Scope and camera combinations for EEVA

[Steve Loy]

Morning all.

I am planning an Observatory and need some advice from learned folks on various combinations of Scopes and Camera's for EEVA.

I am getting to old for the standing out in the cold looking through an eyepiece game, so my Obsy is going to be built with the goal of enabling EEVA observing from the comfort of my home, that can be shared with people in the room watching with me, or even streamed over the internet for friends to enjoy.

Although it might be nice to be able to if I fancy it.... I am not particularly bothered about collecting tons of data for proper astrophotography, my primary aim is to be able to see objects real-time (or near real time for DSOs I guess)

With this in mind, I am making the assumption that two separate Scope / camera combinations is going to be required... as Getting decent EEVA images of both planets and DSO's on the same setup is likely not going to be possible?

• My first question is, Is that assumption correct, and if it's not... then what setup would you recommend that can "do both"

If that assumption is correct, then my second question would be...

• If you were to piggyback a planetary setup, and a DSO setup for EEVA together on the same mount. What two Scope and camera combinations would you use, and why?

At present the only scope I own is an Explorer 150p, but I am perfectly willing and able to purchase whatever combinations of Scope and cameras that I will need.

[Mike JW]

Hi Steve,

You really only need one scope. SCTs can do excellent planetary/lunar work as well as DSOs because they are so flexible.

SCT at its native F10 would do OK for solar system objects. With a standard f6.3 reducer it then becomes fast enough for EEVA. I sometimes operate my SCT at f5. With a hyperstar fitted you can then operate at around F2 which is great for a wider field.

If you look through the EEVA forum you will see folk do well with 8" scopes (which I suggest is the minimum size for DSO/EEVA). I have used a C9.25 very successfully but upgraded to a C11 to gain more light gathering and hence quicker views, and more resolution. (I also use a 15" Dob which ups the speed of getting a result/resolution yet more.)

You may well go for two cameras. I use the starlight express Ultrastar (mono) which gives excellent DSO results (view my various posts). The ultrastar and its cousin the lodestar  work very well with the Jocular Software as produced by Martin Meredith (another regular on the EEVA forum). I do not do solar system EEVA so somebody else will advise you on a camera for these objects.

I know what you mean about sitting outside is getting too much as we age. I suspect this will be the last winter with my C11/iEQ45 pro mount - once the restrictions lift it will be up for sale.

Mike

[Steve Loy]

Hiya. Thanks for the info.
 

My thoughts on two scopes were because the obs will be automated and remotely operated, so I wanted to avoid the need to go in and switch equipment /  cameras around on one scope. (Defeats the object of automating everything if I have to switch equipment around to change target type, if you see what I mean. )

 

good shout re the observation forum, I’ll take a look. 
 

if anyone else wants to chime in, how about this hypothetical ...

 

If you could have two separate setups, one for planetary EEVA, and one for dso EEVA, what would they be and why?

[catburglar]

I wonder if you could still get good results with the large SCT (C11) and 6.3 reducer and something like the ZWO ASI183- with 2.4 micron pixels. If you bin 4x4 gets you 1.1 arc seconds per pixel for DSI’s and then unbinned / ROI for planetary at about 0.3 arcsec per pixel...

The FoV for DSO’s will be a little limited, so I think it depends how wide you want to go...if you’re after galaxies, globulars and planetary nebulae, this would be OK, but if you want M31 or Barnard’s loop, then you’ll need something with a shorter fl.

[Steve Loy]

Perhaps I am misunderstanding somewhat...  I can never get binning to make any difference to the field of view on the FOV calculator... so I assumed it did not have any effect.

 

example...

 

https://astronomy.tools/calculators/field_of_view/?fov[]=39||1115||1|4|0&fov[]=39||1115||1|1|0&solar_system=moon

 

no difference in FOV between 1x1 and 4x4, despite a difference in Resolution

Edited March 1, 2021 by Steve Loy

[catburglar]

Binning doesn't change the field of  view (that's determined solely by the chip size and focal length) but it does change the sampling rate of the image.

For DSO's you want bigger pixels to capture as many photons as possible in a 10-30 second exposure and therefore improve the signal to noise ratio at the expense of image resolution

For planets- it's the reverse, because they're much brighter, you'll want short frames at max resolution to capture the most detail possible.

If you can live with the approx 0.5 degree FoV of the IMX183 chip using the C11 and 6.3 reducer, I think it could be a good combination...particularly if you want remote operation. 

