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Imaging without guide scope. Advice please :)


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I think flats are always important. My best results are with a Neumann panel because the spectrum is pretty coninuous. It is true that cmera lenses can be really evenly illuminated but then again on lens shots you are covering a huge area of sky so the background calibration needs to be even better than for small field telescopic shots where a bit of gradient may not show. On four degrees of sky it will certainly show!

Have a care with bias. The bias is contained within the dark so do not subtract it twice. Many of us only take bias frames in order to make a master bias which we will use exclusively as a dark-for-flats. DSS seems to ask for bias but I have no idea why. Shooting separate darks for flats, one for each filter, would be a real pain in the nether-belows!

Olly

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You can get into guiding for very little dosh. An unmodified webcam and a decent finder scope, together with the physical adaptors necessary, are not expensive.

Thermos, would you say I have all that basic equipment on a budget? Look at my signature, please... What I am looking to acquire now ( I wish I had bought the Ed80, faster scope than the c90 mak) is a good GOTO that will support 1) the camera and later 2) the scope 3) scope with camera. And I would start shooting on a budget.

My research show this options:

1- $319: Celestron NexStar SLT Computerized Mount

2- $399 Celestron Sky-Watcher

3- $469 : NexStar 4 SE and 5 SE Computerized Mount

*Celestron

4- $519: Celestron NexStar 6 SE and 8 SE Computerized Mount

I am not worried about spending more on the mount than in the scope for the moment, if the choice seems to be the most expensive in the least as long as I can attach the camera and do wide fiel AP. My heart is in DEEP into photography.

What is this sky-watcher anyway? Can I mount the scope?

I have rad most of the thread in finding answers, which are usually on the point. Please advise. Very interesting thread.

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For budget Astrophotography with camera and telephoto lens, my system is hard to beat for value. You'd need to get the mount

Orion EQ-1 Equatorial Telescope Mount | Orion Telescopes: Mounts

or the tabletop version

Amazon.com: Orion Min-EQ Tabletop Equatorial Telescope Mount: Camera & Photo

the motor

Orion EQ-1M Electronic Telescope Drive | Orion Telescopes

a camera bracket like this one to attach your camera and finderscope to the mount

Orion 1/4"-20 Adapter for EQ1 Telescope Mount | Orion Telescopes

a finderscope like this

Orion 9x50 Achromatic Telescope Finder Scopes | Orion Telescopes

you'll need a "shoe" that the finderscope attaches to, you need to bolt that onto the bracket above

Orion Dovetail Mounting Bases for Finder Scopes | Orion Telescopes

you'll need a webcam, Philips SPC900NC is considered good and can be found on ebay

and an adaptor to attach your webcam to the finderscope, the only place I know that has these is modernastronomy.com and you want a "SPC900/SPC880 Adapter for Straight Through Finders"

Accessories @ Modern Astronomy

A bit of diy will then get you autoguiding with that setup and get one arcsecond error RMS provided you polar align carefully.

I know Jerry Lodriguss calls this mount a "really bad one" and he's right, it has an error of about 200 arcseconds when not autoguided. I will write to him.

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Your approach is very interesting, but I am not a DIY she-person. Too many parts to put together, and I want to use what I already have... Let's see.

WHAT IF I went for 1-2 least expensive of these mounts

1- $319: Celestron NexStar SLT Computerized Mount

OR

2- $399: Celestron Sky-Watcher

-- use my scope (Celestron C90 MAK) Is it not good for this? It is f/13, 1250mm FL

- C90 has a tripod adapter at the bottom with 1/4 x 20 threaded holes; so the C90

comes ready to be attached to a regular photography tripod.

-- Use the camera bracket to attach the camera and finderscope to the mount

(Don't know if this is needed with that mount) Probably not? Depends on whether the mount has the counterpart which I don't know.

-- Use my Canon 550D either as a stiil camera or video camera.

-- The C90 comes with T-adapter threads to which I have successfully attached the T-adapter that goes between camera and the tube to take photos of what I see.

