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William Optics Adjustable Flat6A III 0.8x Reducer / Flattener


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As a follow on from my Field Flattener/Reducer post, I now have the above optic, and very nicely made it is too.

The Flattener is adjustable, and has a numeric adjustment scale on the barrel.

WO publish a set of adjustment settings for some of their telescopes, but that's as far as it goes. There is no indication as to what the numbers represent.

After an extensive trawl of the internet, I found a post on an American forum, where it was quoted that the numbers represent distances in mm, from the rear element to the rear shoulder of the flattener. For example, a setting on the scale of 5, represents a pre-set back focus of 5 mm.

Therefore, if this is true, then with my 115 and 294c camera, the back focus setup would be as follow.

Required back focus distance = 55mm (pretty much standard).

Front of camera to its sensor is 17.5mm, leaving 37.5mm of spacing to find.

A  20mm + 15mm spacer gives me 35mm, leaving another 2.5mm to find.

If the  numbers on the flattener do represent mm distances in mm from the rear element to the rear shoulder , then a setting of 2.5 on the scale, should give me the required 55mm of required back focus distance, with a bit of "wiggle room" either side.

Well that is the theory anyway, and a live test will prove or disprove it.

It would be nice had WO explained just what the numbers on the scale represent.

From my searches, it seems to be a question asked many times, but one that could be simply answered by WO informing the customer as to what the numbers represent. Maybe I'm thinking too logically 😉

 

Edited by centroid
Typo
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Would you believe it 🙄. The WO flattener/reducer arrived very promptly from FLO,  and the rarity of a clear sky forecast for tonight. I now  realise that I should have ordered an  M48 to M42 adapter to go with it , which I have now ordered.

Ah well, the next clear night then, whenever that will be.

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I had the 6AII and with the adjustment screwed all the way in to the shoulder, that's where 55mm starts from. So with your camera and individual spacers get you to 52.5, then yes, you would use the adjusting ring to screw out to 2.5mm.

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It seems that I'm really not meant to use this flattener 🙄

Having received the flattener, promptly from FLO, I found that I needed an M48 to M42 adapter to attach the camera, so I ordered one from FL, which again came very promptly.

This morning I went to fit the flattener to the scope, only to find that the focuser tube has a female M68 thread, and not the more usual M63.  The flattener is M63 male.

So I need an M68 male to M63 female adapter. Not a common adapter, whereas the reverse gender is.

It looks like it is a TS Optics item, and quite expensive for what it is too, but needs must I guess, and unfortunately, not a FLO stock item.

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40 minutes ago, centroid said:

It seems that I'm really not meant to use this flattener 🙄

Having received the flattener, promptly from FLO, I found that I needed an M48 to M42 adapter to attach the camera, so I ordered one from FL, which again came very promptly.

This morning I went to fit the flattener to the scope, only to find that the focuser tube has a female M68 thread, and not the more usual M63.  The flattener is M63 male.

So I need an M68 male to M63 female adapter. Not a common adapter, whereas the reverse gender is.

It looks like it is a TS Optics item, and quite expensive for what it is too, but needs must I guess, and unfortunately, not a FLO stock item.

Check first if the last element on the focuser is not screwed. It might be an M63 -> M68 conversion. If you remove it, then you get an M63 and you can insert directly your reducer.

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1 hour ago, alexbb said:

Check first if the last element on the focuser is not screwed. It might be an M63 -> M68 conversion. If you remove it, then you get an M63 and you can insert directly your reducer.

No its definitely a fixed M68 attachment Alex. 

The M68 male to M63 female, is a bit of an oddity, and quite uncommon. M68 female to M63 male is readily available.

It seems the only option is from TS Optics in Germany:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p6692_TS-Optics-M68-System-Adapter-von-M68-auf-M63---Riccardi-Anschlussadapter.html

No stock anywhere in the UK, and although FLO offered to order one in from TS, in the interest of expedience, I have ordered direct from TS.

I'll get there in the end 😅

 

Edited by centroid
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4 hours ago, centroid said:

No its definitely a fixed M68 attachment Alex. 

The M68 male to M63 female, is a bit of an oddity, and quite uncommon. M68 female to M63 male is readily available.

It seems the only option is from TS Optics in Germany:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p6692_TS-Optics-M68-System-Adapter-von-M68-auf-M63---Riccardi-Anschlussadapter.html

No stock anywhere in the UK, and although FLO offered to order one in from TS, in the interest of expedience, I have ordered direct from TS.

I'll get there in the end 😅

 

The TS Photoline 102 ED doublet has a 2.5" focuser ending with an M63 female which is then converted to M68. I wasn't aware of that so I bought the adapter too that you shared above, without actually needing it.

