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Old 23-07-2013, 06:42 PM
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LewisM
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Lrgb/nb noob

That'd be me

I bought today an older TEC and water cooled SBIG St8XE with the CFW-8 filter wheel off the trader. I am going to be purchasing a 1/25" LRGB set to go with it (undecided brand at this point in time), but was wondering...

I need to save a little money here, and the 1.25" H-a filters run $190 each. I already have a 2" H-a filter, so is there anything stupid about this proposition:
Finish LRGB with the 1.25" set (parfocals). When done, remove FW and install the 2" H-a filter directly to the nosepiece, refocus, and image that way (I also have already a 2" OIII, plus a 1.25" OIII).

Any issues with this and later integrating the H-a into the LRGB? Will there be any image scale shift doing it this way? Or should I stop being a cheapskate and just fork out for a 1.25" H-a
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Old 23-07-2013, 06:55 PM
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rogerco (Roger)
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I'm in the situation of having an 1.25 Ha filter but needing a 2" Ha are you interested in some sort of a swap?
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Old 23-07-2013, 07:27 PM
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Certainly nothing to stop you putting the 2" filters elsewhere in the light path. I have only 5 slots in my FW so often leave one slot blank and put the 2" NB filters on my 2" nosepiece. You're typically shooting hours (or even nights) worth of data so its not like you're flicking filters every few minutes with NB once you've focused.

I don't like doing it, but the other option is rotate to the L slot and put the 2" NB on the nosepiece - again as long as you focus then shoot with the same configuration.
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Old 23-07-2013, 07:49 PM
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LewisM
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Thanks Rob - exactly what I thought. Considering the H-a will be several nights worth, along with the OIII, I cannot see a general issue with it. Then just do the LRGB with the FW attached.

Roger, what brand of filter? I may be interested.
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Old 26-07-2013, 07:09 AM
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LewisM
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I ended up purchasing Astronomik filters. SHould be a wise choice I think.

LRGB, plus H-a. The OIII I have in Orion, so will have to refocus for that one. No drama.

Now to sell my unused 2" OIII
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