Skywatcher 80ED DSPro and Baader ClickLock

[joecoyle]

Hi

I am about to purchase a Skywatcher 80ED and reducer. I've been told that the .85x focal reducer requires 56mm of back focus. 

I've also been recommended the Baader ClickLock 2inch adapter (by a fellow SGLer) to ensure a more secure fit for the imaging train. 

If I use the Baader, does this alter the back focus of the reducer?

I'm guessing it goes like this:

Atik 414EX --- filterwheel fitted with the M54 adapter --- 7.5mm spacer --- Flo M48 to T adapter --- reducer (+ 2.5mm of delrins in between couplings) (56mm up to here) --- ClickLock

Thanks

Joe

[spaceboy]

Optical length is stated as 36mm on the clicklock so probably looking at around a 15-20mm increase over stock. I know there have been a few members struggled to get enough inward focus using clicklocks but as you want an increased back focus it should suit you just fine.

[joecoyle]

@spaceboy

Ok thanks, now comes the hard part... maths!

reducer back focus = 56mm
Clicklock = 36mm
Total back focus to be achieved  = 92mm? That seems a lot to me, but maybe...

I am never great at calculating these things...

Camera = 13mm
Filterwheel with m54 - m42 adapter fitted = 23mm
M48 to T thread adapter (for the reducer) = 10mm
  ------
= 46mm
  ------

so i need to make up another 46mm using extension tubes? (I actually have a baader varilock 46mm already if that will work!)

Thanks
Joe

[Ricochet]

Bearing in mind that I know nothing about AP or this combination or parts, isn't the 56mm back focus the required distance between the camera chip and the reducer? The reducer has a thread to screw directly onto the standard 80ED focuser so it makes little sense for Skywatcher to make this fixing if you have to source an M56 extension to fit between the two. Assuming that the value of 56mm and your camera/filterwheel/t-thread measurements adding up to 46mm are right then I think you want an extra 10mm spacer between the camera and reducer.

Secondly, if the reducer screws directly onto the focuser, do you need the clicklock? If the optical path of the clicklock is 37mm and the FLO adapter to use the reducer in the adaptor adds another 3mm that means you will need to wind the focuser in 40mm compared to screwing the reducer directly onto the focuser. Does the focuser have that amount of additional infocus?

This picture shows the reducer fitted to the ED80, but using the original 2" eyepiece clamp and the FLO reducer adaptor. I don't know how long the light path of the original clamp is to tell if there is enough room to fit a clicklock there instead (assuming the picture shows the drawtube extension at focus). This is the SGL Thread the image was posted on, you might want to have a look through it in case anything there is useful. (I haven't read it, just googled for a picture of the reducer fitted to the back of the ED80.)

 

[andyo]

Hi

if you are screwing the reducer directly onto the ed80 focuser then the clicklock is not required.I believe the distance from the camrea sensor to the reducers focal plane is 55mm.Then

camera and filter wheel is 35mm

you then need 20mm which would include the 10mm m48 screwthread on the back of the reducer.

I would contact john  (Flo have his email address or you could pm me and i will give you his contact details) make a custom adaptor M54 male to M48 x0.75 female with 10mm screwthread.Total length 20mm.

John made me one of these adaptors not long back and did a great job at a very competitive price about £50-£60.

Then one adaptor is all that is needed

 

[andyo]

On 02/05/2017 at 19:26, joecoyle said:

Hi

I am about to purchase a Skywatcher 80ED and reducer. I've been told that the .85x focal reducer requires 56mm of back focus. 

I've also been recommended the Baader ClickLock 2inch adapter (by a fellow SGLer) to ensure a more secure fit for the imaging train. 

If I use the Baader, does this alter the back focus of the reducer?

I'm guessing it goes like this:

Atik 414EX --- filterwheel fitted with the M54 adapter --- 7.5mm spacer --- Flo M48 to T adapter --- reducer (+ 2.5mm of delrins in between couplings) (56mm up to here) --- ClickLock

Thanks

Joe

Hi Joe,

I have attached the specs for a modified adapter that will give you the right spacing for the reducer to filter wheel and shows the baffle at the back (if using 1.25" filters) this will prevent reflection artefacts. I am fairly sure the m48 female thread is x 0.75 but would double check. 

[andyo]

No problem don't mention it pleased to have been a help or was I !!!!!  

[joecoyle]

Thanks Andy. Apologies for the late reply. FLO have said that I won't need the click lock apparently so I'll give it a shot without. Otherwise I'll investigate a custom adapter. 

 

Joe