2 cameras; Mono + OSC or 2 x Mono ?

[SamAndrew]

Hey everyone, I'm putting together a 2 camera rig, and I'm a bit in limbo about the second camera.

Initial plan was 2 x SW Quattro 8s newtonians, but I feel aligning two smallish fields of view will be tricky, so I'm now thinking 1 x Quattro with 1 x Esprit 100.

I have an ASI 1600 mono on the quattro at the moment, and was wondering if I should run the same again on the Esprit, or a OSC such as the 294MC. My thought process is the Quattro will shoot Luminance and the esprit would be shooting colour pretty much the whole time.

The advantage of going OSC

• Price, the 294MC is about half the price of the 1600mm with a full set of filters and filter wheel.
• Sensitivity - the 294MC is a more sensitive back illuminated design
• Comet photography - I personally don't bother with comets with the mono camera as the little whippets move between filter changes!
• Simplicity, one less thing to setup in the sequence, one less thing to connect to the PC.

Disadvantage

• OSC less useful during the summer twilight we're about to enter
• OSC wont be much use when shooting narrowband with the Quattro (I'm shooting under Bortle 5 skies, so light pollution isn't too crippling, and I'm happy to shoot broadband most of the time)

 

What would you do? 2nd mono camera for the flexibility? or OSC to save money and simplicity?

 

Thanks

Sam

[Skipper Billy]

If I was going to go to the trouble of putting together a two camera rig then I would want the best quality and greatest flexibilty possible ie a two mono camera outfit.

You are going to need a BEEFY mount!!

[Earl]

no simple answer as both concepts work tbh,

[vlaiv]

Just couple of notes:

Different size of chip (but not significantly), and also different focal length.

With Esprit 100 - a lot of FOV will be wasted.

One scope has diffraction spikes - one does not (or rather produces). This will cause some issues when processing and with final appearance of the image.

Maybe best thing would be to match the FOV and both scopes to be refractors - so you don't have to worry about diffraction spikes. Two Quattro 8s could work - but besides aligning Fovs you would have issue of tube rotations and aligning diffraction spikes as well.

 

[Dinglem]

@SamAndrew why would you buy an additional filter wheel and a full set of filters if you are only going to capture luminance through one of your scopes?

[tooth_dr]

29 minutes ago, Dinglem said:

@SamAndrew why would you buy an additional filter wheel and a full set of filters if you are only going to capture luminance through one of your scopes?

He’s going to use narrowband too.  A 5x2” with NB and Lum would be best bet.

@SamAndrew I’ve tried Mono + OSC and now I have Mono + Mono.  I actually liked Mono + OSC a lot and could use the OSC for Ha too (eg for adding Ha to LRGB), but there is no doubt Mono + Mono is superior.

RGB filters are relativity cheap, so even if not used much its not a big issue.

 

Edited May 13, 2020 by tooth_dr

[Dinglem]

@tooth_dr I'm a biy confused by your response to my suggestion, as I was assuming he was already using narrowband filters, but not very often due to having Bortle 5 skies, and you are assuming he hasn't got them already, but his signature only says "ZWO 31mm Filters". My point was that the second scope would only need a Luminance filter while the other scope collected colour.

[emyliano2000]

I recently started something similar to what you are planning to do. I swapped my cameras between the telescopes to have a closer FoV and pixel scale between them and to see what comes out. 

Before the change I was using my qhy183m on the AT106 at 690mm focal lenght giving me 0.72"/px and my ASI294MC on the TS65Q at 420mm focal lenght, 2.27"/px and the following fovs.

Now I'm using the qhy183m on the TS65 at 1.18"/px and the ASI294MC on the AT106 at 1.38"/px and the following Fovs

I don't have the money to invest in a second mono camera so I thought of trying it with what I already have. 

My first test target was M13 and I'm pretty pleased with how it came out. 

I spent 2 hours/setup in 2 nearly full moon nights on it, so a total of 8 hours total integration time, 4 with the mono and 4 with the OSC. With the help of APP, I extracted the channels from the calibrated OSC subs and stacked each of the extracted channels together with the mono ones. I don't know if it's the right method of doing it but the result that I got is not that bad. 

