Faster Scope for imaging

[carastro]

Using the Samyang lens has really spoilt me, and I am now looking for a fast refractor and possibly a triplet as I never seem to get the nice sharp stars others get.

Takahashi's are cost prohibitive, but I have found this scope this morning and apart from the fact that I can't see anywhere to mount my finder guider, it looks ideal.  (I have shot off a few questions to them).

It says you can capture the same data in half the time and I have indeed had to lower the LRGB times (when I have used them on the Samyang lens) otherwise I get a completely white and blown out sensor.

Just wondered whether you guys had any thoughts or opinions on this before I press the buy button:
https://www.teleskop-express.de/shop/product_info.php/info/p7224_TS-Optics-Imaging-Star-80-mm-f-4-4---6-element-Flatfield-APO-Telescope.html

Thanks Carole  8Thank mm f/4.4 - 6-element Flatfield APO Telescope

Edited July 3, 2020 by carastro

[vlaiv]

I have similar scope, but without built in field flattener - this model:

https://www.teleskop-express.de/shop/product_info.php/info/p3881_TS-Optics-PHOTOLINE-80mm-f-6-FPL53-Triplet-APO---2-5--RAP-Focuser.html

It is very good scope and very well worth the cost. I use it with x0.79 FF/FR. There is also x0.75 Riccardi FF/FR that would make it F/4.5 - so pretty close to above scope.

From what I've read - some people had some issues with flat field TS scopes - mostly due to alignment of optics (there are 6 pieces of glass that need to be precisely aligned and spaced), but don't know how often that happens.

In my view, probably better option would be to go for regular triplet and then use good FF/FR like Riccardi one, but again - I have no real experience with flat field version - maybe it is hassle free (no need to purchase adapters, fiddle with distances and so on) and that could be a big plus.

[michael.h.f.wilkinson]

I think their focuser has the usual mounting point for a Baader finder shoe, so the finder guider should fit. You can also attach a guider to the top of the rings (there are threaded holes visible in the photo). I remember their initial 65 mm quadruplet flat-field had some issues with pinched optics, but I believe they have been sorted in the later versions. I have a similar 80mm F/6 triplet to @vlaiv's one, and use that with either a TS 1x flattener, a TV TRF2008 0.8x reducer, and did some experiments with a 0.6x reducer. This gives me multiple options in terms of speed and FOV. I can't fault the scope, either for solar or DSO imaging, or for wide field observing

[vlaiv]

Btw, if you want something really fast, close to Samyang and in focal length of above scope, maybe have a look at this:

https://www.teleskop-express.de/shop/product_info.php/info/p11082_TS-Optics-150-mm-f-2-8-hyperbolic-Astrograph-with-Corrector-and-Carbon-Tube.html

 

[MarkAR]

TS have a very good reputation from what I hear. Another alternative might be Altair Astro, I think they very well may be the same scopes rebranded.

[carastro]

Thanks Vlaiv, I think the hyperbolic one might be a step too far for me to cope with.

I think I like the idea of the one I linked that you can screw the camera directly into the focusser, as I have had problems with tilt using 3 bolts.   

Quote

I think their focuser has the usual mounting point for a Baader finder shoe, so the finder guider should fit. You can also attach a guider to the top of the rings (there are threaded holes visible in the photo).

I hope it has a finderguider shoe, their picture doesn't really show it.  I saw you can attach a guider on top, but I want to use my other scope on top as a dual rig which although a doublet has a faster FR to my ED80 and that has no mounting point for a guider, so need it on the bottom scope. 

Carole    

[carastro]

Quote

Another alternative might be Altair Astro, I think they very well may be the same scopes rebranded.

I did take a look at Altair Astro but could not find anything that looked suitable.  

Carole 

 

Edited July 3, 2020 by carastro

[DaveS]

Beware of this 'scope. I have one and it is *very* sensitive to spacing and squaring on. It is *just about* usable with a not-too-big sensor, but I think anything above an ASI1600 size will be pushing the tolerances.

@ultranova had one, and we had a very long exchange of PMs trying to sort out the spacing before he got fed up and sent it back. I think he got his through a UK dealer which made it easy, but mine came direct from TS so I ended up hanging on to it.

It may well come with a TS camera rotator instead of the tilt adjuster, which can make working out the spacing from TS site data tricky to say the least.

[carastro]

Quote

Beware of this 'scope. I have one and it is *very* sensitive to spacing and squaring on. It is *just about* usable with a not-too-big sensor, but I think anything above an ASI1600 size will be pushing the tolerances.

@ultranova had one, and we had a very long exchange of PMs trying to sort out the spacing before he got fed up and sent it back. I think he got his through a UK dealer which made it easy, but mine came direct from TS so I ended up hanging on to it.

It may well come with a TS camera rotator instead of the tilt adjuster, which can make working out the spacing from TS site data tricky to say the least.

Hmmm, doesn't sound so good then.  

Carole 

[DaveS]

It's not a bad 'scope as such, but it could drive you to distraction getting it set up.

Here's a photo of mine, which I haven't used for quite a while.

I've been meaning to use it again but "stuff" kept getting in the way.

[carastro]

I really don't want items I have to adjust that drive me mad.  Maybe I will do what Vlaiv suggests in that case.

Carole 

[vlaiv]

27 minutes ago, carastro said:

I think I like the idea of the one I linked that you can screw the camera directly into the focusser, as I have had problems with tilt using 3 bolts.   

