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  #21  
Old 28-09-2011, 04:04 PM
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We used to have an expression in primary school in the fifties Peter.
Short and thick does the trick and long and thin won't go in.

Yep whatever floats your boat.

Bert
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  #22  
Old 28-09-2011, 04:17 PM
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This is no joke folks. I am looking at investing about $35k for top of the line equipment.

I own my hacienda in Eltham and have an income unravaged by inflation.
If I wanted to do narrow field I would book time on the Hubble.

What each one of us gets out of what we do is up to ourselves. It is not about satisfying the delusions of others.

This thread is not about what is correct it is about sharing expertise.

Anyone is quite welcome to criticise but expect the same in kind from me.

Bert
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  #23  
Old 28-09-2011, 04:49 PM
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What's cris's price for version with factory fitted atlas ?
Quote:
Originally Posted by avandonk View Post
Mike, Cris Ellis from Astronomy Alive has just informed me that a new version with a carbon fibre tube is now the better version. He can supply this astrograph with adapter and FLI Atlas focuser already factory fitted.
I have also ordered a fancy case to take it to dark sky sites.

The field is 42mm diameter unvignetted but is still sharp after this. The FLI 16803 would vignette slightly at the corners.

I will be patient and not get too excited as I have a lot of work ahead to get up to any sort of competence.

Bert
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  #24  
Old 28-09-2011, 04:50 PM
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Quote:
Originally Posted by avandonk View Post
Mike, Cris Ellis from Astronomy Alive has just informed me that a new version with a carbon fibre tube is now the better version. He can supply this astrograph with adapter and FLI Atlas focuser already factory fitted.
I have also ordered a fancy case to take it to dark sky sites.

The field is 42mm diameter unvignetted but is still sharp after this. The FLI 16803 would vignette slightly at the corners.

I will be patient and not get too excited as I have a lot of work ahead to get up to any sort of competence.

Bert
Ah yes, I knew that these guys fitted the FLI Atlas focusers actually, I should have mentioned it to you but I didn't know about the upgraded tube

The vignetting and correction is as we suspected then so that's cool

Man it is even better now...I'm as excited as you I am sure

Mike
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  #25  
Old 28-09-2011, 04:51 PM
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What each one of us gets out of what we do is up to ourselves. It is not about satisfying the delusions of others.

Bert
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  #26  
Old 28-09-2011, 05:21 PM
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The officiana stellare is a very interesting purchase indeed bert,I'll be interested to see how that goes. Some features in other models are very attractive, like a decEnt back focus. They look great and arE priced right. What is the delivEry time like?
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  #27  
Old 28-09-2011, 05:34 PM
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We used to have an expression in primary school in the fifties Peter.
Short and thick does the trick and long and thin won't go in.

Yep whatever floats your boat.

Bert
Indeed it's your call.

So.. how does long and thick fit in the scheme of things?
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  #28  
Old 28-09-2011, 06:07 PM
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Re-iterating, a 600mm F3 system I suspect will have critical focus and orthogonality issues....have you seen real-world images from the system?

I haven't run the numbers, but wonder what sort of spot size you will get (ie size in microns?) and whether a 9um pixel sensor will be hamstring the resolution as a result.

PMX... great choice...though the MKS5000 pack has yet to see extended field use I would not expect problems.

I'd choose the STX implementation of the 16803 due plug and play guiding, though the 65mm square filters may not be happy with a 42mm field.
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  #29  
Old 28-09-2011, 09:47 PM
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Peter; Tom's images of late have used the same design albeit an f3.8 with the same size sensor. Surely that is close enough. Am I wrong in thinking this?

Click here, or here or here for images. These all look pretty orthagonal.
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  #30  
Old 28-09-2011, 10:31 PM
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Quote:
Originally Posted by Paul Haese View Post
Peter; Tom's images of late have used the same design albeit an f3.8 with the same size sensor. Surely that is close enough. Am I wrong in thinking this?

Click here, or here or here for images. These all look pretty orthagonal.
F3.0 is *very* terse with focus....

An AP RHA ...something I do indeed covet... is a different beastie entirely to the Italian job Bert is considering (hey..don't get me wrong..you probably know what car I adore and drive )

I suppose what I am saying is at "the edge of the envelope" mechanical considerations are just as important as the optical ones.
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  #31  
Old 28-09-2011, 10:42 PM
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Originally Posted by Peter Ward View Post
F3.0 is *very* terse with focus....

