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Old 04-09-2012, 08:42 PM
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alpal
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Join Date: Jan 2012
Location: Melbourne
Posts: 3,612
Hi Guys,
Let's re-calculate more accurately:

CCD Back focus 15mm from CCD surface to M42/0.75 screw plane -
( that is from the camera manual.)


The distance from the glass output side of the coma corrector to the front face of the camera is about 65mm.
( I measured that & it's more than expected because of my TS9 OAG )
add 15mm for the sensor chip

64 + 15 = 79 mm

subtract the length required for the Baader MPCC

79 – 55 = 24mm = too far from the required 55mm

Removing the nose piece & using an adaptor would subtract the 12mm
nose length but add say 3mm for an adaptor so only gain 9mm.
therefore 24 - 9mm = 15 mm = still 15mm too long for the Baader MPCC.

So removing the nose piece still wouldn't work.
Apart from that I don't want to remove the nose piece.
The camera is a sealed chamber which is dried with desiccant to stop condensation.
( I know many people have done that because I have seen plenty
of optical trains where there is hardly any gap between the QHY9 camera & filter wheel. )

The RCC is one solution here:
http://www.teleskop-express.de/shop/...tsabstand.html

It says:

Quote:
Standard coma correctors only offer 55mm from their T2 threads -
just and only enough for a T2 ring and a SLR camera.

The RCC 1 offers, due to its triplet lens design, 91.5mm from its T2 thread



Anyway guys - I've ordered an RCC & I may have it before the weekend.
I'll let you know how it goes.
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