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Author Topic: Alan Gee Mark II Telecompressor  (Read 477 times)

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Offline Phalangium

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Alan Gee Mark II Telecompressor
« on: 11:41:23, 18 November, 2017 »
Does anyone have any experience imaging with a "Alan Gee Mark II Telecompressor"?

I am looking at a second-hand one that has been advertised, but looking at all the info online, they all require lots of bits and pieces between it and the camera and I am wondering how many, if any, are actually necessary.

The setup I would want to use is fairly simple: 200mm sct with telecompressor >> Celestron T-adapter #93633-A [50mm] >> Extension tube [15mm] >> {starlight express usb mini-filter wheel + ZWO ASI 1600} [54.5mm].

This would give me a total of 119.5mm. The info I have found online says it should be 121mm. Would I need to get a 1.5mm ring to make it up to that, or would 119.5 be close enough (I understand some reducers can be very touchy about distances).

And advice/info gratefully received.

Thanks for your help.

Offline chris.bailey

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Re: Alan Gee Mark II Telecompressor
« Reply #1 on: 11:47:56, 18 November, 2017 »
You need to add 1/3 of the thickness of a filter due to its own refraction so with 2mm filters thats a part of the 1.5mm you are missing. Threads often don't fully mate so you may find you are there when you actually measure everything.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Phalangium

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Re: Alan Gee Mark II Telecompressor
« Reply #2 on: 16:43:52, 18 November, 2017 »
Thanks, Chris.
I have some delrin rings, so could make up the extra 0.8mm if necessary.
But does that mean that, if I change from using a filter to using the empty slot, I would need to dismantle everything and add an extra ring?
Is this telecompressor that sensitive?
Thanks.

Offline chris.bailey

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Re: Alan Gee Mark II Telecompressor
« Reply #3 on: 17:43:01, 18 November, 2017 »
I don't know it per se but they can be quite sensitive to spacing though flatteners are more so.

If you switch from a filter to an empty slot, the two images will have slightly different focal lengths so you would need to account for that if you were stacking images from the two together.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

 

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