My second test was on M16 in Ha which is quite a low target for me and also goes over London. I know it's quite a bright target but shooting over London is not that pleasant. 

On this one I shot 19x300sec with the qhy183mono and a baader 3.5nm Ha filter and 19x300sec with the ASI294MC and an Astronomik 6nm Ha filter and the same as M13, I extracted the Ha from  the calibrated subs shot with the OSC and stacked them with the mono ones. 

All in all I'm pretty pleased with what I'm getting from my "dual setup" even though one is mono and one is OSC. The only thing that I don't know how I'm gonna be doing is mix the HSO subs from the mono with the subs shot with my OSC and Altair Tri-Band. I know APP can extract the Oiii from the frames shot with an OSC and a dual narrowband too, so I think I will do the same as I did with the Ha and RGB. 

Emil

 

Edited May 13, 2020 by emyliano2000

[fireballxl5]

Here I've gone for 2 x mono, 1 LRGBHSO and the other LRGBH. Both combo's give an image scale of ~1.7arcsec/pixel. I tend to only image Lum or Ha on the larger scope (also larger FoV) and RGB on the 2nd, smaller scope (smaller FoV). When the Moon is around it's Ha on both 😉

[SamAndrew]

6 hours ago, vlaiv said:

Just couple of notes:

Different size of chip (but not significantly), and also different focal length.

With Esprit 100 - a lot of FOV will be wasted.

One scope has diffraction spikes - one does not (or rather produces). This will cause some issues when processing and with final appearance of the image.

Maybe best thing would be to match the FOV and both scopes to be refractors - so you don't have to worry about diffraction spikes. Two Quattro 8s could work - but besides aligning Fovs you would have issue of tube rotations and aligning diffraction spikes as well.

 

Yes, I'm not too worried about the FOV as the Esprit FOV isn't wasted, I'd esentially get two images, one close in with added detail, one widefield in just colour. Framing of one camera might have to suffer depending on the target, e.g. Line up the centre of the Heart nebula for the Quattro, and the framing might not be quite right for the rest of the nebula for the Esprit.

I could run a reducer with the Esprit to take it down to about 400mm, and then the pixel scale on the Esprit would be twice that of the Quattro if I went with two 1600's.

Not sure how it might impact processing if the Quattro is at 0.98"pp and the Esprit is at 1.7"pp with the 294  (without reducer)- I assume when i register the images, the colour would get resampled to match the L data, but there may be a downside when your pixel scale ratios are 7:4

Had thought about the diffraction spikes, they'd esentially have no colour, but that will just be a feature of the image 😆

Two refractors would be nice, but I don't have the budget for a 6" refractor at the moment, maybe in the future, I do actually have two Quattro's as I picked up a cheap one second hand in anticipation, so it might be worth a try at some point if I can work out a method for accurate alignment - I know Olly has a nice piece of kit for his dual TEC 140 that they don't make any more 😐 

[tooth_dr]

4 hours ago, Dinglem said:

@tooth_dr I'm a biy confused by your response to my suggestion, as I was assuming he was already using narrowband filters, but not very often due to having Bortle 5 skies, and you are assuming he hasn't got them already, but his signature only says "ZWO 31mm Filters". My point was that the second scope would only need a Luminance filter while the other scope collected colour.

I cant read signatures on my phone.

But ok.

Existing setup = Scope 1 - Quattro with 1600 mono camera and filter wheel, I was assuming full set of LRGB HaOiiiSii filters - but shooting mostly luminance with this system, or NB occasionally.

New setup = Scope 2 - I suggest to buy a mono camera, and a 5 x 1.25" EFW (or whatever smallest size fits sensor), then buy LRGB and Ha to use with that camera.

I have LRGBHaOiiSiii in both scopes, and I would shoot L in one and RGB in the other, or Ha in one and Oiii in the other.  I'm by no means the expert on imaging, but I live in a Bortle 4 location (a decent enough 4), and you cant shoot LRGB all the time.  There will be times around the moon when broadband imaging is fruitless, and Ha is the only hope.  That is why I suggested he goes for at least LRGBHa in the other scope, so he can run both scopes if the skies clear and the moon is about.

 

Hope that helps!

