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Wiu-Wiu

C11 Edge test - raw and Dirty :/

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I seem not to be able to get my CCDT67 telecompressor (reducer) working on my C11 edge, as I keep getting coma and elongated stars to the corners. 

So last night I took it out and boldly set off to guiding off axis on the native 2800mm focal length. 

 

Mount used was my CEM 60, guiding and imaging software through the ASIAIR. Imaging camera: asi 071 - 2x2 binning.

NO darks, flats, bias,... just stacking in APP. 

NO filters, as it was just a test, moon was just over first quarter and I live in Bortle 6. 

200 frames were used (30s each so total integration time to a round 100 minutes) 

m81test.jpg.f71c5ea642b02c78df7fc312fb3aff38.jpg

I think guiding and sharpness went pretty well, although I might add an extra autofocuser if I keep using this setup. 

Very pleased of the result, although STUNNED to see that much dirt in my optical train :(

The bunnies might be on the camera sensor window (although I cleaned the outside that day, I think they must be on the inside), the dark spots appear to be ON the sensor 😤

 

Any advice on cleaning this? Before I start opening up the camera... (Camera is new, 4 to 5 months old)

 

Other feedback is also VERY welcome! 

 

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Everyone on this site will tell you you're wasting your time imaging at 2800mm........... 🙂

Nice image.

Michael 

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That’s got lots of potential. Nice one. 

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Thank you! 

 

I noticed the black spots are in the same place as some dark spots in another picture, with the same camera, on another scope. I am afraid it might be frost. 

Anyone any advice on what to do? 

1541195260_triplet60minasi071mcCEM60skywatcher254-1200ddl.thumb.jpg.64d4f710331910d892fca8664bb38ded.jpg

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On 14/05/2019 at 22:26, michael8554 said:

Everyone on this site will tell you you're wasting your time imaging at 2800mm........... 🙂

Nice image.

Michael 

Nope, I like imaging at 2800mm. It’s great for small targets like galaxies and planetary nebula 😀

I wouldn’t worry too much about the dust bunnies, I’ve seen much worse. Flat fielding will take care of it.

Not sure what the dark spots are. 

Cheers, Ian

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Posted (edited)
On 14/05/2019 at 23:26, michael8554 said:

Everyone on this site will tell you you're wasting your time imaging at 2800mm........... 🙂

Nice image.

Michael 

I don't think they would. The real issue is not FL but image scale. These pixels, binned, give an effective pixel size of 9.56 microns so at a FL of 2800mm the image scale is 0.7 arcsecs per pixel. This is optimistic in that it is unlikely to be fully supported by the seeing, but it is far from being a waste of time. Yves Van den Broek and I imaged for two years at slightly less than that, about 0.66"PP from memory. Currently I shoot this kind of target at 0.9"PP using a 1M FL and much smaller pixels. I don't find that there's much to choose between the two approaches. The key factor, though, is image scale. I think members would rightly advise against trying to use an inappropriate camera (one with pixels which are too small and can't be binned) at 2.8 metres. For example an unbinnable DSLR might be working at about 0.3"PP and this would be a waste of time because there is no possibility of resolving at that scale and all the long FL is doing is greatly cropping your field of view.

This is a very good advertisement for the CEM 60!

Olly

Edited by ollypenrice
Clarification.
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Hello Olly; thanks for your comment! 

I chose my camera mainly to image on my 127mm ED apo; the Edge came in after that. I DO like imaging smaller objects, but this range (fl/chip size) is beyond my comfort zone, I admit. 

Seeing that night was extraordinary for Belgian weather, so that picture is 50% of our excellent nights for this year right there. 

 

I am eyeballing a 120 Esprit to replace the 127mm (Better quality glass) - and was hoping to keep the camera going on that one; and the odd planetary on the C11. 

Would you have chosen another camera? (take in mind I have to keep it transportable, and do not want a laptop in the field; Asiair takes care of that - so camera had to be supported)

 

 

As for the spots: It looks like it is frost, forming on irregularities on the sensor. I will clean the sensor as advised by ZWO, and regenerate/replace the desiccant pills. I'll try to store the camera away from moisture and hope to be able to get any remaining spots out with post-processing. 

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10 minutes ago, Wiu-Wiu said:

Hello Olly; thanks for your comment! 

Would you have chosen another camera? (take in mind I have to keep it transportable, and do not want a laptop in the field; Asiair takes care of that - so camera had to be supported)

 

No, I think it's a very workable compromise. The image is good.

