Refractor choice?

[Dave1]

11 hours ago, John said:

They do a 3" as well. Many of these types of scopes are hand made to special order though so they might not actually have one "on the shelf" ready to go out.

Mark Turner of Moonraker will make you a scope to your specification and around an objective lens of your choice if you have the patience and the readies !

They are works of art as well as exellent optical instruments

This French dealer has some interesting older and classic refractors on offer:

http://stores.ebay.co.uk/AnamorFose-photogallery/Telescopes-/_i.html?_fsub=4749028016

Have you ever used a Moonraker scope John? Review one by any chance? What where your thoughts.

[John]

5 hours ago, Dave1 said:

Have you ever used a Moonraker scope John? Review one by any chance? What where your thoughts.

I've not had that pleasure as yet

 

[Stu]

On 10/08/2017 at 15:48, John said:

I've not had that pleasure as yet

 

The thing about Moonraker is that the only common feature is the style of the design. The objectives are obviously what defines much of the scope's capability and they look to be Carton or iStar etc, or sourced by the customer e.g. LZOS triplets etc. Focusers can be whatever is specified, could even be a fairly bog standard one which has been stripped and polished to look good, as will also have been tweaked to function very well too. 

I confess they are not my cup of tea, too much design really but I know Mark will build anything you like, it doesn't have to be fancy pants (  ) and the finish will be superb.

[John]

Yes I agree Stu. Mark will take your objective and turn it into a scope. I have the feeling that he is a brilliant engineer rather than an optical specialist. His scopes certainly are distinctive but I have to confess that I think I prefer the traditional white tube with black fittings.

 

[Chris]

On 8/9/2017 at 08:30, Fozzie said:

Did @Lockie not try one of the 90mm Bressier fracs, and upgrade to a 100mm, maybe he could add something here?

I did indeed buy the Bresser 90mm f/13 and optically it was superb - flat, contrasty, and super sharp. It was tempting to keep it just for the optics, but felt that I really couldn't stand owning a scope made with so much plastic including a plastic clamshell to hold such a long scope of all things! But having said the scope does provide superb optics for very little money so I can see Bresser's possible thinking behind it.

Bresser's mechanical quality steps up with their 4" and above refractor, I know from previously owning their excellent AR127L f/9.4. It was my intention to upgrade to the much better built Bresser 102/1350 f/13 long focus achromat, but this was pending a big mount upgrade which I recently managed, then sold off when I realized that such a setup was both beyond my storage ability, and my inclination to setup/break down such a big heavy setup.

I can endorse Bresser's 4" and above refractors to the OP no problem, providing they have the space for it, such as a big shed or garage, plus the inclination to put a big tall heavy mounting together which can dampen such a long moment arm.

I'm trying to put to bed thoughts of lovely big long fracs as much as I love the things, just not practical for a guy with a 3x5' shed and a town house 'micro' garden.

[Chris]

AR127L f/9.4 mounted on Skytee plus 16" pillar extension at my old house...insanely good for the money, worth considering.

 

[Dave1]

Thanks for the extra input guys, much appreciated. Richard has a 4" F15 lenses he would be will to build a scope from, Which is seriously tempting. Asked the normal questions with regards to the lenses.

I contacted Peak2valleyinstruments today. He can still get D & G telescopes, but warned it maybe 6 months to a year before I'd see it. In Johns opinion he said Istar optics are better and maybe the better choice. My only concern with Istar is they are Chinese optics, which from what I've been able to find only come with a test certificate. 

I might ask who ever I get my telescope from to put the telescope to test, to check wave length and Strehl. To certify the quality or ask if I get it test if it isn't up to scratch if they would exchange or refund. I know I may have to wait a long time in some cases.

Dave

[John]

If you do get a test done I guess you are going to have to determine what will be acceptable to you and what won't

Not as easy as it sounds.

Edit: I'd also add that the Chinese are capable of producing very fine optics these days.

 

 

 

 

[nightfisher]

Price wise i would go for the bresser, its the best bang for buck to own a long achro

If you could get a Carton 4" F13 that would be superb, i have had a look through a skylight 4" and its a thing of beauty

Darn, all this talk of long white achro`s has got me wanting one, maybe i should get the bresser 102 1350 and if i dont like it i can sell it to lockie..........having dabbled with ED fracs i think i do prefer the humble achro

[Chris]

13 minutes ago, nightfisher said:

Darn, all this talk of long white achro`s has got me wanting one, maybe i should get the bresser 102 1350 and if i dont like it i can sell it to lockie

haha! and I'm sure my against the grain attempt to be practical with shorter, compact, more convenient scopes will have ended by the time you're thinking the 4" f/13 is too long to be practical with limited opportunity to use it, extra set up time as you can't keep them mounted unless in an obsy, and space to store it. 

