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Focal Reducer /Field Flattener for explore scientific 102mm triplet FCD 100 refractor

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#1 astroboyabdi

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Posted 09 December 2019 - 12:02 AM

Hi All

I am new member but have lurking and reading for some time.

I am having trouble finding a FF/FR to work and focus with my scope (it’s actually a Saxon branded one but for all intents and purposes it is identical to the Es 102mm triplet with FCD 100 glass.

The astroshop that I bought my stuff when I first got my gear a year ago ordered this ES 0.7 FF/Fr which was supposed to work. It’s a giant piece of glass designed for 3 inch tubes but via a series of adapters it connects to a two inch focuser tube and m42 thread to the dslr.

However after a year of trying I haven’t been able to take a single picture with it that is in focus.

I can take pictures without it via my DsLr at prime focus and that works (after some extension tubes) but with it none.

So I figured that it must not be designed for this F/7 despite what I was told.

So after research on a few forums it seems that this actually doesn’t work for this scope. Then I’m left with finding a replacement.

The problem is most threads then do not conclude what they actually ended up using and whether it worked.

I know the Trevor for AstroBackyard has or had essentially the same scope but similar just this one uses the newer fcd100 glass. Altair Lightwave 0.8X Reducer/Flattener Is the combo he uses.

It’s hard to find that here in Western Australia and I want to make sure I have the right one before I order and wait a few weeks and it still doesn’t work.

I have seen a few options the
1) stellarvue 2inch 0.8 ff/fr designed for
There f/7 refractors at 714mm seems to be suitable
2) skywatcher 0.85x ff/fr might be ok and a similar one from Orion

And apart from that I’m stumped.

So can anyone kindly suggest something that would work well with this scope and the necessary adapters if any to connect the thing to a 2inch focuser tube. I have the t ring for Nikon which I use a d7000 on . I can connect to m48 or m/42 with an tiny adapter and it works well and I get exactly 55mm back focus to image plane.

It’s very frustrating I’ve tried all sorts of extension tubes all the from none to 18cm to no avail.

Edited by astroboyabdi, 09 December 2019 - 06:50 AM.


#2 B 26354

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Posted 09 December 2019 - 01:57 AM

A couple of months ago I e-mailed Vic at Stellarvue with this same question, regarding eventually getting an SV SFFR102-25 2" 0.8X Flattener/Reducer for my ES 102CF (the older, Hoya FCD1 version), because I  knew of two C-N members who had had great success with the SFFR102-25 on their ES ED102 FCD100 Series refractors. He assured me that it would work perfectly with my own 102CF.

 

Due to other expenditures, I have not yet purchased the SV SFFR102-25, so I'm not able to address your "correct adapter" issue. However... knowing that the SFFR102-25 will definitely work with your ES ED102 FCD100... if I were you, I would e-mail SV directly, and ask exactly which adapters would be needed for your Nikon.

 

Stellarvue's technical support and customer service, by the way, are second to none. waytogo.gif


Edited by B 26354, 09 December 2019 - 01:58 AM.


#3 astroboyabdi

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Posted 09 December 2019 - 02:07 AM

Thanks for replying.

That is very helpful. I’ll contact them and in the meantime purchase it and will update this thread with some further information whether it had worked or not for other fellow users looking for a conclusive thread

Many thanks

#4 joshman

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Posted 09 December 2019 - 05:29 AM

Hey mate, have the same Saxon scope, also have tried the Saxon 3" hunk if glass they call a "flattener." biggest waste of money, but make s a shiny paperweight!

I went with a Hotech brand, 2" SCA flattener. It works perfectly, and maintains the full focal length of 714 mm.

#5 astroboyabdi

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Posted 09 December 2019 - 06:47 AM

Ah.... I’m not the only one .

I’ll look Into that flattener , seems like a good idea for maintaining FL.

Have you used a reducer at all? Sometimes I want to frame M42 but can’t quiet manage it properly, a reducer would work like a charm if I could find one lol

I emailed the guys at Stellarvue and will await a response.

Thanks for the help

Edited by astroboyabdi, 09 December 2019 - 06:48 AM.


#6 Hondo

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Posted 09 December 2019 - 07:10 AM

I have seen a few options the
1) stellarvue 2inch 0.8 ff/fr designed for
There f/7 refractors at 714mm seems to be suitable
 

Yes, that will work.  I have an older Essentials version of the ES 102ED and that is the one I use, works a treat.



#7 ks__observer

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Posted 09 December 2019 - 07:16 AM

I have an ES102 FCD and ES tech guided me to the SV .8x FR.



#8 astroboyabdi

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Posted 09 December 2019 - 09:45 AM

Thanks everyone for the pointers.

Just a question which one is it

1) https://www.stellarv...user-sffr102-2/

Or

2) https://www.stellarv...r-sv102-access/

Based on the replies it seems the second one.

But my focuser is 2inch and ideally I want to thread it on to the end of the draw tube after removing the compression ring (on mine it unscrews).

Will the 2) allow threading onto end of draw tube for a solid connection. The description suggests it slots into ie fits into compression ring and secured with screws. Or can anyone suggest otherwise. Also number has more options for use later down the track with 2.5 inch focusers.

Basically I want to be able to thread it on end of draw tube.

Regards

#9 astroboyabdi

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Posted 09 December 2019 - 09:59 AM

Actually never mind I’m an idiot it’s a 2.5 inch focuser. All good.
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#10 ccard

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Posted 09 December 2019 - 03:32 PM

I just purchased a 54 female to 48 male adapter from Agena Astro.. is was a Blue Fireball

https://agenaastro.c...ter-m-02.html  

 

I eliminated my compression ring and made hard contact from my 102 to FR to Camera...sweet!



#11 B 26354

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Posted 09 December 2019 - 07:12 PM

That link doesn't work. Is this it?

 

https://agenaastro.c...apter-m-02.html



#12 astroboyabdi

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Posted 02 January 2020 - 07:27 AM

So for completeness sake.

I purchased the Stellarvue ff/fr listed below and can achieve fine focus with it.

I also purchased a 9mm m54 extension tube and with that attached I have to rack out focuser to 9mm on the scale on the tube. Probably could do away with the extension but then I won’t have any wiggle room.

https://www.stellarv...r-sv102-access/

I also purchased m54 female to m48 male adapter from cyclopsoptics.

The ff/fr came in with adapter for 2.5 inch focuser but it didn’t match up to mine as although my scope is advertised as 2.5 inch focuser, the adapter certainly didn’t screw on to the end of the focuser tube.

But the adapter unscrews and then it’s just a m48 female ring.

Whole setup is connected via threaded connections.

Thanks everyone for the help!
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