The other point to note is that for the dso sessions, you'll be going from your 20Mpixel native resolution to approx 1.2Mpixel DSO image if you bin 4x4...but if you choose a chip with bigger pixels, you'll lose out on the planetary. The ASI1600 might also be a reasonable option, binned 3x3 it'll be a little more sensitive than the 183 and won't loose out too much on planetary, and will give a bit more FoV

[vlaiv]

Rather different requirements.

I'm not sure that EEVA style planetary is even feasible in the sense we think of planetary imaging. Planetary imaging is based on very short exposures that freeze the seeing and optimum sampling rate that will capture everything scope is capable of delivering.

It involves heavy processing with rejection of majority of frames and keeping only the best ones - and afterwards strong sharpening.

None of which is possible in EEVA style planetary. For this reason, I would put planetary requirements in second place - as any camera capable of 30fps will deliver live feed of planet similar to that of observing at the eyepiece.

As far as DSO EEVA is concerned - you want to focus on 4 things:

1. read noise - you want that to be minimal (this is beneficial for planetary imaging as well - but not important for planetary EEVA)

2. QE of sensor - you want that as high as possible

3. Aperture

4. Sampling rate / resolution

In fact - points 3 and 4 combine to give you "aperture at resolution" - which is equal to speed.

Best EEVA setups are large scopes with large sensors. These tend to be the most expensive ones as well. Mono is better than OSC. Planetary views are not going to be as interesting with Mono as with OSC.

For example - imagine that you have 4" scope and you sample at 2"/px. Using 8" scope and sampling at 2"/px will make your setup ~ x4 faster as you will be using x4 more photon collecting area for same sampling resolution.

If you can afford it ASI 2600 either color or mono would be very good choice. Combine that with 10" or 12" F/5 newtonian and you are going to have very fast EEVA setup.

At 1500mm FL with 3.76µm pixel size if you bin x4, you'll get ~2"/px resolution. That is x9 faster than 4" scope at 2"/px.

In fact - depending on your funds and mount - you could be able to piggy back 6-8" Cassegrain with ASI224 for planetary?

 

[Steve Loy]

Hi vlaiv, 

Yes that makes a certain amount of sense. As indicated, I'm not really looking to image in the traditional sense... I just want to be able to look at "live" images of what my Scope is seeing on a screen in comfort  I may take the odd screenshot of what I am seeing, but I think the intricacies of post processing data is not something I am too interested in any more.

I guess my main problem is that I want to be able to look at three or four  very different types of target on the same setup so I don't have to go out to the observatory to change equipment based on what I am looing to see any given evening. 

Planets - small bright objects

Moon- LARGE bright object

Larger DSOs - large faint objects

Smaller DSOs - small faint objects

 

I realise that it will be practically impossible to fulfil all these criteria with one setup, and something has to give, even if  spend the cash and end up with two different setups piggybacked. 

 

I guess I am trying to find the best balance between it all. My thoughts on one setup for DSO and another for planetary piggybacked  is what came from that.

A major issue for me at the moment is that looking through all the available options is sending me into a bit of an information death-spiral (I am Autistic, so I cant help but focus on the detail, which in a situation like this can be counter-productive if there is too much of it) I was hoping some experts in EEVA might be able to "narrow" my focus a little bit... if that makes sense

 

Whilst I could buy it, The camera you mentioned is a little more than I wanted to spend to be honest.

 

I am in the nice position of being able to both buy and install a pulsar observatory, and have some funds left over to buy new scopes and cams, but I don't want to go mad...  a few thousand at most on new scopes / cams.

 

my heartfelt thanks for all the info you have all given so far, I really appreciate you all taking the time to help me out.

[vlaiv]

It would be good to know your approximate budget - you mention few thousand, so that is quite sensible starting point (anything over £2500-£3000 is probably too much).

Another important thing would be the mount - what sort of mount do you have at the moment and do you consider an upgrade to it?

I too often focus on the detail so what would be best for you - if I explain the details and select the best for you, or just select the best without going too much into detail?

Here is setup that will give you good performance:

https://www.firstlightoptics.com/zwo-cameras/zwo-asi-294mc-pro-usb-30-cooled-colour-camera.html

+

https://www.firstlightoptics.com/reflectors/skywatcher-quattro-f4-imaging-newtonian.html

and matching coma corrector:

https://www.firstlightoptics.com/coma-correctors/skywatcher-f4-aplanatic-coma-corrector.html

Totaling ~ £1800

To keep in mind that you'll need quite a few additional gadgets if you think of operating this remotely - like motor focuser and such.

