Help evaluate my Newt!

[david_taurus83]

New-old territory for me. Like many others, I started off with a scope way to big to handle for a beginner getting into imaging! The venerable 200P. After downsizing a few years ago and going through a number of refractors I am back again with another 200P ready for galaxy season, hopefully! This time round I have made a few upgrades. 

Have cleaned (and scratched!) the mirrors

Have fitted a mask to the primary to cover the clips

Tube is fully flocked

Baader Steeltrack focuser

Collimated with an Ocal collimation camera

GPU coma corrector

DIY flocked dew shield

Managed a short first light last night for some testing. One good point is I simply took my imaging kit off my Esprit flattener and fitted straight to the GPU coma corrector and focus point for main camera and OAG remain the same.

See below test images. Single 60s sub, master flat, 20 x 60s stack and quick process up to non linear.

 

 

 

 

Apart from a couple of wobbly stars which may be improved with some tweaks to polar aligning and guiding, is there anything that jumps out to the experienced Light Bucketeers that says collimation issues or anything else?

The OAG shadow on the left is an issue but I'm reluctant to move the prism as its perfectly in focus and can crop out if concentrating on smaller targets. Any help or comments appreciated!

Edited January 31, 2023 by david_taurus83

[ONIKKINEN]

Looks like a working newtonian to me, dont touch anything and hope it stays like this.

Stars look maybe a little bit big, but this was probably the seeing or these are just bright stars (dont recognize the target) so probably nothing you can do anything about.

[david_taurus83]

1 hour ago, ONIKKINEN said:

Looks like a working newtonian to me, dont touch anything and hope it stays like this.

Stars look maybe a little bit big, but this was probably the seeing or these are just bright stars (dont recognize the target) so probably nothing you can do anything about.

Nothing to be improved? I suppose the true telling will be when I try a smaller fainter target.

Surely you recognise above?!

 

[ONIKKINEN]

3 hours ago, david_taurus83 said:

Nothing to be improved? I suppose the true telling will be when I try a smaller fainter target.

Surely you recognise above?!

 

Ah, looked a bit familiar but couldnt tell from where in the sky. Actually have had a chance to image anything in Orion only twice since 2020 because its so low in the sky at my latitude of 60N.

But in case you want to be thorough you could help yourself by measuring the fwhm of your unsaturated (small, background stars) stars. In decent seeing you should be getting close to 3" stars or below, in not so decent maybe towards 4". If you are urban and you have houses nearby messing the seeing then all bets are off on that.

The only thing you could adjust and maybe get an improvement is the backfocus of your CC, which is difficult to tell because the sensor in your 533 is so small the edge artifacts dont show up. In my APS-C sensor i noticed not only edge stars getting sharper but also on-axis stars with adjustments to backfocus distance. Star sizes indicate if its worth pursuing, probably not.

[bottletopburly]

Well your stars look better than my baader mk3 cc but my  collimatiion  may not be helpful, I’ve an Ocal on the way and I’ve reverted back to m42 thread as spacing on the m48 was doing my head in (using a 533mc, 200pds ) fitting an apeture mask over primary does help , but hopefully fingers crossed 🤞 I’m getting there slowly ,fitted a third Ota ring, fan and stronger springs, steeltrack, DSD autofocuser    , debating wether to fit an OAG which I may do at some point though need to be happy with cc and collimation first .

 Btw does your cc protrude into ota ?

Edited January 31, 2023 by bottletopburly

[david_taurus83]

38 minutes ago, bottletopburly said:

Well your stars look better than my baader mk3 cc but my  collimatiion  may not be helpful, I’ve an Ocal on the way and I’ve reverted back to m42 thread as spacing on the m48 was doing my head in (using a 533mc, 200pds ) fitting an apeture mask over primary does help , but hopefully fingers crossed 🤞 I’m getting there slowly ,fitted a third Ota ring, fan and stronger springs, steeltrack, DSD autofocuser    , debating wether to fit an OAG which I may do at some point though need to be happy with cc and collimation first .

 Btw does your cc protrude into ota ?

No, quite the opposite with the GPU. I have a normal 200P and I fully expected to have to drill the ota and move the cell up the tube. I was surprised to find the GPU moves the focus point out quite a bit. The Steeltrack is at focus at around 25mm out! 

It looks relatively clear here for a few hours hopefully so will maybe try a more demanding target and see how I get on.

[david_taurus83]

Wanted to try M51 or M63 the other night as they are the kind of targets I am hoping to do but they were way too low still so opted for M81 to test. I used the previous nights flats but they haven't worked. Can only assume a mirror has shifted slightly so I guess it will be flats every session as well. Guiding was poor as well but so was the seeing and transparency, had to throw out a handful of subs but most were OK. Star shapes look OK to the edges so I guess collimation isn't far off at all.