We should set up a time share for scopes, Jules 

[Dave1]

T

1 hour ago, John said:

If you do get a test done I guess you are going to have to determine what will be acceptable to you and what won't

Not as easy as it sounds.

Edit: I'd also add that the Chinese are capable of producing very fine optics these day

 

 

 

Well its not so much what is acceptable to me, but more of what is the best I can get from all the options I have mentioned. I read somewhere Istar have a Strehl of 0.90.

Trying to find out if I can find out the Strehl for a D & G, just to get an idea.

[nightfisher]

The one achro i would really like to own is what i call the Tal 100rs Mk1, this had the purple coated objective and the 2" r&p focuser....but they dont come up for sale no more

[Chris]

42 minutes ago, nightfisher said:

having dabbled with ED fracs i think i do prefer the humble achro

They are less scope to worry about as they cost less, and they do have a charm about them...you managed to plant the seed regarding the Bresser 102/600 mainly as I can't afford a 4" f/6 Apo mind 

Oh by the way, heads up  

https://www.bresser.de/en/Sale/Display-Items/BRESSER-Messier-AR-102-1000-Hexafoc-Optical-Tube-assembly.html

[nightfisher]

2 minutes ago, Lockie said:

They are less scope to worry about as they cost less, and they do have a charm about them...you managed to plant the seed regarding the Bresser 102/600 mainly as I can't afford a 4" f/6 Apo mind 

Oh by the way, heads up  

https://www.bresser.de/en/Sale/Display-Items/BRESSER-Messier-AR-102-1000-Hexafoc-Optical-Tube-assembly.html

Chris, please refrain from all this temptation, your a very bad person  any way we are hijacking a thread, comment about the 102 600 on my widefield thread

[Chris]

2 hours ago, Dave1 said:

Richard has a 4" F15 lenses he would be will to build a scope from, Which is seriously tempting. Asked the normal questions with regards to the lenses.

Richard makes lovely scopes, I once picked up one of his 60mm f/17 Carton lensed scopes in black and brass from Astrobuyandsell, it was a beautiful thing to just look at and of course had optics to match. You could basically keep pushing the mag until you ran out of light.  

I never did get Richard to make me a proper lens cap for it though 

[Dave1]

Thanks for that Lockie, I have often wondered about getting a F16.7 60mm telescope and what the views are like through them? I've read that they can be used in poor seeing conditions and still produce quite good images? Due to size, and that the images produced can be very good being F16.7.

Dave

[John]

2 hours ago, Dave1 said:

T

Well its not so much what is acceptable to me, but more of what is the best I can get from all the options I have mentioned. I read somewhere Istar have a Strehl of 0.90.

Trying to find out if I can find out the Strehl for a D & G, just to get an idea.

Very few tests of D&G refractors about. I've seen one on the German Astroforen website and it was OK but nothing special. Strehl and figuring accuracy will vary objective to objective. 0.90 is not bad at all - it's better than the  accepted "diffraction limited" standards so the scope should perform to the theoretical limits of it's aperture, all other factors being perfect (which they almost never are of course !).

Personally I'd not get hung up on test results as they can be a bit of a minefield but I do look for consistently good reports on a model from reasonably seasoned observers. Those are the best indicators I think, plus your own eye of course

The Istar Club is a specialised focum that is worth joining or at least browsing. You don't need to own one to join and it's free:

http://istarscopeclub.proboards.com/

 

 

 

[Chris]

13 minutes ago, Dave1 said:

Thanks for that Lockie, I have often wondered about getting a F16.7 60mm telescope and what the views are like through them? I've read that they can be used in poor seeing conditions and still produce quite good images? Due to size, and that the images produced can be very good being F16.7.

Dave

Hi Dave, I'll try and describe it the best I can from memory; I can't remember really noticing atmospheric effect through the Carton 60mm f/17, images of say Jupiter or Saturn were quite still and unchanging compared to larger scopes, and focusing was a pleasure both with the buttery smooth Crawmatch focuser and the very shallow light cone hence large depth of focus an f/17 scope has.

