Which is the better move to improve the definition of my captures?

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Frédéric Ruciak avatar
Hi, I am currently using a TS CFAPO90F6 with a field flattener (540 or 1080mm focal length with a telemate x2), an OSC ASI2600MC, guiding with evoguide50ED and ASI290MM on an AM5.
I was looking for more aperture ,in visual my fever ended up with a 22inches dobsonian ;-), but I am wondering what are my alternatives including moving to a monochrome camera to improve my captures and images.

Here are 3 options, what do you think might produce the most significant improvement?
-moving to APO 110mm f6 with flattener  and keep my OSC Camera?
-moving to a newtonian 150mm f4 with flattener and keep my OSC camera (I have big dobsonian F4 so collimation is not frightening me)?
-keep my APO 90mm and move to the ASI2600MM?

Thanks for your feedback and experience.
CS Frédéric
andrea tasselli avatar
Of the 3 number 2 will yield the most improvements.

P.S.: a newtonian doesn't need a flattener it needs a coma corrector.
Frédéric Ruciak avatar
thanks Andrea, aperture always wins :-)
Dale Penkala avatar
Frédéric Ruciak:
Hi, I am currently using a TS CFAPO90F6 with a field flattener (540 or 1080mm focal length with a telemate x2), an OSC ASI2600MC, guiding with evoguide50ED and ASI290MM on an AM5.
I was looking for more aperture ,in visual my fever ended up with a 22inches dobsonian ;-), but I am wondering what are my alternatives including moving to a monochrome camera to improve my captures and images.

Here are 3 options, what do you think might produce the most significant improvement?
-moving to APO 110mm f6 with flattener  and keep my OSC Camera?
-moving to a newtonian 150mm f4 with flattener and keep my OSC camera (I have big dobsonian F4 so collimation is not frightening me)?
-keep my APO 90mm and move to the ASI2600MM?

Thanks for your feedback and experience.
CS Frédéric

I’m with Andrea on this one, I’m a big newt fan and have used 6”-12” newts in my observatory. Aperture always rules as long as it has decent optics and now a days most do. Feel free to check out my profile for examples. Depending on what you would go with a good coma corrector would be needed.
Tony Gondola avatar
My main imaging scope is a GSO 150mm F/6 Newtonian and I love it. The mirror is excellent and other than making a rear cap, it's giving me great results without any other modifications. I'm not using a corrector but my 585 chip camera is pretty small. The 900mm FL is really useful without stressing the guiding accuracy too much. I vote #2
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Julian Shroff avatar
How do you define "improvement"? Do you want deeper images with less noise? Then Mono (possibly with a reducer instead of a field flattener) is the obvious choice to me. 

If you want substantially higher resolution, an 8" Newtonian seems smartest to me, if you're open to newts anyway.
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Frédéric Ruciak avatar
Hi Julian,
by improvement I think primarily about fine details resolution giving crisp pictures (what french photographers name "piqué"). I understand that mono camera does not suffer from the interpolation of the RGGB matrix (thus smaller sampling) on one hand and on the other mono camera are more efficient that OSC ones. To compensate for efficiency I am ready to extend the time for capturing photons and I now never stop before 6-10hours of integration.
If I had the opportunity to combine several options it would be easier ;-) but I have to make a choice. I already have an 8 inch dobsonian at home and I like it, but I am looking to improve my setup at work in Morocco. That is why I think of a 150mm F4 I will be able to carry easily as a cabin luggage in the airplane.
Thanks for your feedback and CS Frédéric
Oskari Nikkinen avatar
Aperture is what you need. Larger scopes collect more light and thus have a higher signal to noise ratio, and obviously they resolve more than a smaller scope would.

I will suggest a newtonian, but beware, most factory standard newtonians are not natively suitable for proper astrophotography. For something that works out of the box have a look at the TS ONTC newtonians. Set some money aside for a good coma corrector as well as that will be the most important optical component in a newtonian, provided that the mirrors are not complete lemons.
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Frédéric Ruciak avatar
Hi Oskary, for the time being the feedbacks are reinforcing my initial thought to go for a TS ONTC ou UNC 150f4 as I already have the TSGPU for my UNC 200F5 and I know how to collimate fast newtonians (already have two big ones for visual)
Thanks for your feedback, Frédéric
andrea tasselli avatar
Oskari Nikkinen:
I will suggest a newtonian, but beware, most factory standard newtonians are not natively suitable for proper astrophotography. For something that works out of the box have a look at the TS ONTC newtonians. Set some money aside for a good coma corrector as well as that will be the most important optical component in a newtonian, provided that the mirrors are not complete lemons.


My "factory standard", that is not modified in any shape or form, TS Photon 150mm f/4 was quite useable stright out of the box. In the years since I identified only one signficant issue, slop, in the mirror cell which I would one day need to take care of. Other than that it is still one hell of an imagining kit.
Oscar avatar
CarbonStar 150 is a good one

I think it has baffles already, and stiff straight spider vanes, and a good focuser, and the option to get a mirror mask with the order, among other small good things that I probably don't remember
andrea tasselli avatar
Oscar:
CarbonStar 150 is a good one

I think it has baffles already, and stiff straight spider vanes, and a good focuser, and the option to get a mirror mask with the order, among other small good things that I probably don't remember

Except they don't sell them in Europe, afaik.