Best scope for imaging

[bluesilver]

Hi,   I thought it would be best to put this in a separate post as it is a little different question form my previous post.

I was looking at getting a telescope so i can also do a little photography work of the planets and possibly nebula and galaxies.

I also realise this might be a broad question but hoping to get some general information that i can work from.

Basically i don't want it to be a solely dedicated photography scope where i can't use eyepieces. I would like to be able to use it to do both,  

Would i be better of looking at Refractor like say the SkyWatcher Black Diamond 120/900 ED Doublet Refractor

Or the Orion EON 130mm ED Triplet Telescope

Or would i be better of going back and looking at a Cassegrain like the SkyWatcher Black Diamond 180/2700 Mak-Cassegrain

I was looking to mount them on a Skywatcher AZ-EQ6  Mount.

Hope that all makes sense.

Any information would be appreciated.

Thanks.

 

 

 

 

Edited November 22, 2019 by bluesilver

[vlaiv]

Very different requirements so it is very hard to package that all together.

Depends how serious are you regarding each of requirements.

If you are looking at a bit more serious planetary work, 8" scope is start in aperture. Problem with that is that it won't provide wide enough field for larger nebulae (most galaxies and planetaries will be fine at that focal length).

On the other hand if planets are something to try out but you have no greater expectations - you can limit your self to 5-6 inch scope.

In first case, there are really only few choices:

1. EdgeHD 8"

2. Classical Cassegrain - again 8" - like this one: https://www.teleskop-express.de/shop/product_info.php/info/p10753_TS-Optics-8--f-12-Cassegrain-telescope-203-2436-mm-OTA.html

3. 8" F/6 Newtonian (maybe even F/5, but that one will have larger secondary if optimized for photo work and collimation will be more demanding for planets, also higher power barlow / telecentric is required to reach critical sampling)

4. 8" RC scope (mind you, while better option for DSO photography - it's not the best for planetary work and might not suit visual as much as other scopes - large central obstruction).

While you can go with larger scope - I would not recommend that unless you are rather serious with planetary work and are ready to completely neglect wider field DSO work.

In second case - there are much more options.

1. Decent maksutov newtonian (intes micro), or even their photo maksutov cassegrain: https://www.teleskop-express.de/shop/product_info.php/info/p3316_Intes-Mikro-Alter-M606---Photo-Maksutov-Cassegrain-152-912mm.html

There are other options, like SW 190 (Mak-Newt) and Explore scientific Comet Hunter 150mm Mak Newt

2. Decent apo triplet in 130mm class

3. F/5 newtonian of course - something like 150PDS

You should consider cameras that you plan to use for each role and preferred targets when making a choice between scopes.

[bluesilver]

Thanks for the reply and information,  appreciated.

So basically for me to start out with as i don't want a dedicated scope with no eyepiece availability,  well not yet anyway.

The best choice would be to look at something like the EdgeHD 8"  

Rather than an 130 mm Triplet apo

And mount it to a Skywatcher AZ-EQ6  

 

[Benjam]

My first scope I purchased was the 8” Edge HD which I’ve had since April. It’s a fantastic scope for Lunar, Solar and Planetary. I’ve done visual observing as well as imaging the moon, sun and certain galaxies. I’m only using a entry level dslr (un modded) which I use with a 0.7 x reducer. I’ve recently just brought a ccd camera for planetary imaging (ZWO ASI 224MC USB 3.0 Colour Camera) and a 3x Barlow lens, which I intend to use next year, for when the planets will be higher in the UK. 

Checkout the link below, it’s a great tool for showing you what you will be able to see, using any telescope, camera, eyepiece etc etc...  

https://astronomy.tools/calculators/field_of_view/

Not sure where in Aus you live, but from my travels (Bintel) is a great shop in Sydney for telescopes. 

https://www.bintel.com.au/?v=4442e4af0916

Here’s two photos I’ve taken with my 8” Edge HD to give you a rough idea, the last one is the transit of Mercury. 

 

Edited November 23, 2019 by Benjam

[bluesilver]

Thanks for the reply and photos,  appreciated

May i ask what mount you are using with your Edge?

 

[ollypenrice]

You are asking for three capabilities, visual, planetary imaging and deep sky imaging. Vlaiv has identified scopes which can just about offer all three but, personally, I would say that you really have to choose between visual-planetary and visual-deep sky imaging. Imaging is hard enough without throwing yourself curved balls in the form of compromises and the two kinds of imaging, certainly for a beginner, are not catered for by a single instrument. The good beginner targets for deep sky imagng are mostly large, bright nebulae requiring a short focal length. Deep sky imaging at long focal length and high resolution makes heavy demands on autoguiding and shouldn't be attempted without it. There are other ways to attack the problem:

- Inexpensive Dob for visual and small apo refractor for deep sky imaging (and widefield visual.)

- SCT for planetary imaging and visual, plus simple camera lens for widefield deep sky imaging.

Nutshell: if the Universal Telescope existed we'd all be using it. But it doesn't.

