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Help requested in choosing a telescope to image with please


Roog
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Hello fellow stargazers,

I seek your help in selecting the right telescope for me to image deep space objects with.

I am the happy owner of a 10” Dobson Ian with which I enjoy visual astronomy from my back garden, however the lovely people of this forum keep posting their images from their astrophotography rigs and I am getting the itch to give it a go. Madness? Quite possibly.

When I made my dobsonian purchase I did so with the knowledge that big is good and I accepted the potential issue of moving the thing about, but when it comes to choosing a telescope for astrophotography it is not so clear to me.

I trusted family friend has suggested that I select an 80mm triplet APO, of relatively short focal length, SLR imaging camera plus HEQ5 mount and modest tracking scope.
And yet I see that others aim for 100mm and 120mm aperture triplet APO’s with dedicated Astro cameras and even bigger mounts! (Yes this is going to be loads of money) 
So is an 80mm APO with modest focal length enough for a reasonable selection of deep space targets? 

Then I see the likes of Rory aka astrobiscuit promoting the use of a 150mm Newtonian and a well used pro SLR, this all seems so different to the little 80mm APO. Surely these are not equivalent in the astrophotography world?

Sorry, but just to add one more request, I would like to have the opportunity to use the rig for a bit of go-to visual astronomy from time to time for when the Dob is not in the mood to go out in the cold! Would an 80mm /100mm  or 120mm APO serve this function, please. 
 

I would be grateful for your thoughts please, If I could pop into a local telescope shop I would bug them with my daft questions too!

Kind regards Paul
 


 

Edited by Roog
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Depends on what you want to achieve and how much money do you want to spend on getting there.

Used DSLR is really most cost effective way as far as camera goes. Are dedicated astronomy cameras better - yes, some models are, but they are also much more expensive.

With about 700mm of focal length you can get to the limit of what you can achieve in DSO as far as resolution goes. With ~3.8µm pixel size (most modern CMOS sensors have pixels that large) and 700mm of focal length you are already approaching upper limit of 1"/px.

130PDS and 150PDS are both good newtonian scopes for imaging.

APO triplet in range of 100-120mm of aperture is also excellent imaging scope.

Difference is in ease of use - newtonians need collimation and sometimes have some quirks that need to be addressed - like rigidity of OTA / mirror moving / light leaks and so on, while refractors are mostly trouble free and of course the price - good triplet APO will be more expensive than newtonian scope.

Mount will probably be most important thing in your imaging setup - so put the bulk of your budget there.

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Good suggestion @happy-kat I will pay more attention in future.

I suppose given my limited experience using visual only observations I note that some targets are visible to the naked eye and thus viewable in my dobsonian. Even then some are very faint. I have to wonder how well stacking multiple images from a tiny 80mm scope will compare?

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I would point out a few things that came to mind. How quickly do you want to get results? What types of targets do you have in mind? How much do you want to tinker or "lose time" with the setup?

I image with a 200mm newtonian and a poor quality mount and its been mostly trouble the whole time, so i would advice against that. Newtonian with a good mount? Dont know, as i do not have a good mount yet but im hoping my upcoming AZ-EQ6 will be up to the task. But here's the thing: I want to image galaxies, most of which are dim and smaller than nebulae, do not benefit from light pollution blocking filters, and i want to do this kind of imaging quickly as i cannot control the weather. I am also not made of money so a newtonian was really the only option for me. Large aperture compared to price and a very convenient focal length that is not too large really fits my use case perfectly.

But if i had more money i would definitely want an APO in the 130mm and up range to do the same job. Also, if you are already considering the HEQ-5 which is a fair bit of money why not go for the bigger EQ6R-PRO? I really do hate my mount and wish that nobody would try to undermount their telescopes so if i had a time machine i would put almost all of my budget into the mount.

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1 minute ago, Roog said:

I have to wonder how well stacking multiple images from a tiny 80mm scope will compare?

80mm of aperture is not a limit - only invested time is the limit - given enough time, 80mm scope is capable of reproducing Hubble extreme deep field :D - not in resolution though - but in detection of galaxies - sure.

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Heq5 is more than capable of holding 80-100mm frac and image with it.

