Musings in Ha

[Rodd]

Once again I was confronted with clear skys and a bright Moon.  I do not want to start a big project before I switch OTAs, but I could not not image.  So, I decided to pick a target that I would only need 2 filters--the Western Veil (Witches Broom).  the problem was--it wouldn't fit in my FOV.  So I decided to use my camera angle adjuster for the first time.......I did not realize there would be a significant downside.  As you can see from the image--its a perfect fit, but my E, W, S, and N directions were totally screwed up!.  I manually frame my targets, and when my sensor is at 90 or 180 degrees, movement is easy--left is west, right is east north is up and south is down (the E and W are reversed in the west side of the meridian.  Now, movemenst were at awkward angles and it was very difficult to move the stars in teh directions I wanted.  This made me really wish that the CAA was connected to teh system, that the planetarium software would know the angle and adjust the slew directions accordingly.  Anyway, Here is teh start of the Witches Broom--69 300 sec Ha subs.  I definitely need more data, but I am encouraged.  As a bonus, my target hit the trees at midnight--leaving me with 5 hours of clear sky.  So I decided to pick a target and leave the rig running while I slept--putting my temperatute compensation feature ob my focus controlller to the test.  I chose the Horsehead, as that makes a nice mono image.  The image contains 50 300 sec subs.  I want to collect more data for this as well, but I am quite satisfied considering I did not adjust focus over a 5 hour period--and I used all 50 subs.  I will no doubt look tehm over and discard teh worst when I get more data--but for now, the 50 will have to do.  I did teh same for teh Viel as well-used all subs without really looking at them.

By the way--Alnitak was so bad I cropped it out.  the star was perfectly resolved, small and round with its companion a good distance away--but the 

microlensing effect made it look like there was a cloud of perfect circles floating around it--like ballons.  No doubt reflections or ghosts images of teh star itself--perfectly round, contained within a square.  Not sure what teh square is, but I don't like it.  So I cropped it out.  I can see the end of teh AI 1600.  Even teh star in teh Viel has faint microlensing--and that is a 4th magnitude star.  ZWO should be ashamed.

 

 

 

Edited October 17, 2019 by Rodd

[alan potts]

Both really nice images Rodd, the HH is superb, as you say great subject for Mono.

Alan

[Rodd]

5 minutes ago, alan potts said:

Both really nice images Rodd, the HH is superb, as you say great subject for Mono.

Alan

Thanks Alan. I just noticed. Couple of large circles in the HH image. I think they are either thrown reflections (I seem to remember that is common with this target.  I remember seeing something similar when I did it a couple years ago.  Either that or there were a few bad subs.  
Rodd

[alan potts]

Rodd if you have the time can you post something showing this micro lensing you talk about so I can hope to understand it, I have only OSC cameras in the shape of 183 and 071, are they affected too?

Alan

[Allinthehead]

4 hours ago, Rodd said:

ZWO should be ashamed.

Why would Zwo be ashamed? This is a Panasonic sensor and the same issue exists in the Atik, Qhy and other versions. 

[Laurin Dave]

It looks like this Alan..  Esprit 150 at F7...  also another reflection around IC434 which is similar to that on Rodd's image..  I believe these are reflections from other bits of the ZWO kit.    ASI071 doesn't suffer, its a DSLR sensor and I haven't seen or read of anything similar on the ASI183.  Still like the ASI1600 its just choosy about its subjects..    Edit.. just done dust donut/reflection calculation and the large halos are from +/- 27mm..  which is the connection at the scope side of the ZWO EFW.. in my case to their OAG

And this is the Witches Broom Esprit 100 at f5.5, artefacts around the bright star but not as bad as on Rodd's

 

 

Edited October 17, 2019 by Laurin Dave

[Gina]

I haven't seen any of this with my ASI1600MM-Cool or any other ZWO camera I have.

[alan potts]

I see it now, that would annoy me.

Alnitak is always a little wotsit to deal with in the HH, I was given a way by Olly to remove the various halo's it creates and it worked fairly well. There was a technique by one of the Mod's, Rob but I could never follow it though it appeared to work very well indeed.

