Revelation Astro (GSO) 10" F4 Astrograph Newtonian

[laser_jock99]

I have had good experiences with the other Revelation Astro Newtonians I own (6", 8" & 12") so to fill a gap in the range and to have a decent sized scope available to use in the week I brought the 10" F4 from Telescope House

http://www.telescopehouse.com/acatalog/info-BC186.html

The 250mm main mirror is a reassuringly 35mm thick (and correspondingly heavy)- you will need an EQ6 to mount one of these scopes at the very least, the OTA weighs in at a healthy 15kg. The tube is just over 1m long which for me means that this scope is at the top end of easy one person handling. It's bigger brother, the 12" F4 which I also have, is substantially bigger and heavier- I wouldn't recommend one of these unless you are going to permanently mount it in an observatory.

The 10" F4 beside its smaller brother the 6" F4

The fit and finish of the scope is to the usual GSO standards which bearing in mind this is a sub £400 scope are more than acceptable. I will be doing a few minor mods to this scope - but nothing major. The tube will flocked for use in the Light Polluted Zone and I will fit some stronger main mirror cell springs if holding collimation becomes an issue (which so far it seems okay with).

In common with the 12" F4 the 10" F4 features GSO's massive 3" focuser. From previous experience I know these are very stable and it was the deal clincher for me. The manufactures blurbs claims these can hold a 5Kg load- but as long as I can hang a DSLR off it and maybe a CCD camera that will do for me! At any rate I can't make this focuser wobble with reasonable force.

The 3" focuser with standard 1 1/4" eyepiece

  

The 3" focuser de-mounted with my hand for scale!

The linear rail re-circulating ball bearing assembly inside the focuser. This gives the focuser it's linear stability and a decent flat surface for the Crayford roller to act upon.

Access to the world of 3" accessories is via the removable adaptor ring 

The secondary mirror is suitably large and provides good illumination over my APS-C sized CCD chip - whether it's big enough for a larger imaging circle and to make full use of the 3" focuser potential I don't yet know? 

Flat field image at F4 with Baader MPCC III (full dynamic range histogram stretch)

Flat field image at F2.9 with ASA Keller 0.7x corrector/reducer (full dynamic range histogram stretch)

The scope comes with few accessories- 12V cooling fan, 50mm finder, 35mm extension tube, scope rings and a short Vixen dovetail bar. One of my few gripes about budget scopes (and I will include Skywatcher in this rant) is the inadequate dovetail bars they ship with. For the size of scope something bigger is needed- so budget for a Losmandy bar if buying a 10" or larger scope.

The dovetail bar supplied vs the on one I actually fitted!

Finally some quick first light images (more to follow weather permitting!)

Single 120s sub of the Leo Triplet

8th magnitude comet Panstarrs (6x 120s subs)

[Martin Meredith]

Thanks for posting this review. That's a very impressive 120s sub of the Leo triplet!

I'm considering an 8 or 10" f/4 for near-live viewing in the future and this is very useful for me. I'll probably opt for the 8" though having seen the size of the 10" (although I have an AZ-EQ6 to mount, I'd like to be able to mount both scopes at once so a 10" would probably be pushing it). That 3" focuser is about the size of the 80mm refractor I currently use!

Martin

[yelsac]

I have had good experiences with the other Revelation Astro Newtonians I own (6", 8" & 12") so to fill a gap in the range and to have a decent sized scope available to use in the week I brought the 10" F4 from Telescope House

http://www.telescopehouse.com/acatalog/info-BC186.html

The 250mm main mirror is a reassuringly 35mm thick (and correspondingly heavy)- you will need an EQ6 to mount one of these scopes at the very least, the OTA weighs in at a healthy 15kg. The tube is just over 1m long which for me means that this scope is at the top end of easy one person handling. It's bigger brother, the 12" F4 which I also have, is substantially bigger and heavier- I wouldn't recommend one of these unless you are going to permanently mount it in an observatory.

The 10" F4 beside its smaller brother the 6" F4

The fit and finish of the scope is to the usual GSO standards which bearing in mind this is a sub £400 scope are more than acceptable. I will be doing a few minor mods to this scope - but nothing major. The tube will flocked for use in the Light Polluted Zone and I will fit some stronger main mirror cell springs if holding collimation becomes an issue (which so far it seems okay with).

