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Minimalist eyepiece kit build for TS 70ED F6


badhex

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Hello all

I'm building out a lightweight, minimalist grab and go/travel kit based on a TS Optics 70ED which has a FL of 420mm and thus F6.  Overall my goals are not dissimilar to Stu's plan in this thread: https://stargazerslounge.com/topic/374172-small-fracs-for-viewing/


Although obviously this scope is geared towards wide-field/low power, I'd like to also use it for a bit of planetary as well, so I'm in the process of building out my EPs for the kit.

Initial thoughts are as follows:

1x low power
1x medium power
1x high power
1x barlow (currenlty own a 2.5x Revelation/GSO)

I've started with medium power, as that's an easy win - I know I'll be very happy with my Baader Morpheus 17.5mm which gives me 24x or 60x barlowed so I think this will work well.

First troublemaker is the high power; I already have a BCO 10mm (42x / 105x) and BCO 6mm (70x / 175x). I'd like a bit more than 105x when conditions allow, but 175x is too much. 

For the low power, I do have 2" accessories/ EPs already but this adds up quickly, weight wise. I'm debating a 1.25" good-quality plossl in the 32mm range like the Baader Classic Plössl, to keep weight down, which will give me 13x / 33x - and crucially a manageable 5.33mm exit pupil. 

I guess then my questions are:
What should I do with the high power? Perhaps an ortho at 8mm (52x / 131x) or at maximum 7mm (60x / 150x) would fit nicely in that gap? Any suggestions? 

For the low power, I appreciate the FOV will be  restricted by the 1.25" barrel size at low powers, but is it worth adding at least half a kilo for the diagonal plus whatever EP, for that extra degree of sky? 3.8° TFOV vs 4.8. 

Lastly regarding the barlow, as I will be heavily relying on it for the in between steps, is the Revelation going to good enough in a small scope at high(ish) mags, or to get the best of it should I consider investing for example in a Powermate?

Any advice or thoughts welcome! 

Thanks 

Joe 

Edited by badhex
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35 minutes ago, badhex said:

For the low power, I appreciate the FOV will be  restricted by the 1.25" barrel size at low powers, but is it worth adding at least half a kilo for the diagonal plus whatever EP, for that extra degree of sky? 3.8° TFOV vs 4.8.

Not sure where you're getting 4.8 degrees for a max field 2" eyepiece.  Let's assume a 70 degree AFOV 40mm 2" eyepiece such as the 40mm Pentax XW.  It would yield roughly 420/40 = 10.5x with a 70/10.5 = 6.67 degree TFOV.  That's a huge difference relative to the 3.8 degree TFOV of the 32mm Plossl.  Nearly 3 degrees wider.  I do this a lot with my AT72ED when panning rich star fields.  It allows me to pick out clusters and asterisms that are otherwise too big to recognize as such.

For high power, you might try @John's goto of a 7.2-21.5mm zoom combined with a Baader Q-Turret 2.25x Barlow.

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1 hour ago, Louis D said:

That's a huge difference relative to the 3.8 degree TFOV of the 32mm Plossl.  Nearly 3 degrees wider

You're completely right, apologies, I wasn't clear. I was just doing a quick calculation based on my 30mm 2" GSO superview which is the only other 2" EP I have (aside from my Panoptic 41mm which I would be terrified take in my travel kit!). I'll admit I've had a nagging feeling that dropping the 2" diagonal means sacrificing much of what this scope is actually best at! I will have to rethink. 

Regarding the zoom thanks for the heads up - I had actually momentarily forgotten that I have a Seben 8-24mm bought years ago as a stopgap and which doesn't really get used. Perhaps I'll dig it out and give it an airing once the scope arrives. 

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7 hours ago, Louis D said:

Also be aware that this Barlow has been reported to be closer to 2.2x.

Thanks. On the subject of that specific Barlow, I know it's generally thought to be pretty good for the price and in my slower scopes it has been fine, albeit not a daily use item. Much as fast scopes can be more demanding on lower quality EPs is this similarly true of Barlow? My optical knowledge starts to falter a little at this point. 

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  • 3 weeks later...

Quick update on this: I gave up trying to save myself the additional weight of 2" accessories as I now have a Think tank backpack which fits everything in nicely. 

 I won't take the Panoptic 41mm in this kit, and currently have a 2" GSO 30mm Superview in 2" which will give me 14x and 4.8° TFOV but I suspect it will perform very poorly at the edge in this F6 scope, especially since I have the Panoptic to compare it to. 

I will wait and see how it plays out but if it doesn't work out I may be in the market for an Aero ED! 

@Louis DI am yet to try out the Seben 8-24mm zoom in the Celestron travelscope which is virtually the same FR and size as the 70ED. Last time I had it out in a clear night I completely forgot to take the zoom with me, and it's basically been cloudy since. I'll probably be able to test it in the actual 70ED by the time the clouds go away! 

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In my Borg 71, which is f/5.6 (only 400mm focal length) I use 24mm (Pan) for filtered look at some of the biggest objects, but normally it is 13mm, 5mm and 3.5mm Naglers (or a 3mm Delos).

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14 hours ago, BGazing said:

normally it is 13mm, 5mm and 3.5mm Naglers (or a 3mm Delos).