Alan

[Laurin Dave]

I annoyed me so I got another camera!  Still needed the magic of Photoshop..

 

[Rodd]

6 hours ago, Allinthehead said:

Why would Zwo be ashamed? This is a Panasonic sensor and the same issue exists in the Atik, Qhy and other versions. 

Well--when Astrophysics discovered that there serial converter was not "up to snuff" they changed suppliers.  I feel that the excuse "but they made that pat" can only go so far.  But I agree that the primary reason for the microlensing effect (form what I have been told) is due to the sensor design.  In my mind, that does not completely absolve the camera manufacturer from responsibility. 

Rodd

[Rodd]

5 hours ago, Gina said:

I haven't seen any of this with my ASI1600MM-Cool or any other ZWO camera I have.

Can you post an example of a bright star so I can see what it is supposed to look like.  Maybe it will give me some ideas about cause and correction?

Thanks,

Rodd

[Rodd]

But this is not really meant to be a post about microlensing---I am sick of thinking about it--I started another post specific to that issue.

Rodd

[Rodd]

6 hours ago, Laurin Dave said:

just done dust donut/reflection calculation and the large halos are from +/- 27mm..  which is the connection at the scope side of the ZWO EFW.. in my case to their OAG

Dave--would coating the inside of the connectors help?  is it light reflecting off the spacers?  Can they be coated or modified, maybe taped?

Rodd

[Laurin Dave]

10 minutes ago, Rodd said:

Dave--would coating the inside of the connectors help?  is it light reflecting off the spacers?  Can they be coated or modified, maybe taped?

Rodd

I think it is and I’m sure it would help Rodd..  something to do the next time it’s all apart..  I’ve got some Flat black paint and flocking ready to do it..  I suspect it’s the anodising which in some wavelengths is anything but non reflective 

[Rodd]

1 minute ago, Laurin Dave said:

I think it is and I’m sure it would help Rodd..  something to do the next time it’s all apart..  I’ve got some Flat black paint and flocking ready to do it..  I suspect it’s the anodising which in some wavelengths is anything but non reflective 

What product do you recommend.  I will be switching scopes as soon as I finish the Veil, so it will be relatively soon.  Would felt work, or duct tape or...well, what is best?

Rodd

[Rodd]

9 hours ago, alan potts said:

Rodd if you have the time can you post something showing this micro lensing you talk about so I can hope to understand it, I have only OSC cameras in the shape of 183 and 071, are they affected too?

When I get home I will post the uncropped version of the HH.  Its MUCH WORSE than Dave's.  I would try more shorter subs, but I do not want to deal with a 1,000 subs.  Been there, done that.  One of the abilities of this camera is to be able to use 10 sec subs in Ha and render a decent stack---but my sky is not conducive to that approach, so the number of subs grows unmanageable. 

Rodd

[alan potts]

3 minutes ago, Rodd said:

When I get home I will post the uncropped version of the HH.  Its MUCH WORSE than Dave's.  I would try more shorter subs, but I do not want to deal with a 1,000 subs.  Been there, done that.  One of the abilities of this camera is to be able to use 10 sec subs in Ha and render a decent stack---but my sky is not conducive to that approach, so the number of subs grows unmanageable. 

Rodd

Not understand it fully I see this almost stops you including a bright star in frame, I too would not wish to take 100's of subs, though some do. One to look out for though sort of pleased mine are not affected. Just wondering how you can really do the HH with out having Alnitak, though you did a nice take on it in my view.

Alan

[Rodd]

27 minutes ago, alan potts said:

Not understand it fully I see this almost stops you including a bright star in frame, I too would not wish to take 100's of subs, though some do. One to look out for though sort of pleased mine are not affected. Just wondering how you can really do the HH with out having Alnitak, though you did a nice take on it in my view.