This is up to 2 hours from very light polluted area taken with 80mm triplet on Heq5:

image.png.08a29c7d7eb972eb46aadefe3fa8fbe6.png

Did not bother to process out satellite trails. Same image contains like dozen or so galaxies.

image.png.cad4a5a877a30be823dc59c36307d1fb.png

image.png.6a991df908a3b466cb96a91a4f4585c4.png

Here are few more shots with different cameras (again 80mm / heq5):

image.png.1b2332e4b9c42b5b165aa1508c457bd1.png

image.png.bf62b4505df50100ed4e160b05d8d20b.png

image.png.7cbe8dc883689f3069a3e2157db9ef9f.png

Edited by vlaiv
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12 minutes ago, vlaiv said:

Depends on what you want to achieve and how much money do you want to spend on getting there.

Used DSLR is really most cost effective way as far as camera goes. Are dedicated astronomy cameras better - yes, some models are, but they are also much more expensive.

With about 700mm of focal length you can get to the limit of what you can achieve in DSO as far as resolution goes. With ~3.8µm pixel size (most modern CMOS sensors have pixels that large) and 700mm of focal length you are already approaching upper limit of 1"/px.

130PDS and 150PDS are both good newtonian scopes for imaging.

APO triplet in range of 100-120mm of aperture is also excellent imaging scope.

Difference is in ease of use - newtonians need collimation and sometimes have some quirks that need to be addressed - like rigidity of OTA / mirror moving / light leaks and so on, while refractors are mostly trouble free and of course the price - good triplet APO will be more expensive than newtonian scope.

Mount will probably be most important thing in your imaging setup - so put the bulk of your budget there.

I totally agree with your points @vlaiv thank you for your advice. As far as budget is concerned I would, like most people prefer to pay no more than necessary, however I get very frustrated when I buy in at the lower end and end up buying twice.

if a smaller quality telescope can do the job, I would be happy.

Similarly, I have read a fair bit about the popular mounts made by Skywatcher HEQ5 and 6 R models, people like to tweak and tune them and they seem to offer good payload and yet I read threads which say they aren’t a patch on ioptron CEM60 and above, actually I think they were less complementary than that! 
i can see that the performance of the mount is very important to accurately tracking the target and quality of the final image, it is for this reason that I am especially concerned about getting this right. 

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If you're just starting out a good apochromatic refractor may be best though they do cost. Your mount will be the most important purchase, if you're looking at 100mm plus refractor even more so, and also more so if your focal length increases as you'll need better guiding accuracy. A used dslr (ir filter modded if you can find one) will be a good start though you will quickly move onto dedicated astro cameras once you progress.

80mm is a decent choice, I've got 60mm and it's forgiving as it's a fairly short focal length so allows quite wide field captures and guiding doesn't necessarily have to be autoguided (can get away with sidereal mount movement). I also have a 130pds and the light gathering is of a magnitude higher but the scope is larger hence more of a burden on the mount I have. Depending on which type of scope you get and how finicky you are about field flatness you will also either consider a field flattener for the refractor or a coma corrector for the reflector.

Depends on your area and the level of light pollution as to which you decide on. Do you have a budget in mind?

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19 minutes ago, vlaiv said:

Heq5 is more than capable of holding 80-100mm frac and image with it.

This is up to 2 hours from very light polluted area taken with 80mm triplet on Heq5:

image.png.08a29c7d7eb972eb46aadefe3fa8fbe6.png

Did not bother to process out satellite trails. Same image contains like dozen or so galaxies.

image.png.cad4a5a877a30be823dc59c36307d1fb.png

image.png.6a991df908a3b466cb96a91a4f4585c4.png

Here are few more shots with different cameras (again 80mm / heq5):

image.png.1b2332e4b9c42b5b165aa1508c457bd1.png

image.png.bf62b4505df50100ed4e160b05d8d20b.png

image.png.7cbe8dc883689f3069a3e2157db9ef9f.png

Thank you again @vlaiv your images and posts are very helpful.

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As you can see from my signature I have a range of scopes and I have imaged with all of them. Personally if I was starting out I would go with a refractor for ease of use. AP is hard enough without the complexities of newtonians. My first set up was the SW ED80 with and HEQ5 which was very good. I have now upgraded to the 90mm triplet - but I am still waiting to assess the difference. One day the sky will clear..... The refractors are limited in FL, but at longer FL you will need to bin anyway so you will loose some of the benefit. Also, the lower FL is more forgiving and allows widefield images of nebulae. Having said this, the RC8 is a great galaxy scope - but does need a bit more work to the get the results.

As most will tell you. Spend the money on the mount. Personally I find the AZ-EQ6 perfectly adequate but it does need regular fettling to keep it going well. Similarly the HEQ5 is good enough up to about 1000mm FL.

At the end of the day, the better the mount the easier it will be. (Cheaper options work - but are a pain in backside). After that choose your scope based on what you want to image.