Cheapest planetary option would be to go with:

https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150pl-ota.html

+

https://www.firstlightoptics.com/zwo-cameras/zwo-asi224mc-usb-3-colour-camera.html

For additional ~£450 or so without accessories (you'll need 2x barlow and motor focuser again).

[Steve Loy]

I could certainly Spend £2500-£3000 without a problem.

At the moment I have an EQ5 synscan goto (purchased in 2013)

My current thoughts are that if I am to piggyback two setups I am likely going to have to upgrade to something like an EQ6-R PRO.

Indeed I am aware that some ancillary equipment is going to be required, that should not be an issue either in terms of budget. 

I was actually leaning away from Newts, in favour of something like the 8" EDGE HD, is there a particular reason both scopes you picked are Newts (I already have a explorer 150p)

 

[vlaiv]

30 minutes ago, Steve Loy said:

My current thoughts are that if I am to piggyback two setups I am likely going to have to upgrade to something like an EQ6-R PRO.

You might like to consider something like iOptron 70 maybe. You want mount that can handle about 20Kg of equipment with ease. EQ6-R has 20Kg max payload - and that is for visual.

8" Scope is going to be around 10Kg mark - add another one and all the gear and you'll easily hit 18-20Kg of gear

34 minutes ago, Steve Loy said:

I was actually leaning away from Newts, in favour of something like the 8" EDGE HD, is there a particular reason both scopes you picked are Newts (I already have a explorer 150p)

It was rather simple - I went by your requirements. You wanted to look at both small and large DSOs.

From camera and pixel size - this means about 800mm of focal length. I just picked telescope with largest aperture at that focal length.

Here is comparison of two scopes:

EdgeHD 8" can't properly frame even Orion's nebula with smaller sensor. You either need to spend money on large sensor or compromise on telescope design. In this case - it is fast F/4 optics.

As for planetary - I was going by the budget. Realistically, in 6" size - 6" F/8 newtonian is one of the best planetary scopes - and in fact the best if you are not willing to spend £2000-£2500 on the scope alone and get 6" APO / ED doublet (Even SW 150ED is £1800 for OTA).

You can get 6" CC - but it will have 34% central obstruction versus 25% CO of this newtonian.

[Martin Meredith]

An alternative is to get a small sensor and that way you won't need a coma corrector either. There are actually not that many objects that require a large FOV. The problem with FOV calculators is that they mainly show large objects, which is fine if you plan to stop observing after viewing 20-odd Messiers, but as the threads in the EEVA observing section demonstrate, there is an awful lot of other interesting stuff to observe.

cheers

Martin

 

[vlaiv]

Problem with small sensors is that they give too small image size for reasonable sampling rates with larger telescopes.

Say you want to use ASI224 - which is excellent small sensor for EEVA. It is 1304 x 976 with pixels of 3.75µm. Pair that with larger telescope of about 750mm of focal length (6" F/5 newtonian for example). That combination will give you 1"/px - too high for EEVA (and even too high for regular imaging if you as me). You therefore want to bin that to at least 2"/px.

Resulting image size is: 652 x 488

That is on smaller size of things, would you not say? I think that images in 1000x600 range are good match for computer observing?

With larger sensor - there is more "room" to put enough "large" pixels. Larger sensors are faster sensors (when properly paired with optics and binned).

ASI183 is not bad choice in this regard. It is small sensor but has enough pixels. Even if one bins 4x4 (and they will likely do so because pixels are small at 2.4µm) they still have 1374 x 918 image size (originally 5496 x 3672). However, ASI183 is not far away in price to ASI294 - £780 vs £980 with area increase of 113% (more than double) versus only 25% increase in price.

For someone on limited budget - it does make sense to go with smaller sensor, but if budget allows - I'd say go with larger sensor.

 

[Martin Meredith]

Vlaiv, I think you are over-generalising from one example. I do perfectly well with my 800mm focal length scope and a Lodestar with around 570 x 750 pixels at 2.11"/pix, and have done so for nearly 7 years. Mike JW does great work with his Ultrastar and scopes up to 15". Likewise others with small sensors. It really is remarkable what one can observe with such a setup (see the EEVA observing section for 100s of examples of all types of object). There are various combinations of FL and sensor sizes that would be rated small by today's standards which are nevertheless perfectly adequate for optimal viewing of 99.99% of DSOs out there. 

There are plenty of advantages to small sensors besides cost. Fast download, easy to store everything you ever capture, and most important to my mind is that advanced processing can be done near live on small pixel count arrays that cannot currently be done with larger sensors. The entire user experience is different when the processing is fast enough to 'interact' with live at the scope.

