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Delos 17.3 filter thread


Andyb90

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Hi Everyone,

I had my new Delos 17.3 out last night and decided to attach my 0III filter.

The filter attached to the EP fine, but I was only able to give it a couple of turns in the thread. Is that normal?

Does the 17.3 just have a shallow thread?

The EP is brand new. I purchased it from TH.

I'll update the post with a picture of the thread end this evening.

Andy.

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I find my Lumicons don't fit any TeleVue  eyepieces, yet all my Baader filters fit them. I think there are three types of thread variety and only one is compatible with all three. I know Baader use a M28.5x0.6 thread. This seems to be virtually universally compatible. Not all diagonals have universal filter compatible threads either.

Celestron T-adaptor minus Barlow element.jpg

Every filter I own: Lumicon, Baader, Celestron and TeleVue fit this Celestron T-Adaptor. It's the only way I can make my filters compatible and I often use this in the diagonal. Although, in a Newtonian, it may cause back focus issues.

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23 minutes ago, Moonshane said:

I have three filters in my lunt wedge and all three screw together in any order but my baader SC will not screw onto my Delites, although my Polarising filter and ND3.0 will! weird.

Yeah, weird isn't the word. There doesn't seem to be any consistency to the incompatibility so we can actually deduce what the cause is. If it was some form of manufacturing deterioration due to factory cutting tools wearing, I think an incompatible filter would be difficult to thread onto anything. But I find that all of my filters happily thread onto something, it's just finding which ones fit what.

Also, I'm wary of having a loose fitting filter threaded into an eyepiece placed into a diagonal. It may damage the male or female threads and wouldn't seem secure to me.

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Here are some pics of the 17.3

The first shows the thread. There is a black inner ring at the end of he thread.

I'm wondering if it could be removed or if it's a permanent part of the EP.

The second pic shows my 0III filter attached, where you can see it does thread on but not all the way.

Andy.

delos173top.jpg

 

Delos173filter.jpg

 

Delos173topside.jpg

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Yes, that could be expensive. I think the only alternative with A Newtonian would be some sort of filter wheel. Luckily, all my filters thread onto my T-adaptor, so I can place that into the diagonal of my Mak's or SCT. It might work on a Newtonian but there could be back focus issues.

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10 hours ago, Moonshane said:

I tend to use 2" filters in the 2-1.25" adapter.

That might be a better option for me. I only really use my 0III and UHC filters so could just go for 2" ones. That would avoid having to fiddle about with screwing and unscrewing the filters.

I guess I could even get a couple of adapters and have a filtered and unfiltered one to swap in and out for different targets.

Andy.

 

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The filters most renowned for not threading on correctly are the Korean-made filters from Orion Telescopes in the US.

They do exactly what you described--thread in a couple turns and stop.

As for other brands, there are always +/- tolerances on filter threads and eyepieces.  You may have simply run into a + filter and a - eyepiece.

If you tried another filter of the same brand, it might be different.

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