120 ED and reducer threads

[Granada]

Hi, I'm confused about what adapters/rings/etc to look for to link my Skywatcher 120 ED with a focal reducer and a Canon DSLR. I've attached a few photos to show what I've already got in hope someone can tell me what I'm missing.


Starting with the first photo containing the entire setup, from left to right is the OTA (http://www.skywatcher.com/product/bk-120ed-otaw/), followed by the focal reducer (http://www.skywatcher.com/product/focal-reducer-120ed/), followed by Bintel's 2" camera adapter and lastly Bintel's Canon EOS T-ring. I assume I don't need the camera adapter, but a M48-M42 step down ring, correct? That just leaves me with something to couple the OTA with the reducer...



Many thanks

[Granada]

By the way, I've just realised that if I spin the reducer the other way around, so that the male part is facing the camera adapter, and the female part is facing the OTA, I can get the 2" adapter to work just fine without any step down rings.

[brisen]

You should be able to unscrew the end off the focuser tube - the bit with the thumbscrews unscrews and should be the same thread as the reducer which will screw on. Turn it around to the opposite of how you have it in the photo. Does the 2" to T2 then screw onto the end of the reducer? If not you will need to get the step down from the reducer to the 2" to T2. I have an ED 120 but not with the reducer - so cant check the size. I assume also that you will need to get the spacing correct for the back focus distance which for Canon is 55mm to the sensor.

Brian

[Granada]

That seems to have done the trick. I didn't even think about unscrewing the end of the focuser tube :lol:





Yep, it does





Yeah that's why I wasn't sure if the camera adapter is adequate for this purpose. Might need to do some experimenting...

[Outcast]

If you are shooting with a Canon, your T2 adaptor screwed directly to the flattener should get you exceptionally close to the 55mm sensor spacing...

Might just need a slight tweak here or there to get it spot on...

[Granada]

Yep that's what I'm planning to do: OTA -> focuser -> T2 adapter -> EOS T-ring -> DSLR

[Outcast]

Sorry, I misspoke.. t ring should get you pretty close on its own... from memory, sensor depth on a Canon with nothing fitted is around 52mm..

[Outcast]

Bugger...

I have t adapter on the brain.. I meant T ring.. I've edited the previous post...

For example: I only use a t-adapter of 50mm when I am using a focal reducer & require 105mm of back focus... If using my flattener or coma corrector (dependant on scope being used) I only connect to my T-ring (m42 thread)... that's for my Canon 70d..

If I use my ZWO I need to factor in an additional 43mm as the sensor depth on that camera is only 12mm.. hope that makes more sense...

[Granada]

Oh ok I see. My t-ring isn't compatible with the focuser, so I'll probably need to buy a M48-M42 step down ring then. Hopefully that'll be just about right in terms of focus

[Outcast]

You can, I believe, get a t ring that has an m48 thread... but, yes, a step down ring may work..

[kon1966]

Hi,
Had a custom adapter made by Josh for my ed80. I wanted a 2 inch adapter where I could screw a filter on permanently then screw on a celestron f6.3 reducer and then screw on my canon eos. Look at my link below for pics and the thread and hope ithelps

http://www.iceinspace.com.au/forum/attachment.php?attachmentid=249061

Regards
Kon