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WO FF IV on SW120ED


Jessun

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Hello all,

Did anyone manage to use the William Optics field flattener IV on a Skywatcher 120 ED? I hit the inward stop trying to get focus...

Maybe this is why WO APO's seem to have big draw tubes.... good and bad maybe but at least offers better range for "extras".

I got this on the note that it would fit most refractors...

Thanks!

/Jessun

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It is a tricky beast, especially with some of WO's own refractors. I have an FLT98 and have found the sweet spot in terms of setting (flattener lens to chip distance) needing to be within 0.5 mm in order to get good results!

If your scope doesn't focus, you could try an extension tube. It would be a cheap test and may fix it, and you don't have to try a bunch of other flatteners first.

Just watch out for the setting... My guess is that an extension tube goes between the flattener and the scope, not between the flattener and the camera...

All the best from foggy Saltsjöbaden :D

/per

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Thanks Per, fellow Swede...

I have a set of extension rings but I see focus gettig better and better retracting the draw tube into the scope and then I hit the stop before it's perfect... Really annoying...

/Jessun

PS lucky you to have a proper WO instead of this ol' SW!

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Well, there are refractors and there are refractors. Some cheap-o refractors turn out to be real gems, while others can be catagorized as "you get what you pay for". The reverse is true too. I started my refractor "career" by buying a WO Megrez 90. It had pinched optics straight out of the box and never worked. The optics were sent to Taiwan and back and there was abolutely no change. It ended with a return and a price reduction to an FLT-98.

Now, the 98 is good! It's a triplet and that is a fantastic optic design. I like it a lot but I miss the spikes of the Newtonian. But, then there is Star Spikes Pro 2, which adds the spikes selectively :icon_salut:

I will sell my Newtonian soon as I have a Celestron Edge 9.25 coming in a week or two. With a 0.61 focal reducer it will double for my Explorer 250P at almost the same focal length. At that point I have two really compact scopes that cover 500mm, 1400 mm and 2350 mm. What more can an old man wish for?

Going to miss the massive astro shopping, though :D

/per

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That's a very nice collection! I have been looking at WO but they are too expensive and there's so much to be done with my SW duo! The weekest link is me still when it comes to imaging which is what I enjoy most!

Cheers!

/Jessun

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