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2 minutes ago, Roog said:

I totally agree with your points @vlaiv thank you for your advice. As far as budget is concerned I would, like most people prefer to pay no more than necessary, however I get very frustrated when I buy in at the lower end and end up buying twice.

if a smaller quality telescope can do the job, I would be happy.

Similarly, I have read a fair bit about the popular mounts made by Skywatcher HEQ5 and 6 R models, people like to tweak and tune them and they seem to offer good payload and yet I read threads which say they aren’t a patch on ioptron CEM60 and above, actually I think they were less complementary than that! 
i can see that the performance of the mount is very important to accurately tracking the target and quality of the final image, it is for this reason that I am especially concerned about getting this right. 

Well, I currently have Heq5 that I'm happy with (within it's limits of course). It is heavily modded - I tuned and did belt mod, changed saddle plate and put it on Berlebach Planet tripod. When all adds up - it is probably twice the price of stock model and already in iOptron 40/45 territory.

In such condition it just carries 80mm without any issues. In fact - it can achieve rather good results with 8" 1600mm FL scope.

My next mount is going to be a bit more serious than that. At the moment I'm eyeballing E.fric mount.

If I were starting now, and I had the budget, I would consider iOptron 40/45 line. I would first do extensive research as I've seen some people complaining about QA, although most praise finish of the mounts. I've seen couple complaints about iOptron customer service as well (to be fair - I never ever thought about Synta/Skywatcher customer service and I replaced cracked bearing on my Heq5 myself).

Step up would be iOptron Cem70. I was actually really keen on Cem60 but they are now discontinued and almost the same mount - Cem70 is sold with considerable price increase (I wonder why :D ).

 

 

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If there is one main factor that matters  in visual, it is perhaps the size. If there is such one factor in photography , than it is the mount . As mentioned by some people above, it is not a bad idea to  allocate significant part of estimated starting budget to good mount and tripod.  Underperforming mount can't be compensated by type of scope/camera.

The type  of objects and and the level of details  you wish to see will determine the type of scope , although seeing is the limiting factor.  The focal length in the range of 500-900 mm is perhaps a good start . Is it Newtonian or refractor , it depends. Newtonian is more bulky , requires collimation but for the same money you can get larger aperture .

Refractor is the easiest to start with , but is more expensive.  I am relatively new  in  this hobby , but started wrong way for a beginner. (SCT with 2m focal length , HEQ5  mount and small pixel "2600" type OSC camera ) . Evolved very quickly to iOptron CEM70 mount and Esprit 120mm triplet refractor with focal reducer.  

Of course, the budget is always the limit for most of us , but if I would be starting now and the budget would be sufficient I would start with:

-The mount with 20-35 kg payload and good base (tripod, or pier) 

-100-130 mm triplet refractor (middle range like  Esprit 100 or 120  or something in that class )  and focal reducer .  Of course , APM LZOS  or Takahashi or TEC  would be better but is quite expensive

-APS-C format OSC cooled camera ( like QHY26C or ASI2600 or Omegon veTEC571 or any other clone based on Sony IMX571 sensor) 

-Dual band filter like Optolong L-Extreme or Antlia 5nm Ha/OIII dual band 

That would let you start quickly with collecting good images and enable you to change the focus from your gear  to yourself and learn image processing , which is more complex and requires more time and effort than  collecting the data 

 

 

 

 

 

Edited by Stefek
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Hi @Stefek your story is familiar to me, I have already started to collect too many redundant bits and pieces of Astro gear due to my ignorance of the topic, reading around it helps a little but hearing other people’s experience is very helpful. 
 

I plan to arrange a proper chat with our family friend on the topic in the new year, it would be good to discuss my anxieties face to face and to get a feel for the limitations of going smaller rather than jumping in with big and expensive straightaway.

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Also think about storage and setup location. A heavy mount, heavy telescope (refractors can be heavy) and guiding setup, cameras, cables and power can take a while to setup to take a first image if you don't have a permanent observatory. Some use more portable setups with small lightweight refractor or lens.

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12 hours ago, Clarkey said:

At the end of the day, the better the mount the easier it will be. (Cheaper options work - but are a pain in backside). After that choose your scope based on what you want to image.

