ED80 DS-Pro and ASI533

[Mike Read]

Hello,

I've just the ASI533 camera (previous was a Canon DSLR) and want to know how best to connect it to the ED80. I have it currently connected to the camera via the 2" focus extension T adapter, however I suspect this might be not the best option as the ZWO site talks about backfocus of 55mm - Does this apply although I dont have a reducer?? Any help would be appreciated for a newbie.

[geeklee]

1 hour ago, Mike Read said:

I've just the ASI533 camera (previous was a Canon DSLR) and want to know how best to connect it to the ED80. I have it currently connected to the camera via the 2" focus extension T adapter, however I suspect this might be not the best option as the ZWO site talks about backfocus of 55mm - Does this apply although I dont have a reducer?? Any help would be appreciated for a newbie.

Hi Mike - I think what you've done sounds fine - if you've got the camera -> adapter -> 2" tube of 80ED.  Just need to get the adapter length suitable for enough focus extension.  Fire it up and test it out 🙂

If you don't have a reducer with a back focus requirement, then - as far as I know - the back focus explanations for 55mm on ZWO site are not applicable.

 

[Gina]

1 minute ago, geeklee said:

If you don't have a reducer with a back focus requirement, then - as far as I know - the back focus explanations for 55mm on ZWO site are not applicable.

Correct.

[Mike Read]

Thanks Both.

[Adam J]

2 hours ago, Mike Read said:

Hello,

I've just the ASI533 camera (previous was a Canon DSLR) and want to know how best to connect it to the ED80. I have it currently connected to the camera via the 2" focus extension T adapter, however I suspect this might be not the best option as the ZWO site talks about backfocus of 55mm - Does this apply although I dont have a reducer?? Any help would be appreciated for a newbie.

Everything you will need, in terms of adapters for a 55mm back focus comes in the box with the camera. You will not need to buy anything.

[Mike Read]

21 minutes ago, Adam J said:

Everything you will need, in terms of adapters for a 55mm back focus comes in the box with the camera. You will not need to buy anything.

There’s the problem and the reason I asked. I couldn’t see how to get the camera connected to the scope without the 2” (70mm length) adapter. 

[Adam J]

5 minutes ago, Mike Read said:

There’s the problem and the reason I asked. I couldn’t see how to get the camera connected to the scope without the 2” (70mm length) adapter. 

I see, you will almost inevitably want a flatterer / reducer in the near future for imaging.

[Lonestar70]

17 hours ago, Mike Read said:

There’s the problem and the reason I asked. I couldn’t see how to get the camera connected to the scope without the 2” (70mm length) adapter. 

Hi Mike,

The ED80 focal length includes the optical length of the 90 degree diagonal.

If you remove the diagonal, to attach a camera to the focuser draw tube, then you will need to use the extension to replace the optical distance originally provided by the diagonal and connect your camera to the extension... otherwise you will not have enough outward travel on the scopes focuser to reach focus.

If you, eventually, obtain a focal reducer/field flattener then the extension will not be required since the focal reducer/field flattener does the same job, however this is where the 55mm back focus distance comes into play.

The reducer/field flattener requires that the camera sensor is located at 55mm from the rear flat face of the reducer/field flattener (this is an optical distance imposed by the construction/design of the reducer/field flattener) which will entail the need for a short extension of approx 38.5mm total length (assuming your cameras back focus is 6.5mm).

Some of this 38.5mm could be provided by the optical path length of a filter mechanism (should you fit one) with only a small amount of extra extension required to make up any difference... but that is for the future.

I hope this helps you to understand what is required and why.

Good luck and clear skies.

[Mike Read]

5 hours ago, Lonestar70 said:

Hi Mike,

The ED80 focal length includes the optical length of the 90 degree diagonal.

If you remove the diagonal, to attach a camera to the focuser draw tube, then you will need to use the extension to replace the optical distance originally provided by the diagonal and connect your camera to the extension... otherwise you will not have enough outward travel on the scopes focuser to reach focus.

If you, eventually, obtain a focal reducer/field flattener then the extension will not be required since the focal reducer/field flattener does the same job, however this is where the 55mm back focus distance comes into play.

The reducer/field flattener requires that the camera sensor is located at 55mm from the rear flat face of the reducer/field flattener (this is an optical distance imposed by the construction/design of the reducer/field flattener) which will entail the need for a short extension of approx 38.5mm total length (assuming your cameras back focus is 6.5mm).

Some of this 38.5mm could be provided by the optical path length of a filter mechanism (should you fit one) with only a small amount of extra extension required to make up any difference... but that is for the future.

I hope this helps you to understand what is required and why.

Good luck and clear skies.

Thanks, just need some clear nights to give it another try. So much to try and learn about this hobby ... in a few hrs of cloud free nights.

[2STAR]

On 15/02/2020 at 20:15, Adam J said:

I see, you will almost inevitably want a flatterer / reducer in the near future for imaging.

Vignetting should not be a problem with the 533 sq chip size and 80ed from what I have read so a Flattener is not required.

eric

[Adam J]

24 minutes ago, 2STAR said:

Vignetting should not be a problem with the 533 sq chip size and 80ed from what I have read so a Flattener is not required.

eric

Flattners dont correct vignetting, they correct for field curvature. Apart from that imaging at F7.5 is also not so great.

[2STAR]

17 minutes ago, Adam J said:

Flattners dont correct vignetting, they correct for field curvature. Apart from that imaging at F7.5 is also not so great.

