Not many images out there as yet, but I did come across this (see the bottom of the pager under Images - and note that it was 'taken under "really bad" conditions for imaging, by Preston Starr, Observartory Manager, University of North Texas': http://www.astronomics.com/main/prod...duct_id/AT12RC
Here is an image of the scope on the mount. As you can see this scope is pretty big. It makes the mount look average. I would suggest any ideas of using this scope on a small mount should be quelled. You will note that I have three counter weights on the mount for this scope. Each counter weight is 9 kgs. I am expecting to put more weights on when I put the STL11 on the scope.
With any luck the cloud will POQ and I can do some testing in the next couple of weeks. Thanks for your patience.
Looking forward to seeing some images, however as per comments made when a few got into the 8 inch version, these scopes seem only to get used on the brighter objects such as m8 eta m42 etc. I suspect it will do incredibly well on such targets but it wont see much else.
Looking forward to seeing some images, however as per comments made when a few got into the 8 inch version, these scopes seem only to get used on the brighter objects such as m8 eta m42 etc. I suspect it will do incredibly well on such targets but it wont see much else.
Yeah I don't follow your argument here Clive either. Faint objects that I have done with the RC8 are M83, Horse head, Antennae Galaxy, Thors helmet, Centaurus A and the Running chicken. Not to mention NGC253 (needs reshooting for the stars) and NGC4945. Pretty faint those ones, how much fainter do you want? I plan on using it as a galaxy scope, so tell us what you mean Clive. I am interested.
Clive, is this an indictment on the GSO RCs on dimmer objects? Or that the reviewers tend to focus on those bright, popular objects when testing the optics?
I don't particularly consider some of those previously listed targets to be too dim, m83 and centaurs a are about the brightest galaxies around.... You can add 253 to that list.
Some of the faint stuff is like the extended nebulosity in some of jases recent images. I can hunt down one if you like.
It's not an indictment on the optics but probably a combination of f ratio plus the usual reshooting of bright objects.
I had a quick look at the link you provided Paul and the answer lies in the fine print
Optics GSO RC 10" Reduced to F/5.3 1320mm. With AP-CCDT67 - Astrograph Ritchie-chrichten
That's F5.3 which would certainly open up your options.
As you are aware I have not posted any images for some time so I guess I cant criticize too loudly, but generally there is a preponderance to reshoot the same 20 or so objects, this occurs year after year, there has been some variation with jase doing his stitched up panoramas, mike going uber deep, bassnut zooming in and doing some star removal. Then of course there is toms dust..... ( apologize for those overlooked) however generally most work is a repeat, albeit a refinement, on previous projects.
It may well be that others outside of the forum are doing some interesting and different things with these scopes, but here, it has been mostly as I previously said the brighter objects.
I have no intention of putting anyone down, it's just my observation of these scopes and what I have seen on IIS. THe fact that a link was provided from off forum somewhat confirms that.
Should I have missed some of your work Paul I apologize .... But I hope you do explore the scope to it's fullest potential, it's what we all want to see.
It may well be I see things differently, I want to see things I haven't seen before, or a different take on it...
Example , johns Hothershalls centaurus A had the Ha added to a normal color image, as I ahdnt seen that before I found it interesting and inspiring
For me astronomy is a journey of exploration, I would like to see galaxies that generally DONT get imaged done, we all know what 253, centaurus A, sombrero, m51 etc look like, if it can be done differently to stand out from the crowd GREAT !!.
I'm sure others will disagree and I'm not going to take offense, it's my take on it.
Clive, I don't have a problem with what you are saying here but how does imaging non glossies with this scope test its abilities? I plan on doing NGC253 because:
a) people know what this looks like. Or more importantly should look like.
b) it can be compared to many other versions and that is important for testing and comparisons.
c) the detail is easily seen. You can tell instantly if the image is sharp or not and if there are defects in the optics.
Your complaint here really lies with what people are imaging and not with the telescopes. If you want to see variety maybe make a list and ask people to image them or maybe get into the list yourself.
The longer f ratio does not limit the scope it just means I have to go longer to get the background ADU up. Fainter objects take more time and I want to do the object justice. That is why the brighter objects get done first and then one starts being more selective. It can take years to get to this stage.
You will eventually see galaxies that don't get imaged much, but you might have to wait more than a couple of years. As I keep saying to people and as it was said to me. This hobby is not for the impatient.
Besides I spent over 12 months imaging with the RC8 and only produced 15 or so images. Then I got board with that and went back to wide field. I have just sorted the issues with my PME and produced 12 images since last August with wide field. Not bad 27 images in 2 years. Not to mention the solar and planetary images I produce each year. Not enough time in the week to work. Time you kept up Clive.
Choice of gear and how it is setup is heavily influenced by the type of target you intend imaging. 12 inch F8 is really a long focal length instrument ideal for galaxies with a modest chip size (STL11 would be close to ideal there). It would not be suitable for imaging the dust areas Jase recently imaged though as the FOV will be too narrow. But targets for the 12 inch RC would be the large number of galaxies that seem to all be near NGC253. There are quite a few around it for some reason.
Fast F ratio with large aperture and large chips though is the direction this pursuit is generally taking. It tends to reveal hidden dust, detail in commonly imaged targets etc. A reducer may work with this new RC, yet to be determined. It would be tough. I was not able to use one successfully with an STL on an RCOS 12.5 inch. The AP reducer was more for small chips like the ST10.
