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Filters with 350d, C8-N

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Hi all,

I know I've asked this before, but I thought I'd ask again :) - does anyone use filters on the above setup (350d on C8-N)?

The reason I ask is that I'd like to add a LPR filter and I'm trying to work out the most cost-effective way to do it. The cost of EOS clip filters makes my eyes water, so I'd rather avoid that if I can! :D

I currently attach my 350d to the t-adaptor that came with my C8-N (images a and b) This works well, and comes to focus easily (as you would expect).

When I was using a refractor, I used a 2" t-adaptor (image c) directly in the focuser tube with a 1 1/4" filter attached. Why isn't the focuser tube on the C8-N 2" diameter? It's just a little too wide...

I have the 2" eyepiece holder (image d) that came with the scope also, but the camera won't come to focus (not enough inward travel). I assume that I would have the same problem with a 1 1/4" t-adaptor in the standard 1 1/4" eyepiece holder also, as it looks like the same height as the 2" one.

Someone suggested ages ago that I could (and I think they have done it themselves) buy a 2" t-adaptor with filter threads, chop it in 2 and attach it inside the Celestron adaptor (a and b). The problem with this solution is I doubt my hacksaw skills would be uo to the job and it'll end up not being square on the end and causing all kinds of problems!

I would also need to buy 2" filters, which are obviously more expensive than 1 1/4" ones. I know 1 1/4" will probably introduce vignetting, but I can live with that (my imaging can't really be considered too serious anyway :p )

So, any suggestions? :clouds1: Surely someone else must have the same setup and have solved this... :clouds2:

Thanks in advance,






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HI Trev,

I learnt the hard way spending on cheap 1.25" then Decent 1.25" filters but if your using a DSLR that larger sensor really does cry out for 2" or better still the clip-ins if you want to avoid vignetting and get the best possible raw data to process..

You say your imaging isn't that serious and you could live with vignetting... trust me it becomes addictive once you start seeing what you can produce in that evenly lit circle in the full frame you want it edge to edge...

I know Steve (Steppenwolf) made some adaptors to optimally position 1.25" filters in the lightpath...


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I would look for the Orion 2" LPR filter. I bought one and it works perfectly, it's a bit cheaper at around £60 for a 2" version.

I also read somewhere (and now cannot find the refrence) that the response curve of the Orion is the same as the Astronomik filter (I think)

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Thanks for your responses, everyone. :D

Danny & Billy, I kind of know the EOS clip-in filters make the most sense, easiest to fit, no vignetting, etc - I just don't like the price! :p

Craig, the Orion is tempting (or even more so the SkyWatcher LPR - see Ant's recent post here)

The question remains, though, how to fit it in the light path? Is the only option to butcher a 2" t-adaptor and fit it inside my existing one? How easy is that to do? :)


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I have a 1 1/4" eyepiece adaptor, but no nosepiece. However, the eyepiece adaptor is the same length as the 2" one (image d), and since that doesn't come to focus, I'm guessing the 1 1/4" one won't either.


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