Can anyone help me find a compatible focal reducer?

[Trippelforge]

I have been searching around for a few weeks trying to find a compatible focal reducer / field flattener for my scope. The problem is everyone of them that I find points out it only will work with "X" manufacturer / model. My scope (Barska) is pretty rare and hasn't been in production for many years. So finding anything that directly says it's compatible has been impossible.

My scope is a 80mm f/7 triplet, is there anything that "should" work OK with it?

Thanks for the help!

 

[vlaiv]

I think that any of these will work (listed in ascending price order, and possibly ascending quality - but not 100% sure on that. Last one is top level reducer and will be of higher quality than the rest):

https://www.teleskop-express.de/shop/product_info.php/info/p5239_TS-Optics-REFRACTOR-0-8x-Reducer-Corrector-for-80-mm-f-7-ED--and-APO.html

https://www.teleskop-express.de/shop/product_info.php/info/p5965_TS-Optics-REFRACTOR-0-79x-2--ED-Reducer-Corrector-fuer-APO-und-ED.html

https://www.teleskop-express.de/shop/product_info.php/info/p12939_TS-Optics-REFRACTOR-0-8x-Corrector-for-TS-80-mm-f-6-CF-and-Photoline-80mm-Triplet-Apo.html

https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html

 

 

[Trippelforge]

7 minutes ago, vlaiv said:

I think that any of these will work (listed in ascending price order, and possibly ascending quality - but not 100% sure on that. Last one is top level reducer and will be of higher quality than the rest):

https://www.teleskop-express.de/shop/product_info.php/info/p5239_TS-Optics-REFRACTOR-0-8x-Reducer-Corrector-for-80-mm-f-7-ED--and-APO.html

https://www.teleskop-express.de/shop/product_info.php/info/p5965_TS-Optics-REFRACTOR-0-79x-2--ED-Reducer-Corrector-fuer-APO-und-ED.html

https://www.teleskop-express.de/shop/product_info.php/info/p12939_TS-Optics-REFRACTOR-0-8x-Corrector-for-TS-80-mm-f-6-CF-and-Photoline-80mm-Triplet-Apo.html

https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html

 

 

Thanks and I forgot everyone here lives in Europe... lol. I am going to try and search for those in my area. 

Edited November 28, 2022 by Trippelforge

[vlaiv]

1 minute ago, Trippelforge said:

Thanks and I forgot everyone here lives in Europe... lol. I am going to try and search for those in my area. 

@Louis D orders things from TS and I believe everything is OK with regards to shipping and import fees.

I even believe that you have something like $800 limit below which you don't pay any import fees and sometimes it is even cheaper to order from abroad, but I'm not 100% certain on that one (and it might be state dependent).

[Trippelforge]

45 minutes ago, vlaiv said:

@Louis D orders things from TS and I believe everything is OK with regards to shipping and import fees.

I even believe that you have something like $800 limit below which you don't pay any import fees and sometimes it is even cheaper to order from abroad, but I'm not 100% certain on that one (and it might be state dependent).

Oh OK, thank you for the help!

[Louis D]

Definitely no import tariffs or other tax issues from abroad, new or used, under the $800 de minimis exemption.  It is great for small items because you bypass the 25% special tariff and state and local sales taxes that generally more than pay for shipping fees from many retailers.  Some retailers do insist on using super expensive 3 day or less shipping options, so you have to watch out.

[Trippelforge]

19 hours ago, vlaiv said:

@Louis D orders things from TS and I believe everything is OK with regards to shipping and import fees.

I even believe that you have something like $800 limit below which you don't pay any import fees and sometimes it is even cheaper to order from abroad, but I'm not 100% certain on that one (and it might be state dependent).

Quick question, how do these connect to a dedicated camera? I never gave that much thought as currently I am using a DSLR so it's obviously a standard t-adapter and ring. Oh and why do they make some of them without grooves for safety reasons? 

[vlaiv]

5 hours ago, Trippelforge said:

Quick question, how do these connect to a dedicated camera?

Most astro photography gear comes with either T2 or M48 threaded connection (larger items do tend to use M54, M63 or M68 and there are a lot of custom threads as well for some reason).

You can see technical details for each of them to see what sort of thread is available:

2" Filter thread is M48 thread.

You need to work out distance needed between sensor and corrector and then plan your spacers, extension tubes, and adapters accordingly.

This one for example needs 55mm (but this value is often "start" value that you adjust based on your optics as these FF/FRs work with different scopes and each will have slightly different distance) between T2 thread and sensor.

Now you look up dedicated astro camera to work out rest of the spacing - for example:

In this case you would need ~48.5mm of distance with T2-T2 adapter (or rather just T2 extension tube - you can chain several of them, and there are even ones that are adjustable - which is very handy in situations like these).

https://www.teleskop-express.de/shop/product_info.php/info/p3732_Baader-VariLock-46---locakble-variable-T2-extension-29-46-mm--T2-part--25V-.html

5 hours ago, Trippelforge said:

Oh and why do they make some of them without grooves for safety reasons? 

No idea, but as a general rule - clamped connections should be avoided for astrophotography.

Threaded connections are much more secure and are much better at avoiding tilt.

One reason that grooves / undercuts are not popular might be precisely because of tilt issues.

Apply compression ring to undercut/groove and you can see how it can easily go out of whack.

[Trippelforge]

Thank you very much for laying that all out for me! 

[Oldfort]

You could also look at this from Televue:

https://televue.com/engine/TV3b_page.asp?id=71&Tab=_TRF

 

No problem with import duty as you are in the USA.