yobbo89 wrote: ↑Sat Mar 28, 2020 4:46 am
a 12" f4 newt can be difficult for planetary imaging, I see this topic come up quite often, achieving a long focal length can be difficult, while stacking barlows does work, it sometimes introduces reflection/ artifact depending on the quality of the Barlow and the distance between the two.
Focusing also is a bit of a problem.this diagram Can help you understand, even though you could get the f5 scope to f8, I'm sure a barlow, or two barlows stacked will throw out the critical zone, ie. A f5 scope with a 2x barlow would have a shorter critcal zone then a scope made for f10, I have no support for this claim, but from my experience I have found or feel that a 12" sct VS a 12" f4 with a barlow at the same fl that the sct had a longer critical zone and was easier to focus.
To be honest you're going to be better of with something like a 9" sct over a 12" f4 for planetary imaging. Keep in mind a 12" f4 weighs a tone.
If someone could get a similar diagram but with a barlow, that would be good.feel free to approve or disapprove this.
Now it seems you have a set budget, if i we're to head towards Newtonian planetary imaging ie dobsonian,Newtonian type of scope, I would be looking at scopes that are atleast f5 or longer and or possible 14"-16" mirror, I'm a bit hands on and like building stuff, but if you are in the same boat you could do the same, purchase a large primary and secondary and build a dob and a platform tracker.
Some of these 14"-16" dobsonian planetary are on par with 14" sct images, given that people who have these types of setups are stacking barlows and I'm sure they have a lilttle bit more of a hurdle to overcome.
12"f4 certainly doable, but I recommend maybe a f5, a nice motorised focuser and some decent barlows.
Ok, how about the following points or answers from my side?
1. I do have Tele Vue 3x, and 2x with 5x Powermate, and i even planning to get 4x Powermate, Damian Peach himself voted for 4x as the best, so?
2. Actually i am thinking about 12" F5 not F4, but i saw that F4 is very slightly less weight by 1-2kg than F5, and i wanted to try it on my EQ6 mount, so i was thinking that 12" is already too much, so 1-2kg could do wonders maybe, but i am still having my mind on F5 Newt version actually.
3. I did thinking about building a
dob, can buy mirrors, but that will cost me much more than i buy one ready and replace the mirror later, so i will go with buying a ready one then, and for that case, a
dob is also in my plan, between 12" up to 16", but last year i requested for 20"
Dob customized build, so i decided i will go with smaller
dob such as 12" or 14" to fit between 20" in future and my current 7"/8" scopes, and i feel like 12" is enough, but i can't buy a
goto 14", i can barely buy
goto 12"
dob maybe, but no
EQ platform, and then i may have difficult time doing planetary then, visual is there if i can't do imaging, but i don't want to get into situation where i get bored of visual or i feel regret that it is not ready for imaging yet, so i better get something as Newt or
Dob for imaging and worry about visual later.
4. How much is that 9"
SCT OTA compared to 10" Newt? how much is that C11 compared to 12" or even 14"
dob? How much is that 12"
SCT from Meade compared a 12" Newt/
Dob although that 12" Meade
SCT is less weight and still a lot for EQ6 as Newt? Price and weight are like opponents to each other, i looked all around and i see much more people using 12" Newt or even
dob than using 12"
SCT from Meade, i saw many used C11 or C9.25, but i will never buy anything less than 12" no matter how good, and i saw results from Newt and dobs from 10" up to 20", so my mind is already set for Newt or
dob as long i can choose something right, i don't mind going with something like 12"
dob or 14"
dob now without
EQ platform and i ignore the planets for now until i can afford
EQ platform then i start again, planets isn't an issue for me in my area, i can see them clearly high or good position in the sky every year, last two years i spent with my 7" Mak, want to jump from 7" to 12" or larger at once, not gradually from 7" to 10 then to 14 and whatever.
5. I am planning to buy autofcuser for all my new scopes i will buy from planetary or
DSO, so this is another plan i will do later, and changing focuser is also applicable later as long i choose the scope first, in fact with that 20"
dob i was planing or going to provide it with all the top best parts in the world, best secondary, best primary, best focuser [from Feather Touch] and all accessories as
GOTO and
EQ and whatever, so i was planning to not spend more than $1200 on a scope i want to buy now for planetary such as a Newt or a
dob, many Chinese newt/
dob are at this price from 12"-14" somehow unless i choose something with extras.
You can tell me anything more so i can let you know how i plan things, i know people have some ideas of how they choose, and i respect that and i can do, but i have my own experience that putting me always into regret route that sometimes i feel that people advice don't fit me or don't last long and i better try harder than what they told me, i got that idea from people about
buy now sell later a lot,
THIS IS DEFINITELY A BAAAD IDEA FOR ME IN MY LIFE.
Telescope: SkyWatcher: Skymax 180mm F15 Mak, StarTravel 80mm f/5 ---- Meade LX70 8" F5 Newt
Mount: SkyWatcher AZ-EQ6 GoTo
Cameras: QHY163M, QHY5L-II-M, ZWO [ASI174MM, ASI290MM, ASI385MC, ASI120MC(damaged)], Sony A7r + Canon DSLRs + lenses [Hasselbald, Canon, Sony, Sigma, Samyang], Hasselbald H4D-60
Filters: Astrodon Ha 5nm, Cyclops Optics LUX-Series RGB, Optolong NB, Baader filters [M&S Neodymium, Contrast Booster], Skywatcher UHC & OIII
Software: SGPro, PixInsight, APP, APT, DeepSkyStacker, Nebulosity, SharpCap, FireCapture, PHD2, CDC, Photoshop CC