I realise this is counter-current, but I'm simply relating my own experience.

Martin

 

[vlaiv]

15 minutes ago, Martin Meredith said:

Vlaiv, I think you are over-generalising from one example. I do perfectly well with my 800mm focal length scope and a Lodestar with around 570 x 750 pixels at 2.11"/pix, and have done so for nearly 7 years. Mike JW does great work with his Ultrastar and scopes up to 15". Likewise others with small sensors. It really is remarkable what one can observe with such a setup (see the EEVA observing section for 100s of examples of all types of object). There are various combinations of FL and sensor sizes that would be rated small by today's standards which are nevertheless perfectly adequate for optimal viewing of 99.99% of DSOs out there. 

There are plenty of advantages to small sensors besides cost. Fast download, easy to store everything you ever capture, and most important to my mind is that advanced processing can be done near live on small pixel count arrays that cannot currently be done with larger sensors. The entire user experience is different when the processing is fast enough to 'interact' with live at the scope.

I realise this is counter-current, but I'm simply relating my own experience.

Martin

 

I don't see where our views differ except for maybe resulting image size.

You also have the setup that I recommended 8" F/4 scope sampling at 2"/px. Your camera has 8.3µm pixel size and you don't need to bin in order to get 2.11"/px. It does not have cooling so you probably don't apply darks, or take darks at the beginning of each session - which is not going to be convenient for remote setup.

I just pointed out that 1000 x 600 image might be preferable to 750 x 500 one and that larger sensor is faster sensor (when properly utilized).

We might not agree on preferable image size, but I think we agree on everything else?

 

[Mike JW]

Hi Vlaiv,

 I was sitting at the computer feeling I wanted to express my thoughts re cameras. pixels, sensor size. I always enjoy following your input but as I lack technical knowledge I get lost so quickly. Martin's thoughts have just entered the thread and he sums up my experience. I use my ultrastar on my 7" MakCas (at f6), my C11 (at f6.3) and my 15" Dob at either f3.5 or f4.5. Often I use 2x2 binning to speed things up. I am regularly in awe of what I end up 'seeing' via the camera. I never know whether the camera is matched to the scope I am using but what I so enjoy about EEVA using my scopes/ultrastar is the thousands of objects I am seeing (and I only post a few of my observations). I never saw this level of detail with my former big Dob. The strength of my set up is its simplicity - point and shoot, my laptop handles the data coming in reasonably easily and I adjust the view as the data arrives in Jocular and I have a view of worth in less than 2 minutes (but tend to sit and enjoy it and let the subs stack for 5 minutes.). I have tried other software (Sharpcap, Altair Astro..) - I end up spending time working out how to use the software (not fun for me because I wish to 'observe') and get poor or no results.  For most of the targets I go after I generally only post the zoomed in view - that is the target of interest., thus large sensors seem irrelevant to most of the objects (as Martin suggests).

EEVA for me is about 'observing' as easily as possible with minimal technology to get pleasing results. 

It took me 2 years of following technical threads, trying to ask questions but none the wiser due to my lack of computer, software, digital knowledge. I wish someone had said, buy a lodestar (before the ultrastar was produced) as it will fit into your Dob, download SLL and point and shoot - you will be amazed. It would have saved me much time and questioning. I still point and shoot and as indicated I know not what is happening other than I shall never live long enough to visit all the thousands  of targets.

Mike

[vlaiv]

Mike, I'm totally with you regarding experience of using equipment and observing.

This is primarily thanks to good software that you are using. Software in general should remove all the complexities of operation and just present you with good image.

I'm not disputing that small sensor is also able to render small targets adequately.

I advocate large sensor for two reasons:

1. Large sensor is faster than small sensor when paired with appropriate optics.

Here is example of M13 being observed with Lodestar X2 and with ASI294MM for example. First is using 8" scope and second is using 16" scope. If we bin x4 ASI294MM we will also get 2"/px. 

We thus have same sampling rate, same FOV and x4 light gathering capability. Which one do you think will be closer to "real time" observing?

2. OP said he is interested in larger DSO objects as well.

You simply can't observe larger objects with small sensor. You can most of the galaxies except for few largest ones - but not larger DSOs like California nebula

This way you get to see only small piece of it. But with large sensor - you get to see more of it.

You also get the chance to view large objects very fast - you can bin 4x4 for resolution of almost 5"/px - that is going to present you with decent image of nebulosity in less than a minute.

