Getting back into imaging after a long break

[Gina]

The Fujinon lens focuses alright with the ASI 1600MM-Cool without filter.  Here's an image using ROI 1500x1500 pixels at X=1550 and Y=1000.

 

 

[Gina]

This gives me two options :-

1. ASI 178MM with a cooling setup like the ASC - a lot of work and a Peltier TEC to buy even then the cooling is nowhere as good as a proper cooled camera.  It all needs a dry chamber same as the ASC.
2. ASI 1600MM-Cool with a filter placed inside the camera in the dry chamber.  This is my No.2 1600 which is a ZWO version 1 and several years old.  The top unscrews and the inside is dried with desiccant tablets.  I imagine silica gel will work just as well and there's quite a lot of room.  Some sort of dew prevention will be needed for the lens but being well away from the cooling system a simple dew heater may be adequate.

Edited April 15, 2019 by Gina

[Gina]

I think I like option 2. best.  Less to do and better performance.  Lower resolution but still plenty I think. 

[Gina]

I'm using the lens that I thought was imperfect but now I'm wondering if it was dew or something else that caused the stretched stars near the edge.  I've been waiting for a reply from the seller but I think I'll do some more tests before sending it back.

[Gina]

I've taken the Astrodon 5nm Ha filter out of my filter wheel, taken the filter out of the mount and fitted it inside the ASI 1600MM-Cool camera.  I've retained the desiccant pellets as they were fine last time I used this camera but a nighttime run will tell.  The image above taken with the Ha filter in the camera.

Should add - I already have Astrodon 3mm Ha, OIII and SII plus IR/UV cut in the FW.

Edited April 15, 2019 by Gina

[Dr_Ju_ju]

To rejuvenate the tablets, just pop them into the microwave & blast for 5 mins, I do it at least once a year...

[Gina]

I think I have an idea for easy dew prevention - redirect the warm air from the camera cooler up to the lens.  Air would be drawn in from the bottom of the camera, through the cooling fins and out the sides.

The next question is where to put this rig.  The observatory scope room and EQ8 mount have obscured views to north and west.  On a pole like the ASC may be a possibility (I have the other half of the length I cut for the ASC) but with a fixed rig the stars will rotate around Polaris (possible corrected in the stacking).  Alternatively, I could produce an extension attached to the mount and follow the stars.  Of course the FOV changes as the night progresses whatever I do.

For NB imaging either long exposures or many short one ares needed to get enough data fro a decent image.  This may mean imaging over several night due to the changing FOV as the night proceeds.  It will be interesting if this idea will actually work.

[Gina]

3 minutes ago, Dr_Ju_ju said:

To rejuvenate the tablets, just pop them into the microwave & blast for 5 mins, I do it at least once a year...

Yes, I've done that in the past.

[Gina]

Now like everyone else, I want some clear night skies!  The weekend might be alright except for the full moon!!  Not so bad for NB, of course.  And the narrower bandwidth the less bright the moon is compared with nebulosity.  Maybe I should have put the 3nm Ha filter in the ASI 1600MM-Cool camera.  I still could, of course.

[Gina]

Been checking on previous NB imaging (getting on for two years ago) to see how much total exposure I might need to get something reasonable.  The Quote below is from my Widefield Single Imaging Rig Blog.  Camera temperature was -30°C.  I can go up to 90s before significant star elongation and the lens is f1.8 rather than f3.5 which is about 2 stops better (4x as much light), so overall a x12 in effective maximum exposure before needing tracking.  I think this is hopeful.

On 05/10/2017 at 22:23, Gina said:

I've found Cygnus   This is a 30s exposure, gain of 600 (60dB).   Astrodon 3nm Ha filter.  28mm f3.5 lens.  Screenshot from KStars.

Edited April 15, 2019 by Gina

[Gina]

Connected the 12v power input to the camera so that I could run the cooling.  Now down to -17°C and no sign of misting up so I think the desiccant tablets are fine.  The view of the far hill several miles away is clearer in the image than it is with no.1 eyeball - it's covered in mist.  That shows how well red light goes through mist (Ha wavelength).

[Gina]

With the camera cooling running the casing gets slightly warm and so does the lens so I don't think dew will be a problem but it wouldn't hurt to direct the warm air up to the lens.  I'll produce a casing [removed word] support bracket tomorrow.

[Dr_Ju_ju]

I 'm shocked ?, now what 'removed word' was it ????

[Stu]

1 hour ago, Dr_Ju_ju said:

I 'm shocked ?, now what 'removed word' was it ????

Funny. I have no idea what it was, the swear filter obviously got confused.

[Gina]

A Latin word meaning "with/including".  LINK

Edited April 16, 2019 by Gina

[Stu]

4 minutes ago, Gina said:

A Latin word meaning "with/including".  LINK

Ah, that would do it! ?

[Dr_Ju_ju]

ROFLMAO ?

[Gina]

An example of where common English has used a non-English word to concisely express the meaning or two or more words.

[Knight of Clear Skies]

The forum also censors the highest point in Cornwall (Brown Willy) and a number of counties (Essex, Middlesex, Sussex).

Edit - or has that been tweaked now?

Edited April 16, 2019 by Knight of Clear Skies

[Gina]

I've also come across cases where the seemingly American based word censor objects to English words that have another meaning in the USA.  Admittedly that was some time ago and it may have changed.

[Gina]

Here is a design for the casing.  The side extension and pillars are for the focus motor (28BYJ-48).  The casing is taken up level with the edge of the lens to direct warm air for dew heating.

Edited April 16, 2019 by Gina

[Gina]

Now 3D printing the casing, having serviced my Mini printer (and been out a lot).

[Gina]

4 hours into the print and it's gone wrong! 

[teoria_del_big_bang]

it happens ? 

Steve

[Gina]

I think I have the all sky NB Ha rig just about ready to test tonight before the moon comes up.