Jump to content


Flattner, reducer Sky Watcher 120/600m star startravel

Recommended Posts


I have recently put this together, i hear mentions of flattners and reducers, yes im a newbie and have no idea.

Do you think i will need one?


Can anyone recommend one?


Many thanks


Any comments appreciated.














Link to comment
Share on other sites

What are you intending to imagine? that is a planetary camera but the telescope is for widefield views, so quite a mismatch. In other words planets will be tiny but many of the popular deep sky objects won't fit in the field of view. If you haven't already looked it up go to Astronomy Tools website and look for the field of view calculator, select your equipment and choose a target to see how big or small it will be. I wouldn't at this stage buy any more equipment until you have a clear idea of what you want to see/image. Just a note that mounting the guide scope as shown will cause you all sorts of grief as it's just not rigid enough, at the very least swap the asiair and guide scope around.

Link to comment
Share on other sites

Hi yeah, my thinking was, (as I usually use my Nikon P1000 for the Moon) I would get the same as I got with my 130 Newtonian.

I was looking at the Mosaic feature of the Asiair Plus, The FOV is tighter on the moon so would get better results for each part of the mosaic?

Have I got this completely wrong lol, very new to this and the camera I picked up cheap.

Also want to look at DSO but not read enough yet.

The gudie is actually as sturdy as the dovetail as it's bottomed out, I'm looking to remove the pastic winder with just a small bolt and also remove the bottom end of the L bracket on the guide scope and mount at yellow arrow.





Link to comment
Share on other sites

For lunar imaging should be fine scale wise, and as you will be taking high frame rate videos to stack guiding won't really be an issue. Scale wise also ok for the smaller galaxies but not for the popular larger nebula or Andromeda for example. For DSO though the biggest issue could be tracking and guiding accuracy, depending on what mount you are using. At your pixel scale I would think you need to guide reliably well below 1 arcsec to not have elongated or trailed stars. 

Link to comment
Share on other sites

I have the smaller Startravel - the 102mm f5, (which I also use with an ASI224MC) and find it has significant chromatic aberration which shows up when imaging brighter stars.  (One can anticipate that the chromatic aberration will be worse with the larger ST120.) I use the ST102 for EVAA imaging of galaxies and star clusters and do not feel it is fit for much else.  With the small chip camera, no field flattener is necessary, and f5 is fast enough. 

TBH, the amount of pricey looking red kit you have attached to your ST120 would be better used with a small ED or APO refractor. A smaller aperture than 120mm, along with a DSLR or large chip astro camera would be more suited to deep space imaging. 

To image planets, a long focal length telescope, ASI224MC and a laptop would be sufficient. 

  • Like 1
Link to comment
Share on other sites

1 hour ago, Cosmic Geoff said:

(One can anticipate that the chromatic aberration will be worse with the larger ST120.) I use the ST102 for EVAA imaging of galaxies and star clusters and do not feel it is fit for much else.

Based on my visual experience with my KUO 152 f/5.9, I would think nebula would be ideal for these fast scopes.  I certainly can't see any chromatic aberration in the actual nebula.  Of course, there is a bit in the stars in and around them.  However, if you used narrow band filters and refocus for each, I would think they would largely suppress both chromatic and spherical aberrations.  Star colors might not be very natural, but perhaps software could be used to remove them?

Link to comment
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
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.