If someone wants these additional "features" and budget is allowing for that - why not?

 

[Mike JW]

Thanks Vlaiv  for the helpful illustration. I did not realise it was possible to 4x4 bin. I have sometimes looked at the ASI 294MM but stop short of buying one because every time I have tried using SharpCap (with the Ultrastar) or I tried using the Altair Astro software (with a GPCam) I could not even get an image. Also I found the interface hopelessly complicated compared to SLL/Jocular.  It really was the case when I finally went down the Lodestar/SLL route that I had an image within 5 minutes on my first attempt - I have never looked back. If someone could write a simple EEVA style software for such a camera as the ASI294, I would consider that route.

Thanks again,

Mike

[Steve Loy]

1 hour ago, Martin Meredith said:

The entire user experience is different when the processing is fast enough to 'interact' with live at the scope.

This particular sentence caught my attention...  It almost exactly encompasses what I feel as though I am aiming for with this project.

I admit to still be quite overwhelmed by all this, HOWEVER, I think it has been useful in that given everything said, it would make sense for me to get a start in this aspect of the hobby by narrowing my focus as I intended with this thread, and focusing (heh... that pun keeps cropping up doesn't it?) on the majority of DSO objects I am likely to want to see... IE.. the smaller FOV ones.  I can always, at a later date,  invest some more into equipment when I have a better understanding of what it is I might need. to meet my extra goals.

if that makes sense?

So....

We're looking for a setup that can provide EEVA remotely, where "the processing is fast enough to interact with live at the scope" and that will provide nice "live views" of most of the Smaller DSOs I might come across.

I was playing about with the FOV calc, and was trying various options, and this particular combination seemed to provide similar view of most of the DSOs as i scrolled through the list

Thoughts?

(For some reason i still seem to be drawn to the ZWO camera's and the 8HD)

 

EDIT after reading Mikes comments about software issues  for ZWO cameras, now I'm not so sure... oh dear!

 

Edited March 1, 2021 by Steve Loy

[catburglar]

I think the 224 may not a good match with the sct for EVA. Binned 2x2 you’re capturing at approx 1.3 arcsec per pixel and with 200mm aperture, you might not get sufficient signal in the short exposures usually employed in EEVA.

With this camera, you probably want a 12 inch (2.25 x collecting area) at f/4 (for comparable image scale)

If you could find one of the f3.3 reducers, then you’d be at around 2.3 arcsec per pixel, which could work OK. It’s not too far from the configuration that Martin uses successfully, but you’ve arrived at it by a different combination of factors.

[Steve Loy]

Hmm. 

I guess I didn't quite grasp it after all then... 

Starting to develop a head-ache after staring at FLO listings for various scopes and camera's, time to call it a night I think.

I'll try again tomorrow  

thanks for all your help so far.

[Steve Loy]

After some reflection, and further advice, I have more or less decided on an Ultrastar (Difference between the base model and the Pro model?) thankyou all for your help with this.

Now to decide which scope to pair it with assuming a focus on the smaller DSO's (the likes of which I have been perusing in the reports forum for EEVA... cool stuff folks!) 

This might be trickier because I need the equipment to be as "maintenance free" as possible. 

The eventual setup will be using Autofocusers, etc, if I have to hop down into the obs before every session to collimate, it defeats the purpose of having an automated obs in the first place

 

 

[vlaiv]

34 minutes ago, Steve Loy said:

After some reflection, and further advice, I have more or less decided on an Ultrastar (Difference between the base model and the Pro model?) thankyou all for your help with this.

Out of interest - what made you choose that particular camera?

[callump]

43 minutes ago, Steve Loy said:

After some reflection, and further advice, I have more or less decided on an Ultrastar (Difference between the base model and the Pro model?)

I have the Pro  version - it works well with my C11 and f/6.3 reducer (you can find a few of my images on the EEVA observing reports forum).

There are not many differences over the older version - reportedly faster download times and lower read noise. Also comes with a blue body (SX standard colour scheme now).

Callum

Edited March 2, 2021 by callump

[Steve Loy]

48 minutes ago, vlaiv said:

Out of interest - what made you choose that particular camera?

It came down to a matter of practical examples of what it can do in the reports forum, the familiarity of several users here with that particular camera singing it's praises. And some kind words of encouragement on getting started simply, so that I can arm myself with knowledge further down the line if I want to branch out  into other equipment. 

You help and advice on cameras so far has been brilliant (if confusing for a newbie ), I cant thank you all enough.

Any thoughts on an appropriate scope to pair with it for EEVA?