yes but I've got an excuse! I earn my living with it...

OK, I never said it was a good excuse!   

What I would say, though, is that in a vote for best optics for buck I think I'd have to go for the subject of this thread, the 6 inch RC. Or the 8 inch. John and Sara really do show what's possible. The resolution on that Pacman above is astounding.

Olly

[halli]

Ok having seen what is possible with this scope  - I am up for the challenge ! -  and aim to get the ALtair Astro 8 inch.  Although am tempted by the 10 inch but the cost is another £1000 !  

Any views in whether this is worth the investment ? Have a NEQ6 so  should be ok.  

Many thanks for all the contributors to this thread and in particular Johnrt who has proven that the scope can be taken to a workable device which takes great images of small DSO.  This has helped consolidate my view although it may be a rocky ride !

I have a 130pds for widefield and want to hop on to an evolutionary path to more aperture and focal length for smaller objects - only have a DSLR at the moment  so am hoping that this will be OK at F8 wrt S/N.  However the end point is  CCD but a little later and I guess a focal reducer will bring the Focal ratio to a manageable state.  

Has anyone any views on the best FR to use ?

Thanks in anticipation.

Ian

[r3i]

I've got the Atlair 8" version and with an OTA weight of 7.5kg it sits well on the NEQ6.  I was also tempted by the 10" but is considerably more expensive and heavier at nearly 16kg so I erred on the side of caution. 

The Astro Physics CCD67T focal reducer works well with these scopes.

[swag72]

I had an AT8 carbon fibre - It was a great scope and sat on my Avalon Linear Fast reverse without difficulty. It did have the Feathertouch focuser fitted and I have to say that this was a sublime focuser that made life much easier. I did find that it lost focus quite significantly with temperature changes and so this led me to automating the focus otherwise I was having to throw half of my data away.

I didn't bother using the focal reducer (the CCD67T is the general recommendation with these scopes) as I wanted the longer focal length, and I didn't want to mess about with spacing.

Whatever you do, make sure that you get the extension tubes with the scope - These are essential to achieve focus and are extremely and stupidly expensive to buy separately. 

This is a great scope in all of it's clones and I would totally recommend it. 

[johnrt]

Thanks Ian, so long as you’re prepared you won’t regret buying either the 6 or 8” RC.

Just on the subject of focus drift - I used to have a carbon 80mm triplet refractor and found that the scope contracted a large amount moving the focus point as the temp dropped, it is as Sara says, a problem if you are manual focusing. However with the metal tube of the 6” RC I find there is no focus adjustment needed at all, just focus at the start of the night and forget about it. Perhaps this is due to the carbon body that just expands and contracts more than the standard metal tube?

The reducer that is commonly used with the 6, 8 & 10” RC’s is the Astrophysics CCDT67, it works brilliantly. I’ll also agree with Sara that the feathertouch is a must have.

Have you now sold your 8” RC Sara?

This thread is rather old as hasn’t got any recent pics from the 6” RC in it, so here’s a couple from galaxy season earlier this year (before the light nights ruined the fun).

John.

Edited July 13, 2015 by johnrt

[kirkster501]

John do you ever use your system at native FL or always with the CCDT67?

[johnrt]

John do you ever use your system at native FL or always with the CCDT67?

Always with the reducer Steve, f/9 would be sooooooo slooooooooooowwwwwww!!!!

[kirkster501]

Always with the reducer Steve, f/9 would be sooooooo slooooooooooowwwwwww!!!!

Lol, thanks John, as I thought.  Good job  have one then eh? ;-)

[ollypenrice]

Always with the reducer Steve, f/9 would be sooooooo slooooooooooowwwwwww!!!!

But would it? On the images (the exquisitely lovely images!) you've posted above you have a fair amount of space around the main targets so you might be able to frame them at native FL. Reducers bring no new object photons to the table, we must remember. All your reducer does is pour the same number onto fewer pixels. If you present the image at a smaller size won't you have the same effect minus the light loss of the reducer? I'd be strongly inclined to give it a try.

If I were to buy one of these (distinctly possible) I'd be after the focal length.

Olly

Edited July 13, 2015 by ollypenrice

[swag72]

I agree with Olly here - The 1.6m focal length of the 8" was nice and I always felt that it was a massive shame to reduce it down to a little over 1m...... a pretty useless in between focal length in my opinion.

Now what would be nice would be a nice big 12" RC reduced down ............ a nice focal length at a nice speed as well......... win / win!!!!!

[ollypenrice]

Yes. The serious imager with the luxury of money on the table needs to begin with focal length. What do I want to image?  Next comes How big is my chip? I need a FL which will cause my targets to fill it. And then comes the killer. What F ratio can I afford? If you've already decided what FL you want this really means, What aperture can I afford?

In reality amateur imagers (99.9% of them) simply have to accept that, as their focal length goes up, their focal ratio goes down. Personally I'm up for accepting that. I've already accepted it. Our TEC140 at 980mm FL is F7 while at 530mm we have the pleasure Mr Takahashi's  F5. I have no desire to focally reduce the TEC, even if this could be done without filling the images with reflections, which is doubtful. I want it for the FL it brings. If I do go for something approaching 2M FL I'm going to be very lucky (and out of pocket) if I don't accept F8 or (quel horreur) even less. But I'm thinking about it.

Olly