I think all of you have more or less said this, I like the idea of choosing a refractor this time, not least because I don’t currently own one, although the cost of a big one is a bit eye watering.
I note that a few of you have raised the thorny issue of my ‘Budget’, this is tricky for me, like many of us money is hard fought for, but, I don’t mind saving and forking out for something if I think it is worth it.
Similarly, as a competent electrical/electronics engineer with a good appreciation of small scale mechanics, I quite like making and refining things, I made a motorised portable alt/ az system for a TV satellite dish years ago, it needed a lot of care and understanding to work  but when it comes to a  tracking mount driven by a computer I would probably appreciate one that just works as I will be at the limit of my mental capacity just dealing with the process of Astrophotography.
Actually this raises another very important issue for me, that of guiding and imaging software, this really needs to be as intuitive as possible for me. I am not sure if my choice of mount influences this at all?

I can see that the choice of mount will influence the experience when tracking, It would be nice to be able to buy just one and be happy forever, but I fear I ask too much.

thanks again, I’m off to read up on what has been said already.

kind regards Paul

Edited by Roog
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37 minutes ago, happy-kat said:

Also think about storage and setup location. A heavy mount, heavy telescope (refractors can be heavy) and guiding setup, cameras, cables and power can take a while to setup to take a first image if you don't have a permanent observatory. Some use more portable setups with small lightweight refractor or lens.

Yes, I am beginning to see that astrophotography requires a lot of commitment, lugging my Dob out through the house and down the kitchen step is a pain, but once out it is easy to get observing.

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A William Optics 81 mm triplet is a good choice (I have the 81 GT IV). You will still need a flattener, you can either use a dedicated WO flattener/reducer (which will give you a focal length of about 380 mm) or a general purpose flattener (I use a Hotech 1x flattener, which gives a focal length of 478 mm). This gives good round stars right out to the edge of an APS-C sized sensor, and at 478 mm focal length, the field of view is 2.8 x 1.9 degrees, with a resolution of about 2.1" per pixel, so autoguiding should be pretty straightforward. A larger refractor will usually have a longer focal length, so a smaller field of view, which can be good for some targets, like galaxies. 

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If your polar alignment is good you can use the mounts in built sidereal rate to move with the rotation of the stars (earth) as long as the mount has motors built in or bundled with therefore unguided. I'd start from there.

When you decide to go down the autoguide route it'll empty your wallet pretty quick as you'll have to buy astro cameras and associated equipment of which you'd want a decent one so it can perform more than one duty. Then there's the technical issues you WILL face and have to overcome before you even get into a position to start imaging. If you want easy, an Asiair pro/plus makes the process so much easier though it's another purchase and you're tied to using ZWO cameras (or a supported dslr). There are cheaper options like a raspberry pi or pc but it depends on how much you want to lug around and setup.

Start simple. Once you reach a limit move onto something else then. You'll forever always be looking for the next upgrade with this hobby.

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13 hours ago, ONIKKINEN said:

I would point out a few things that came to mind. How quickly do you want to get results? What types of targets do you have in mind? How much do you want to tinker or "lose time" with the setup?

I image with a 200mm newtonian and a poor quality mount and its been mostly trouble the whole time, so i would advice against that. Newtonian with a good mount? Dont know, as i do not have a good mount yet but im hoping my upcoming AZ-EQ6 will be up to the task. But here's the thing: I want to image galaxies, most of which are dim and smaller than nebulae, do not benefit from light pollution blocking filters, and i want to do this kind of imaging quickly as i cannot control the weather. I am also not made of money so a newtonian was really the only option for me. Large aperture compared to price and a very convenient focal length that is not too large really fits my use case perfectly.

But if i had more money i would definitely want an APO in the 130mm and up range to do the same job. Also, if you are already considering the HEQ-5 which is a fair bit of money why not go for the bigger EQ6R-PRO? I really do hate my mount and wish that nobody would try to undermount their telescopes so if i had a time machine i would put almost all of my budget into the mount.

Thank you @ONIKKINEN, I see your point about having the time vs aperture, Vlaiv   Also made the same point but coming from the other direction, small can work if you can invest the time. It’s a bit of a balancing act isn’t it.

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9 minutes ago, Elp said:

If your polar alignment is good you can use the mounts in built sidereal rate to move with the rotation of the stars (earth) as long as the mount has motors built in or bundled with therefore unguided. I'd start from there.

When you decide to go down the autoguide route it'll empty your wallet pretty quick as you'll have to buy astro cameras and associated equipment of which you'd want a decent one so it can perform more than one duty. Then there's the technical issues you WILL face and have to overcome before you even get into a position to start imaging. If you want easy, an Asiair pro/plus makes the process so much easier though it's another purchase and you're tied to using ZWO cameras (or a supported dslr). There are cheaper options like a raspberry pi or pc but it depends on how much you want to lug around and setup.