Alan

Well--I do not get the microlensing or reflection issues with the FSQ--at least not with the .6x reducer.  Here is the HH done with that scope in Ha.  It has a halo--but no microlensing.  I can live with this--so all is not lost.  I did get this camera specifically to use at F3 with that scope, so worst case scenario, I use my STT-8300 with the TOA and the 1600 with the FSQ.  And--many targets don't have stars bright enough to cuase teh effect.  Some do.  But I havent really been bothered by it intill I shot M13 and now the HH (and western Viel).  I have not yet tried the ASI 1600 with the TOA and .7x reducer.  If that works out--I won't feel too badly as I think native with this camera is a bit to much for a 5" scope in my sky.  .78 arcsec/pixelo is getting down around C11Edge territoty.   I might throw the .7x reducer on and check it out before I move to teh FSQ for serious imaging.  I hate to lose the imaging time--but I think it would be smart to do...and I have been hankering for an enlarged FOV and a bit lower resolution.  1.12 is still pretty high.

[Laurin Dave]

39 minutes ago, Rodd said:

What product do you recommend.  I will be switching scopes as soon as I finish the Veil, so it will be relatively soon.  Would felt work, or duct tape or...well, what is best?

Rodd

Hi Rodd.... I've used this ... Krylon Camouflage paint in flat black and also black flocking that I got from FLO..  to get the flocking inside tubes a trick I read is to stick it onto some thin plastic sheet and then insert that into the tube.  it expands to fit..   much easier than trying to stick it on..

38 minutes ago, Rodd said:

When I get home I will post the uncropped version of the HH.  Its MUCH WORSE than Dave's.  I would try more shorter subs, but I do not want to deal with a 1,000 subs.  Been there, done that.  One of the abilities of this camera is to be able to use 10 sec subs in Ha and render a decent stack---but my sky is not conducive to that approach, so the number of subs grows unmanageable. 

Rodd

I tried more shorter subs Rodd...  for me it made no difference when stacked... but then why would it as we stack loads of subs to bring out the faint detail .. others may of course have different results. 

Dave

 

 

 

[Rodd]

Just now, Laurin Dave said:

I tried more shorter subs Rodd...  for me it made no difference when stacked... but then why would it as we stack loads of subs to bring out the faint detail .. others may of course have different results

Kind of suspected this would be the case.  thanks for saving me the time!

Rodd

[Rodd]

2 minutes ago, Laurin Dave said:

Hi Rodd.... I've used this ... Krylon Camouflage paint in flat black and also black flocking that I got from FLO..  to get the flocking inside tubes a trick I read is to stick it onto some thin plastic sheet and then insert that into the tube.  it expands to fit..   much easier than trying to stick it on..

What is flocking?  Like felt?  Fortunately the ZWO spacers I use are only 25mm (a 5 and a 10).  Coating the inside with paint will be easy.  or--mayb I will have a precise part made so I do not need the ZWO spacers--that would be the best solution if it works.

Rodd

[Laurin Dave]

Just now, Rodd said:

What is flocking?  Like felt?  Fortunately the ZWO spacers I use are only 25mm (a 5 and a 10).  Coating the inside with paint will be easy.  or--mayb I will have a precise part made so I do not need the ZWO spacers--that would be the best solution if it works.

Rodd

It's a man made fibre black velvet (not Guinness and champagne though) with sticky backing.  Awesome Ha Horsehead !

[Rodd]

1 minute ago, Laurin Dave said:

It's a man made fibre black velvet (not Guinness and champagne though) with sticky backing.  Awesome Ha Horsehead !

Thanks--where can I get it?  I think it would be prudent to put on all spacers/connectors. (probably don't want to mess with reduces and flatners though.  Do you think the flocking is better than the paint?

Rodd

[Laurin Dave]

2 minutes ago, Rodd said:

Thanks--where can I get it?  I think it would be prudent to put on all spacers/connectors. (probably don't want to mess with reduces and flatners though.  Do you think the flocking is better than the paint?

Rodd

I got it from Amazon...  if you go to the Krylon Website they have a "Where to buy" tab..  eg Walmart 161 Berlin Rd CT

[Rodd]

5 minutes ago, Laurin Dave said:

 eg Walmart 161 Berlin Rd CT

Great--there is a Walmart about a mile from my house.  Amazon works too though.

Rodd