Have I made a wrong decission?

[wouter]

Hi all,

I am new to SGL. I became member because I want to start with astrophotography and hope to learn some tips and tricks and receive some advice from you guys

I'm not new to astronomy at all, but I'm very new to imaging.

So I have a few first questions now about getting started with imaging.

Until recently I used my unmotorized SW 150mm reflector only for observing.

I have sold that scope now and have purchased a Celestron C9.25 SGT XLT on a CG5 mount.

I've got the the T-adapter, T-ring and barlow lens for the T-adapter with the scope.

The reason I decided to go with this scope is for the following reasons.

- I wanted a setup that would be in my budget of max $3000

- I wanted a scope that is bigger, for more light gathering power, yet portable enough to move in and out the house to the garden.

- I wanted a scope that is good for observing too, not only for myself, but also for my family.

They mostly like to see the moon or planets. I read this scope is really good for solar system observation (which I can confirm already!)

- But for myself I really wanted a scope that would be good for imaging.

The shop I bought it at confirmed me that this is a really great telescope for both planetary and DSO imaging.

So all these factors considered, I thought this would be the best starting gear for my needs.

However, now I am reading some articles (on SGL and elsewhere) that the C9.25 is not really good for imaging DSO's.

From what I read it seems that a C8 would have been a better choice.

I still don't fully understand the reasons why though, if it's really the case could somebody please explain me?

I am not talking about the mount, but purely about the optics.

As far as I know all Advanced series are F10 telescopes (including the C9.25), so I don't really see what the problem is.

Now I really can't consider selling this scope and buying a new one...

So my question is: What can I do to make this C9.25 as much worthy as possible for DSO imaging?

Another thing I want to add is that I can't change the mount, simply can't afford that right now.

I was thinking about getting a good focal reducer and corrector f/6.3 if I would go for DSLR imaging.

I currently have a Canon Eos 550D.

Or I could go for CCD imaging and in that case I could even get an f/3 focal reducer, am I correct here?

On the other hand, a CCD camera costs a lot more.

Also I would like to place an auto guiding scope, something very light so not to overencumber the mount.

For example I found this Orion complete auto guiding system which I think is quite lightweight.

http://www.telescope.com/catalog/product.jsp?productId=24770&id=cjdf&utm_medium=aff&utm_campaign=commission%2Bjunction&utm_source=CJ

If you have any other recommendations, please let me know.

Another question I have.

If using a focal reducer at prime focal imaging with my canon Eos 550D, will I be able to fit the whole of M31 in the field of view of my camera?

I checked the specs and the sensor is 22.3mm by 14.9mm.

Because I may not have made the best decission for my main scope, could you please tell me what you would do to make this a worthy DSO imaging setup?

I don't know if it's really grounded, but I'm feeling quite depressed having read those articles saying that the scope which I looked forward to so much may finally not be suitable for what I really want to do with it.

Well no need to comfort me, I just hope and am looking forward to your advice and suggestions.

Thanks in advance!

Wouter

[rowan46]

Welcome to Sgl I am not an expert imager I am just writing to keep you at the top So here is what I do know. The reason the c8 is preferred on that mount is because of weight. An off axis guider instead of a guide scope should keep your weight down. You will definitely need a focal reducer which type the experts will tell you. All is not lost you have a cracking planetery imaging scope and an excellent visual scope but it may require a little more cash to make a great dso imaging scope out of it. I am sure though somebody will be along to help you get some worthwhile product out of it.

[atmenterprises]

I think the setup you have is probably better suited for planetary or moon imaging because they don't require precise tracking or long exposures.

The focal length of the 9.25 is long, meaning exposures of any length are going to require precise tracking. Also, the 9.25 has a fairly small aperture (f/10 if I remember), so to get the same amount of light on a camera sensor your exposures will need to be longer than, say, a f/6 or an f/4 scope.

The CG-5 mount may not provide enough sturdiness to hold the tube and a camera without shake if there's any wind. But I'm sure you could find some folks on here who have had success with that combination.

A focal reducer may be good - Andromeda would fit into a FOV at about 500mm. It would also open up your aperture a bit more to allow you shorter exposures.

Why not give planetary and lunar some photography time? Jupiter is up high in the sky now and Saturn will be poised for pretty good shots soon.

[rowan46]

I have just had a think. It may be cheaper to put an ed 80 refractor on that mount for imaging dso's and then use the c9'25 when you want to do visual or planetary imaging.