Olly

[bluesilver]

Thanks for the reply,  that makes sense now you have put it that way.

I have a large Dob for deep sky visual.

So to make it a tad easier,  i am mainly really interested in mostly planetary imaging.

So going with that,  the best bet would be the EdgeHD 8" ?

If i was looking for nebular and Galaxies,  i would be best looking for a Refractor,  dose that sound roughly correct?

 

[Physopto]

I was just about to post a reply, when I saw Olly's answer. Absolutely correct, I would say.

I tried this when I started. Bought a 12" Meade for visual use but after a short while of use decided it was not really what I wanted. I then bought a 132mm William optics frac. I still have this, but have found that for the targets I wish to image that an 85mm aperture frac is more in keeping. The 132 is also not powerful enough for the deeper space targets, so either I fit a 2,3,4x convert or as these  can cause problems for fitting your camera and other devices, buy a bigger frac. Yet more expense !!!  The tracking of targets is important and requires some patience to get right, more so when using bigger scopes with more magnification. Larger targets require many more subs and often stitching together (mosaic). Using a smaller aperture can alleviate this, or even eliminate the need altogether.

If you stay with visual it is another matter as Olly says. 

Try if possible/ask, in an Astro club before you buy and remember, your  bank balance will be the decider, or her indoors 🤔

Do not rush in it is an expensive choice to make if wrong ! I know that now.

Derek

[Benjam]

34 minutes ago, bluesilver said:

Thanks for the reply and photos,  appreciated

May i ask what mount you are using with your Edge?

 

Celestron AVX 

[ollypenrice]

43 minutes ago, bluesilver said:

Thanks for the reply,  that makes sense now you have put it that way.

I have a large Dob for deep sky visual.

So to make it a tad easier,  i am mainly really interested in mostly planetary imaging.

So going with that,  the best bet would be the EdgeHD 8" ?

If i was looking for nebular and Galaxies,  i would be best looking for a Refractor,  dose that sound roughly correct?

 

Yes. The smaller galaxies can be imaged with an 8 inch SCT but it won't be easy because high resolution imaging needs very precise tracking and guiding. This needn't be impossible. Consider, also, that you might do much better on DS imaging with an SCT if you used a mono camera which could be binned 2x2 to improve the speed and ask less of the guiding.

Olly

[vlaiv]

1 hour ago, bluesilver said:

Thanks for the reply,  that makes sense now you have put it that way.

I have a large Dob for deep sky visual.

So to make it a tad easier,  i am mainly really interested in mostly planetary imaging.

So going with that,  the best bet would be the EdgeHD 8" ?

If i was looking for nebular and Galaxies,  i would be best looking for a Refractor,  dose that sound roughly correct?

 

What sort of large dob do you have?

Aperture rules in planetary imaging (if decent optical quality). In planetary AP, mount is not as important as in regular AP (where that importance can't be overstated - it really needs to be the best you can afford).

Cheapest way into very good planetary imaging would be adding tracking to already existing dob if it is large and of decent optical quality. If it is goto dob - you are pretty much set, if not - have a look at suitable equatorial platform. That combination won't be as "plug&play" as goto mount - there will be learning curve to get scope onto target especially with small chip - maybe flip mirror could help there or similar - but that combination will get the job done and you will get good results - just use good planetary camera and appropriate barlow / telecentric lens.

Depending on your budget, next option for planetary - both viewing and imaging would be largest compact scope you can afford and mount on AZEQ6 - something like C9.25 or maybe even 10" Classical Cassegrain.

For DSO imaging to start with you want something that is in range of 500-700mm focal length and there are quite a range of options there.

- for rather painless imaging - refractor + suitable field flattener/ reducer will do the trick

- cheap option would be newtonian + coma corrector (130PDS / 150PDS class scope). You can go with 8" F/4 scope as well - but as you go faster, collimation and tube stiffness and rigidity and quality of focuser become increasingly important so you really step outside cheap range there

- Maksutov newtonians are worth a look a well in this category

 

[gorann]

As everyone says, there is no single telescope that can do it all, so after a while we all seem to end up with a bunch of them. You initially indicate an interest in a 5" apo refractor. To add to your choices of an intermediate focal length scope you could have a look at a new 6" doublet from Altair Astro that received a very favourable review in the latest issue of Sky at Night Magazine. Appears to perform like a triplet but at half the price:

https://www.skyatnightmagazine.com/reviews/telescopes/altair-150edf-apochromatic-doublet-refractor-review/

[bluesilver]

Thanks heaps again for the replies,   Lots of very good information here.

The Dob i have is a Skywatcher 16inch GOTO,  i have only just started to play around trying to attach my DLSR camera to get images of the planets but didn't work out at all,  just get a bright blur,  camera is a Canon EOS 5DSR.

Unfortunately i don't have a club close here,  so i kind of have to do a lot of research and learn as much as i can.

If i could get a good camera to work with the 16 inch Dob that could be another option also.

Yes i was initially looking a apo refractor as what i have read is that they give you a more crisper cleaner view compared to a Maksutov or SCT

Silly question,  but would the 8" Edge HD outperform the 180/2700 Mak ?