Thanks. I might look into sub-4mm as an option, as 3mm gives me 140x which is really the max. mags I think this scope will be comfortable with. I'm actually not sure what's on the market at that focal length which has decent eye relief at F6 and doesn't break the bank! I don't want much do I? :D 

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6 hours ago, badhex said:

Thanks. I might look into sub-4mm as an option, as 3mm gives me 140x which is really the max. mags I think this scope will be comfortable with. I'm actually not sure what's on the market at that focal length which has decent eye relief at F6 and doesn't break the bank! I don't want much do I? :D 

The 62° TeleVue Delite comes in a 3mm.  I recommend it, and use one myself.

It is less expensive than the Takahashi TOE 3.3mm and 2.5mm

The BST Starguider ED 60° eyepiece comes in a 3.2mm.  Available under many labels.

The Celestron X-Cel LX 60° eyepiece comes in a 2.3mm.

The Altair Lightwave LER 55° comes in a 3mm. Inexpensive.

All have fairly long eye reliefs except the Takahashis.

 

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19 hours ago, Don Pensack said:

All have fairly long eye reliefs except the Takahashis.

Thanks! Great list, I'll take a look. I did see that there was a Starguider in 3.2mm and I understand they are very well thought of but have never looked through one myself. I'm based in Germany, I think Artesky is the branding for those here but seems to be quite a lot more expensive than the UK.

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1 hour ago, johninderby said:

Telescope Express does their version of the Starguider but much more expensive.

Thanks. Yeah not sure why there is such a big difference. The Artesky version is on astroshop.eu for €79, which is better but still about 25eur more than FLO. That said anything from the UK will definitely get stuck in customs and have at least an extra 20eur on in tax and "handling fee". 

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On 14/05/2021 at 19:29, Don Pensack said:

The BST Starguider ED 60° eyepiece comes in a 3.2mm.  Available under many labels.

On 15/05/2021 at 22:01, Louis D said:

Maybe they hand check each eyepiece like Tele Vue for quality assurance to justify their higher price. 🤣

In the end, I took advantage of @FLO's lower pricing and 10% discount on 2+ items from the same line and bought the 3.2mm and 5mm starguiders. As the VAT is also removed by FLO if shipping outside the UK, this should hopefully mean that even after customs, shipping etc. the two EPs should come in at around EUR65 each which is still at least EUR20 cheaper than the cheapest option plus shipping direct from Germany. 🤞

I did enquire about a price match from a mainland European retailer but apparently they will not match prices from "countries outside Europe". Appreciate that the UK is no longer part of the EU but last time I checked it was still on the same continent 😂

Edited by badhex
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Final update: Sadly my scope has been delayed for ages (mid July earliest) but I managed to find competitive pricing on a 35mm Aero ED (the TS-flavour) so I decided to take the plunge, as well as the above mentioned Starguiders. Everything arrived in the last two days, so the lightweight kit is now complete! Worht noting that I was pretty much bang on in my estimations of final cost for the BSTs after customs and shipping etc - they came in at EUR66 each, compared to the best price I could find of EUR82 each from mainland Europe. 

I actually also did a quick calculation of what they've have been to import from @FLO pre-brexit, which would have been EUR65 - so in the end only one euro difference!

Screenshot_20210520-135743_Gallery.thumb.jpg.a217fbac65b9fb466a59a9ca247aa60b.jpgimage.thumb.png.b5361f00b4c1772ddb7cad32270e7173.png

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21 minutes ago, Don Pensack said:

"Paracor 35mm"???

I've seen them come up in Europe occasionally.  They're the same as the Aero ED 35mm in the UK, Titan II 35mm in the US, or Sky Rover 35mm direct from China.  I'm not sure which vendor is/was selling them labelled as Paracor, but I'll wager it's a continental European vendor.

It does seem odd to choose a name so close to Tele Vue's Paracorr.

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3 minutes ago, badhex said:

Indeed! I did a double-take when I opened the box! Note the trademark-defeating single R at the end 😉

I take it yours came from TS-Optics.  Their website images don't show the Paracor branding:

spacer.png

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13 minutes ago, Louis D said:

I'll wager it's a continental European vendor.

It does seem odd to choose a name so close to Tele Vue's Paracorr.

You are correct. This came from Teleskop Service but I don't know if it's a model name they chose or what, probably just from the factory like that? 

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24 minutes ago, Louis D said:

I take it yours came from TS-Optics.  Their website images don't show the Paracor branding:

Exactly - hence my thinking that it's just generic branding rather than specifically chosen, but 🤷 

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9 minutes ago, Voyager 3 said:

Or maybe Paragon misspelled 🤪 ? But seriously Paracor ? Louis , I couldn't find the the 35mm eyepiece in the TS website . Are they still sold by TS ? 

Think this is the one

https://www.teleskop-express.de/shop/product_info.php/info/p2334_TS-Optics-35-mm-2--UFL-Eyepiece---69--Field-of-View---6-Element-Design.html

Edited by johninderby
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2 hours ago, johninderby said:

Think this is the one

Yep, that's the one

3 hours ago, Voyager 3 said:

Or maybe Paragon misspelled 🤪

I understand from @John and others that these were supposed to be originally based on the TMB Paragon - the 30mm and 40mm at least - so I wondered if there was a vague link there. 

Regardless, it's an unusual choice of naming!

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