[atmenterprises]

I have just had a think. It may be cheaper to put an ed 80 refractor on that mount for imaging dso's and then use the c9'25 when you want to do visual or planetary imaging.

An 80 would certainly be more forgiving of tracking errors than the 9.25, no doubt.

To the OP, the rule of thumb for imaging is to only have 50% of the rated payload of the mount used. Not sure what the rated payload is for your CG-5, but add the weight of your tube, your camera, your t-mount, t-ring and any guiding equipment and finder scope and see if it comes to 50% of that.

[swamp thing]

I'm also not an imager but I think what I would do is use the 9.25 for planetary imaging and visual observing, as for this it works very well. When I wanted to start deep sky imaging i would buy a small fast frac that would fit on that mount.

Not sure I'd bother trying to do deep sky AP with a SCT myself.

oops! Gotta type faster

[ollypenrice]

SCTs are outragoeuosly over-sold to beginners in DS imaging. This is something I bang on about a lot. You need extreme accuracy in a mount to image at long focal lengths and that means a serious mount. Serious mounts are expensive.

The 3.3 reducer is still being sold but the good vendors point out that it is totally useless on anything but a webcam sized chip. Judge your vendors accordingly. The 6.3 is no great shakes but it is obviously essential if you want to use a DSLR with an SCT. It won't cover a n APS chip, though.

Go for a short FL apo on your mount for AP? Yes, absolutely. That's the way to get results.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=1793797527&k=WMbNhhG

[Ewan]

Hi Wouter, i have the smaller C8 so i cannot comment on the 9.25 to an extent but i cannot see why you should struggle with doing DSO's at all, agreed about the mount but i guess one day you could upgrade to a better mount.

I use a 6.3 FR at the moment but i am also looking at getting a 3.3 FR then my FL should be about 670mm compared to 2032 standard or 1278 using the 6.3, i have imaged M57,M51,M27,M56,NGC 6205,NGC 7662,NGC 869,NGC 884,NGC 6871 so far without problems (i guess they may be the easier objects to go for) oh & i got the core of M31 as it was too big for my sensor.

Take your time setting the mount up & dont forget to level it, do the star align then do a few calib stars too then check again it really does make a big difference & saves your hair falling out.

I have seen a lot of images people have taken of various DSO's http://hwilson.zenfolio.com/galaxies/h1884854d#h1884854d, & this is awesome http://www.flickr.com/photos/kevinsheavens/5523865212/sizes/l/in/photostream/

I'm no expert & still learning & i also hate that niggling feeling when you have just spent your hard earned money & still not sure if you got it right, it's your scope now enjoy it what ever you do with it, i'm sure you will love it either way.

Let us know how you get on with it :-)

[wouter]

Thank you very much for all your advice and encouragement.

I will certainly take all of it in consideration as I'm hearing from the pro's here

Buying a lighter, shorter focal length refractor does seem to be an option worth to consider, but then I will still need to invest in a guiding system and maybe some other accessories?

I now came to realise something I had totally forgotten about.

My scope comes with fastar (hyperstar) compatibility.

Celestron doesn't make fastar lenses anymore, but starzonia does.

If what they say is right, I can quickly convert my scope into an F2 imager.

They also state that starting from C9.25 and up you can also use DSLR's without any problem. So I can save the cost of an expensive ccd camera.

A hyperstar lens is quite expensive (about $800) but a new APO and guiding system will not be far from away from that I guess.

Also I don't have to switch ota's everytime I just want to do observing.

However I barely know anything about Hyperstar, I understand the basics and how it works and the facts and acquired image's quality look all very promissing, but what I've read up to now is all from commercial sources.

So I'd like to ask if anyone has experience using hyperstar for celestron? Could you give me your opinions and advice? if you don't personally have it or use it, no problem, I'm all ears to all opinions / advice.

I was thinking if this Fastar (Hyperstar) is a good idea indeed, I'd like to get started with planetary imaging and easier DSO's with my DSLR or a cheap webcam and once I get a hang on that upgrade to Fastar.

But first of all I'd like to know if this Fastar is that good indeed and whether it is a good idea for me?

Thanks for all your help in advance

Wouter

[astrofox]

The C9.25 is a cracking scope for planetary imaging. You can consider using a f6.3 focal reducer/flatner for DSO's but as others have said a 80mm APO would be better.However if you move to an 80mm dont let ithe C9.25 go you will regret it.

[RikM]

I have never used hyperstar, but an ED80+ flattener/reducer and an 9x50mm finderguider package would cost about £700 (rough figure) but would be easy to use and give great results. For deep sky imaging anything that is easy to use is a big plus.