 

 

[vlaiv]

25 minutes ago, bluesilver said:

Thanks heaps again for the replies,   Lots of very good information here.

The Dob i have is a Skywatcher 16inch GOTO,  i have only just started to play around trying to attach my DLSR camera to get images of the planets but didn't work out at all,  just get a bright blur,  camera is a Canon EOS 5DSR.

Unfortunately i don't have a club close here,  so i kind of have to do a lot of research and learn as much as i can.

If i could get a good camera to work with the 16 inch Dob that could be another option also.

Yes i was initially looking a apo refractor as what i have read is that they give you a more crisper cleaner view compared to a Maksutov or SCT

Silly question,  but would the 8" Edge HD outperform the 180/2700 Mak ?

 

 

I think that easiest solution for planetary imaging that will give you best images and will cost the least - is simply getting dedicated planetary camera.

ASI224 / ASI385 would be a very good choice (if not the best). You will need such planetary camera regardless of the scope you are planing to use.

Next thing would be to learn about planetary imaging. It is completely different thing than both daytime photography and also deep sky long exposure photography. It consists of recording a video rather than image (in fact very fast sequence of short exposures - as much as you can get) - most of the time up to few minutes in length with very short exposures and lots of frames - something like 200fps and above is ideal.

You will of course need a laptop with USB3 connection and preferably SSD disk to be able to record that video in time.

After that there is processing stage - where you calibrate, stack and sharpen and color balance your image. All software tools for this are available, and they are free - it is just a matter of learning the process.

[bluesilver]

Thanks again for the reply.

I am at least familiar with the part you mentioned recording video rather than taking long exposures and then using the software to stack and edit that recorded footage.

Familiar in the sense of watched the videos and the different software that people use.

I have kind of gone around it backwards in that regards on things.

I will have a look at those two cameras that you have mentioned,  appreciate that.

Is there much differance between the two cameras, ZWO AS1224MC USB3.0 Colour Astronomy Camera,  and ZWO AS1385MC Astronomy Camera

From what i can see it that the only real differance is that the AS1385 has more pixels and is basically the updated version of the the AS1224

Sound like i could be better of first getting one of these cameras and see how it goes with the Dob first.

Appreciate all the advice.

 

 

 

[vlaiv]

10 hours ago, bluesilver said:

Thanks again for the reply.

I am at least familiar with the part you mentioned recording video rather than taking long exposures and then using the software to stack and edit that recorded footage.

Familiar in the sense of watched the videos and the different software that people use.

I have kind of gone around it backwards in that regards on things.

I will have a look at those two cameras that you have mentioned,  appreciate that.

Is there much differance between the two cameras, ZWO AS1224MC USB3.0 Colour Astronomy Camera,  and ZWO AS1385MC Astronomy Camera

From what i can see it that the only real differance is that the AS1385 has more pixels and is basically the updated version of the the AS1224

Sound like i could be better of first getting one of these cameras and see how it goes with the Dob first.

Appreciate all the advice.

 

 

 

When choosing planetary camera there are couple of things that are important:

- good QE. This is of course important for every application, better quantum efficiency means better SNR in same exposure time. This can be compensated in deep sky AP by using longer integration time (shooting for 5h instead of 4h for example), but not in planetary - where system is dynamic and you have limited window for data gathering (planets rotate and if you shoot too much you will have rotation blur - there is a way around that by "derotating" videos, but still, there is time limit on how much data you can gather).

- fast readout time. This is essential. In planetary AP one uses very short exposure times - couple of milliseconds. This is related to coherence time for given seeing, but in general it is below 10ms most of the time (only very good seeing provides coherence time larger than about 10ms). This means that number of captured frames will be limited by readout speed rather than exposure length (for 30ms exposure you can only do about 33fps, but with 5ms exposure you can do 200fps, and if camera supports only up to 150fps you will be loosing about 1/4 of the frames because it can't download them fast enough).

- read noise. This is also essential for planetary AP. Difference between one large exposure and stack of small exposures that have same total integration time as large exposure differs only in read noise. Read noise is only kind of noise that does not grow with time and is tied to single frame readout. When you gather tens of thousands of frames per recording - each one will have read noise associated. This is why you want your read noise to be the least possible.

Above cameras have these characteristics, but they are not only possible options. ASI290 is also rather good and available as mono version. ASI178 is also decent camera.

I'm listing only ZWO cameras because I know their model names, but you don't have to choose their cameras - other vendors also provide models of cameras with these sensors.

Mind you, good planetary images can be recorded even with "entry level" planetary/guide cameras like ASI120. Good seeing will make more difference than camera model, but if you have the budget - go for best that you can afford.

[bluesilver]

Thanks again for the information.

I think i have a good or at least better understanding now on what to look for and how to go about it.

Appreciated.

 

[MimasDeathStar]

This is a fascinating thread I've really enjoyed reading it thanks everyone for the useful information I had no idea Imaging was so complicated!