Cheap scope [doublet or ED triplet] for astrophotography

Equipment Refractors Narrowband
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Which scope to be used with mono camera for narrowbanding?
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50% (17 votes)
38% (13 votes)
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Tareq Abdulla avatar
Tareq Abdulla avatar
Hi all,

I want to know if using a cheap doublet say ED or even with FPL53/FCD100 can be nice in astrophotography using only Narrowbanding filters, or even using it for luminance signal with a cut off narrower lum filter or one of those LP filters as lum with mono camera?

I don't want to spend a lot for setup of everything specially i have enough but wanted to get more if i find offers so it can help me do things when i can't with say one single setup, i have very bad time in my life situations which prevent me to do enough imaging, and no observatory so i must carry in and out my gear for imaging every night [and day for solar], means i have a lot of wasted time here and there, and that means i have to use like 10 scopes at once if i have to, and for that if possible i really don't want to have all my scopes as top high quality as well if one or some will be used for only Narrowbanding or even the least problematic filter of RGB which is the Green.
Andy Vo avatar
Andy Vo avatar
A simple ED doublet with a field flattener can produce fantastic results. Something like the Sky-Watcher 72 ED will work great and is extremely light which means you can even get away with a lighter mount like a Star Adventurer or EQM35. You can search astronbin for examples. Those mounts won't give you much room to grow in terms of getting larger scopes but EQM35 could handle up to a 100mm refractor.
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Tareq Abdulla avatar
Tareq Abdulla avatar
Andy Vo:
A simple ED doublet with a field flattener can produce fantastic results. Something like the Sky-Watcher 72 ED will work great and is extremely light which means you can even get away with a lighter mount like a Star Adventurer or EQM35. You can search astronbin for examples. Those mounts won't give you much room to grow in terms of getting larger scopes but EQM35 could handle up to a 100mm refractor.

Thank you very much

I already have AZ-EQ6, and i don't know if it can handle my new scope of 10" RC, if not then i must buy another capable mount for that, and then my AZ-EQ6 will be for those small scopes, but i really think about a lightweight mount which i can take out easily so i can do imaging a lot, i hope that this EQM35 could handle two small refractors such as two 60mm doublets.

I am asking this topic because i am planning to buy maybe a third APS-C mono camera, and for this i was thinking if i must choose a triplet also or i can just be fine with a doublet [any refractor i will buy a flattener with it or a reducer if it doesn't come with one or built in].
Andy Vo avatar
Andy Vo avatar
I doubt the EQM36 can handle two small scopes plus cameras. You AZ-EQ6 should be able to easily handle that though. The 10" newt might be a bit big for it but you might be able to get away with it if you very carefully balance it and use shorter exposures. Is it a f/4 or f/5 newtonian? If it's a f/4 you can add a Starizon Nexus and make it an f/3. At f/3 you can get away with very short exposures such as 90 seconds for narroband and 30 seconds for broadband.
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Ryan Abbott avatar
Ryan Abbott avatar
I have a William Optics ZS61ii (doublet FPL53) and it produces very acceptable results for it's price point with the matching flattener. If you pixel peep the stars you can certainly see there's abberation but it's very manageable. Check out my gallery if you're interested in seeing any images with it. I think you could expect similar results from any doublet with FPL53/FCD100, so it just comes down to preference with how much of a pixel peeper you are/how much the abberation bothers you.

On a side note it's worth noting that if you're a Pixinsight user, any version of WBPP above (I think) 4.5 has an option to stack the colour channels separately and recombine them later, which helps with dealing with abberation from doublets or non corrected glass. I've not had a chance to test it myself yet but I've seen online it does certainly help.

CS,
Ryan

Edit: Apologies I just noticed you're on a mono workflow anyway, so you can ignore the bit about separating the colour channels in WBPP, but the point remains RGB combination after stacking will help deal with abberation slightly.
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Connor Kessler avatar
Connor Kessler avatar
My very first astrograph was the Skywatcher ED80 doublet with the .85x reducer/flattener and it still blows my mind.  Honestly, I feel I maybe jumped the gun to "upgrade" too quick and didn't really give myself a chance to push the ED80 to it's true potential.  I'm not exaggerating when I say that the star and color quality rivals on par with my William Optics GT71 which is a triplet, smaller, and is equal in price with the corrector.  The GT71 flattener has been a bit of a pain and the stars are very stretched and egg-y when the WO field rotator attached as it's tightening knob is very poorly designed and balanced.  So if we're talking about doublets vs triplets, in my personal experience with these two scopes, the Skywatcher ED80 is of significantly better value.