The only thing I don't know is if I can attach the C90 to this mount with this type of camera connection or other. (?)

Or... if I can attach my camera with a 50mm, 250mm lens to these two specific mount(s) with no further brackets and thingies. IS that possible? The I would not need the spotting scope which I would use for the moon, birds and animals of the lake.

Then.. I would start to be unsatisfied with the scope and would try something else, and something else more (this is the part I don't like and what I want to keep controlled, so the cheap approach but good mount for astrophotography)

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For long exposure astrophotography, none of these mounts will do. They will be ok for moon and planets, though. The C90 has a large focal length so it is especially suited for the moon and planets. I see that people image with it quite successfully This pdf file shows you how to attach a DSLR to the C90.

http://www.celestron.com/c3/images/files/downloads/C90_Mak_52265.pdf

I guess you have succeeded in using your camera with the C90, yes? So you are trying to find out which mount to buy for it? As far as I can tell, the C90 has a standard tripod thread. A lot of mounts use a "Vixen style dovetail" arrangement instead. You can buy a little adapter that is a dovetail with bolt sticking out that will mate to your C90 tripod thread and it will let you mount your C90 on this "Vixen style" mounts.

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Yes to the question, I have attached DSLR. The attachment you talk about for the dovetail was described in the previous answer to my quest, so check mark that also(^).

What nobody seems to take into consideration is the 64000 ISO Of my specific DSLR. I suppose that is a plus and shortens time of exposure. But this is not what is most important, which is that the scope is not the best for this, isn't it?

Nor anyone has addressed the seemingly made-for-this-purpose, mount #3, the Skywatcher,which has a camera-type connection for either 1) a camera OR 2) C90

If my little scope is no good for this type of AP,good. I would be content to take a photo of Jupiter where I can see the bands - as shown in many forum writers and the Celestron gallery-- or to use my camera and lens alone for whatever is in reach. See that the Skywatcher is around $400, similarly priced, but is designed to take cameras (and c90).

Otherwise... Tell me what should I aim for in terms of min. Equipment.

You say these mounts will not work For long exposure AP, so I assume that they are not capable of tracking. Then, which are? Or how do I make them track? I am assuming the Skywatcher can. but it isnot only this, is the little scope that can't! Right? I Looked at Orion ed80, f/5... (?).starmax 127 ...

I may be asking too much and forgive me for asking for so much leniency. Can you read the info for the Skywatcher? I wanted to have a mount for both my DSLR and/or c90 for my BD on march 14, seems it will not possible since I am running in circles from info to info without finding a definite answer. I do undearstand the c90 has little power, so I will not be able to see much beyond planets. What would be my best choice the, forgetting the c90? On a budget. Still going back and forward, not knowing in which direction to go. I am hoping whatever I spend should give me "assignments" for a year or two, looking at the sky. assuming I do not have many clear skies.

Uff! It has taken long to write this on my iPad! Hope it is worth the explanation, rant, and desperation of not knowing much and wanting to reach a decision.

Clear skies and patience!

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What nobody seems to take into consideration is the 64000 ISO Of my specific DSLR. I suppose that is a plus and shortens time of exposure.

No, it doesn't. Your camera is not 80 times more sensitive than an ISO800 camera. There are a lot of myths around about ISO and I can't go into details right now.

Nor anyone has addressed the seemingly made-for-this-purpose, mount #3, the Skywatcher,which has a camera-type connection for either 1) a camera OR 2) C90

It is not so important that the mount cant take a dovetail and a tripod thread as there are adaptors on the market.

You say these mounts will not work For long exposure AP, so I assume that they are not capable of tracking.

No, they are capable of tracking. The problem is that they are Altitude/Azimuth mounts and not equatorial mounts. This means that the way they hold the camera as they track will result in smeared photos as the whole field of view will rotate during the exposure. This is a subtle geometric effect and not immediately obvious to people.

Then, which are?

For long exposure astrophotography with your camera and your nice lenses, and if you have money to burn, then the Vixen Polarie would be a natural fit.