Adam.

 

 

[SamAndrew]

6 hours ago, Dinglem said:

@SamAndrew why would you buy an additional filter wheel and a full set of filters if you are only going to capture luminance through one of your scopes?

If I went mono then I'd want to shoot NB too, so I might not need a full set of filters, but the package deals available for the 1600 mean you esentially get the LRGB filters for free if you get a wheel with a full set of narrow band

[tooth_dr]

1 minute ago, SamAndrew said:

Not sure how it might impact processing if the Quattro is at 0.98"pp and the Esprit is at 1.7"pp with the 294  (without reducer)- I assume when i register the images, the colour would get resampled to match the L data, but there may be a downside when your pixel scale ratios are 7:4

I am currently experimenting with a 10" at 0.93"/px for luminance and a 80mm at 2.13"/px for RGB.  So far I would say that it's satisfactory.  I didnt purposely buy the scopes for this purpose, I just had them both and thought it might work.  In the future I think I will match up a larger refractor with the 10", but that isnt going to happen for while!

Like you I dont mind the colourless diffraction spikes.  When it comes to processing, you can choose to scale the data either way.  Depending on how good or bad your guiding/seeing is could determine which way you go.

[SamAndrew]

6 hours ago, tooth_dr said:

He’s going to use narrowband too.  A 5x2” with NB and Lum would be best bet.

@SamAndrew I’ve tried Mono + OSC and now I have Mono + Mono.  I actually liked Mono + OSC a lot and could use the OSC for Ha too (eg for adding Ha to LRGB), but there is no doubt Mono + Mono is superior.

RGB filters are relativity cheap, so even if not used much its not a big issue.

 

Agreed I think 2 x mono would yeild superior results, but superior enough to justify the added price? £1009 for the 294MC, £1579 for as 1600 with Mini Filter Wheel and 31mm LRGB & Ha Filters. I guess the whole sunk cost in the whole setup is so much, that trying to save £500 isn't that logical. 

[SamAndrew]

4 hours ago, emyliano2000 said:

I recently started something similar to what you are planning to do. I swapped my cameras between the telescopes to have a closer FoV and pixel scale between them and to see what comes out. 

Before the change I was using my qhy183m on the AT106 at 690mm focal lenght giving me 0.72"/px and my ASI294MC on the TS65Q at 420mm focal lenght, 2.27"/px and the following fovs.

Now I'm using the qhy183m on the TS65 at 1.18"/px and the ASI294MC on the AT106 at 1.38"/px and the following Fovs

I don't have the money to invest in a second mono camera so I thought of trying it with what I already have. 

My first test target was M13 and I'm pretty pleased with how it came out. 

I spent 2 hours/setup in 2 nearly full moon nights on it, so a total of 8 hours total integration time, 4 with the mono and 4 with the OSC. With the help of APP, I extracted the channels from the calibrated OSC subs and stacked each of the extracted channels together with the mono ones. I don't know if it's the right method of doing it but the result that I got is not that bad. 

 

My second test was on M16 in Ha which is quite a low target for me and also goes over London. I know it's quite a bright target but shooting over London is not that pleasant. 

On this one I shot 19x300sec with the qhy183mono and a baader 3.5nm Ha filter and 19x300sec with the ASI294MC and an Astronomik 6nm Ha filter and the same as M13, I extracted the Ha from  the calibrated subs shot with the OSC and stacked them with the mono ones. 

 

All in all I'm pretty pleased with what I'm getting from my "dual setup" even though one is mono and one is OSC. The only thing that I don't know how I'm gonna be doing is mix the HSO subs from the mono with the subs shot with my OSC and Altair Tri-Band. I know APP can extract the Oiii from the frames shot with an OSC and a dual narrowband too, so I think I will do the same as I did with the Ha and RGB. 

Emil

 

Results look great  How did you get the two scopes aligned? The other constraint I have, is my setup will be remote so I can't add filters in front of the OSC without a filter wheel, although I guess it's possible. The Tri-Band filters do add the possibility to shoot narrowband with the OSC.... 🤔

[SamAndrew]

2 hours ago, fireballxl5 said:

Here I've gone for 2 x mono, 1 LRGBHSO and the other LRGBH. Both combo's give an image scale of ~1.7arcsec/pixel. I tend to only image Lum or Ha on the larger scope (also larger FoV) and RGB on the 2nd, smaller scope (smaller FoV). When the Moon is around it's Ha on both 😉

What was your method for alligning the two scopes?