I had issues with tilt as well, that is why I switched to threaded connection using this adapter:

https://www.teleskop-express.de/shop/product_info.php/info/p9781_TS-Optics-360--Rotation---Thread-Adapter---M63-to-M68--M54-and-2-.html

together with this one:

https://www.teleskop-express.de/shop/product_info.php/info/p5144_TS-Optics-Adapter-from-M68-and-M63-to-M48---Riccardi-Connection-Adapter.html

Very versatile combination - provides many different threads for camera side connection and also a M48 filter thread on telescope side - inside focuser. Useful for both reducers and filters (like 2" LP filter).

 

[carastro]

@vlaiv

OK, I am now coming round to the idea of Vlaiv's scope, and the FR so can I ask you a few questions about the scope Vlaiv?

1) It appears in the photos to have a guidescope bracket, is this standard with the scope and will it fit a Skywatcher bracket?  Presume it doesn't actually come with a finderscope?

2.  The retracting dew shield - can it be locked to stop it slipping, I have similar on my WO scope and there is no way to stop it slipping and it has caused me a lot of problems.  

Thanks

Carole 

 

Edited July 3, 2020 by carastro

[vlaiv]

@carastro

Here is my scope (old image - when it was brand new):

As you can see, it has two sets of screws on focuser - silver ones, one set at each side. These screws use hex wrench and don't hold anything on the scope - they are ideal, and in all likelihood meant to hold finder shoe. I use them like that.

You can also mount your guide scope on top of rings - they have flat surface and M6 holes (x3 each) - also visible in the image.

In the end, I've found dew shield to be rather stiff in motion and unless under heavy load - stays in place. When I'm doing flats - I turn scope vertically and rest flat panel on dew shield. Sometimes it will hold flat panel without issues, other times it will start to slip slowly - I guess it depends on temperature as it probably expands differently then the rest of the scope.

In any case, there are three very small hex bolts - best seen in this image (but also visible in image above):

I believe that these are used to tighten / loose dew shield sliding action. Not 100% sure as I have not tried - but I can't see them being used for anything else.

 

[andrew s]

I think you have a choice. Built in flattener and rely on the manufacturer to get it right or separate FF and have to fiddle with it.

You pays your money and takes your choice.

Regards Andrew 

[DaveS]

This is an image of the Rosette I made with my TS 80mm f/4.4 and ASI1600

If you look in the corners you will see some decidedly dodgy stars, even though I had been fiddling with spacing and squaring till my eyes went funny.

[RayD]

59 minutes ago, carastro said:

@vlaiv

OK, I am now coming round to the idea of Vlaiv's scope, and the FR so can I ask you a few questions about the scope Vlaiv?

1) It appears in the photos to have a guidescope bracket, is this standard with the scope and will it fit a Skywatcher bracket?  Presume it doesn't actually come with a finderscope?

2.  The retracting dew shield - can it be locked to stop it slipping, I have similar on my WO scope and there is no way to stop it slipping and it has caused me a lot of problems.  

Thanks

Carole 

 

I have a TS80 Photoline that I use very rarely which you are more than welcome to use for a while Carole to see if you get on with it.

[carastro]

I can't get your image to enlarge Dave (I have this problem sometimes with SGL), so can't see the corners.  

@RayD  

That's really good of you Ray, yes please.  I guess I would need to pick it up asap (socially distancing of course) since you are going to Spain soon.  I'll message you.  Great idea to try first.

Carole 

[carastro]

Quote

If you look in the corners you will see some decidedly dodgy stars, even though I had been fiddling with spacing and squaring till my eyes went funny.

Finally got the Forum to "play ball" and enlarge the image, yes I see what you mean.  As an aside, was this taken with your Astrodon 3nm filter?

Carole

[nfotis]

Maybe a stupid idea, but why not use the Canon 400mm/5.6L lens instead?

I think that it should play excellently with your Canon body, and I suspect that'll be a more general purpose lens?

(I own that lens, and I plan to use it when I get my mount)

 

N.F.

 

[Wyvernp]

I am also fighting the same issue with my GT81, even with the field flattener. It seems very sensitive to backfocus. Waiting for a clear night to have another play now that I have my calipers out.

[michael.h.f.wilkinson]

7 minutes ago, nfotis said:

Maybe a stupid idea, but why not use the Canon 400mm/5.6L lens instead?

I think that it should play excellently with your Canon body, and I suspect that'll be a more general purpose lens?

(I own that lens, and I plan to use it when I get my mount)

 

N.F.

 

The 80 mm F/6 with 0.8x reducer is actually faster (F/4.8, or some 60% more light for a given exposure time) at nearly the same focal length (384mm), and you have a 480mm as well. Besides, in my experience you almost always need to stop a camera lens down to get good stars in the corners

[DaveS]

2 hours ago, carastro said:

Finally got the Forum to "play ball" and enlarge the image, yes I see what you mean.  As an aside, was this taken with your Astrodon 3nm filter?

Carole

Sorry, missed the replies here., 

Yes, with the 3nm Astrodon. I also have it in [NII] and [OIII], but the alignment was so bad that I had to crop it down to about half the overall size.

[DaveS]

Regarding the dew shield. The 80mm f/4.4 had a thumb screw to secure the dew shield, while my 130 f/7 TS Photoline has the three little hex grub screw that do the  same.

[ollypenrice]

 A one litre engine can be made to produce 50 brake horsepower, 75 bhp, 100 bhp, or even (yes, seriously) 200 bhp. Which do you think will do 500,000 miles?

If you look at the threads on here, Takahashi are struggling to get reliable results out of F5 on the FSQ106 at £5-6K.

What more do you need to know? Nobody has ever made 'fast and cheap' at serious aperture.

Olly