Jump to content

Narrowband

SW 200PDS for TS-PHOTON 6” f/4


Recommended Posts

Hi all, 

I have the chance to swap my brand new Sky-Watcher 200PDS for an also brand TS-PHOTON 6” f/4 (metal version). The motivation is that imaging with a 600D at 1000mm of FL might be a bit oversampling (0,89”/px). Also appropriate if jumping to an astro-dedicated cam (ASI294MM and  ASI2600MC in the bullseye). 
I would like to know your thoughts about this idea, and gather any opinion about the TS-PHOTON series (equivalent to the SW Explorers?). 
Thank you very much in advance for your comments.

Link to comment
Share on other sites

I think it is a good scope - but not sure if it will be that good with APS-C and Full frame sensors. I would personally use it as wide field instrument for imaging with 4/3 sensor and suitable coma corrector (GPU CC for example).

One thing that I really like about F/4 version is that it has longer tube than other F/4 newtonians - which is good.

What I don't like is gap around primary mirror. It is good for cool down but care needs to be taken when imaging and taking darks - as there is great potential for light leak.

  • Thanks 1
Link to comment
Share on other sites

1 hour ago, barbulo said:

Thank you very much @vlaiv 

How do you know APSC size is tight? Would it cause vignetting? 
I have a Baader MPCC MkIII which I hope do the job. 
I hope the primary mirror leaks can be tackled with some covering. 

I don't know for sure.

What I do know is that I've seen images taken with that scope and GPU CC and ASI1600 and I had no objection to correction of the field.

I usually have objection to stars on images taken with fast newtonian scopes. Rarely are stars tight and without distortion over the whole field.

When I look at spot diagrams - they rarely represent anything close to diffraction limited optics.

Have a look at this comparison of performances of coma correctors:

https://www.astrofotoblog.eu/?p=856

Do note that camera used has Kaf8300 sensor - which is 22.5mm diagonal sensor - so 4/3 format and look at corner stars. Telescope used is F/4 10" newtonian.

  • Thanks 1
Link to comment
Share on other sites

Thank you @vlaiv

I took some lights with the MPCC and the result was this:

M13_PS.thumb.jpg.c7e323618d0087dc55c1e08d2a54b867.jpg

This was a test, so I didn't take any flats or bias, the integration time was <1hr and only quickly stretched the result. 

The field seems to be somewhat corrected, but still there is an evident coma effect in the upper left corner. Could it be related to a deficient collimation or it's the CC?

Edited by barbulo
Link to comment
Share on other sites

30 minutes ago, barbulo said:

The field seems to be somewhat corrected, but still there is an evident coma effect in the upper left corner. Could it be related to a deficient collimation or it's the CC?

My first impression was that your collimation is not very good.

If you look at your image, stars somewhere right and below globular are the most round ones. Opposite corner to that shows most coma / elongation.

I would first collimate the scope without CC to get round stars in center of the FOV and equal amount of coma in the corners (so that image is symmetric) and after I would work on CC spacing to get best correction.

  • Like 1
  • Thanks 1
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
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • 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.