In common with the 12" F4 the 10" F4 features GSO's massive 3" focuser. From previous experience I know these are very stable and it was the deal clincher for me. The manufactures blurbs claims these can hold a 5Kg load- but as long as I can hang a DSLR off it and maybe a CCD camera that will do for me! At any rate I can't make this focuser wobble with reasonable force.

The 3" focuser with standard 1 1/4" eyepiece

  

The 3" focuser de-mounted with my hand for scale!

The linear rail re-circulating ball bearing assembly inside the focuser. This gives the focuser it's linear stability and a decent flat surface for the Crayford roller to act upon.

Access to the world of 3" accessories is via the removable adaptor ring 

The secondary mirror is suitably large and provides good illumination over my APS-C sized CCD chip - whether it's big enough for a larger imaging circle and to make full use of the 3" focuser potential I don't yet know? 

Flat field image at F4 with Baader MPCC III (full dynamic range histogram stretch)

Flat field image at F2.9 with ASA Keller 0.7x corrector/reducer (full dynamic range histogram stretch)

The scope comes with few accessories- 12V cooling fan, 50mm finder, 35mm extension tube, scope rings and a short Vixen dovetail bar. One of my few gripes about budget scopes (and I will include Skywatcher in this rant) is the inadequate dovetail bars they ship with. For the size of scope something bigger is needed- so budget for a Losmandy bar if buying a 10" or larger scope.

The dovetail bar supplied vs the on one I actually fitted!

Finally some quick first light images (more to follow weather permitting!)

Single 120s sub of the Leo Triplet

8th magnitude comet Panstarrs (6x 120s subs)

Wow thats looks an amazing scope

One quick question (probably silly I Know) does the huge focuser have a thread so you can attach/screw on a DSLR with a t-ring like the skywatcher reflectors have?

thanks

[frostynixon]

Thanks for the review. I was amused to see the 6" scope next to the 10" . How happy are you with the 6" scope?

[laser_jock99]

Wow thats looks an amazing scope

One quick question (probably silly I Know) does the huge focuser have a thread so you can attach/screw on a DSLR with a t-ring like the skywatcher reflectors have?

thanks

To attach a DSLR directly you would have to buy  T-adaptor like this one (to suit your lens mount)

http://www.firstlightoptics.com/coma-correctors/skywatcher-dslr-m48-ring-adapter.html

and then either a plain 2" fitting tube

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

or better still a coma corrector that screws directly to the camera T-adaptor

http://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

[laser_jock99]

Thanks for the review. I was amused to see the 6" scope next to the 10" . How happy are you with the 6" scope?

I think the 6" F4 is a great scope and to be honest gets a lot more use than my 10" F4 purely on account of being easier to handle and therefore a lot quicker to set up and get going.

The 6" has a nice wide FOV and when coupled with my ASA Keller 0.7x corrector/reducer gives me 420mm FL F2.8 instrument which is great for widefield imaging.

Come 'Galaxy Season' this Spring I will be more and more tempted by the 1000mm FL of the 10" scope. You need long focal lengths to adequately image galaxies!

[yelsac]

To attach a DSLR directly you would have to buy  T-adaptor like this one (to suit your lens mount)

http://www.firstlightoptics.com/coma-correctors/skywatcher-dslr-m48-ring-adapter.html

and then either a plain 2" fitting tube

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

or better still a coma corrector that screws directly to the camera T-adaptor

http://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html

Hi thanks for that

I have a T-adapter for my Canon 1100d which attache's to a barlow for use with my 5" Mak which can also be used as a extention tube with small barlow unscrewed.

I Noticed in the description from Telescope house it has included "with a 35mm extension tube to ensure the attachment of a whole host of visual and photographic accessories"

Would that be ok for the DSLR?

Also would you recommend the 10" for astrophotography?

[frostynixon]

I think the 6" F4 is a great scope and to be honest gets a lot more use than my 10" F4 purely on account of being easier to handle and therefore a lot quicker to set up and get going.

The 6" has a nice wide FOV and when coupled with my ASA Keller 0.7x corrector/reducer gives me 420mm FL F2.8 instrument which is great for widefield imaging.

Come 'Galaxy Season' this Spring I will be more and more tempted by the 1000mm FL of the 10" scope. You need long focal lengths to adequately image galaxies!