[rowan46]

I am sure you would get some product out of it but you still have the problem of an undermounted scope (at least for imaging) You are asking a lot for that mount to image such a heavy scope and expect great pics. You may be able to do it but it's unlikely to be fun my guess is you will probably throw much more than %50 of your subs away which is a lot of wasted starlight. Webcam imaging with that scope on that mount will be easy and fun dso imaging will be frustrating. You really are better off with a small apo and that lightweight guiding outfit from orion. I am not saying it can't be done but what we do is supposed to be fun and there is nothing more frustrating than throwing good money after bad. You do not have a bad scope you do in fact have a very good one it;s just that on a lightweight mount It's not up to imaging dso's. The way I see it you have 2 options to successful imaging with that set up either change the mount or the scope. The scope is the cheaper option.You haven't made a bad buy. You have a great visual scope and a stunning planetary imaging scope one of the very best, but there is no such thing as a scope that does it all unless you want to spend a lot more than you already have.

Have a read of this book

http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

It tells you what you need and more importantly why. In the meantime don't buy anything for deep space imaging Just look through your wonderful scope at some truly wonderful views and enjoy the beautiful pics of jupiter, saturn et al that you will be able to take with a webcam. When you have read the book you will understand better the advice given and if you decide not to take the advice that's ok because at least that choice will then be informed.

[ollypenrice]

The Hyperstar is a powerful bit of kit but the commercial sources don't talk about the difficulties. Consider the light cone at F2. It comes in at an incredibly steep angle which means that you have a terribly shallow depth of field. You are in focus here but a few microns away you are not. There are some obvious consequences. Firstly you must be dead right on focus and the Celestron moving mirror focus is not an inherently accurate system. It will need an upgrade to work to the design limits of the Hyperstar. Such upgrades (eg Feathertouch) are available. Secondly your chip must be dead square to the light cone or one side will be in focus while the other won't. Thirdly collimation will have to be bang on.

In a nutshell the Hyperstar is a 'work in progress' setup rather than a 'plug and play' and this seems to me to account for why Hyperstar images range from the excellent to the very poor. You have to get them right. As a beginner this might not be dead easy. It's also worth noting that the makers of high end fast astrographs like the Takahashi Epsilon, the OOUK AOG series etc all stop well short of offering F2 sytems. F2.8 seems to be as far as they want to go and they are not using cheap mass produced optics like Celestron and Meade. The Hyperstar can work for some and fail for others. Be aware, that's all, and if you are up for it have a go.

The weight of the scope on the mount is only a small part of the story. If you bring the focal length of the SCT way down with a Hyperstar, and the exposre times way down with a Hyperstar, a mount that wouldn't have a hope in hell of working at native FL will cope easily. There is far too much talk of weight determining mount performance. The truth is that focal length is what stresses mounts the most.

But, honest opinion, at around half a metre of focal length a CCD camera in a cheap ED80 will beat a DSLR in any optics known to man.

Olly

[wouter]

Thank you all for your great advice!

I've been giving it more thought and I think I will go with an ED80 scope on my CG-5 mount.

However first I want to conduct a few tests to see what I'm capable of with the gear I have a the moment.

So last night I went out, it was a nice clear sky for a couple of hours, so I tried to take my first image ever!

I polar alligned my scope with the polar finder scope, so it wasn't perfect. (I don't have a illuminated recticle EP yet so I couldn't do it using the drift method)

I only used one callibration star.

Also I couldn't take my laptop out. so the max I could do was a 30sec exposure.

I made only one shot, but I made some stupid mistakes, I left the ISO on 100 and saved as JPG format instead of RAW...

Anyway I think the result was not that bad after all, I'll try to find out how to post it in here.

Now I'm thinking of going to the local observatory here. They told me I could use their illuminated EP and focal reducer for a few shots and I'll bring my laptop as well.

If the results are satisfying enough with longer exposures, I think I will stick to what I have now, if not I'll get an ED80 later.

One last question: would this mini autoguider be a good idea for my C9.25.

http://www.telescope.com/Astrophotography/Autoguiding-Solutions/Orion-Magnificent-Mini-AutoGuider-Package/pc/-1/c/4/sc/60/p/99631.uts

I was looking at this since it's so light and compact.

They say it's for scopes with a focal length of max 1500mm.

Now if I put a f/6.3 focal reducer on my C9.25 does that meet this criteria?

2350mm normal focal length at f6.3 would give me 1480.5mm focal, right?