 

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I have been using the WO Flat73R Variant and it is a very fiddly. The back focus I need is 56.8mm according to the WO brochure. So 2.4mm additional

If you get tight corners, Please post up pictures of barrel distance measurement. 

Edited by Skyline
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I use a 1x Hotech flattener (which in fact can be used for any scope between f/5 and f/8) on my William Optics 81 GT IV and have been happy with it - although it isn't a reducer (so focal length is the native 478 mm).

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6 minutes ago, Skyline said:

I have been using the WO73R Variant and it is a very fiddly. The back focus I need is 56.8mm according to the WO brochure. So 2.4mm additional

If you get tight corners, Please post up pictures of barrel distance measurement. 

The "calculated" distance setting on the flattener, taking into account the added width of the M68 to M63 adapter will introduce, is a theoretical l.5mm.

Until the adapter arrives from Germany, any experimenting will have to wait, then of course the need of a clear night.

If I get it working, I will post a picture for you.

I will also feed back my findings to FLO, as requested.

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7 hours ago, The Admiral said:

I got mine from 365 Astronomy when I attached my WO flatener to my Altair Astro scope. Here: https://www.365astronomy.com/ts-optics-m68-system-adapter-from-m68-to-m63-riccardi-connection-adapter?search=m68 adapter

Ian

I could have done that, but he didn't have it in stock,  nor did anyone else in the UK.

As such, I ordered it direct from TS optics in Germany, snd it will be here via UPS, on Tuesday.

 

 

 

 

 

 

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8 hours ago, iantaylor2uk said:

I use a 1x Hotech flattener (which in fact can be used for any scope between f/5 and f/8) on my William Optics 81 GT IV and have been happy with it - although it isn't a reducer (so focal length is the native 478 mm).

Hmm interesting, I'm using the Flat6AIII on mine but often think about a touch more focal length....

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Anybody have a list of scopes that the 6AIII is suitable for?

I have the GT71, would like to know if it fits any 90mm or thereabouts scopes..

 

 

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19 hours ago, iantaylor2uk said:

I use a 1x Hotech flattener (which in fact can be used for any scope between f/5 and f/8) on my William Optics 81 GT IV and have been happy with it - although it isn't a reducer (so focal length is the native 478 mm).

Hi Ian

What image circle do you get with the Hotech? I'm interested in how it would work with an APS-C sensor (field flatness and edge artifacts..) as I have a GT71 and the extra FL gives me some options..

Could also use it with an ASI533MC I suppose when I get round to getting one, the smaller square sensor will be pretty forgiving I think

 

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4 minutes ago, 900SL said:

Apologies my mistake.. I have the 6AIII and the GT71, just wondered if I could use it on a longer scope. Looks like the GT81 and ZS103 from the link

ah ok, understood and yes I have it on my GT81.

Edited by scotty38
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20 hours ago, iantaylor2uk said:

I use a 1x Hotech flattener (which in fact can be used for any scope between f/5 and f/8) on my William Optics 81 GT IV and have been happy with it - although it isn't a reducer (so focal length is the native 478 mm).

I read from other people's comment - the hotech is very good!

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34 minutes ago, 900SL said:

Hi Ian

What image circle do you get with the Hotech? I'm interested in how it would work with an APS-C sensor (field flatness and edge artifacts..) as I have a GT71 and the extra FL gives me some options..

Could also use it with an ASI533MC I suppose when I get round to getting one, the smaller square sensor will be pretty forgiving I think

 

I use my WO 81 GT IV scope with 1x Hotech flattener with an APS-C camera (a ZWO 071) and it is pretty flat right out to the edges - you can play with the spacing to get it right but I use a spacing of 55 mm from sensor to shoulder of flattener. Some photos taken with this combination can be seen on my blog. The recent one of the Rosette nebula was good, although this has been cropped down a bit.

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5 minutes ago, iantaylor2uk said:

I use my WO 81 GT IV scope with 1x Hotech flattener with an APS-C camera (a ZWO 071) and it is pretty flat right out to the edges - you can play with the spacing to get it right but I use a spacing of 55 mm from sensor to shoulder of flattener. Some photos taken with this combination can be seen on my blog. The recent one of the Rosette nebula was good, although this has been cropped down a bit.

How do you find the connection to the GT81? I assume it does not use the 63mm screw thread to attach to the rotator so does the rotator still work ok once the Hotech is fitted?

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It just pushes in and then you rotate the adjuster on the flattener which forces the three rubber bands onto the inside of the tube, and acts as a self centring mechanism when it is properly tightened. There is a video on YouTube, I'll see if I can find the link

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1 hour ago, scotty38 said:

How do you find the connection to the GT81? I assume it does not use the 63mm screw thread to attach to the rotator so does the rotator still work ok once the Hotech is fitted?

The rotator still works with the flattener attached

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