The lastest larger chips from Kodak in the really large sizes like 31megapixels and up are either one shot colour (KAF 31600, KAF40000)
with peak QE around 43% or low QE (mono versions of KAF39000 30% and KAF50100 25% which is really pretty low). STL11 is around 51% and 31% the for Ha band. The 16803 is peak 60-61% and about 58% in the Ha band. KAF3200 (peak QE around 89%) is very high in the Ha band so is the KAF6303 (65% at Ha band).
So to reveal new dust/Ha structures would require a large aperture, fast F ratio and longer total exposure to capture it with these larger chips. Or you get a back thinned very expensive chip with 93% QE or you get a compromise - the largest FOV chip, with the best QE, the largest dynamic range, lowest noise and biggest well depth (so long exposures don't overexpose stars, bright objects). It seems to be a compromise very often. Some chips seem to have a lot of these factors aligned and these are the ones that become popular - KAF8300 ( QE 56-60% full well 25,500 small pixels - good for fast systems, short focal length) 11002 chip (QE 51% full well 60,000 a good compromise that suits most scopes and does not suffer from ghosting) KAF16803 (60% QE, 100,000 full well 79db dynamic range - this is the best of the current chips).
KAF 09000 and KAF3200 suffer from RBI a lot (ghost imaging) requiring a fix in Apogee and FLI cameras that has a side effect of increased noise and really requires heavy cooling to minimise this trapped charge leakage during an exposure from the ghosting control.
Too bad. On paper the KAF 09000 would be the chip of choice.
The conclusion being that these newer really large chips (larger than 17 megapixels) are not really that suited to astrophotography.
The only factor the scope has to play here is larger aperture has a better chance of picking up smaller objects and faster f ratio or higher QE will ensure you can image it successfully without taking 2 weeks of often rare clear skies.
Even with your own home observatory there is a definite limit imposed by the weather about how much you can image a particular spot. This then tends to limit experimenting with new and untried.
I like to do better than what I did before but I also like to image new things.
A list of reasonable targets would be helpful. I am always looking for new and unusual targets. There have been a few here on this site in the last few months.
ic 2631 from the fellow in Chile (Leonardo?) I also imaged this one
Marco's Supernova remnant he imaged (I tried to image this one but its too low still)
NGC346 in the SMC I also imaged this one (yet to be released)
Jase's recent South Pole area nebulas
Many galaxies are very small and not very photogenic but there must be a decent list still of those that are not often imaged.
Can you make a list of what you think would be interesting targets? I would be interested.
Greg.
Last edited by gregbradley; 17-08-2011 at 08:38 PM.
A reducer may work with this new RC, yet to be determined. It would be tough. I was not able to use one successfully with an STL on an RCOS 12.5 inch. The AP reducer was more for small chips like the ST10.
Greg, was that the CCDT67 reducer? I have a 27TVPH in the mail that I'm hoping will work nicely with my GSO RC10. It should provide a 42mm fully illuminated circle at 0.75X.
Rick I think you will find that the CCDT67 is the one recommended for the RC10 the other is only recommended for fast scopes below f9.
From AP "Originally developed to tame the focal length of our 10" f14.6 Mak-Cass, this telecompressor will provide full coverage of the ST10E chip with scopes ranging from f9 to f18 focal ratio " The only pics I have seen with a TC used the T67 ?
Rick I think you will find that the CCDT67 is the one recommended for the RC10 the other is only recommended for fast scopes below f9.
From AP "Originally developed to tame the focal length of our 10" f14.6 Mak-Cass, this telecompressor will provide full coverage of the ST10E chip with scopes ranging from f9 to f18 focal ratio " The only pics I have seen with a TC used the T67 ?
Mark
Mark, people appear to be using both of the AP reducers on RC scopes. I liked the 27TVPH better because it has a longer focal length and larger image circle. I hope to include an AO unit and filter wheel in my image train and the CCDT67 focal length isn't long enough to accommodate this. Of course, the 27TVPH plus required adapters is also more expensive...
Paul , yes selection of targets is my main interest. I predict the following though despite that the scope is probably very good
1. A high f ratio will limit the depth most people will use it for, for a number of reasons including mount, so as said the glossies will be the targets.
2. Given general movements in scope purchasing, there is a trend to try to get a better scope.....or camera Resulting in a rerun of the glossies
Don't take it as a personal issue it's not, and having seen results from the 8 inch it has every chance of being a good scope,
Witht the gear you have I couldn't see any limitations to what you could do.
Thanks Clive, if this scope pans out I will be doing a lot of deep work with it. It has a two year warrantee on it, so I have some time to test its performance. Stay tuned.
Just a little bit of an update.
Although the focusor looks really beefy I have concerns that is might just have a little slop in it. So with that in mind I purchased a Feather Touch for it. It comes with an adapter to screw the STL11K straight into it and the focusor is focus max compliant. I just need to buy the electronics for it at a later date (the focusor alone costs enough).
My thinking here is that the focusor will be the most likely spot where there will be any movement. So to give the scope a fair chance on the tests I have planned I opted for the expense of a better focusor.
I should get the focusor early next week and then in the following weeks I will be putting it altogether and doing a pointing run. So by next new moon I hope to have some data and a review for you. My general plan is to have an in and out of focus star test, a baffle test and an image of NGC253. If anyone can think of any other things you want tested let me know and I will consider it.
You will be very happy with the FT Paul and its internal baffling is so much better. I got it with the micro focuser and works seamlessly with Maxim and Focus max. I got around to checking the collimation with the Tak scope
and it only needed the primary adjusted a touch , the secondary looked
pretty good and for those wondering it has a centre spot marked on the
secondary as well
Time you kept up Clive.