Or am I being too noob now?

Anyway here is my very first image as I talked about.

Are there any conclusions you can make from this first photo?

Let me know what you think

Wouter

[wouter]

Oh I forgot to point out that I don't have a good way to focus yet.

Just standard turning the focusser on the back.

[SteveNickolls]

Hi wouter,

I have the same 'scope and mount as you and a Canon EOS 600D DSLR. Do you have the Canon EOS Utility programme, it will allow you to live view through the DSLR on your laptop and help you focus using a much larger screen? AP is not my main interest at all but I like to experiment with what I have and intend to try out the camera/scope/software set up this season. Also a Bahtinov mask is a useful physical way of focussing. I can also recommend the Starlight Instruments Feathertouch microfucusser for the 'scope too-had lovely sharp views of Jupiter recently.

Hope you get sorted out. The 'scope is smashing for visual use too-I'm sure you will enjoy it.

Best Regards,

Steve

[jackrussell0232]

Wouter,

Your maths are about right, you will achieve that reduction in focal length, and the orion autoguider package works well. But I can honestly say that I wouldn't use it with the 9.25, I'd use it with the ED80 - this is a proven combo. Save the 9.25 for visual observing and planetary imaging - it's a great scope for that. I have an LX90, but my best photos all come from my ED80 (and now a wave 115). As Olly has implied, you can't make a CG-5 perform like an AP900 by autoguiding, regardless of what focal length you guide at. It's tracking speed will constantly be varying tiny amounts due to gear and worm noise, and while these movements will be imperceptible to the naked eye, and unlikely to ruin an image taken with an ED80, they will happily smudge the picture from a c9.25 and leave you frustrated.

Just for reference, I bought that very autoguiding package, and with hindsight it would have made more sense (financially) to buy a QHY5 and separate guide scope (I eventualy bought a used ST80). It takes practice of course, but with ED80, CG5, QHY5 autoguiding, you can soon be getting great images. And you can still enjoy the reach of the 9.25 paired to your mk1 eyeball. Please have a look at the images on my site, because stuff like this is within your grasp. I would insert the URL as a hyperlink, but doesn't seem to be playing, sorry. http://www.alphageek.co.uk/page24.html.

Part of the satisfaction comes from the fact that it's 'a bit of a challenge' - setting up, discovering what works, what to target, how to do the processing etc. Astrophotograhy happens overnight, but learning how doesn't.

Good luck.

Jack

[jackrussell0232]

Sorry, wasn't expecting that to auto insert as a hyperlink, and the full stop at the end of the URL stops it working. If you want to have a look, try this instead

http://www.alphageek.co.uk/page24.html

Hopefully that will help. Apologies for the extra post.

[wouter]

Hi Jack,

Thanks a lot for your opinion and advice.

Actually I was thinking of getting that Orion autoguiding scope package now for my C9.25 and practice with it.

It will probably be much harder and more frustrating but somewhere I'm thinking that learning the hard way can give me a lot more insight in how it all works.

Since all the factors that can disturb an imaging session will be greatly magnified with my C9.25, I will be able to learn a lot more I believe.

I want to buy that small autoguiding scope and keep it for later when I have saved up some more money (and more importantly have more experience) to buy a nice ED80 or ED100.

Thanks a lot for the advice and by the way your astro images look amazing especially I like the M33 one, you got some really great detail in there and obviously the removal of the IR cut filter has brought much more color in the red zones.

For some reason it's an object I haven't seen many really clear pictures of, despite its angular size and magnitude.

So I want to say great job there! I hope someday I can come as close to that

[ollypenrice]

I've commented on your other thread that I thnk the mini guider marginal for guiding an SCT. I'd use an off axis guider.

Olly

[wouter]

Thanks and sorry I opened a new thread about that finder guide.

I want my uncle to pick up some gear for me before he comes back

[Ewan]

Hi Wouter, nice progress so far :-), what about this bit of kit ? http://www.altairastro.com/product.php?productid=16558&cat=108&page=1 i was looking for the Astro 60mm finder kit for £150.00 Altair were out of stock but suggested the one in the link instead, i have not done any auto guiding yet so im no expert but it looks like a very good kit.

[ollypenrice]

I wouldn't bother with guide rings myself. They are a thing of the past since modern guide cameras are so sensitive that a fast guidescope will always find a star. None of our guidescopes are in adjustable rings, which are quite expensive and prone to flexure. If you really do want them then the ones in the link are good. I've tried them for a different purpose.

Olly