Orion also has a carbon fiber ED80 that seems to be well liked (I think the CF version is a triplet? Need to double check that) and a cheaper, regular ED80 doublet that is the Orion sister to the Skywatcher ED80 (The Skywatcher having a better focuser and arguably better build quality)

Personally, the processing power of some of these programs go a long ways in mitigating chromatic aberration so I believe doublets should be considered more often for "serious" astrophotography.  It's also worth noting that sometimes people focus so much on how many elements there are or the type of glass that they don't really consider taking a deeper look at the images produced by them.

My Skywatcher ED80 is only a doublet but has FPL-53 and my Orion EON 130 is a triplet with some type of glass supposedly equal to FPL-51.  Both take fantastic images.  At this point, the only issues are entirely from my own skills.


Hopefully this is helpful in helping you make a decision.  I can tend to ramble and still deal with major imposter syndrome with my work and credibility to add input on anything.
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Tareq Abdulla avatar
Tareq Abdulla avatar
Andy Vo:
I doubt the EQM36 can handle two small scopes plus cameras. You AZ-EQ6 should be able to easily handle that though. The 10" newt might be a bit big for it but you might be able to get away with it if you very carefully balance it and use shorter exposures. Is it a f/4 or f/5 newtonian? If it's a f/4 you can add a Starizon Nexus and make it an f/3. At f/3 you can get away with very short exposures such as 90 seconds for narroband and 30 seconds for broadband.

Ok, for the mount part well, it can handle even medium sizes two scopes a long i don't add much accessories all around, so i can work on that, but if i buy say that EQM36 then i can easily put one scope on it and put another two on my AZ-EQ6 and this way i can have 3 scopes all running flawlessly i hope.

No i don't have 10" Newtonian, i have/bought 10" RC Truss design one with great price, its weight if no much accessories is about 35lb [or pound], that is roughly 16KG, and my mount is rated for about 18-20KG, i saw people even added like 22-24KG on it just fine, and sure i won't go for long exposure and i will try to have less accessories with it, but this is just an option as next year i am trying to buy a really stronger mount but not very expensive as those high end ones, so then i can place this 10" RC with ease, but because i have many dual/triad imaging setup i really want to add another scope as pair for 10" RC, and the only two choices i can afford will be either 10" whatever Newtonian or 12" Newtonian, i can go with 0.75x for faster or go with Paracorr with Barlow effect to match this RC reduced, i can't afford another 10" RC or SCT.

I have cameras, and i started this thread topic here because i am trying to think between a second APS-C mono camera or a second APS-C color camera [IMX571], the prices is very tempting that i feel greedy to add a third one, because the two i have are connected to my two 90mm triplet scopes, so if i want to have more data capturing then adding a third one and i will be almost complete, and that means i have to see if i should buy an achromat or doublet or cheap triplet if possible, and then i can also think about a mount to handle more upcoming gear with the current one, i try to finish buy and collect maximum by next year so then i can return back to imaging so strong and quicker pace for data.
Tareq Abdulla avatar
Tareq Abdulla avatar
Ryan Abbott:
I have a William Optics ZS61ii (doublet FPL53) and it produces very acceptable results for it's price point with the matching flattener. If you pixel peep the stars you can certainly see there's abberation but it's very manageable. Check out my gallery if you're interested in seeing any images with it. I think you could expect similar results from any doublet with FPL53/FCD100, so it just comes down to preference with how much of a pixel peeper you are/how much the abberation bothers you.

On a side note it's worth noting that if you're a Pixinsight user, any version of WBPP above (I think) 4.5 has an option to stack the colour channels separately and recombine them later, which helps with dealing with abberation from doublets or non corrected glass. I've not had a chance to test it myself yet but I've seen online it does certainly help.

CS,
Ryan

Edit: Apologies I just noticed you're on a mono workflow anyway, so you can ignore the bit about separating the colour channels in WBPP, but the point remains RGB combination after stacking will help deal with abberation slightly.

Hey Ryan,

Well well well, i don't have WO doublet but i have another two brands 60mm doublets, one is stated to have FPL53 optic inside, and the other is just a copy paste so i assume it is also having high quality optics, could be also FPL-53 or FCD100 or something similar to them, the quality from both are the same to my eyes which indicate that both are in same level quality-wise, and both with dedicated reducer/flattener that i need to manage precisely.

