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Old 07-05-2015, 08:20 PM
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I have finally identified the source of flex and eradicated it...now I need to correct the spacing between CCD and the flattener (there is some field curvature in the corners), but otherwise everything seems to be going well. What a relief, it has been a long journey...

Out of curiosity, and to see how well will the CCD handle longer exposures, I tried a single 30-minute exposure through H-alpha filter. The resolution is 1.34 arc seconds per pixel, simple stretch only.

The result, I think, is not too bad

http://www.astrobin.com/full/178552/0/
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Last edited by Slawomir; 07-05-2015 at 09:20 PM.
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  #22  
Old 07-05-2015, 08:46 PM
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Excellent result, Slawomir!
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  #23  
Old 08-05-2015, 08:34 PM
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Excellent result, Slawomir!
Thank you Rick. I am really happy to be able to take longer subs now, in particular that it took me quite a lot of time to find the bug in the rig. 5-10 minute exposures were quite good with this camera and allowed me to compose a few exciting images, but now I am looking forward to stepping into pretty much unknown to me territory of 20-30 minute narrowband subs.
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Old 09-05-2015, 05:47 PM
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That's great Slawomir. Are you sure though you need a flattener with that small chip? A lot of scopes would not.

Flatteners are usually needed around APS sized sensors and up on a lot of scopes. That is 25mm x 16mm. The Sony sensor is only 13 x 10mm or so.

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Old 09-05-2015, 07:18 PM
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Thank you Greg.

You are probably right, such a small chip probably does not need flattener, nevertheles small pixels can highlight imperfections and there is some small curvature right in the corners; being aware of it does not allow me to rest until I eliminate it from my images
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Old 09-05-2015, 07:53 PM
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In the corners with the flattener? Have you tried without?
Spacing and correct adapter size is a bit of a pain and sometimes gets complicated by not enough backfocus.

I wouldn't mind one of these cameras. I think its a beauty.
Although if I end up getting an icx814 camera it'd probably be the Trius as I am all setup for the Trius.
The other camera which I think might be interesting is the Starlight Express H36 which is the KAI16070 sensor. On paper it
appears to be a more modern version of the venerable KAI11002.

Greg.
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Old 09-05-2015, 09:24 PM
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I am using a reducer/flattener, and CCD inspector is showing curvature in the corners with the CCD being about 4mm away from the optimal distance. I can live with that, but at the same time would be nice to have perfect stars to the corners.

Yes, one day I would like to be able to get a camera with a larger CCD, and 16070 definitely looks interesting. Also maybe in a few years we will be able to choose between CCD and CMOS cameras?
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Old 10-05-2015, 06:52 AM
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I am using a reducer/flattener, and CCD inspector is showing curvature in the corners with the CCD being about 4mm away from the optimal distance. I can live with that, but at the same time would be nice to have perfect stars to the corners.

Yes, one day I would like to be able to get a camera with a larger CCD, and 16070 definitely looks interesting. Also maybe in a few years we will be able to choose between CCD and CMOS cameras?
Oh I see. I don't think there is such a thing as a reducer/flattener. That's some false marketing hype. Its one or the other. Reducers do tend to elongate the stars in the corners if not at the right spacing and have a limited corrected field whereas flatteners are usually fairly tolerant.

Its like William Optics marketing their scopes as fluorite which is false. They use FPL53 glass which has a lot of fluorite in it yet the public understand that marketing as the lens is made from CaF2 which it is not. CaF2 has less scatter and a better refractive index.

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Old 10-05-2015, 08:52 AM
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Thank you Greg for clarifying that. It appears that there is always something new and interesting to learn. One thing is certain, my next telescope will have top quality glass, sturdy focuser, will give a reasonable FOV with my QSI 690 and will have a flattener built in...FSQ 85 looks very tempting...
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Old 10-05-2015, 09:52 AM
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Thank you Greg for clarifying that. It appears that there is always something new and interesting to learn. One thing is certain, my next telescope will have top quality glass, sturdy focuser, will give a reasonable FOV with my QSI 690 and will have a flattener built in...FSQ 85 looks very tempting...
Hmm FSQ85, I would pass on that one. Too many bad reports.
FSQ106ED is a proven performer as is the earlier model FSQ106N (the one with 2 fluorite lenses but limited backfocus and some vignetting in bright edge stars).

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Old 10-05-2015, 10:08 AM
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Hmm FSQ85, I would pass on that one. Too many bad reports.
That's interesting, I have not come across any bad reports on the net - will need to search deeper...
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Old 10-05-2015, 01:55 PM
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https://groups.yahoo.com/neo/groups/...messages/63260

Plus Louie on this site was posting at one point about difficulties with the FSQ85. I think the focuser is too weak and flexes. FSQ106ED's also have a number of internet complaints about focuser flex with heavy imaging trains. I had one that was fine but I read complaints quite frequently.
Tak changed a focuser support from Teflon to metal to help with that.

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Old 10-05-2015, 09:16 PM
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Thank you Greg again, but the link you provided is about FSQ106, not the BabyQ. Nevertheless, it is a bit of a worry when expensive telescopes that are designed for astroimaging have issues with flex...

So far all I could find in regards to problems with FSQ85 is that there were issues when people used a reducer, but otherwise everyone seems to be very happy with the scope. Anyway, I am not in a rush...
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Old 10-05-2015, 10:24 PM
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The Baby Q is a nickname for the FSQ85 so that post is referring to the FSQ85.

Also Louie Atlas was complaining about his FSQ85 a while ago (1 year or so ago). As I recall he had to pull apart the focuser and was dismayed at the quality of it.
There may be a thread about it that can be searched for here.

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Old 17-05-2015, 08:01 PM
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Thank you for the hint Greg. I was hoping that Baby Q would be a nice match for my QSi690 giving me a wider field and I believed Tak telescopes are of the rare type 'buy it and enjoy using it as is without needing to upgrade the focuser, rings, flattener etc'.

My current telescope gives me 1.34 arcsec per pixel with a reducer and 1.09 arcsec per pixel without, and it would be nice to have additionally a quality refractor with a built-in flattener that would allow for around 2.5 arcsec per pixel for a wider field.

FSQ106 with a reducer sounds very good (apart from the cost), but F3.6 might be a bit of a challenge, in particular that I need to use 3nm filters.

Maybe WO -Star 71mm would be a cheaper and perhaps a reasonable alternative?

Last edited by Slawomir; 17-05-2015 at 08:11 PM.
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Old 17-05-2015, 08:34 PM
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I don't think there is such a thing as a reducer/flattener. That's some false marketing hype. Its one or the other.
Astro-Physics documentation for their general purpose reducers says: "Finally, the 27TVPH and CCDT67 do not add any field curvature. In fact, they have a little bit of a flattening effect."

In this case I'm inclined to trust Roland though that doesn't necessarily translate to non A-P reducers.

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