An AP RHA ...something I do indeed covet... is a different beastie entirely to the Italian job Bert is considering (hey..don't get me wrong..you probably know what car I adore and drive )

I suppose what I am saying is at "the edge of the envelope" mechanical considerations are just as important as the optical ones.
Yes I know which car you drive, wish I could afford one too.

Perhaps the Italian scope is a bit different but the same was being bandied around a couple of years ago about a humble 8" RC. True the price is pretty high, but I gather from checking out the other gear these guys make (it is not the first time I have come across their gear) it is all precision made. It is even red like your car. I reckon buying it locally is a good idea for warrantee purposes. Worth a punt I think. Then again I tend to be an early adopter, so I tend to take a few risks.
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  #32  
Old 29-09-2011, 08:07 AM
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Superb choice of imaging setup Bert. I was eyeing off that 200mm Riccardi Honders F3. I don't quite understand why its bigger brother is so expensive in comparison to the 8 inch.

Proline should be 65mm shutter standard, check with Greg at FLI though to be sure.

50mm square filters are what I use and they are fine.

I use Astrodon Gen 11 filters and original Astrodon Gen 1 5nm Ha O111 and S11. They all work fine. Astrodon Gen 1 filters gave bad reflections with 16803 chipped cameras which show up the optical imperfections of the scope quite badly.

Astrodon Gen 11, latest Baader (I would check them out thoroughly though to make sure they don't still have some reflection issues - not certain on this point but I do recall a cople of images on the net where reflections were still not good enough). Astronomik latest generation.

Basically the filter needs the antireflection coatings otherwise you will get nasty reflections as every scope with this large of a chip needs a flattener and the reflections bounce back and forth.

PMX should be great.

I did read one negative comment though about the 200mm Honders though. Best to check it out for yourself. I was unsure how someone could comment as they are new to the market. A friend of mine Bob Fera images using an Officina Stellarvue 14.5 inch RC and his images are great.

Being a new scope though I wonder if all the little bugs have been sorted. AP and Massimo Riccardi worked together to help produce the AP version which is a slightly different design and a bit slower at F3.6. It has a separate mirror, the Massimo one has a mirror on the back of the corrector plate like a Mak Cass I believe.

It would be worth checking out as it appears to be an awesome cutting edge scope. Main issues would be whether it has a large enough corrected circle for the 16803 which is 52mm, also how bad the vignetting would be. Do they publish a vignetting diagram? I get heavy vignetting with my CDK17 but it flat fields out largely then I usually have to do some gradient processing to take it the rest of the way. Most scopes show some vignetting with this large chip. I can post you flats of various scopes to show you what I mean. You would be shocked by some of them!

As far as bandpass width of narrowband that is probably its own debate. I use 5nm, I have used 6nm and 7nm. I had Baader 7nm Ha and I got a bad filter -it was defective, but looking past the black spots defect it seemed good.

I find though even with 5nm I can't really image with the CDK17 if the moon is to close by. It lets too much in and there is no contrast to make an image with. 200mm F3 - the F3 will affect the bandpass anyway. There is an article about this on the Astrodon site. As I recall it makes your 3nm wider because of the light ray angles in the fast scope hitting the filter at such an oblique angle.

Have you considered a FLI Microline 16803? It weighs a lot less, cools only 3 or 4C less than the Proline and has the same features.
The Proline has a USB hub (2 extra USB slots) and 2 extra power outlets but the USB hub like most USB hubs can jam with some other equipment and still require a separate cable (my ST402 often seems incompatible with the Proline). Tilt in the focuser at F3 will be ciritical to achieving round stars to the corners.



Greg.

Last edited by gregbradley; 29-09-2011 at 06:27 PM.
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  #33  
Old 29-09-2011, 05:47 PM
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wow bert.. that is one dream setup on the way! hopefully one day you can invite a few of us locals around to have a look.

i guess once you get this setup at home you won't want to move it, but i'd love to see you drag it away to a dark sky sometime too!? there's still an open invitation for you at heathcote anytime you want to try it.

you've done remarkably well with your widefield mosaics from light polluted suburbs so you know what you're in for, but i would guess that as you push this system light pollution gradients even with filters may eventually become an issue?

the mount and camera are pretty easy choices and not much to regret about those.

exciting times!

cheers
phil
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  #34  
Old 29-09-2011, 06:47 PM
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I just looked up the Veloce 200mm on optcorp.com where they have more info on the scope than the Officina Stellare site.

It says the scope has a 60mm flat field and 6 micron stars and 8 micron at 26mm which is really really high performance. Better than a Tak BRC250.

