Eastern Veil - Ha - Test of Chroma 3nm Filter

[gnomus]

I finally managed to get my dual rig working thanks primarily to @Patrick Gilliland.  This meant I could try out the Chroma 3nm filter in my Moravian G2-8300 camera attached to my Williams Optics Star 71.  Mount is the Mesu 200.  The target is the Eastern Veil.  This is 19 x 1200s (= 6 hours 20 mins) - processed primarily in PI. 

[nucdoc]

Wow very nice !

I imaged the same target, with the same scope, but using an Astronomic 6nm filter, you have way more detail, and only 1 hour more imaging than me, that filter makes a big difference.

 

[Dark Horizon]

Crikey!!!  Now that's detailed!!  Very nice work, well done.

 

[Maximidius]

That's a corker with incredible detail....I just checked the price of the filter and fell off my chair lol. 

[gnomus]

52 minutes ago, Maximidius said:

That's a corker with incredible detail....I just checked the price of the filter and fell off my chair lol. 

It's worse than you think - prices are even higher than those shown due to Sterling devaluation.  And the problem is ... now i need to get an OIII.  

[swag72]

That's looking good Steve - Interesting to see the Chroma filter in action....... What issues did you have with the dual and how did you sort them? I can PM if you'd rather not clutter up this specific thread with the answers  

[ChrisLX200]

56 minutes ago, gnomus said:

It's worse than you think - prices are even higher than those shown due to Sterling devaluation.  And the problem is ... now i need to get an OIII.  

Be thankful you don't need the 50x50mm square versions to be found in my Moravian G4-16000! They are good filters though, no trace of halo with the 3nM OIII

ChrisH

[gnomus]

1 minute ago, swag72 said:

That's looking good Steve - Interesting to see the Chroma filter in action....... What issues did you have with the dual and how did you sort them? I can PM if you'd rather not clutter up this specific thread with the answers  

I don't mind a bit of clutter.  I was trying to have a small scope and a large scope sitting in a dual bar - large scope (Esprit 120) on the left and small (WO Star 71) on the right (as you looked from the camera end).   I did this for convenience - I could switch between scopes without having to tear one down and set the new one up.  Guiding is done via an OAG on the Esprit.

What I was finding was that the results from the Esprit (at 0.9" per pixel) were consistently good - whereas those from the WO Star 71 (3.2" per pixel) were highly variable.  Sometimes I got a good result - sometimes I got significant trailing.  I assumed I must have something moving somewhere on the WO side and spent ages trying various things (I won't bore you with all the details).   But in conversation with Paddy I came to the realization that, whilst the Esprit and WO 71 were balanced, their optical centres were different distances from the midline of the mount.   The Esprit (being much heavier) ended up much nearer the midline of the mount than the WO Star 71.  I think this means that a small movement of the Esprit when a guide correction is sent, is amplified on the WO Star 71 side.  Hence trailing.  One option might have been to get the weight of the WO Star 71 side identical to that of the Esprit side, so that the optical centres of both scopes were equidistant from the midline of the mount.   But that would have been a lot more weight -  which I didn't have.  And in any event that seemed inelegant.  So I removed the dual bar.  Put the Esprit directly into the saddle of the mount and put the WO Star 71 on top of the Esprit.  I have had round stars from the WO Star 71 ever since I did this.

Whilst the rig is still primarily for 'convenience' - I have the option of using the WO Star 71 or the Esprit 120 - I am finding that the Eastern Veil is lending itself nicely to 'simultaneous' imaging.  In fact my 'real' target is the 'Bat' portion of the Veil using the Esprit.  I thought I'd just see what I got through the WO 71 at the same time.  Dithering will of course mess up the Star 71 images.  I have turned off dither for now.  The autofocus routine on the Esprit (the one with the OAG) causes a horrible spike in PHD2 when it does a BIG shift - that is when the focuser swings out to start my 9 point model and when it returns to focus from the furthest IN point.  The smaller steps in-between seem to make little difference and, in any event, the WO Star 71 images seem unaffected by these brief spikes.  If I could reduce the speed of the focuser (it's a Feathertouch Focus Lynx) I think things might be better, but I don't see a way of doing that.

I'm hoping the SGP guys will eventually get round to allowing multi-camera imaging in the near future.    

I hope that has outlined my thinking, but do feel free to PM if you want me to give any more detail.  I don't know if my 'theory' is correct - so long as I get round stars though, I'm not sure I care.  There may be an ADM dual bar coming up for sale soon....

Steve

     

[steppenwolf]

The conclusion that you have drawn regarding non-matching weight telescopes on a side by side bar is the same one that I came to but for a different reason - the telescope centres would not be guaranteed to point through the centre of my dome's aperture at every orientation so I am mounting my two refractors in piggy-back fashion so that all I have to do to swap from one instrument to the other is change one parameter in the 'slaving' set-up.

I love your Veil image - some quite amazing detail in there.

[gnomus]

Thanks Steve.  

