coma adjustment

[spillage]

Evening All,

 

Really starting to over think this. I know there was a good thread on here regarding coma corrector set up but for the life of me I cannot find it.

I am sure I have collimation issue going on here but am sure I cannot need to add anymore spacing but I have it in my head that the image shows the cc is too close?? Any help really would be appreciated. I know this new toy would be harder than my dslr but really having issues.

 

Spill.

 

 

[spillage]

I have attached a close view of the problem. I have never used a dedicated camera before so the settings may be also making the problems look worse.

Having spent all day at work searching google and this forum I am still none the wiser, but I have ordered a set of t2 adapters to see if this helps.

[The-MathMog]

What Coma Corrector do you use? That might give insight in how much spacing the CC needs. Also what spacing do you have right now? That right there makes me think the CC is way too close to the camera, but it's not a topic I am very experienced in.

[spillage]

Hi @The-MathMog

It the baader mpcc111 and it should be 57.5mm.  Just getting really lost with which bits I need for it.

[Grimbles]

Hi

I have a 150pds (flocked) and use a modded 450d with Baader MPCC and I am fairly sure that with my T2 Eos adapter my spacing is 55mm.  I will be able to check tomorrow and get back to you ( I could be imagining things), but i did not need any other adapters. However looking at the image I am not certain that this is just coma, I flocked my pds myself and when I reassembled and tried to collimate found that I had some focuser tilt which was giving strange results, also I must have a little play somewhere as it can be a bit of a fiddle to get the camera to sit totally square in the focuser tube which again gives odd results.

Is this the star shape you get across the whole image or just at the edges and corners ? How does the colimation of the scope look visually without the coma corrector ?

Just a bit of food for thought for now but I will get back to you tomorrow with my spacing and if possible some images of the corrector to camera 'connection'.

Martin

[spillage]

Hi @Grimbles

This is a new upgrade from my dslr so I am in at the deep end. Trying to get the camera, filter wheel and corrector together was like being in the krypton factor but using my baader canon t2 adapter I think I may of cracked the 55mm/57.5mm (57.5 to the m48?) Anyway I have it very close so will have to wait for some clear skies. I also took the time to collimate and insulate the scope.

Spill.

[Adam J]

Spacing is a long way out to produce that effect. A picture of the camera on the scope is in order.

[Grimbles]

7 hours ago, spillage said:

Hi @Grimbles

This is a new upgrade from my dslr so I am in at the deep end. Trying to get the camera, filter wheel and corrector together was like being in the krypton factor but using my baader canon t2 adapter I think I may of cracked the 55mm/57.5mm (57.5 to the m48?) Anyway I have it very close so will have to wait for some clear skies. I also took the time to collimate and insulate the scope.

Spill.

Hi Spill

Sorry didn't realise you were using a filter wheel in the chain and at M48 which I believe you are correct with the 57.5mm also thought you were still using DSLR ( should have read the question properly ) .  Glad you seem to be nearly there, I would be very interested to hear how you get on and your final solution as I have been toying with the idea of a filter wheel for a Ha filter.  I have decided not to go down the clip filter route as I am sure at some point will also change to CCD imaging.

Martin

[alacant]

Hi. I don't think we'll be able to help unless you tell us what camera, telescope, cc and accessories you're using. Cheers.

[spillage]

I am going to wait until I can retest my spacing. Last night I ended up sat on the floor surrounded with bits all around me, but after an hour or two I think I may now be much closer.

asi1600mm-c baader mpcc111 (with the photo kit( and starlight sx wheel. I also have the baader canon t2 adapter.

I am sat at work cutting out some spacer should they be needed.

[alacant]

Hi. I calculate the spacer should be (37.5 - the thickness of the filter wheel)mm. HTH.

[spillage]

I have been measuring from the rear lip on the mpcc to the face of the camera then adding the 6.5mm for back focus.

[alacant]

1 hour ago, spillage said:

face of the camera

Hi. ...face? Not sure what you mean, but I thought the sensor was 17.5mm from the t2 thread. Rough estimate: the sensor on my mate's 1600 is buried about 2 cm into the camera body from the opening where the t2 threads start, so his figure of 17.5 seems right.

Sorry, I may have misunderstood. I'm translating as I don't own a 1600 myself but went through something similar as above a while back. HTH anyway.

[spillage]

I am going by this info that states 6.5mm back focus. Maybe I am doing something wrong. I then take into account that the width of my filter wheel is 29mm from adapter plate to adapter plate. Leaving 22mm  +/- 1mm