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New Celestron Rowe-Ackermann F/2.2 Astrograph!

Grant_FLO

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FLO

FLO

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Now the new Celestron Rowe Ackermann Astrograph (RASA) has arrived and is shipping we know it has a CGE dovetail (Losmandy-style) top and bottom, not the single dovetail shown in previous photos. The bottom dovetail is for attaching to a mount and the top for a guidescope or piggy-backing. 

Also, our earliest early adopter is the indubitable Harry Page  :icon_salut: Harry is probably best known for his Pixinsight tutorials and is active here at SGL and at PAIG so I don't think it'll be long before we see some user feedback :smiley:

Steve 

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ollypenrice

ollypenrice

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I'm interested, too. I think it has to be OSC and, so far as I know, there is no small bodied, big chip OSC in production so the scope can't, at this stage, really strut it's entire stuff. That might change. That said, a small chipped, small bodied camera would make fewer demands on the optics and might make a nice fast system, albeit expensive for the FOV currently available. (You're paying for an image circle not exploitable on any current cameras of which I'm aware.)

Your thoughts, anyone? As I say, my interest is piqued.

Olly

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DrRobin

DrRobin

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I used a Canon on my Hyperstar C11, worked really well. Of course it blocks a bit of aperture, but you don't see it when focused. Mind if I was buying one of these that can only be used with a front mounted camera I would be buying a small bodied OSC, perhaps a SX35 or SX36.

Robin

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Gina

Gina

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Seems rather strange to me to buy such an expensive scope when you can only use a poorer camera with it.  I guess you could use a mono camera with single filter fitting and change it by hand.  Maybe take one colour/wavelength per night.  OR buy three and buy three mono cameras and set up a triple imaging rig :eek:   That should gather quite a few photons! :D

Surely there are some mono CCD cameras with full frame image size and small enough bodies not to obstruct further the central obstruction?  I thinking of say the Starlight Xpress Trius SX-35.

Wonder what mount would handle three of these astrographs and all associated gear :D

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harry page

harry page

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Hi

First of I am goinb to use my sx m25 osc which is smaller than the central obstruction, so no probs there and next I will try the sx h35 which is 118mm so not much bigger ---as for the central size, the secondry on my 14 inch newt is 120mm

so while not perfect I do not see it as a major problem (famous last words)

As for filters I intend to use a single filter draw , again not ideal but workable

I have a few other problems to sort before first light ( deorating the hall ) but will report Asap

regards Harry

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Gina

Gina

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I shall watch your results with interest Harry :)

I thought when Atik went from "short and fat" in their 3 series cameras to "long and thin" with the 4 series, that they had realised the benefit of the new format but it seems not with the 11000 going back to "short and fat" :(  Or are there any advantages of "short and fat"?

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sharkmelley

sharkmelley

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Rowe Ackermann has a 41% central obstruction (114mm/279mm)

My Tak Epsilon has a 44% central obstruction which is perfectly acceptable.

The Atik 11000 has a diameter of 125mm which would give a C.O. of 44.8% on the Rowe Ackermann - hardly any different from the Tak's

I think the 11000 would be almost ideal, though still not utilising the whole 70mm imaging circle!  Also, Baader now have a range of f/2 narrowband filters that fix the frequency shift issue:

http://www.firstlightoptics.com/narrowband/baader-f2-highspeed-narrowband-filters.html

I've just taken delivery of the H-alpha version of the f/2 filter and  when I can borrow a "standard" 2 inch H-alpha filter I'll do a direct comparison on the Hyperstar to see how contrast compares at very short F-ratios.

If the usual SCT mirror flop issue is truly solved on the RoweAckermann then this could be a very serious imaging rig indeed. Looking forward to seeing in depth reviews!

Mark

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ollypenrice

ollypenrice

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At last I've had a chance to get my hands on one of these, rather briefly as it turns out, but I hope for a second chance. It's true that the 11000 would be no big deal being just over the central obstruction size. I was struck, though, by what a big boy it is physically. It's far longer than the C11 and makes my 10 inch meade look like grab and go.

Since the camera fits straight onto a T thread I wonder how you'd fit a UV/IR filter with an OSC. I have to admit that I can't remember whether or not I used one with my Atik 4000 OSC. Now where did I put my memory...?

Olly

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Earl

Earl

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At last I've had a chance to get my hands on one of these, rather briefly as it turns out, but I hope for a second chance. It's true that the 11000 would be no big deal being just over the central obstruction size. I was struck, though, by what a big boy it is physically. It's far longer than the C11 and makes my 10 inch meade look like grab and go.

Since the camera fits straight onto a T thread I wonder how you'd fit a UV/IR filter with an OSC. I have to admit that I can't remember whether or not I used one with my Atik 4000 OSC. Now where did I put my memory...?

Olly

Just pop a Astronomik T-Cell filter on the end of the camera, they are load bearing. Hopfully this wont mees with the focus too much

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Chris

Chris

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If the usual SCT mirror flop issue is truly solved on the RoweAckermann then this could be a very serious imaging rig indeed. Looking forward to seeing in depth reviews!

Mark

Hi Mark, if the mirror lock system is the same as my C8 Edge? then I can confirm that it works very nicely indeed! I tested this out last night imaging 3 different objects and  even though these objects were in different parts of the sky, once I tightened those mirror clutches the focus didn't shift one bit. Worlds apart from the big Meade Lx200's I used at Uni many Moons ago, they had terrible mirror flop!

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ollypenrice

ollypenrice

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Hi Mark, if the mirror lock system is the same as my C8 Edge? then I can confirm that it works very nicely indeed! I tested this out last night imaging 3 different objects and  even though these objects were in different parts of the sky, once I tightened those mirror clutches the focus didn't shift one bit. Worlds apart from the big Meade Lx200's I used at Uni many Moons ago, they had terrible mirror flop!

I think it is the same, though what works at normal F ratios may be more taxed at F2.2 since the focal depth is so shallow. It seemed a well made systeml, though.

Olly

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