baader coma mkiii

[Fieldsy]

Just spoke to the shop where I purchased coma for the correct placement.

Camera ,filter wheel, coma, scope.?

Camera ---------55mm------coma .

Is this right it makes sense and I have managed to achieve this .

Thanks

[teoria_del_big_bang]

That's what I was led to believe.

I have a MkIII as well. This is an extract for the VIP edition manual as I could not find reference to it in the MkIII manual (probably on line somewhere) but I am sure it is the same for both.

Steve

[Fieldsy]

1 hour ago, teoria_del_big_bang said:

That's what I was led to believe.

I have a MkIII as well. This is an extract for the VIP edition manual as I could not find reference to it in the MkIII manual (probably on line somewhere) but I am sure it is the same for both.

Steve

Well I've measured 55mm to the centre of the coma to the sensor, that pic looks like the start of the case of the coma to the sensor.think I will post pic with ruler on it .

Edited September 26, 2019 by Fieldsy

[teoria_del_big_bang]

I am fairly new to AP but I now have 2 different flatteners and this cc and they all have dimensions from the camera end of the flattener / corrector to the imagings plane. I cannot see the manufacturers giving dimensions from the centre. I just can't see how you would measure this to less than 1 mm.

Steve

[Fieldsy]

So the sensor site 12mm back from the tip of the camera nose (red)

[Adam J]

2 minutes ago, Fieldsy said:

Well I've measured 55mm to the centre of the coma to the sensor, that pic looks like the start of the case of the coma to the sensor.think I will post pic with ruler on it .

No its not the centre of the coma corrector is the rear mating surface of the coma corrector to the sensor. 

So: Sensor - 55mm - Coma corrector rear surface (the ring just after the T2 thread))

Not: Camera - 55mm - centre of the coma corrector. 

Hence you need to know the depth of the sensor within the camera from its mating surface, in your case thats 12.5mm 

Hence Camera = 12.5mm 

Male to male T2 converter - 2mm (assuming its the ZWO one) 

Filter wheel = 20mm 

That totals 34.5mm and so you need an additional 20.5mm of T2 spacers between the filter wheel and the back of the corrector. 

Adam

 

 

[Adam J]

4 minutes ago, Fieldsy said:

So the sensor site 12mm back from the tip of the camera nose (red)

No, see above, and its actually 12.5mm back. 

and you measure from the rear of the corrector not the centre. 

As shown in your image your spacing is currently 36mm assuming the ring that comes with the corrector is tight onto the corrector, if not then the measurement will be off. 

Adam

Edited September 26, 2019 by Adam J

[Fieldsy]

Just now, Adam J said:

No, see above, and its actually 12.5mm back. 

and you measure from the rear of the corrector not the centre. 

Adam

Cool makes it a bit easier to figure it out .only prob I have now is all my extenders are 1.25 not 2 inch lol.

[Adam J]

8 minutes ago, Fieldsy said:

Cool makes it a bit easier to figure it out .only prob I have now is all my extenders are 1.25 not 2 inch lol.

get one of these and stick it between the corrector and the wheel. 

https://www.firstlightoptics.com/zwo-accessories/zwo-m42-m42-extender-21mm.html

it will leave you 0.5mm too long but that is within tolerance.

Adam 

Edited September 26, 2019 by Adam J

[teoria_del_big_bang]

 

 

Edited September 26, 2019 by teoria_del_big_bang