For aberrations, i can think about different ways, but i asked here because i already have two triplets, so then i can keep one for RGB camera to have almost no aberration or very very minimal abberation better than from a doublet, so it will leave me with a third scope choice with the mono camera, and i don't want to have like all triplets if i will use two mono cameras, one of them i will just image Ha signal so that can be nice with any scope, but how much nice is nice, that i need to know so i don't spend and waste, buying same scope i have is a bit expensive for now, and i won't buy that third camera if i won't afford the scope next later much sooner, but if i can go with cheap scopes not triplet for example then that could be possible then.

I have PixInsight updated always.
Tareq Abdulla avatar
Tareq Abdulla avatar
Connor Kessler:
My very first astrograph was the Skywatcher ED80 doublet with the .85x reducer/flattener and it still blows my mind.  Honestly, I feel I maybe jumped the gun to "upgrade" too quick and didn't really give myself a chance to push the ED80 to it's true potential.  I'm not exaggerating when I say that the star and color quality rivals on par with my William Optics GT71 which is a triplet, smaller, and is equal in price with the corrector.  The GT71 flattener has been a bit of a pain and the stars are very stretched and egg-y when the WO field rotator attached as it's tightening knob is very poorly designed and balanced.  So if we're talking about doublets vs triplets, in my personal experience with these two scopes, the Skywatcher ED80 is of significantly better value.

Orion also has a carbon fiber ED80 that seems to be well liked (I think the CF version is a triplet? Need to double check that) and a cheaper, regular ED80 doublet that is the Orion sister to the Skywatcher ED80 (The Skywatcher having a better focuser and arguably better build quality)

Personally, the processing power of some of these programs go a long ways in mitigating chromatic aberration so I believe doublets should be considered more often for "serious" astrophotography.  It's also worth noting that sometimes people focus so much on how many elements there are or the type of glass that they don't really consider taking a deeper look at the images produced by them.

My Skywatcher ED80 is only a doublet but has FPL-53 and my Orion EON 130 is a triplet with some type of glass supposedly equal to FPL-51.  Both take fantastic images.  At this point, the only issues are entirely from my own skills.


Hopefully this is helpful in helping you make a decision.  I can tend to ramble and still deal with major imposter syndrome with my work and credibility to add input on anything.

Hi Connor,

I still asked about a mono camera with narrowbanding, i have two triplet scopes the same [TS Optics 90mm f/6 CF APO FPL-55], amazing wonderful scope, and i use same sensor but one is a mono and one is a color cameras for both, so technically i am using the same camera regardless one is mono and one is color as long they are both of same sensor [IMX571 sensor], so now i am thinking about buying another same sensor either a mono or a color, if a color then i have to force myself i go with a triplet, if a mono then i don't know if a triplet is a must, also i can think about that if i already have a mono then why not a second color camera and something like a doublet or even achro so i use this with the mono and the two triplets with the color cameras, i want to use one color camera only mainly to capture RGB of stars, the other color or if both mono are to capture narrowbanding [SHO] and Luminance filters, i don't want to waste time using RGB filters even if the scope is great.

So to summarize it up:

1. I have two triplets with two same sensor cameras, this is a dual imaging setup now, i want to add a third for same setup or 99% same FOV if possible.
2. Two cameras above are the same sensor as i said, but one is a mono and one is a color, so which third to buy, a mono or OSC?
3. The third choice of camera will determine my choice of that third scope.
4. I heard people or they told me for stars i really don't need to have same exact setup, so that can open the door for more options/choices.
5. Not expensive scopes, the cameras are known prices, so i want to cut the price of scopes in this case, if i go with the mono camera then i can buy a scope at about $500-700, if i buy the color camera then i can pay at about $800-1100, maybe even more if the prices of cameras going lower more and i got lucky with some budget to increase the payment.
Ryan Abbott avatar
Ryan Abbott avatar
Tareq Abdulla:
Ryan Abbott:
I have a William Optics ZS61ii (doublet FPL53) and it produces very acceptable results for it's price point with the matching flattener. If you pixel peep the stars you can certainly see there's abberation but it's very manageable. Check out my gallery if you're interested in seeing any images with it. I think you could expect similar results from any doublet with FPL53/FCD100, so it just comes down to preference with how much of a pixel peeper you are/how much the abberation bothers you.

On a side note it's worth noting that if you're a Pixinsight user, any version of WBPP above (I think) 4.5 has an option to stack the colour channels separately and recombine them later, which helps with dealing with abberation from doublets or non corrected glass. I've not had a chance to test it myself yet but I've seen online it does certainly help.