Vixen Optics- Polarie Star Tracker for Astrophotography

I really think you need to go to a shop and have a chat with a dealer who will be able to explain all the issues carefully.

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OAG is more of a palaver and totally unnecessary at shorter FLs. It gets to be a boon with big SCTs etc. I vote for ST80 and pc based autoguider.

Personally the humble ED80 would be my choice of imaging refractor on a budget. It performs out of its skin.

Olly

what mount would you use for the ST80?

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No, it doesn't. Your camera is not 80 times more sensitive than an ISO800 camera. There are a lot of myths around about ISO and I can't go into details right now.

It is not so important that the mount cant take a dovetail and a tripod thread as there are adaptors on the market.

No, they are capable of tracking. The problem is that they are Altitude/Azimuth mounts and not equatorial mounts. This means that the way they hold the camera as they track will result in smeared photos as the whole field of view will rotate during the exposure. This is a subtle geometric effect and not immediately obvious to people.

For long exposure astrophotography with your camera and your nice lenses, and if you have money to burn, then the Vixen Polarie would be a natural fit.

Vixen Optics- Polarie Star Tracker for Astrophotography

I really think you need to go to a shop and have a chat with a dealer who will be able to explain all the issues carefully.

Well, this is much,much better, I like the you can say why they are not good for tracking and not getting into details which I don't need nor want to know. BTW; i had already found the Vixen Polarie on my research, nice piece of equipment. Will go back to review it.

Thank you...

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The Astrotrac is in the same category as the Polarie, I guess. There are cheaper options but they require an experienced operator who will be able to diagnose any issues quickly.

If you start considering small telescopes like the ST80, then you should be considering a proper German Equatorial mount like this one

Celestron Omni CG-4 Mount Telescope - Mounts & Tripods

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You can image with the Mak unguided. Yes it takes longer and you have to use shorter subs, but it is possible and a solid polar alignment is key.

I can manage 1 minute subs on my 180 Mak and that is 2700mm FL at f15. So it'll never be good on faint fuzzies but works fine on brighter objects, globulars for example. Should add that is on a NEQ6 though.

With the 80ED on the same mount I can get 2 minute subs before stars change shape. And with the focal reducer/flattener, it's pretty fast and you can grab a lot of light.

Cheers

Ian

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themos

I had already found the CG4 in amazon at $249 and several other Orion and Celestron brand, some of which I can add motorized guiding.

- CG4 at Amazon for $ 249

- Orion EQ-2 @ $199, to which I can add the EQ-2M drive ($80)

- Orion AstroView ($249.99) Equatorial Telescope Mount to which I can add the EQ-3M drive ($139)

I think these are my choices, plus de ED80 or slightly better scope. Advise accepted.

I suppose you (themos) will vote for the CG4... Better be prepared.

--- and iwatkins: Thanks for a positive view of the world of imaging. I liked your photos.

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You can image without guiding but so much depends on the quality of your mount's drive system and the acuracy of your polar alignment. The longest I've managed unguided is 180s through a 900mm fl refractor on an EQ6. Normally I would only go for 120s exposures due to drive periodic errors.

Here's my example of 3 minutes unguided.

Dscf3265.jpg

Just to re-iterate the above sub is the exception rather than the rule. I would get some star elongation in 80% of my frames if used 180s exposures all the time, but it shows whats possible without guiding. Ultimately I need to get my guider set up and in use. I'm just lacking time & cloud free nights!

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The Astroview and the CG4 are basically the same mount and I would discount the Eq2 if you are serious about DSO imaging with an Ed80. The dual axis motor drive for the Astroview doesn't have the required ST4 for guiding (a simple modification can be made by following the instructions on the Shoestring Astronomy website). The mount you should be considering as a minimum is the Celestron CG5GT / Skyview Pro or Orion Sirius or Altas.

Peter

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Hi! I'm at a similar stage and currently saving for what I have it worked out as:

Got a mak 127 on the typical Alt/Az mount. For visual it's perfect. To get into AP I bought the SPC880 and flashed it to start making planetary images. That worked surprisingly well - see my gallery.

