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NGC2174 (Monkey head nebula) in Ha

swag72

By swag72
in Imaging - Deep Sky

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swag72

swag72

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This was another test last night to see if I had finally nailed the problem I was having with my mount and guiding. I think that I can say that I won that battle (Makes a change in imaging) and I really have learnt a lot about balance, weight and guiding settings along the way.

I went for the Monkey Head as it started at 20 degrees above my horizon and probably about as low as I can get. Also being towards the South, this was an area that I had failed to guide in previously. This was about as hard a test as I could throw at the HEQ5.

I think that it passed the test, but please do judge for yourselves.

Details:

M: HEQ5

T: Pentax 75SDHF

C: Atik 460EX with Baader 7nm Ha filter

17x1200s Ha subs - No calibration files used at this stage.

post-5681-0-65372200-1355128330_thumb.jp

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swag72

swag72

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Thanks all - You made me go and look at the original sized tiff Martin and there's no oval stars there that I can see!!!

I was thinking of perhaps a narrowband on this one, although it really was just a test - I'll see how the weather goes. It's not looking good at the moment.

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swag72

swag72

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Thanks for looking guys and taking the time to comment. I don't think there'll be any OIII or SII soon as I have just received my Optec reducer and IF that works, it will be staying on forever!!!

More spacing tests to do - Hurrah!

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swag72

swag72

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Cheers Adrian - I've got the reducer now but unfortunately my spacing is about 5mm out at the moment. My concern is that I can not get focus, not enough inward travel, and not sure that 5mm will make that much difference.

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opticalpath

opticalpath

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Cheers Adrian - I've got the reducer now but unfortunately my spacing is about 5mm out at the moment. My concern is that I can not get focus, not enough inward travel, and not sure that 5mm will make that much difference.

How are you attaching the reducer to the Pentax, Sara? Any way to get the reducer further up inside the drawtube without compromising the spacing more?

Adrian

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swag72

swag72

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I'm using the adaptor that slides over the 2" barrel, holds on with grub screws, then fits into the focuser. The reducer has a 2" barrel, but the Optec adaptor to get me an M48 thread has a ring larger than 2", so the reducer is as far into the focuser as it will go.

I'm definitely not hopeful and think that it will soon be on it's way back to TS.

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opticalpath

opticalpath

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I'm using the adaptor that slides over the 2" barrel, holds on with grub screws, then fits into the focuser. The reducer has a 2" barrel, but the Optec adaptor to get me an M48 thread has a ring larger than 2", so the reducer is as far into the focuser as it will go.

I'm definitely not hopeful and think that it will soon be on it's way back to TS.

What a shame. Really frustrating to be defeated by a few millimetres!.

The field of the Pentax is so flat over a large circle that we really want a reducer that doesn't try to flatten the field any further. I often wondered if the bigger AP 27TVPH would be a good bet. The longer focal length should help with back-focus issues and the more conservative reduction and larger diameter optics would hopefully keep the field flat over a big area. But I'm not sure how it could easily be adapted to fit the Pentax focuser .... and it would be rather an expensive experiment.

Adrian

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davew

davew

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Being Japanese it's got a non standard visual back. I've just checked and it's 60mm or there abouts. TS do an adapter -

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p1627_Adapter-auf-2--fuer-den-Pentax-75-SDHF---ohne-optischen-Weg.html

Would that sort it ? You'll have to contact them pronto. Your " Loan period " will soon run out :)

Dave.

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swag72

swag72

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Dave, I *think* that I have this - Or something similar. It is a sleeve with 4 grub screws on it that inside accepts 2" barrels and then slots right into the focuser and is then tightened in the focuser.

My issue at the moment is that the Optec adaptor that gets to an M48 thread is larger than 2", so the focuser adaptor can not go over it and get it further into the drawtube - If that makes sense.

Still awaiting my adaptor that will give me the correct spacing, should be with me by the end of the week, but I'm not hopeful that I will be able to get focus with it. The sticking point seems to be this damn reducer / M48 adaptor.

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opticalpath

opticalpath

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Sara, I see what you mean. I thought that the flange on the Optec reducer might fit inside the Pentax drawtube, allowing you to push the whole reducer well forward. But I can see from your photo that it's just a bit too big a diameter to fit inside.

I've used two types of Pentax-to-2" adapters. The first was a rather crude split ring spacer; something like your sleeve adapter but without the set screws. It had a piece cut out of the cylinder so it was springy: a tight fit over a 2" fitting, then relied on the Pentax clamp screw to hold everything tightly - not very satisfactory. Then I got lucky and spotted this, at Scopenskies, I think. It was actually made for the Pentax and is a nice snug fit, with two clamp screws to hold the inserted 2" fitting. The narrow flange obviously prevents it from being fully inserted inside the draw tube, though, like your reducer.

Pentax_adapter.jpg

Hope you get a reply from that other contact.

Adrian

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