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EP Help On Mak 180


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Got my SW Skymax Pro 180 Mak a couple of days ago, been waiting for it since mid January. Been watching loads of stuff on it beforehand and decided to get the SW 2" dual Crayford focuser as per Dions video, didn't need the adaptor as it all comes with a 2" SCT thread on the visual back these days. It might be a 2" SCT thread, and they do supply a 2" diagonal, but the actual aperture is still 1.25"! Now I know it is a planetary/lunar scope and that's what I bought it for, but why put a 2" visual back on it if you only need a narrow field to do lunar/planetary and more to the point why increase it from 1.25" to 2" ? Second issue, when using an Explore Scientific 2" 24mm, 32mm & 40mm to see what happened I was getting an orange ring around the entire edge of the fov? The only 2" that didn't was the 18mm . so why make it 2" if it does this? Also tried the same eps with the original SW 2" visual back and they did the same? Can someone give me a heads up on why or is it simply that these 2" eps are simply too big for the smaller 1.25" visual back aperture and if so why supply a 2" diagonal?



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I've never understood why Synta have put a 2" visual back into some of their Mak's. I believe that even some of the 127mm Mak's now have a 2" back. 




Apparently most of the newer 127's, including mine, can be converted to a 2" back. I'm not sure what's caused the 'ring of fire' you're experiencing. Although I'd suspect that it may be due to vignetting in some way. I have the 2" ES 18mm and this EP has quite a small eye relief, regardless of what ES claim.




I originally bought it for my f/7.5 80mm Evostar but it is mainly used with my ST102. At f/4.9 it doesn't feel quite so claustrophobic and I don't need a compound eye to use it lol. The ring of fire is probably there with the ES 18mm on your 180 but you can't see it due to the 18mm's eye relief ergonomics.  I'm also pretty sure the 180mm and 127mm Mak's have internal baffles which also seems to make a 2" EP a bit redundant. My guess is that the 2" visual back/diagonal is some sort of Synta marketing strategy. It might be more stable for binoviewing. I suppose it gives you a choice between 2" and 1.25".  It's unlikely I'd change my 127mm Mak to a 2" back though. Like you, I see it predominantly as a lunar/planetary scope. 

Edited by Nightspore
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Thanks, yes does seem odd as the tube baffle inside is still only 1.25", luckily I have a set of Pentax-XL's which work nicely. Downside is I bought a Baader 2" diagonal for it but will now have to use that with the 1.25" adaptor in it.



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