My mistake , it reduces halation, I have obviously been given some duff information

regards

eric

[Shimrod]

On 16/02/2020 at 19:47, Mike Read said:

Thanks, just need some clear nights to give it another try. So much to try and learn about this hobby ... in a few hrs of cloud free nights.

Hi Mike, how are you getting on with this? I've just got the same camera to go with my 80ed and like you I don't have a reducer (I had the skywatcher one on order, but cancelled it for now). What length extension tube did you have to add to get focus without the reducer? I've been thinking of getting the Altair lightwave reducer to see how that performs in the meantime - are you still using the camera without a reducer or did you find that you needed one?

 

thanks

[Lonestar70]

Hi Shimrod and Mike,

You will need to have a 2" dia extension of between 55 -65 mm optical length to compensate for the removal of the diagonal.

This should achieve focus with the 533 at around the halfway point of the outward focuser travel.

The focal point of the ED80 is approx 110mm from the outer face of the focuser draw tube without the diagonal fitted, and with the focuser fully retracted.

Hope this helps.

Good luck and clear sky's.

 

[Shimrod]

11 hours ago, Lonestar70 said:

Hi Shimrod and Mike,

You will need to have a 2" dia extension of between 55 -65 mm optical length to compensate for the removal of the diagonal.

This should achieve focus with the 533 at around the halfway point of the outward focuser travel.

The focal point of the ED80 is approx 110mm from the outer face of the focuser draw tube without the diagonal fitted, and with the focuser fully retracted.

Hope this helps.

Good luck and clear sky's.

 

Thanks for this - I had a brief check last night to confirm the camera was working but couldn't get a focus on anything out the window (although changing patterns of colour) so I know the camera is working ok.  I was some way off 110mm - I'll have to see what I can cannibalise to see if I can reach that. I might just order the lightwave reducer anyway if I don't have enough extension tubes - FLO have said the SW reducer won't be available until at least mid-October.

[Mike Read]

On 11/09/2020 at 22:34, Shimrod said:

Hi Mike, how are you getting on with this? I've just got the same camera to go with my 80ed and like you I don't have a reducer (I had the skywatcher one on order, but cancelled it for now). What length extension tube did you have to add to get focus without the reducer? I've been thinking of getting the Altair lightwave reducer to see how that performs in the meantime - are you still using the camera without a reducer or did you find that you needed one?

 

thanks

Hi Shimrod,  I purchased the Skywatcher reducer, and totally love it. As mentioned, everything is in the box to get back focus. Everything is crisp to the edge.

[Shimrod]

1 hour ago, Mike Read said:

Hi Shimrod,  I purchased the Skywatcher reducer, and totally love it. As mentioned, everything is in the box to get back focus. Everything is crisp to the edge.

Hi Mike,

I bought the lightwave reducer and also a couple of extension tubes from Altair. I can now get focus with the reducer (using the standard 55mm extension tubes) and without the reducer using an extra couple of extension tubes. What's most frustrating is I have had only two clear nights since buying the camera!

[Mike Read]

On 22/11/2020 at 14:20, Shimrod said:

Hi Mike,

I bought the lightwave reducer and also a couple of extension tubes from Altair. I can now get focus with the reducer (using the standard 55mm extension tubes) and without the reducer using an extra couple of extension tubes. What's most frustrating is I have had only two clear nights since buying the camera!

LOL - Its everyone buying kit in lockdown. I'm considering a pier for my EQ6R to speed my setup times...

 

[Craig a]

3 hours ago, Mike Read said:

LOL - Its everyone buying kit in lockdown. I'm considering a pier for my EQ6R to speed my setup times...

 

I did the same thing, and everything is kept on the pier, the scope and all the cables the only thing I take inside is my camera, I have the 533 also, I cover my setup with a telegizmos 365 cover and it’s excellent it’s really well made it’s been through some quite severe storms with bucket loads of rain and everything it’s kept nice and dry although I do take the cover off for a couple of hours on nice days to give everything an airing, but so far it’s performed flawlessly 

[Mike Read]

11 hours ago, Craig a said:

I did the same thing, and everything is kept on the pier, the scope and all the cables the only thing I take inside is my camera, I have the 533 also, I cover my setup with a telegizmos 365 cover and it’s excellent it’s really well made it’s been through some quite severe storms with bucket loads of rain and everything it’s kept nice and dry although I do take the cover off for a couple of hours on nice days to give everything an airing, but so far it’s performed flawlessly 

I know we are going off topic...but... would be great to see some pictures? and which pier?

[Craig a]

I use this 

https://www.bristolcameras.co.uk/p-skywatcher-pillar-tripod-support-for-eq6-mount.htm

so it’s semi permanent the bolts on the end screw down to level it and lift it off it’s wheels once the mount head and scope is on it weighs a ton, I’ve had no problems of it moving upto 100mph winds, I will post a picture of it with its cover on when I get chance, this pier is black in the link but they are now white 

Edited November 24, 2020 by Craig a

[Mike Read]

1 hour ago, Craig a said:

I use this 

https://www.bristolcameras.co.uk/p-skywatcher-pillar-tripod-support-for-eq6-mount.htm

so it’s semi permanent the bolts on the end screw down to level it and lift it off it’s wheels once the mount head and scope is on it weighs a ton, I’ve had no problems of it moving upto 100mph winds, I will post a picture of it with its cover on when I get chance, this pier is black in the link but they are now white 

Thanks Craig