6" F/4 Newtonian, is it a regret?

[TareqPhoto]

Just now, alacant said:

Hi

Do you have a Cheshire sight tube with cross hairs? Do exactly as you do with your other Newtonian. The only difference you'll see is a (at first quite alarming) secondary offset.

Cheers.

Hi,

Yes, i do have a Cheshire collimator from FLO, i do have also laser collimator which i collimated it as well to make it accurate, and someone told me to use a Barlow i have to magnify it for better collimating, i will give it a try, so, with a Cheshire one, is that sufficient?

[alacant]

51 minutes ago, TareqPhoto said:

with a Cheshire one, is that sufficient?

If it is a combination type (tube and crosshairs) then for me, yes. I've never used anything else. The collimation myths saved me loadsa time;)

Cheers

[TareqPhoto]

2 minutes ago, alacant said:

If it is a combination type (tube and crosshairs) then for me, yes. I've never used anything else. The collimation myths saved me loadsa time;)

Cheers

This is what i have, HIGHLY recommended, but do you know something else i should think of?

https://www.firstlightoptics.com/other-collimation-tools/premium-cheshire-collimating-eyepiece.html

[Macavity]

13 hours ago, laser_jock99 said:

These fast Newts are 'interesting' scopes and capable of good results but probably not 'out of the box'.
Be prepared to modify & fettle the scope to get the best results.

Sound right to me. But then I adopted the idea of "re-springing" the Primary from... @laser_jock99 🥳
Fitted it with Bob's Knobs too! But then I only expected it to be a "Video (Astronomy) Lightbucket".
That (even the thin walled Steel tuber!) worked well enough for / gave significant enjoyment to me...

IIRC: the "Sweet spot size" goes as a CUBE of f-number. Only "two times worse" than an f/5 Newt? 😛
Like many things in Astronomy (Science generally?) it doesn't become *instantly* BAD though...
I often wonder how many Newt owners operate with fairly rubbish collimation! (puts hand up! lol) 😏

Edited April 18, 2020 by Macavity

[TareqPhoto]

2 minutes ago, Macavity said:

Sound right to me. But then I adopted the idea of "re-springing" the Primary from... @laser_jock99 🥳
Fitted it with Bob's Knobs too! But then I only expected it to be a "Video (Astronomy) Lightbucket".
That (even the thin walled Steel tuber!) worked well enough for / gave significant enjoyment to me...

IIRC: the "Sweet spot size" goes as a CUBE of f-number. Only "two times worse" than an f/5 Newt? 😛
Like many things in Astronomy (Science generally?) it doesn't become *instantly* BAD though...
Sometimes wonder how many Newt owners operate with fairly rubbish collimation! (puts hand up) 😏

Ok 😊

[laser_jock99]

Working at F4 isn't too trying- F2.9 is a different ball game. Only go down that avenue if you like being told 'it can't be done'!

I have bunch of F4 Newtonians and use the 0.73x Coma Corrector on all of them at times. So the 12" F2.9 scope is interesting.....M51 in just 140 seconds.

Edited April 18, 2020 by laser_jock99

[laser_jock99]

Here's a picture of my 6" F4 scope on the outside pier. The 80mm refractor is the guide scope (or an alternative imager). Note though how I use a top & bottom dovetail bar for extra stability. You will also notice they are 2x longer than supplied dovetail bars- this is important to reduce tube flexure in the Newt's steel tube. If you can get Lossmandy type long dovetail bars- use those. Much stiffer than Skywatcher type.

The 6" F4 optical tube assembly is quite cheap- but I found it requires a bit more investment to get the best out of it.

[TareqPhoto]

35 minutes ago, laser_jock99 said:

Working at F4 isn't too trying- F2.9 is a different ball game. Only go down that avenue if you like being told 'it can't be done'!

I have bunch of F4 Newtonians and use the 0.73x Coma Corrector on all of them at times. So the 12" F2.9 scope is interesting.....M51 in just 140 seconds.

I mentioned that i will make or it is already in my wishlist of having that 0.73x reducer, i never mind to have it regardless of its price, but not now, later until i can get most out of my Newt the current one and the coming one, nice image there, it is nice to see the result under that short time, but i think you are living under nicer Bortle sky to get it right, i live under high light pollution sky, so now sure if i use faster scope it will help, i did shoot Orion with my F2 lens, didn't process it yet at all, and i felt like no matter how fast it is, i am still can't get out of it much in this sky until i can have much more frames or if possible much longer exposures.

[TareqPhoto]

23 minutes ago, laser_jock99 said:

Here's a picture of my 6" F4 scope on the outside pier. The 80mm refractor is the guide scope (or an alternative imager). Note though how I use a top & bottom dovetail bar for extra stability. You will also notice they are 2x longer than supplied dovetail bars- this is important to reduce tube flexure in the Newt's steel tube. If you can get Lossmandy type long dovetail bars- use those. Much stiffer than Skywatcher type.

The 6" F4 optical tube assembly is quite cheap- but I found it requires a bit more investment to get the best out of it.

Nice setup, and that is exactly what i will do, to have larger or longer dovetails, i do have Losmandy 14" dovetail bar or plate, but i may buy a wide dovetail bar that long, 14" or 400mm is good i think, but i am not planning to put any big guide scope on top of it, i already bought mini guide scope with small camera so that will cut or reduce the weight or payload much, my ST80 is really heavy now with its replaced focuser, and my ZWO 60mm guide scope i hate it because of Helical focusing which rotates everything behind, and i didn't know how to reach focus until some mentioned that it needs an extension, so my mini guide scope and camera is like perfect, but i don't know if that won't work with Newt of any size, we will see that, and nice setup you have there, you used many counterweights, and did you add that extra shaft or extension bar for counterweight that is came with the mount? Balancing is my main problem really.

 

Thank you very much

[Spaced Out]

On 16/04/2020 at 18:53, TareqPhoto said:

It will be for DSO imaging and sometimes the moon.

I'll be very interested to hear how you get on with this. I was considering purchasing this for DSO imaging, but have been put off by worrying about maintaining critical collimation, especially as I would be moving the telescope back indoors after every session (no obs).

https://www.teleskop-express.de/shop/product_info.php/info/p5881_TS-Optics-6--f-4-UNC-Newtonian-Telescope---Carbon-Tube---made-in-Germany.html

[TareqPhoto]

2 hours ago, Spaced Out said:

I'll be very interested to hear how you get on with this. I was considering purchasing this for DSO imaging, but have been put off by worrying about maintaining critical collimation, especially as I would be moving the telescope back indoors after every session (no obs).

https://www.teleskop-express.de/shop/product_info.php/info/p5881_TS-Optics-6--f-4-UNC-Newtonian-Telescope---Carbon-Tube---made-in-Germany.html

I will be honest with you, i don't care much about collimation, i do collimation inside house so i can spend even 1 hour trying, and i think it is too much drama about losing the collimation with any movement, i have a feeling it is not that much sensitive, i can collimate inside house precisely as much as i can, and when i take it out i can fix collimation maybe easily as it won't change collimation completely off, maybe slight shift, so i may re-collimate it in shorter time outdoor, i only care when i take it out not when i take it back inside, so i will collimate it inside and keep it there until the time of imaging, then i take it out carefully and check out again, if it is good then i just do imaging, if not then i try to make it quick while i am out before the imaging, in all cases i don't want to think about it as it is impossible or HOURS to spend, if that is the case then just image with it, i use my ST80 for imaging with all kind of issues and people still like the results, so i won't make it as a big deal, you can wait me until i get the scope to test and confirm you or you just buy and deal with it.