Stars were really quite stunningly tight orbs showing nice colour set against a very dark sky, so very aesthetically pleasing from a stellar point of view. The Moon showed for all intense purposes zero chromatic aberration and good contrast and depth along the terminator considering it's aperture. Pumping up the mag on Jupiter would show several belts and a crisp looking disc and Moons, although the drop in light made Jove look really delicate and translucent. Despite the lack of resolution and brightness it was nice not waiting for a gap in the seeing to see all that was on offer.

I had the Skylight 60mm setup next to my C100ED a few times and the image in the C100ED was brighter and more detailed, i.e. you could clearly see the Cassini devision and globe shading in the ED100, where's this was just hinted at with the 60mm, however, I seemed to spend more time at the 60mm as it was just a nicer scope to use. Only partly because I really don't like the focuser on the C100ED for visual. 

White light solar with BV's really surprised me with the sharp detail seen on sunspots, it was also the first time I had used BV's for white light and it really made a positive difference to the wow factor.    

I can imagine a 4" f/15 to be pretty incredible, although it would be very tricky to properly mount one I feel, an 80mm f/15 would be a good compromise between views and mounting I feel, or maybe a 100mm f/12 ish?

[Dave1]

12 hours ago, John said:

Very few tests of D&G refractors about. I've seen one on the German Astroforen website and it was OK but nothing special. Strehl and figuring accuracy will vary objective to objective. 0.90 is not bad at all - it's better than the  accepted "diffraction limited" standards so the scope should perform to the theoretical limits of it's aperture, all other factors being perfect (which they almost never are of course !).

Personally I'd not get hung up on test results as they can be a bit of a minefield but I do look for consistently good reports on a model from reasonably seasoned observers. Those are the best indicators I think, plus your own eye of course

The Istar Club is a specialised focum that is worth joining or at least browsing. You don't need to own one to join and it's free:

http://istarscopeclub.proboards.com/

 

 

 

Thanks for the link John. Yes i usually go by owner reviews. I was also trying to incorporate test results into this to help the process of selection along. 

The thing is i can generally find good reports for D & G. But i can't find a report at all for Istar. Which is why i am cautious of Istar and why i'm trying to find test results for D & G, so that i can compare the two.

 

 

[Dave1]

@Lockie thanks for such a detailed and indepth insight into your 60mm, was really helpful to see how it compared to the larger ED scope. 

I already have a Towa 339 which is 80mm F15. Which im awaiting parts, so that i can bring it into this centuary. 

[John]

27 minutes ago, Dave1 said:

Thanks for the link John. Yes i usually go by owner reviews. I was also trying to incorporate test results into this to help the process of selection along. 

The thing is i can generally find good reports for D & G. But i can't find a report at all for Istar. Which is why i am cautious of Istar and why i'm trying to find test results for D & G, so that i can compare the two.

 

 

 

Good luck that exercise Dave !

 

[Dave1]

Thanks when i get home tonight i'm going to check out the astrofen forums, see if i can the D & G test.

I'm also going to check out the Istar forum aswell to see if i find any reports on Istar long achro.

[John]

This thread from the "Cloudynights" forum has some relevent stuff regarding Istar and D&G tests etc:

https://www.cloudynights.com/topic/427823-istar-150-f10-tested-by-wolfgang-rohr/

The thing to remember is that the tests are of a single example of the objective lens. There will be variation lens to lens, sometimes quite wide variation.

[F15Rules]

On 8/10/2017 at 10:32, Dave1 said:

Have you ever used a Moonraker scope John? Review one by any chance? What where your thoughts.

Dave, 

I have an 80mm F15 Moonraker prototype. It was originally built using a Meade 339 80mm F15 as a donor scope (same as a Towa Topic like yours, which I've also owned several of). Mark at Moonraker built a new tube, rings, dewshield (longest dewshield I've ever seen, apart from possibly Skylights), and had a Crawmach (USA) 2" dual speed focuser fitted. I've added a few of photos of it below, (the first two were taken shortly after delivery to Neil English I believe, the others on my own drive), and you should find a post or two on this scope on here if you search Moonraker. It was built for Neil English, then went to another SGL member before coming into my care.

The scope is not flawless, it was after all a prototype from when Mark was just setting up his business and refining his building skills, but it is optically the same lens set as in the Topic, and is a superb double star and lunar scope/planetary scope - within it's 80mm limitations.  The intricacy of some of the machining is unbelievable, all in solid aluminium.

I just really like it as it's one of a kind and kind of modern retro look. I'd still prefer a simple black and white tube though!

 

[Dave1]

Thanks for the reply @F15Rules. That is one beautiful telescope. I suspect she is a joy to use. 

Options option options.