Need advise for extension tube SW80ED

[GiovanniAprea]

Hi all,

waiting for Jupiter to show up earlier and earlier I wanna get an extension tube for my SW80ED so I can try some prime focus photography either with a Nikon D800 through T adapter or with a DX sensor Fuji X-Trans sensor camera through T adapter and then Fuji to Nikon adapter (so I can do it all with the same T adapter I use to mount Nikon F bayonet on to the scope).

I read somewhere that to reach focus without diagonal it needs at least 4cm extension, what I need to know is, out of your knowledge, which is the required length to reach focus, which is the thread and where, in EU, I can buy one online.

Also, I would maybe also like to strengthen the tube lock, it seems quite loose with the two supplied screws, the D-SLR is quite a heavy setup, to make it stiffer do I have to change the whole focuser (something I was evaluating as to have micrometrical precision which the stock focuser doesn't really give) or can I just change the supplied ring with a better one?

Thank you so much

Giovanni

[Lonestar70]

Hi Giovanni, Welcome to SGL.

Assuming you are not using the Skywatcher field flattener/focal reducer then you will need an 80mm extension to reach focus using a Nikon camera on the ED80 when not using the diagonal.

I am not sure what parts you currently have, however, these are the parts I use on mine with a Nikon D90.

Camera T-ring adapter: -

http://www.firstlightoptics.com/adapters/t-rings.html

T-Mount adapter: -

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

Extension(80mm): -

https://www.harrisontelescopes.co.uk/cgi-bin/sh000001.pl?WD=extension%20tube%202%2080mm&PN=Revelation_80mm_Extension_Tube_2_.html#SID=627

Both companies will ship to Europe.

Alternatively you could mount the Skywatcher Field Flattener/Focal reducer for the ED80 directly to the focuser draw tube instead of the diagonal... then you would only need the special M48 camera t-ring adapter shown below: -

http://www.firstlightoptics.com/adapters/skywatcher-dslr-m48-ring-adapter.html

 http://www.firstlightoptics.com/reducersflatteners/skywatcher-85x-reducer-flattener-for-ed80.html

With these 2 components fitted you would not require any additional extensions and the special M48 t-ring adapter will give the correct backfocus for the Nikon camera.

I have had no trouble with the stock focuser on my ED80 when using the Nikon, so cannot comment or advise if you are having a problem with yours... perhaps another member can provide this for you.

I hope this helps.

Best regards.

Sandy.

[GiovanniAprea]

Hi Giovanni, Welcome to SGL.

Assuming you are not using the Skywatcher field flattener/focal reducer then you will need an 80mm extension to reach focus using a Nikon camera on the ED80 when not using the diagonal.

I am not sure what parts you currently have, however, these are the parts I use on mine with a Nikon D90.

Camera T-ring adapter: -

http://www.firstlightoptics.com/adapters/t-rings.html

T-Mount adapter: -

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

Extension(80mm): -

https://www.harrisontelescopes.co.uk/cgi-bin/sh000001.pl?WD=extension%20tube%202%2080mm&PN=Revelation_80mm_Extension_Tube_2_.html#SID=627

Both companies will ship to Europe.

Alternatively you could mount the Skywatcher Field Flattener/Focal reducer for the ED80 directly to the focuser draw tube instead of the diagonal... then you would only need the special M48 camera t-ring adapter shown below: -

http://www.firstlightoptics.com/adapters/skywatcher-dslr-m48-ring-adapter.html

 http://www.firstlightoptics.com/reducersflatteners/skywatcher-85x-reducer-flattener-for-ed80.html

With these 2 components fitted you would not require any additional extensions and the special M48 t-ring adapter will give the correct backfocus for the Nikon camera.

I have had no trouble with the stock focuser on my ED80 when using the Nikon, so cannot comment or advise if you are having a problem with yours... perhaps another member can provide this for you.

I hope this helps.

Best regards.

Sandy.

Hello Sandy,

first and foremost thank you for your detailed reply!

No, I don't have a field flattener, am a beginner, bought the scope to take my son and his classmates to observe the sky a few years ago and now would like to pick up again and to also attempt some photography through prime focus.

I already have a T ring to fit my Nikon camera to the scope and could use the same ring to mount the lighter Fuji on it through an adapter which allows to mount Nikon F bayonet on Fuji X one, so I am set with that and as far as it seems the first thing I have to get is the extension tube which you state having to be 80mm to supply the lack of diagonal to enable focusing, am I correct with this?

Also, the ring on the scope focuser is quite weak, I am wondering if there is a way to change it with a  sturdier and more secure one without to have to replace the whole focuser (something I have been thinking about but hard to justify the expense for the use I make of the scope).

Thank you again

[MattJenko]

I put a Baader 2.25 barlow in there for some planetary imaging and it looked like the image below. Prime focus will be much closer in.

[PeterCPC]

Have a look here http://stargazerslounge.com/topic/258370-sw80ed-ds-any-comments/

See post #11 in that thread re the holding ring.

Peter