Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_constellations.thumb.jpg.6034fe99df7fe590f77a776877551964.jpg

FLO

Sky-Watcher Evostar 72ED DS-Pro

Recommended Posts

I think SW need to go back to the drawing board and produce a dedicated reducer for the scope. 

Someone call me lazy if you wish...

Edited by Skyline

Share this post


Link to post
Share on other sites

I have a suspicion that they are always made to require at least a small spacer to allow for variations in camera sensor distances.

Coma correctors don't seem to need similar adjustment so I'm guessing they are less critical as they work in a different way.

Edited by Stub Mandrel

Share this post


Link to post
Share on other sites

Has anyone tried this with a 1:1 flattner (no reduction) will that allow more back focus? If so which one did you use. I can live with F5.8.

This is shoddy from SW. 

Adam

 

Share this post


Link to post
Share on other sites
14 hours ago, Adam J said:

Has anyone tried this with a 1:1 flattner (no reduction) will that allow more back focus? If so which one did you use. I can live with F5.8.

This is shoddy from SW. 

Adam

 

I have some results with the OVL field flattener. I only added a few mm to the flattener-sensor distance so about 57mm and I was left with enough focus travel.

 

Share this post


Link to post
Share on other sites
1 hour ago, moise212 said:

I have some results with the OVL field flattener. I only added a few mm to the flattener-sensor distance so about 57mm and I was left with enough focus travel.

Agreed.  I tried all sorts of spacing and testing with both, and for me the OVL one works better over all.

Share this post


Link to post
Share on other sites

One more thing: with the OVL flattener I measured the FL to be ~430mm and with the "dedicated" flattener, ~377mm. These were with the extra-spacers I used. With the OVL I had the backfocus at ~57mm and with the SW one it was at ~60mm.

Share this post


Link to post
Share on other sites

I'm still yet to get around to buying my first refractor. 

As the ED72 has been out for a few months now, I have a couple of questions...

Firstly, will it hold the weight of my Canon 80D DSLR? It's an APS-C DSLR and weighs a bit more than a Canon 700D but not more than a 7D Mk2.

Secondly, how easy is it to achieve a good reliable performance. Ideally I would want a refractor which I can just plug things into and it works, because I come from a photography background where you just pop a lens on and away you go, so spacing, and measuring, and back focus distance is all alien to me. Would it be easy enough for me to achieve, if someone would be so kind as to tell me what I need and give clear instructions as to how to go about fitting everything together.

Or 3) Would it be too much hassle and would I be better off buying a refractor like say, a Z73 and just buying the flattener for that and everything works straight away?

That's where I am at, any help or advice would be greatly appreciated.

Share this post


Link to post
Share on other sites
3 hours ago, smr said:

I'm still yet to get around to buying my first refractor. 

As the ED72 has been out for a few months now, I have a couple of questions...

Firstly, will it hold the weight of my Canon 80D DSLR? It's an APS-C DSLR and weighs a bit more than a Canon 700D but not more than a 7D Mk2.

Secondly, how easy is it to achieve a good reliable performance. Ideally I would want a refractor which I can just plug things into and it works, because I come from a photography background where you just pop a lens on and away you go, so spacing, and measuring, and back focus distance is all alien to me. Would it be easy enough for me to achieve, if someone would be so kind as to tell me what I need and give clear instructions as to how to go about fitting everything together.

Or 3) Would it be too much hassle and would I be better off buying a refractor like say, a Z73 and just buying the flattener for that and everything works straight away?

That's where I am at, any help or advice would be greatly appreciated.

 

Let´s go little by little.

1st Weight: I own a QHY168C cooled its weight is 700 grams aprox. plus the weight of the flattener-reducer and spacers I guess the total weight for the imaging trains could be around 1kg. At least I haven´t seen tilt or slip on the focuser.

2º As the QHY168C sensor is an APS-C from Nikon, I would recommend you the TS x0.79 reducer flattener in order to achieve focus. For a usual DSLR the distance from the M42 thread from the flattener to the sensor use to be 55mm, but with the TS reducer and this scope of 420mm focal length you will need 65mm. So the math is the following

Focuser + TS reducer + Extensors +M42 to Canon Bayonet (like this https://www.teleskop-express.de/shop/product_info.php/info/p194_TS-Optics-T2-Adaptor-for-CANON-EOS-Cameras.html)

The problem is that in TS page they do not specify the thickness of the M42 to Canon adapter, something important you need in order to achieve a perfect field with any refractor.

A list of M42 (T2) extensors with different thicknesses are available.

https://www.firstlightoptics.com/adapters/baader-t2-extension-12-16mm.html

https://www.firstlightoptics.com/adapters/t2-extension-tube-set.html

You should ask FLO or TS or any other dealer to get the data

Edited by Susaron

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×

Important Information

By using this site, you agree to our Terms of Use.