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Considering upgrading scope optical train- barlow and diagonal


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Hi all

I eecently bought a new refractor (140mm APM doublet f/7) and considering whether I should upgrade some of my current optical train - a TS Optics 2.5x barlow and a Skywatcher dielectric diagonal - in case I'm "missing something" in terms of getting the most out of the scope visually. I mainly like visual observing, the moon, the planets, double stars and open clusters.

Here are the specs of my current barlow and diagonal.

https://www.teleskop-express.de/shop/product_info.php/info/p55_TS-Optics-Optics-TSB251-2-5x-Barlow-Lens--1-25-inch---apochromatic-triplet-design.html

https://www.firstlightoptics.com/diagonals/skywatcher-di-electric-star-diagonal.html

I use the barlow extensively to get different magnifications with my limited set of 4 eyepieces so it's an essential part of my kit.

I'm considering buying a new barlow like the TeleVue Powermate 2.5x ~€300 and a TeleVue Everbrite 2" diagonal €500.  Total cost ~€800 + shipping.. not exactly cheap, could afford a new scope for that! 😐 

 

The key question is would either of these accessories be worthwhile upgrades i.e. have a marked difference visually let's say ~40-50% improvement in images or would the difference be only subtle ~10-20%. If the latter, I would rather not be wasteful in spending and save the hard earned cash for something else.

I would very much appreciate any advice on this especially from those who have experience of going from stock/mid range accessories to high end.

Thanks

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Hello,

Just to complete the picture, can you let us know what eyepieces you currently have to use with this scope ?

On the performance increases, having often compared the views using both low-mid price and much more expensive accessories I feel the differences are almost always subtle so much more in the 10%-20% area. That's not to say that such improvements are not worth having but I guess I'm trying to be realistic with the gains that can be made.

Nice scope to own by the way :smiley:

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The SW 2" Dielectric diagonal I had was like the one they supply with their ED refractors and I thought it was very good, it was very well collimated. Since then I've been using prism diagonals with all my refractors and prefer them for the shorter light path, especially for bino's.

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Some time ago I acquired a better quality Circle T diagonal for my Maksutov, replacing the budget diagonal that was part of the kit. I could not see any improvement in quality when viewing.

Elsewhere I have read that spending money on costly diagonals gets you better build quality and durability rather than any obvious visual improvement.

Later I bought a new £50 Celestron Omni barlow to try instead of the cheap kit Sky-watcher one. Again I could not see any difference at all, either visually or when doing planetary imaging.

On the basis of this, you should expect to see little or no difference should you upgrade, rather than an obvious improvement.

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11 hours ago, John said:

Hello,

Just to complete the picture, can you let us know what eyepieces you currently have to use with this scope ?

On the performance increases, having often compared the views using both low-mid price and much more expensive accessories I feel the differences are almost always subtle so much more in the 10%-20% area. That's not to say that such improvements are not worth having but I guess I'm trying to be realistic with the gains that can be made.

Nice scope to own by the way :smiley:

Thanks John. This is super helpful and precisely answers my question,  so gains are not mind blowing 40-50% let's say.

I currently have a set of 3 Luminos eyepieces 10mm, 15mm and 31mm and a Celestron x cel 9mm. I know others have strong opinion on the Luminos range but I like mine, they give me good views.

I love the new scope, there's something special about a large refractor, it's simplicity,  it's views and oh it looks great! 😀.  Here's a pic of a new member of our family 

16409502597582299491892028093204.jpg

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11 hours ago, jetstream said:

Does it show much scatter? My Sw diag is vg with a bit of scatter but its just the one that came with the scope, yours is most likely an upgrade from mine.

Mine is also a stock diagonal that came with a Skywatcher evostar scope I bought a few years back. I haven't noticed scatter or anything wrong with the diagonal but wondering if views could be substantially better that I don't know about.