CS,
Ryan

Edit: Apologies I just noticed you're on a mono workflow anyway, so you can ignore the bit about separating the colour channels in WBPP, but the point remains RGB combination after stacking will help deal with abberation slightly.

Hey Ryan,

Well well well, i don't have WO doublet but i have another two brands 60mm doublets, one is stated to have FPL53 optic inside, and the other is just a copy paste so i assume it is also having high quality optics, could be also FPL-53 or FCD100 or something similar to them, the quality from both are the same to my eyes which indicate that both are in same level quality-wise, and both with dedicated reducer/flattener that i need to manage precisely.

For aberrations, i can think about different ways, but i asked here because i already have two triplets, so then i can keep one for RGB camera to have almost no aberration or very very minimal abberation better than from a doublet, so it will leave me with a third scope choice with the mono camera, and i don't want to have like all triplets if i will use two mono cameras, one of them i will just image Ha signal so that can be nice with any scope, but how much nice is nice, that i need to know so i don't spend and waste, buying same scope i have is a bit expensive for now, and i won't buy that third camera if i won't afford the scope next later much sooner, but if i can go with cheap scopes not triplet for example then that could be possible then.

I have PixInsight updated always.

I focused mainly on abberations in my response as it's the biggest difference, but there are others to note between the two designs:
  1. Sharpness - A triplet will give you sharper results but more or less it will depend on resolution/seeing/tracking whether you get noticeable differences.
  2. Focusers - Doublets usually have less robust focusers, so with a weighty mono setup attached it could introduce tilt issues. Depends on the filter wheel & camera being used really.

With abberations being addressed from shooting mono, it comes down to how highly you value the above differences. If it's high - go with a cheap triplet as it will no doubt solve them. If you don't mind the differences - or like you say the price of even a cheap triplet is a stretch with you wanting a new camera too - go with the FPL/FCD doublet.

CS,
Ryan
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Tareq Abdulla avatar
Tareq Abdulla avatar
Ryan Abbott:
Tareq Abdulla:
Ryan Abbott:
I have a William Optics ZS61ii (doublet FPL53) and it produces very acceptable results for it's price point with the matching flattener. If you pixel peep the stars you can certainly see there's abberation but it's very manageable. Check out my gallery if you're interested in seeing any images with it. I think you could expect similar results from any doublet with FPL53/FCD100, so it just comes down to preference with how much of a pixel peeper you are/how much the abberation bothers you.

On a side note it's worth noting that if you're a Pixinsight user, any version of WBPP above (I think) 4.5 has an option to stack the colour channels separately and recombine them later, which helps with dealing with abberation from doublets or non corrected glass. I've not had a chance to test it myself yet but I've seen online it does certainly help.

CS,
Ryan

Edit: Apologies I just noticed you're on a mono workflow anyway, so you can ignore the bit about separating the colour channels in WBPP, but the point remains RGB combination after stacking will help deal with abberation slightly.

Hey Ryan,

Well well well, i don't have WO doublet but i have another two brands 60mm doublets, one is stated to have FPL53 optic inside, and the other is just a copy paste so i assume it is also having high quality optics, could be also FPL-53 or FCD100 or something similar to them, the quality from both are the same to my eyes which indicate that both are in same level quality-wise, and both with dedicated reducer/flattener that i need to manage precisely.

For aberrations, i can think about different ways, but i asked here because i already have two triplets, so then i can keep one for RGB camera to have almost no aberration or very very minimal abberation better than from a doublet, so it will leave me with a third scope choice with the mono camera, and i don't want to have like all triplets if i will use two mono cameras, one of them i will just image Ha signal so that can be nice with any scope, but how much nice is nice, that i need to know so i don't spend and waste, buying same scope i have is a bit expensive for now, and i won't buy that third camera if i won't afford the scope next later much sooner, but if i can go with cheap scopes not triplet for example then that could be possible then.

I have PixInsight updated always.

I focused mainly on abberations in my response as it's the biggest difference, but there are others to note between the two designs:
  1. Sharpness - A triplet will give you sharper results but more or less it will depend on resolution/seeing/tracking whether you get noticeable differences.
  2. Focusers - Doublets usually have less robust focusers, so with a weighty mono setup attached it could introduce tilt issues. Depends on the filter wheel & camera being used really.

With abberations being addressed from shooting mono, it comes down to how highly you value the above differences. If it's high - go with a cheap triplet as it will no doubt solve them. If you don't mind the differences - or like you say the price of even a cheap triplet is a stretch with you wanting a new camera too - go with the FPL/FCD doublet.

CS,
Ryan

Cool, thank you very much
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