Greg.
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  #35  
Old 29-09-2011, 07:12 PM
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Quote:
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I just looked up the Veloce 200mm on optcorp.com where they have more info on the scope than the Officina Stellare site.

It says the scope has a 60mm flat field and 6 micron stars and 8 micron at 26mm which is really really high performance. Better than a Tak BRC250.

Greg.
Pretty good huh?...got you thinkin...?

he he
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  #36  
Old 29-09-2011, 07:30 PM
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I just looked up the Veloce 200mm on optcorp.com where they have more info on the scope than the Officina Stellare site.

It says the scope has a 60mm flat field and 6 micron stars and 8 micron at 26mm which is really really high performance. Better than a Tak BRC250.

Greg.
Those are pretty nice stats. Not bad for 9300 AUD.
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  #37  
Old 30-09-2011, 07:41 AM
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I guess the devil is in the detail.

OPT say the focuser has been redesigned. Very little info about the focuser details and the focuser would be critical as any flex would hammer you at F3 and a Proline 16803 which weighs 9lbs without filter wheel or MMOAG. It seems the focuser is quite short so that may help with flex.

It'd be nice to see more images and images with people using similar cameras and weight loadings. I suppose you could always just get rid of the focuser, use a solid screw on adapter and the FLI Atlas which is one option they sell. I would prefer that myself as drawtube focusers have to be super well made to handle these heavy imaging trains and even name brands are not meeting the task. That is a similar imaging train I used on a Tak BRC250 I had (what a wonderful scope that was) and I had no problems with tilt or flexure.

The main advantages of RH scope are; super compact, super fast for large aperture, no diffraction spikes on stars, tight stars, sealed corrector plate means less dirt on mirrors but harder to clean if it needs it, wide corrected flat field, I imagine collimation is less of an issue especially with the Officina model.
The disadvantages are: super fast = high potential for flexure and focuser issues, corrector plate dewing up like an SCT,the very fast F ratio means star shapes not as perfect as a slower APO per Roland Christen however looking at AP RHA images stars look fabulous., quite expensive for the aperture.

The closest competitor would be a Tak Epsilon 180ED but that had problems with the focuser. Tak beefed up the focuser but I don't know if it would be strong enough for such a heavy imaging train. Others would know and it'd be the first thing I'd check. I'd also check spot sizes as the Veloce appears to have unbeatably small spot sizes even 26mm offaxis, those numbers are really really low.

One point as well, the mounting dovetail. It mentions it is a Vixen style. That is silly, Vixen dovetails are tiny and could not possibly hold all that weight steady. Perhaps that aspect should be checked out as it sounds like a weak spot. If you use a MMOAG for guiding it would be less of an issue but if you used a guidescope expect flex.

Overall it looks superbly made and an exotic high performance instrument that could outperform many other scopes for imaging and F3 - wow, that sounds wonderful. Steve Crouch used a Tak Epsilon 180ED, it would be interesting to hear his view on imaging that fast.

Richard Crisp posted the same object imaged with both a Tak Epsilon 180ED F2.8 and an FSQ 106N F5. As I recall the Tak Epsilon got the same depth of image saturation in about 1/3rd the time. But images from the ED180 are not as sharp as FSQ106N. Always compromises.

Greg
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  #38  
Old 30-09-2011, 08:19 AM
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Greg just look at the image below. I agree there could be some flex with the RH200 flimsy mount. We have the technology to bolt it down so it cannot struggle.

Bert
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  #39  
Old 30-09-2011, 08:46 AM
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Greg I could go for a one shot camera but the real resolution then is twice the native pixel size.

I intend to dither between exposures which will give the real resolution of pixel spacing.

I will guide with a Mak with at least double the FL of the RH200. I have a very solid side by side from StarStuff which has no flex that is discernible at this FL.

I have a slight advantage as I have a degree in Applied Physics and I am a bit of an expert in optics and x-ray optics.

Thanks for your input Greg.
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  #40  
Old 30-09-2011, 08:53 AM
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That image you put there Bert looks like they have a losmandy style dove tail underneath so that should mean there is the capacity to fit such a plate.

Greg that is good if they have fixed the problems with the focusor. A low profile focusor that is very beefy is certainly preferred over large units. I am about to find out what an STL does to a 3.5" Feather Touch. No doubt it will flex to some degree. Although I have given it a good builder type reefing and could feel no immediate flex. At 2m's though I am bound to find out.

Just out of interest what is the back focus of the scope Bert? Is there going to be much option for differing focusors?
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