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1 hour ago, Cosmic Geoff said:

Some time ago I acquired a better quality Circle T diagonal for my Maksutov, replacing the budget diagonal that was part of the kit. I could not see any improvement in quality when viewing.

Elsewhere I have read that spending money on costly diagonals gets you better build quality and durability rather than any obvious visual improvement.

Later I bought a new £50 Celestron Omni barlow to try instead of the cheap kit Sky-watcher one. Again I could not see any difference at all, either visually or when doing planetary imaging.

On the basis of this, you should expect to see little or no difference should you upgrade, rather than an obvious improvement.

This is very helpful @Cosmic Geoff. Thanks for that.

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1 hour ago, Mr Spock said:

I'm more than happy with my Revelation 2" diagonal. It's a step up from the Skywatcher I have.

The TS Barlow is a three element apo design. I've not used one of these but I would expect it to be decent quality.

Thanks @Mr Spock, super helpful. Yes the barlow is a 3 element design and it gives views similar to the stock Celestron one I have that came with their eyepiece set. I guess as others are saying, differences are small in last mile performance in terms of value for money. 

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11 hours ago, Franklin said:

The SW 2" Dielectric diagonal I had was like the one they supply with their ED refractors and I thought it was very good, it was very well collimated. Since then I've been using prism diagonals with all my refractors and prefer them for the shorter light path, especially for bino's.

Thanks @Franklin. I've not considered prism diagonals as I read somewhere they are more suited to slower FL scopes.

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58 minutes ago, Kunwar said:

I've not considered prism diagonals as I read somewhere they are more suited to slower FL scopes.

I read that as well and I think it is probably correct for very fast instruments. I think F/7 is kind of in the middle. I use prisms at F/7.7 to good effect.

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The Powermate is a telecentric lens and works in a different way than a traditional barlow to achieve the same result. When used with short focal length eyepieces for high mag views, I believe it is indistinguishable from a quality 3-lens barlow. However it is better suited for longer focal length wide fov ones like your 31mm celestron than barlows as it minimises vignetting, edge degradation and eye position movement. ES tele-extender is the same design I believe but much cheaper.

Edited by KP82
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19 hours ago, KP82 said:

The Powermate is a telecentric lens and works in a different way than a traditional barlow to achieve the same result. When used with short focal length eyepieces for high mag views, I believe it is indistinguishable from a quality 3-lens barlow. However it is better suited for longer focal length wide fov ones like your 31mm celestron than barlows as it minimises vignetting, edge degradation and eye position movement. ES tele-extender is the same design I believe but much cheaper.

Ok thank you. in that case and also considering advice from others, I think I'll stick with my current 3 element TS optics barlow. I'm considering getting the Baader BBHS later this year though. As I'm interested in double stars, I think it will help with the views especially splitting close doubles. Hopefully fingers crossed.

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A chain is a strong as its weakest link... So everything depends on the quality of your scope.
Your scope sits in the top quality range I believe, so to get the best out of it, you should use top quality accessories as well.

TV PowerMates and Baader BBHS diagonals will get the best out your scope, and you will see the difference. Maybe you can borrow them from a nearby fellow astronomer or a club in the neighborhood to get a taste. I would lent you mines, if you were closer...
The PowerMate as well as the BBHS just seem to disappear and that is what you want...

Just my 2 €cents 

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On 02/01/2022 at 06:52, Waldemar said:

A chain is a strong as its weakest link... So everything depends on the quality of your scope.
Your scope sits in the top quality range I believe, so to get the best out of it, you should use top quality accessories as well.

TV PowerMates and Baader BBHS diagonals will get the best out your scope, and you will see the difference. Maybe you can borrow them from a nearby fellow astronomer or a club in the neighborhood to get a taste. I would lent you mines, if you were closer...
The PowerMate as well as the BBHS just seem to disappear and that is what you want...

Just my 2 €cents 

Thanks @Waldemarit's a good idea to test before buying but difficult for me to find someone locally.  I'll definitely prioritise the diagonal first.

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