Olly

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On 14/05/2019 at 21:20, Wiu-Wiu said:

The bunnies might be on the camera sensor window (although I cleaned the outside that day, I think they must be on the inside), the dark spots appear to be ON the sensor 😤

Any advice on cleaning this? Before I start opening up the camera... (Camera is new, 4 to 5 months old)

To work out where the dust is you could try CCDware's dust donut calculator https://www.ccdware.com/resources/dust.cfm

Otherwise, a nice image under difficult circumstances. It's good to see some long FL shots here.

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Nice image!

Regarding your reducer: For Celestron EdgeHD and Meade ACF, a reducer that is also a flattener will not work since those scopes already have flat fields. In that case the flattener function will create a curved field. However, you probably know this and I though maybe the CCDT67 was one of those that do not flatten the field. I know the Celestron original reducer for your scope is quite expensive but a relatively inexpensive reducer that is suposed to work is Optec Lepus 0.62x. However, the FOW of that one (and the CCDT67) is quite a bit smaller than the original Celestron reducers.

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The ccdt67 doesn't flatten the field and is very well made.  The main problem I have found is a little  image tilt due to the weight of the extended optical train.

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Really quite good and shows that my local seeing is typically bad. Sigh, as I like to try some smaller targets and was considering maybe a edge 11 at some point.

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15 minutes ago, MartinB said:

The ccdt67 doesn't flatten the field and is very well made.  The main problem I have found is a little  image tilt due to the weight of the extended optical train.

Used on my Meade SCT  the APTCCDT67 fits inside the autofocuser so doesn't add to the imaging train length, I get nice round stars in to corners but I'm only using an Atik 314L so not sure how much of the available FOV I'm utilizing.

Dave

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6 hours ago, ollypenrice said:

Everyone on this site will tell you you're wasting your time imaging at 2800mm........... 🙂

Nice image.

Michael 

I regularly image at 2800mm using a deforked CPC1100 Edge.  I mount it on an Takahashi EM200 mount which works a treat.  As you say, it is good for very small targets.  But I don't use a reducer - crazy price.  I do however, use a large pixel camera - Atik 4000, and I always bin 2x2 (and even 3x3 sometimes for RGB).  This gives a tad over 1"PP which is about the max for my sky.  My only complaint is that the stars always look a bit bloated.

Chris

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1 hour ago, Davey-T said:

Used on my Meade SCT  the APTCCDT67 fits inside the autofocuser so doesn't add to the imaging train length, I get nice round stars in to corners but I'm only using an Atik 314L so not sure how much of the available FOV I'm utilizing.

Dave

You need the spacing between the reducer and the camera chip.  Because it isn't a flattener you can vary the spacing.  The recommended for the specified  reduction is 85mm.  Obviously you normally arrange things so that your filter wheel, OAG  and any other stuff fit in the space but even then you often have to use spacers.  In my case with my 10" LX200 I usually use an AO unit with OAG and a QSI with built in filter wheel but still have to add to the distance.  

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Regarding the spots, they are just dust bunnies on your chip, Nothing to be too anxious about.  They are images crying out for flats!

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1 hour ago, MartinB said:

In my case with my 10" LX200 I usually use an AO unit with OAG and a QSI with built in filter wheel but still have to add to the distance.  

Same scope with Atik EFW2, Atik OAG and Atik314L works out about right and the CCDT67 fits inside the micro focuser.

Lucas out in Poland is using a similar setup.

Might get around to plate solving an image sometime to check statistics :grin:

Dave

APCCDT67-2.png.a25cc8cb1712c5dee4251b9f14fbfb7e.png

 

 

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Ccdt67 image inspection if the “best” image I reached with it. 

6BE471FE-1517-4B6C-858E-FB4984B1830C.png.97e69ae3fb1dfa4a6cfad75b4b7629e5.png

Image train:

D2D1163E-3E40-468E-A5FA-27D6355965CC.thumb.jpeg.2081fcb3fd973e5c8c175ff173c46c11.jpeg

 

I feel it might be the precise location of the telecompressor into the 2” fitting that is off. I tried to reach about 1 - 1.5mm on the inside of the fitting, as seen on the internet, but still no round stars in the corners. (Nor in the guidescope of the OAG)

 

I don’t like the fact it varies too much, depending the placing. I rather like reducers that are screw-on or that have stopping rings. 

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