Why not newtonians?

[VinSnr]

Hi all,

Last night, had a little discussion with Kay Heem about my scope and he brought out one stark reality in singastro - People here seldom fancy reflectors.

Thinking back, it's true. Very seldom I have seen reflectors here. There are many SCTs owners and there are loads of refractors owners. Not sure if it's because of portability issue or what.....but the lack of reflectors here is quite a sad case.

I have owned Mak-Cass, SCTs, refractors, reflectors and I can tell you that the design that yields the best images is the reflector. With only two optical path (2 mirrors only, no lenses nothing), there is very little optical distortion and absorption on the incoming light.

Another good thing I love about reflectors is that it is very easily upgradable. Don't like your secondary spider? Chuck it and change a new one. Prefer a moonlite focuser? Well just drill the tube and put in a new focuser. Want better contrast? Get some flock paper and flock it. All can be done easily because it's open tube and all parts can be easily assembled again.

But best of all, it's cheap. The ratio of image quality/price is the best compared to any design. You really can't beat that. Also, you don't really have dew problems to worry about.

Only problem is portability. But I don't see how difficult it is to transport say a 10" truss tube compared to a SCT/refractor where you still have to transport the heavy tripod and weights.

Maybe it's because people here are afraid to tinker with collimation. Actually the best part of a reflector is the collimation. It's the easiest to do compared to most designs. A well collimated reflector with a 1/8 wave mirror costing less than a 1000 bucks will beat scopes of its size costing much much more most of the time.

People here should really look at reflectors. They give you awesome images without breaking the bank.

Maybe we should discuss here...why you guys don't like reflectors?

[weixing]

Hi,
I own an 6" F5 Newtonian... it is my primary scope and I like it very much... can go wide view (I used it as a 6" 2 degree finder scope), can go high magnification and no more odd observation position.

I think most people don't like newtonian mainly because it is not very portable especially in larger aperture. For example, most people will go for a 8" SCT rather than a 8" Newtonian, because the 8" Newtonian OTA is heavy and the OTA is quite long... even at F5.... not suitable for people without a car. Of course, if you don't require tracking, a larger newtonian will be possible.

Anyway, for my case, I don't have a car and I need to travel at least 200m to my observation site, so I think the 6" F5 newtonian or the 8" F4 Vixen R200SS is the larger newtonian that I can manage alone... remember I still need to carry the Vixen GP mount alone. Also, my 6" Newtonian is as heavy as a Celestron C8 SCT and also longer than the C8, so if I'm upgrading to a 8" scope, a 8" Newtonian will be out of question... unless I can find a cheap Vixen 8" F4 R200SS Newtonian.

Have a nice day.

[ariefm71]

for me newtonian is so 70s (just joking ). weixing is right, most ppl prefer sct over newtonian for larger aperture is because sct provides the best ratio of image quality/portability.

[VinSnr]

Hi,
I own an 6" F5 Newtonian... it is my primary scope and I like it very much... can go wide view (I used it as a 6" 2 degree finder scope), can go high magnification and no more odd observation position.

I think most people don't like newtonian mainly because it is not very portable especially in larger aperture. For example, most people will go for a 8" SCT rather than a 8" Newtonian, because the 8" Newtonian OTA is heavy and the OTA is quite long... even at F5.... not suitable for people without a car. Of course, if you don't require tracking, a larger newtonian will be possible.

Anyway, for my case, I don't have a car and I need to travel at least 200m to my observation site, so I think the 6" F5 newtonian or the 8" F4 Vixen R200SS is the larger newtonian that I can manage alone... remember I still need to carry the Vixen GP mount alone. Also, my 6" Newtonian is as heavy as a Celestron C8 SCT and also longer than the C8, so if I'm upgrading to a 8" scope, a 8" Newtonian will be out of question... unless I can find a cheap Vixen 8" F4 R200SS Newtonian.

Have a nice day.

actually talking about portability, there is always ways to go about solving it.

I have seen people throwing the whole GP mount into a golf bag and they use a shoulder strap on their 8" newtonian. So they slign the newtonian on their shoulder (across the back) and pull the golf bag (has wheels below) with their mount and tripod in it. Look quite portable to me. For their eyepieces, they use a waist pouch....and some inside the golf bag.

10 kg (weight of a 8" newtonian) sling on the shoulders and back is quite light.

[VinSnr]

for me newtonian is so 70s (just joking ). weixing is right, most ppl prefer sct over newtonian for larger aperture is because sct provides the best ratio of image quality/portability.

yeah, the newtonian is a bit old fashion, but don't forget that old designs normally work best...

Modern scopes have too many lenses, mirrors, which robs all the precious light.

That's why sometimes, the good old Ortho eyepiece is still the best.

[kayheem]

Hi,
I think most people don't like newtonian mainly because it is not very portable especially in larger aperture. For example, most people will go for a 8" SCT rather than a 8" Newtonian, because the 8" Newtonian OTA is heavy and the OTA is quite long... even at F5.... not suitable for people without a car. Of course, if you don't require tracking, a larger newtonian will be possible.

Have a nice day.

A solid tube newt is definitely longer and less portable than an SCT with similar aperture. That is why they have truss dobs. I can pack up my 10" truss dob and base and walk to my car in 1 trip. I do not think there are many scopes in the same aperture range that can do the same.

GEMs are heavy because of the counter weights.

It is no longer true that dobs cannot track. There are motorized dobs that can track in the Alt-Az modes and there are motorized Eq platforms that enable the user to do long-exposure astrophotography.

A dob still gives the best value (in aperture) for the dollar.

Kay Heem

[ariefm71]

That is why they have truss dobs. I can pack up my 10" truss dob and base and walk to my car in 1 trip. I do not think there are many scopes in the same aperture range that can do the same.

GEMs are heavy because of the counter weights.

which makes me wondering why you want to trade your 10" truss dob with an 8" sct ...

[kayheem]

which makes me wondering why you want to trade your 10" truss dob with an 8" sct ...

OK, this requires an essay answer...

1. Setup time for SCT is definitely faster (in alt-az mode). I am a bit lazy.

2. As mentioned in my 1st post, I do not think I have time to go Mersing that frequently, so my viewing would be limited to my home with bright lights around i.e. on brighter objects. 8" SCT would be easier to reach high mag on planets, given its higher F-ratio. The 10" dob would be sitting in my cabinet.

3. I like to move into binoviewing more frequently. This would be easier in an SCT given its long back-focus. Balancing would be trickier on my dob.

That's all for now. Once I think of something else, I will let you know.

Kay Heem

[weixing]

Hi,

1. Setup time for SCT is definitely faster (in alt-az mode). I am a bit lazy.

That's also a reason why truss dob newtonian is not popular in singapore... setup time is long. I think newtonian problem is not that the design is inferior or what... it just that it too "troublesome" and bulky, so a lots of us in Singapore do not prefer a newtonian. For example, comparing a 8" SCT and a 8" F5 Newtonian... I think 90% of us will go for a 8" SCT... although 8" F5 Newtonian is much cheaper, because it just more portable and easier to use... and we will use it more offen because of that. Unless you are looking for a wide field scope, then you may select the 8" F5 Newtonian.... But now SCT also got focal reducer, so
wide field is also reachable.

Have a nice day.

[kingkong]

i want a newtonian for my next scope. :!:
mainly because:
1. best aperture:$$$$
2. better for dso
also because:
3. better viewing position
4. i've a st102 az. can still fit an 8"SN+EQ in my car trunk
5. my usual viewing location is <50m from my storage location - hmmm... i think i still like to build a permanent observatory with fixed pier and all =P

so... any one taking order for lxd75 8" s-n?