[emyliano2000]

1 minute ago, SamAndrew said:

Results look great  How did you get the two scopes aligned? The other constraint I have, is my setup will be remote so I can't add filters in front of the OSC without a filter wheel, although I guess it's possible. The Tri-Band filters do add the possibility to shoot narrowband with the OSC.... 🤔

The thing is, I'm using 2 mounts so aligning was not a problem but I had 2 scopes on a single mount at some point and the only way to align them without spending money on one of those side by side plates, was to use some guide rings for my small refractor but I suppose you won't be able to do that with any of your scopes so you might have to invest in one if those dual rig dovetails. 

[fireballxl5]

52 minutes ago, SamAndrew said:

What was your method for alligning the two scopes?

I use one of these for the smaller scope

https://www.firstlightoptics.com/misc/jtd-dual-rig-telescope-alignment-saddle.html

 

[SamAndrew]

24 minutes ago, fireballxl5 said:

I use one of these for the smaller scope

https://www.firstlightoptics.com/misc/jtd-dual-rig-telescope-alignment-saddle.html

 

Ah hadn't spotted that, just what i needed

[ollypenrice]

I've tried both and settled for two monos.

I found that Ha/OSC worked fine, as in this camera lens image:

However, L/OSC did not work as well as I'd hoped. The colour was rather thin under a dedicated luminance layer. Other members have also tried it and given up on it.

If you're not robotic you'd only need a manual filterwheel on one side because you could shoot L and Ha in blocks. 

I agree with Vlaiv on the difficulty of mixing reflector and refractor data and I would also warn you that any mirror movement will mess up your captures because you only have one guider. To my mind a dual rig is best made with refractors. We did once try and fail, here, using two reflectors on a dual rig. One always trailed.

Olly

[swag72]

I went for 2 mono camera's. In one camera I have a full set of LRGBHSO filters. The other camera only has a 5 position filter wheel so I thought carefully about what to put in there. I settled on Luminance and Ha to start with. Then realised that an additional O3 filter would help..... and that's where I've stopped. It works well. My scopes and camera's are the same focal length and chip so I use a JTD saddle to align them exactly. It works well.

[SamAndrew]

12 hours ago, ollypenrice said:

 

I agree with Vlaiv on the difficulty of mixing reflector and refractor data and I would also warn you that any mirror movement will mess up your captures because you only have one guider. To my mind a dual rig is best made with refractors. We did once try and fail, here, using two reflectors on a dual rig. One always trailed.

Olly

Thanks, ok quite a few experienced dual riggers saying 2 x mono  

I'm running an OAG on the Quattro - the advantage of going for a lower resolution on the second scope is it wouldn't matter if there was a little flexure somewhere between them. I'd hope that if i ran two of exactly the same scope, the movement of both of the mirrors would be similar enough to not notice any differential.

[SamAndrew]

12 hours ago, swag72 said:

I went for 2 mono camera's. In one camera I have a full set of LRGBHSO filters. The other camera only has a 5 position filter wheel so I thought carefully about what to put in there. I settled on Luminance and Ha to start with. Then realised that an additional O3 filter would help..... and that's where I've stopped. It works well. My scopes and camera's are the same focal length and chip so I use a JTD saddle to align them exactly. It works well.

Yes thinking about it I'd go for a 5 position wheel, I wouldn't actually need any extra filters, I'd move the RGB across and maybe one NB filter. However the ZWO package deals mean it's cheaper to get the 5 position wheel and LRGB filters than it is to get the camera and filter wheel separately.

[SamAndrew]

Not convinced yet that the Quattro is suitable for remote imaging - I'm going to check my rig tomorrow now the lock down rules have been relaxed here - haven't touched the collimation since Christmas, but it looks like it has slipped a bit.

[Miguel1983]

i'm in the same situation here, going back and forth between an OSC or another 1600mm for the second rig, but i think i'll go mono.