8" Newt for AP

[cadman342001]

Ok so my plan for doing AP is, cos I'm basically unemployed/retired, is that rather than spend over a grand for an 80mm refractor I'm going to get an 8" Newt which will be about half that.

It's my 50th in December so I'm getting this sorted now so that I can my wife and the kids the lowdown on the exact present that I want ! :D :D

Considerations - Refractor vs Relector

Cool down / warm up times - I live in Cairns, the temperature inside and outside the house are always the same. We have/use no heating or AC.

Collimation - never done it but don't think it's that hard and will get a Cheshire laser thingy ?

Diffraction spikes ? I like 'em personally !

I have a HEQ5 Pro so am limited to 13.7kg payload which rules out the 10" I think as I can't afford the CF version.

What else ?

Better to go with a 1000mm/200=f5 or 800/200=f4 ? I guess it's a trade off between more coma with the f4 (which can be corrected with a corrector right?) but shorter FL so "easier"/longer subs, or the f5 less coma but the longer FL makes harder?

These are the options (all proper Newts optimised for AP) :

https://www.bintel.com.au/product/bintel-bt200-f4-imaging-ota/

http://www.astropetes.com.au/telescopes/NewtAstro_8.html

http://www.myastroshop.com.au/products/details.asp?id=MAS-069A4

Bintel seems to give lots of info on theirs and why it's better, and they have a good reputation (eg check and collimate their scopes before they send them out) but is the Black Diamond better ? Might be able to stretch to the price of that if it is. I've seen that one at $999 elsewhere.

What do you think ?

Andy

[glend]

Check out Andrews website, they are cheaper than Bintel and the scopes are exactly the same.

http://www.andrewscom.com.au/optical-telescopes

[xelasnave]

It is my impression from using a cheap 80 mm that you need to spend it to get it.
The reflector seems a better choice f5 before a f4 little better and cheaper.
I am going for f5 from Bintel because although dearer they are near the fish market which is an important consideration.
Andrews are great but not near a fish market.
Good luck let us know how you go.
Alex

[xelasnave]

http://www.andrewscom.com.au/site-content-section-10-guansheng.htm
Page down past the pictorial adds and you will see them there.
Alex

[xelasnave]

$469
Alex

[cadman342001]

Remembering as a child having to walk through the Fish Market to get to the normal market, I reckon the further away the better ! :D

[that_guy]

I'm sure it wasn't andrewscom's fault but I did receive a pretty bad dud when purchasing their 8" f/4 newt. I've since bought a large triplet refractor and havent looked back since. Don't have to worry about camera focus or collimation! But newts are more economical i guess aha. Make sure the newt can come in to focus with a camera, there are some that don't and some that are supposed to but were mismanufactured!

[ChrisV]

I got a GSO 8" F5 here on IIS. It was virtually new. Love it. A great complement to my 80mm refractor for imaging.

You'll need to factor in a good coma corrector, e.g. baader mpcc. I don't know about F5 v f4. But I'd love to try an f4 sometime.

Newts are a great price compared to refractors. Especially second hand. Collimating is no biggie. And I also like the diffraction spikes.

[cadman342001]

I'd rather pay a bit more from say Bintel and know that it's been checked before dispatch, especially living in Cairns. Andrews website annoys the **** out me too !

[cadman342001]

I'm now thinking of a 6" due to weight, which in turn means more funds for stuff like coma corrector, guide scope etc.

[RobF]

Focus on sorting out one thing at a time well, because the "wants" and costs are never going to end ;)
8" is a lot more light sucking power than the 6" - you may regret not getting the 8" later on.

If you get hooked you'll eventually be buying more cameras, guide scopes, guide cameras, computers, laptops, software, possibly an off-axis guider, focus motor, dew heaters. It all starts with the mount and OTA.

8" on HEQ5Pro is a very workable combo. I've only ever used F5, but believe F4 a lot more demanding to collimate and focus for the extra FOV you gain. Guiding around 1000mm focal length is a reasonable challenge best of times whichever you buy. Just be aware you're getting in the deeper end of the pool if you skip starting with out with a refractor.

What camera will you be using?

[ChrisV]

Alex

Maybe Andrews is better for Andy. A visit to the fish markets could also end up making this a very expensive Newt.

A couple of lobsters. A few dozen pacific oysters .....

Chris

[cadman342001]

Yeah, I realise it will all snowball but I'm fine with incremental investments via add-ons after the initial lump sum !

Camera is a Nikon D800 but may pick up a cheap used possibly converted crop Canon in the future as the clip in narrowband filters are not available for Nikon I think. I've been told the D800's 36 MP are too many for AP ? I do have the option of crop mode 15MP files and it does have excellent dynamic range.

[cadman342001]

Plane tickets for one ! not too keen on oysters though so that would save some cash :)

[xelasnave]

I used a 6_inch reflector almost exclusively.
The only reason I am going to 8 inch is because the 6 inch needs resurfacing.

I did use my 12 inch a few times but unguided because I felt I was pushing the weight aspect and tried without a guide scope.
It was about that time I stopped posting images and decided just to do stuff without seeking others views.


I am very tempted to go with a small high quality refractor but I can be happy with less than perfect.

A six inch is very cheap but enables you to have more cash and you never know you may need more cash.

Whatever you get regard it as a personal challenge.
Getting the best you can from the gear you use I found satisfying.

Captures are only part of the game as you may know.

Good luck.

Alex

[cadman342001]

Thanks everyone ! I will get a 6".
*
The Skywatcher Black Diamond BKP 150 OTAW Dual Speed is what I'm looking at as I notice it has the 10:1 dual speed crayford style focusser. None of the other 6 inch Newts I have seen here has that.
*
Only thing is, it's an f5 not f4 - longer FL (750 vs 600), more reach, less coma, easier to collimate but less light ?

Anyone know if there is an f4 equivalent ? can't seem to find one in Oz online

[that_guy]

checkout astropetes he has one for i think 350?

EDIT: disregard post aha they only have f/5

[cometcatcher]

6" F5 is good. I've got one of those. 8" F5 is good too, longer in focal length. 750mm vrs 1000mm. The HEQ5 Pro will easily handle an 8" F5. F4 scopes can be a challenge to collimate. ED Refractors are also a good option. Be like me, have one of each. ;)

[Tropo-Bob]

I have sent a PM to Andy.

[ChrisV]

Andrews have a 6" F4 with 10:1 Crayford. Says currently out of stock though

[ChrisV]

Kevin
How hard is it to collimate an f4?
And I agree. My newt and refractor complement each other really well
Chris

[cometcatcher]

Some people probably have the knack of doing it. I don't. It's not just collimation. Focal plane tilt and focus become much less forgiving also.

[RobF]

Yes, which mightn't bee a problem if the focuser drawtube was rigid, the tube showed no flex, and the secondary assembly rigid. Unfortunately in Chinese OTAs there can be a bit of play in all of these making adjustment (and staying there) harder.

I think my F5 8" is great value, but also expect to have to show some patience and work a little harder to get the best results from it.

[cometcatcher]

Yeah the carbon fiber tubes should help with rigidity. The steel ones flex, a lot. If one really wants F4, CF would be a better choice.