That sounds great! Do you have to modifiy the scope in order to use the asa coma corrector or does it work out of the box? Would i be able to reach focus with the scope and corrector and DSLR? Thanks in advance!

[laser_jock99]

Hi thanks for that

I have a T-adapter for my Canon 1100d which attache's to a barlow for use with my 5" Mak which can also be used as a extention tube with small barlow unscrewed.

I Noticed in the description from Telescope house it has included "with a 35mm extension tube to ensure the attachment of a whole host of visual and photographic accessories"

Would that be ok for the DSLR?

Also would you recommend the 10" for astrophotography?

The supplied 35mm extension tube is only needed for eyepiece viewing in my experience. I always acheive focus when using a DSRL + Coma Corrector within the normal travel of the focuser.

The 10" F4 is a good 'budget' instrument. There are modified variants of this scope out there with carbon fibre tubes, for example, which sell for a lot more but are supposedly more thermally stable than the steel tube version.

To do good AP with this scope you'll need a solid mount (I see you have an NEQ6) as at 15kg (+camera+guide scope) it's getting quite heavy. Additionally any F4 scope must be well collimated, and will need checking/adjusting before each imaging session. With the right collimation tools this should only take a few minutes - I use a Howie Glatter laser collimator which I consider to be an excellent piece of kit (I always struggled with collimation before). Finally a good quality coma corrector is a must (you can see the ££££££ are adding up here........)

I have also found this scope is considerably improved by fitting stronger collimation springs and flocking the tube.

[laser_jock99]

That sounds great! Do you have to modifiy the scope in order to use the asa coma corrector or does it work out of the box? Would i be able to reach focus with the scope and corrector and DSLR? Thanks in advance!

The ASA Keller corrector/reducer is an excellent (if rather pricey) bit of kit. It works as a normal coma corrector would only it makes the scope optically 'faster' as well.

It is pretty much a case of screwing the corrector to your camera/CCD T-adaptor and putting it in the focuser tube as you would a normal 2" eyepiece. It is critical to get the CCD-to-corrector distance exactly right as this can affect star shapes and edge sharpness. To achieve this with my current Fuji DSLR's I need a 10mm spacer ring between the corrector and camera (other cameras wil vary).  The 10mm 'gap' allows the use of filters or an off axis guider if you need any accessories between the corrector and the camera. But 10mm isn't that much- thankfully most of my work is done under dark skies and with no filters.

Two other points to add:

When using an ASA Keller corrector/reducer collimation becomes uber critcal- remember you are working at F2.9 here!

To get the most out of an F2.9 scope a dark sky site is handy otherwise you will reach overexposure very quickly (unless working with narrowband filters (which is something I have not really tried)).

[frostynixon]

Thanks for your extensive answer! I know that the ASA corrector is pricey. I would like to buy a reasonably fast widefield scope in the future and the combination of the 6" F4 and the ASA corrector would give me an ultra fast setup. I see the ASA correctors now and then used for 500,- to 600,-. Together with the 6" F4 scope i would have a very fast widefield system for about 1000,- €. At this price point only this refractor would be an alternative: http://www.teleskop-express.de/shop/product_info.php/language/en/info/p7085_TS-Imaging-Star71---71mm-f-4-9--5-element-Flat-Field-APO-fuer-gro-e-Sensoren.html , but that`s "only" F5.

 Your Fujifilm camera should have the same backfocus requirement as my Nikon camera, so that`s good news!

I recently aquired a mono modded Nikon D5100 with which i plan to enter the narrow band arena. So a fast scope would be really nice .

On the other hand (as you said), f2.8 might be tricky to use...

Damn i wished somebody nearby had your scope combination

best regards Matthias

[laser_jock99]

Good luck if you go with the GSO 6" F4 + ASA combination, it is an interesting scope which inexpliclably doesn't seem to be widely used. The ASA corrector can of course be used other Newtonians should you start a 'collection' of them.

You can buy the combination as a Boren-Simon Powernewt for this you will get a carbon fibre tube and Baader Steeltrack as extras.

I like wide FOV of the 6" F4 and it has become one of my most used scopes.

At F2.9 you can either go very deep on a single DSO or even image a lot of DSO's in a single night!

[frostynixon]

Very nice examples! The only thing i`m worried about with the ASA/6" F4 combo is usuability, but i guess one can practice that .