Start simple. Once you reach a limit move onto something else then. You'll forever always be looking for the next upgrade with this hobby.

All that you say @Elpmakes sense, it seems to me a case of pitching my starting point at a place where I will be motivated to persist and not demotivated due to too many technical obstacles or limitations 

 

cheers Paul

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I am maybe not as experienced as many that have already given advice as it was only about 3 1/2 years ago I was asking the same sort of questions on SGL, and very glad I did.
But, this is probably one of the most asked questions, certainly from newcomers to the hobby, and also maybe one of the harder questions to give a definitive reply.
Why, well for various reasons, different scope / cameras will give very different FOV's and so lend themselves to different targets and as a newbie its very difficult to say what targets you really want to aim for, many times before you are into AP you are not sure. So maybe the only decision at that stage you can make (and I think you need to) is Planets or DSO's, as those requirements are quite different and I suspect you are aiming for DSO's.
My route was very similar to your own, and I suspect many others, starting with a Dobsonian and then getting enthralled by the hobby and wanting to take some images.
So from my short time in AP the bits of advice I could give is yes there is the route of saving and buying the best you can afford with a view to having a scope and mount for life, but in essence if you find out AP is for you and you get through all the pitfalls and difficulties you WILL encounter (good images do not come easily) and do not fall by the wayside and sell up (many do) then you more than likely will go on and the equipment you start with will not be what you are using 3 or 4 years down the line.
Also, you will find that AP does need more than a good scope and sturdy mount, so there will be more stuff to spend your hard earned cash on when you get into the hobby:

  • Guiding scope and CCD - may not be actually essential to start with, if mount has good tracking and is polar aligned accurately, but you will probably want this eventually.
  • Processing software, to calibrate, stack and to bring the details of your images to life. There are many free programs to do this but probably the better ones do come with some outlay.
  • Filters- may be in the form of LRGB (if you go the Mono route), Narrowband,  Light pollution filters
  • Flat field panels for taking flats - again not necessary to start with but you will probably and up buying one.
  • Auto focusers - again not needed to begin with but you will find this invaluable later in the hobby.
  • Imaging software to set up sequences and just make the whole process of imaging much easier - so many of these are free and great programs.
  • Flattener - yes you can take images without but really in order to get the best out of your scope you will more than likely want one and it is better to start off with a scope and flattener that is designed for use with that scope.

So which route do you take ?
I probably am not helping and can only tell you my experience.
With lots of advice from SGL I ended up starting out with a New WO73, flattener, 2nd hand HEq5 (which I then added the belt mod), 2nd hand DSLR from Ebay, New WO guidescope and 2nd hand guide camera. Cost probably about £1400 3 1/2 years ago. Now although the gear I use has all changed this was a great start and was perfectly fine to take very reasonable images (Only thing preventing this was my own inability and nothing to do with equipment).
And that's really the point I am trying to make with this long ramble. One of the main requirements for good images is your own ability, not necessarily the equipment, and that is not something you can order and get it straight out of the box.

So yes get equipment that is capable of taking good images (many do achieve good images with small mounts and maybe scopes really too heavy for the mounts but it does get that much harder so best not to go that route unless money prevents you doing otherwise) but I would say do not spend more than you need to to start with. Getting the best gear in the world will more than likely not yield great images for many months, even years until you develop your skills (both in obtaining the data and with the processing of that data).
Much of the gear you probably can get 2nd hand to save some cost but I would say a HEQ5 is a good start and a refractor of 70 to 100 mm and a DSLR. I initially bought a guidescope and cam but due to having enough on lining up targets and getting exposures right and all the other things a newbie has to learn I didn't actually use the guiding for almost a year, I just concentrated on 60 to 90 second exposures and relied on good polar alignment and tracking of the mount to achieve images with no (or very little) star trails. And this is probably how I would suggest you start as @Elp suggests.

Use a simple but sturdy setup and then invest the time into yourself and developing your skills for a year or two, then decide the way you want to go, probably as many do going the mono route with filter-wheel, filters, dedicated CCD and so on but the two years with the simpler gear will not have gone to waste.
In addition you will find a HEQ5, 70mm (ish) small lightweight refractor and flattener, either a dedicated colour CCD or DSLR is maybe not the lightest of grab and go rigs but it is not too bad and certainly able to be used as a mobile rig.

Sorry for the waffling on and hope this helps and does not just confuse you even more 🙂 

Steve 

 

Edited by teoria_del_big_bang
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