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Old 17-10-2014, 08:40 PM
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sungrazer (Karen)
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Dmk21au for a qsi683wsg

Hi
Does anyone know what the back focus of a dmk21 au is - I've tried to find it everywhere but can't find anything

I've put it on the qsi but can't seem to get focus - what am I missing
Cheers karen
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Old 18-10-2014, 02:37 PM
SteveInNZ
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The camera is a C mount and it comes with a CS mount adapter.
Like the T-mount, the mount type defines the distance from the flange to the sensor.
The C-mount is 17.526mm and with the adapter ring (CS-mount) it is 12.5mm.

Steve.
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Old 18-10-2014, 05:30 PM
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Hi Steve thanks
The qsi is specified for 12.5 mm, the spacer for the DMK will now go back on and tonight i will try again.

cheers
Karen


Quote:
Originally Posted by SteveInNZ View Post
The camera is a C mount and it comes with a CS mount adapter.
Like the T-mount, the mount type defines the distance from the flange to the sensor.
The C-mount is 17.526mm and with the adapter ring (CS-mount) it is 12.5mm.

Steve.
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Old 19-10-2014, 04:40 PM
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phd graph for drift align

Hi All,

I got focus without the spacer- or as close to it as I could.

Here is the phd drift align graph for a 10inch lx200 with a QSI683 on the back and the DMK21AU04

its a shocker. I know it looks like its not polar aligned too but over a period it is quite close to the pole and only small movements on the meade wedge either way influence the direction of the trendline. With the way the graph jumps around I'm not sure i could get it any better.

I really don't know what to make of this - of course the guiding is turned off so what is causing the star to jump around so much - i don't know - balance is OK I think - heavy to the east and heavy camera end.

Settings:
I checked the settings - pixels are 5.6 and focal length of the scope is 2500 in PHD.

Any ideas?.

The second graph is one I have taken with guiding ON as orion was rising. It looks better but is still swinging around wildly too. the 5 minute subs of orion are unusable and obviously show each star moving around.


cheers
Karen
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Last edited by sungrazer; 19-10-2014 at 05:06 PM.
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Old 14-12-2014, 06:40 PM
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dmk21 with QSI683 on Lx200 settings

Hi Everyone,

here is an update.

I managed to get the DMK working on the QSI683wsg, so they are both shooting through the 10' Lx200.

I had to fiddle quite a bit to get focus on the DMK through the QSI but in the end i persisted and got there.

Basically the set up is an LX200 - with the QSI and the DMK on the top of the QSI, so no extra weight and no extra guidescope -the LX200 is the guide scope as well.

After much fiddling with pempro I have the scope guiding much better and this is last nights graph (with PHD2 settings for anyone interested). This is probably the most useful piece of information.

It still gives teardrop shaped stars for a 5 minute sub though which I don't understand. I would have thought this PhD graph looked pretty good. Any opinions welcome. What can i do now to get round stars?

I'm going to refine the pempro pec again and hope to get something better but this PhD graph looks quite good at about 6arcseconds peak to peak.

All suggestions welcome.
cheers
Karen
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Old 14-12-2014, 08:00 PM
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Remember that you are imaging at 0.45 arc seconds per pixel, this means that if your guiding is smearing your RA by 6 arc seconds that will show as trailing over 12 pixels! I would be binning the camera to try to get your oversampling down.
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Old 14-12-2014, 09:29 PM
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Quote:
Originally Posted by Peter.M View Post
Remember that you are imaging at 0.45 arc seconds per pixel, this means that if your guiding is smearing your RA by 6 arc seconds that will show as trailing over 12 pixels! I would be binning the camera to try to get your oversampling down.
hi peter thanks for the advice

Are you suggesting the lights as well as R g b in 2x binning - and should I also bin 2x the dmk???

Thanks
Karen
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