Unfortunately, I then wanted to take long exposure images...

I got my 2nd SPC wich had a long exposure mod and simply had a go at M42. Lots of things became apparent: my mak's magnification is too large, the mount tracks but is not accurate enough, the mount is too whimsical and moves too easily with even little windgusts, the alt/az field rotation problem.

I have uploaded what you can expect to get with such a setup in my library, have a look at those three M42 shots at 5s, 10s, 20s exposures. Most of the subs were blurry and had to be discarded...

So, I now know I need a stable mount. That's at least a HEQ5. Don't save money on that. Then I'd like a greater FOV - a nice option is any of the ED80s (there are differences mind). Then I'll try unguided AP until I can get myself some auto guider system like QHY5 for example. And at the end I'll want a better camera.

Hope that helps.

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I am getting somewhere definite now with the last two posts added to previous discussions. I guess this is what I didn't want to do; mistakes that cost $$$. Your experience is very valuable to us and is appreciated. I am sorry most of us have to spend money to find out that was not what we wanted. We end up with several scopes, hopefully we can donate to young people so they can start on their own paths into astronomy.

My significant other is already raiising one brow. If two are up, I will be in trouble. So, cg5 is the way to go... I am almost positive that this is the equivalent to the HEQ5.. Good they have the same numbers. I cannot order HEQ5 since I think it will come from UK, costing more...I may not be right, though. This is going good.

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The CG5 isn't equivalent to a HEQ5. It's more of an EQ5 with a few modifications i.e. 2" tripod legs and better bearings. So the CG5 sits in between an EQ5 and HEQ5..closer to an EQ5 though. An HEQ5 is an Orion Sirius EQ-G over in the states I believe and the Orion SkyView is similar to an EQ5.

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I see! Hum! I am looking into equip I can get from the USA. Many details to consider that one doesn't know. So based on this, Orion Sirius on the sturdiers side or CG5 or Orion Skyview on the low limit from sturdy to less sturdy.

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Maybe you will find the US site Telescope Reviews | Cloudy Nights more suitable.

That site has these problems:

I cannot go back to pages with back-arrow/back page; I have to do a new search each time (annoying!)

When I do a search on XYZ I get lots of things that are not XYZ. Can't ever find what I 'm looking for

Is Not as well organized as this forum

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The CG5 gt doesn't carry as heavy scopes as the HEQ5. If you stick to your mak and an ED80, you'll be absolutely fine though, even with a guide scope, should you add one later. The best payable mount to buy is the NEQ6. BUT, you'll have trouble lifting it, no matter what people will say out here.

Stability is the main thing for long exposure AP, and you will get this mainly from a NEQ6 or HEQ5. Anything less, might have issues with the scopes you put on it!

For visual, it doesn't matter at all.

Oh, and HEQ5 is not HEQ5. The HEQ5 Pro GOTO has an ST4 port, which is a plug you need to connect your mount with a guider (comp/guidecamp).

So, if you don't want to buy yet another mount in the future - the CG5 GT is fine but might not satisfy. The HEQ5 pro GOTO will be your best bet and the NEQ6 is the most stable but buy far least portable version.

So that's 750£ + shipping. For the scope, you'd have to make up your mind. There isn't so much you can do wrong. No scope can do everything, so you'll end up with two at least, maybe more.

DSO's are usually too large for the mak. Planets are too small for apos. Newtonians need collimating and what's the trouble with SCT's, I forget! Nothing is perfect, so relax. Start with smth affordable and see where that takes you scope-wise.

That's just my little amount of drivel on a sunday afternoon.

My brother btw is gonna buy his first scope in April and didn't listen to our advice here at all. He'll get a Meade LS 8" I think on a fork alt/az mount. That'll set him back well enough, but I wonder whether he'll soon regret his mount. Most people I know wanted to start clicking pictures very soon. And, an alt az mount is only suitable for rather short exposures.

Hope I'm making sense!!!

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