[MartinFransson]

Wow! Look at all those delicate strands of gas. Good thing I use s DSLR so I don't even have to consider a 3nm filter

[gnomus]

21 minutes ago, MartinFransson said:

......Good thing I use s DSLR so I don't even have to consider a 3nm filter

For now, Martin.  Only for now.  Can't you hear that cooled-CCD calling out to you?

[swag72]

Thanks for that info Steve regarding your dual issues. I'm sure that my issues are different as the scopes I am using are both the same focal length and the adjustment saddle gets them pointing in the same place  Those Chroma filters are just slightly cheaper than the Astrodons .... food for thought in the future perhaps

[MartinFransson]

19 minutes ago, gnomus said:

For now, Martin.  Only for now.  Can't you hear that cooled-CCD calling out to you?

STOP THAT!!!!

[gnomus]

4 minutes ago, swag72 said:

Thanks for that info Steve regarding your dual issues. I'm sure that my issues are different as the scopes I am using are both the same focal length and the adjustment saddle gets them pointing in the same place  Those Chroma filters are just slightly cheaper than the Astrodons .... food for thought in the future perhaps

You are probably right.  My original plan was to have two of the same scope in the dual rig - the WO Star 71.  But that was scuppered, when I found out that WO didn't make two good WO Star 71s 

However, even then there would have been problems with distance from the midline.  Both sides of my original-planned rig would have been different because I would have had a guide scope on top of one of the Star 71s, making that side substantially heavier.  This would therefore have led to an offset rig (without counter-weighting).  There would still have been some asymmetry therefore, though clearly not as bad as with the 120 vs 71.

Steve

[PatrickGilliland]

2 hours ago, gnomus said:

I'm hoping the SGP guys will eventually get round to allowing multi-camera imaging in the near future. 

Hi Steve - well that's done the trick then. Pulling that detail through nicely.  I spoke to SGP (and others) on this issue and there is plans for this, as i understood.  There are some additional but fairly simple pieces of logic to get right (EG if 600 lum and 300 RGB running and one camera takes 5 secs to download and the other 12) you may have to ensure that continuous guiding is achieved with no interruption as well as planning in focus runs while other camera is 'off' not to mention the times downloads occur simultaneously.  Simple feature rapidly becomes less so but it is achievable and if you get the logic correct it should run n camera's.  Not just two.  Be interesting to see who gets there first - the demand is growing for a solution.

You have had better luck than me with skies.  No matter when i look up there is a cloud there.

 

Paddy   

[gnomus]

24 minutes ago, PatrickGilliland said:

.....You have had better luck than me with skies.  No matter when i look up there is a cloud there.

 

I thought you had various remote imaging setups circling the planet Paddy.  Are you clouded out at all of them?

[PatrickGilliland]

5 minutes ago, gnomus said:

I thought you had various remote imaging setups circling the planet Paddy.  Are you clouded out at all of them?

Lol no - just at home.  Still have that extra attachment to my personal data.  Just posted up some recent 'remote' works which keep me ticking over.

With each day that passes though the urgency to get my local set up to a better location increases.  I reckon its one of the most expensive sheds in the area just now.  Just a storage facility most of the time for inactive gear.

Paddy

[Sp@ce_d]

Looking good.. I just checked on the cost of my Astrodons now & choked too! I've been wanting another set. Has anyone done a comparison with the Chroma's? Tempting..

I had exactly the same problems with my triple shooter... spent way too much time & money on it. Nearly got there with the software side of things if I'd have gone with Tom How's multi MaximDl sync solution but it didn't support dithering & led me to rethink & go down the ACP route. Regarding the multi dithering etc.. I believe Tom How has now overcome this.. http://astro.neutral.org/software/multiple-camera-sync-ccdSoft-TheSkyX.html

[Barry-Wilson]

Lovely sharp Ha mono Steve.

That Chroma filter looks a winner and helps assert, in my mind, the quality of the brand for NB filters alongside Astrodon with this second example after Chris's big 50mm square purchase .

(I managed to get a few hours in on Friday night with the help of a mate - fractured wrist just about willing, LOL!)

[gnomus]

Just now, Barry-Wilson said:

Lovely sharp Ha mono Steve.

That Chroma filter looks a winner and helps assert, in my mind, the quality of the brand for NB filters alongside Astrodon with this second example after Chris's big 50mm square purchase .

(I managed to get a few hours in on Friday night with the help of a mate - fractured wrist just about willing, LOL!)

Glad to hear you are back in the game Barry.  Are you still having to type with one finger?

[Barry-Wilson]

Oui, oui . . . pun completely intended, LOL!

[gnomus]

10 minutes ago, Barry-Wilson said:

Oui, oui . . . pun completely intended, LOL!

Aaaaah.   Doesn't bear thinking about.  I will ask no more questions.    

[ChrisLX200]

Those owners of 383 cameras thinking of trading it in for an ASI1600MMC should really look closely at this image

ChrisH

[gnomus]

4 minutes ago, ChrisLX200 said:

Those owners of 383 cameras thinking of trading it in for an ASI1600MMC should really look closely at this image

ChrisH

That's very kind of you Chris.