Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Guiding and Imaging

  • Please log in to reply
13 replies to this topic

#1 Arthur Hucksake

Arthur Hucksake

    Lift Off

  • -----
  • topic starter
  • Posts: 15
  • Joined: 28 Oct 2021
  • Loc: London England

Posted 05 October 2022 - 03:28 AM

Dear All.

               I have a ZWO 462 that's good for Planetary Pics.  I wonder though, Is it possible to Guide and Image at the same time with just this Unit.  I have emailed ZWO, but as yet no reply, what do you guys think?   

 

 



#2 WilliamAstro

WilliamAstro

    Vostok 1

  • -----
  • Posts: 111
  • Joined: 20 Mar 2022

Posted 05 October 2022 - 03:49 AM

The ZWO 462 is capable of having such great frame rates and light capturing abilities on planets, especially Uranus & Neptune with their moons, but the problem is that it is not a cooled camera and a cooled camera will have the capabilities to capture DSO without dead pixels. You could give a shot at photographing a bright deepsky object with the camera such as Andromeda galaxy.

 

Regarding the guiding, I think it is better to get a guiding camera such as the ZWO ASI120MM Mini as it is very sensitive to light and extremely capable for guiding, I own one for myself and it works very nice. :)


  • Arthur Hucksake and Drothgeb like this

#3 Mike7Mak

Mike7Mak

    Vanguard

  • *****
  • Posts: 2,115
  • Joined: 07 Dec 2011
  • Loc: New York

Posted 05 October 2022 - 03:49 AM

No, not yet at least. I wouldn't put it past ZWO to come up with a camera that can do it. The problem with the concept is guiding with the imaging chip puts it behind any possible filters you might use and seriously limit the choice of guide stars.


  • Arthur Hucksake likes this

#4 kathyastro

kathyastro

    Fly Me to the Moon

  • *****
  • Posts: 5,138
  • Joined: 23 Dec 2016
  • Loc: Nova Scotia

Posted 05 October 2022 - 05:00 AM

You are talking about guiding and imaging with the same camera at the same time.  That is not possible.  Doing that would require the camera to be taking two different pictures at the same time.  A few years ago, someone had a camera that actually contained two cameras in the same housing, for this purpose, but it didn't catch on.



#5 Mike7Mak

Mike7Mak

    Vanguard

  • *****
  • Posts: 2,115
  • Joined: 07 Dec 2011
  • Loc: New York

Posted 05 October 2022 - 05:28 AM

A few years ago, someone had a camera that actually contained two cameras in the same housing, for this purpose, but it didn't catch on.

Yes it was SBIG. They had a line of 'self guided' cameras that contained two imaging chips, several sizes of main imaging chips and a smaller chip placed right next to the main ccd. The reason it didn't catch on is what I said in my post above. The minute you throw a filter, especially narrowband, on the camera the guide chip became worthless.

 

Never had one myself but I imagine for taking unfiltered monochrome images only they were the cat's...uuh, meow. smile.gif



#6 Phil Sherman

Phil Sherman

    Skylab

  • *****
  • Posts: 4,140
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 05 October 2022 - 09:07 AM

You are talking about guiding and imaging with the same camera at the same time.  That is not possible.  Doing that would require the camera to be taking two different pictures at the same time.  A few years ago, someone had a camera that actually contained two cameras in the same housing, for this purpose, but it didn't catch on.

While not true today, it may be possible in the near future if you're willing to live with the consequences. There's an imaging chip that's already in production that has two cells beneath each of the individual Bayer filters. The chip is designed to allow reading out only half of the cells (left vs right under each filter) with each half set for different exposure times. One half could be used for the long exposure image while the other uses short exposures for guiding. The obvious consequence for astro imaging is that the half of the captured photons used for guiding won't be part of the long exposure image.

 

An obvious use for this chip would be a mirrorless DSLR.



#7 HunterofPhotons

HunterofPhotons

    Surveyor 1

  • *----
  • Posts: 1,596
  • Joined: 26 Apr 2008
  • Loc: Rhode Island, USA

Posted 05 October 2022 - 09:28 AM

Yes it was SBIG. They had a line of 'self guided' cameras that contained two imaging chips, several sizes of main imaging chips and a smaller chip placed right next to the main ccd. The reason it didn't catch on is what I said in my post above. The minute you throw a filter, especially narrowband, on the camera the guide chip became worthless....

 

 

"worthless"?  I think not.  There were thousands of us who had no problem guiding with these units, even behind narrowband filters.

All you had to do was choose a bright guide star and lengthen your guide exposure appropriately.

SBIG now makes models that place the guide chip in front of the filter wheel.

OAGs and the SBIG dual chip cameras are the perfect solution for flexure-afflicted imagers.

 

dan k.



#8 WadeH237

WadeH237

    Cosmos

  • *****
  • Moderators
  • Posts: 8,946
  • Joined: 24 Feb 2007
  • Loc: Ellensburg, WA

Posted 05 October 2022 - 11:14 AM

You are talking about guiding and imaging with the same camera at the same time.  That is not possible.  Doing that would require the camera to be taking two different pictures at the same time.  A few years ago, someone had a camera that actually contained two cameras in the same housing, for this purpose, but it didn't catch on.

There were actually two manufacturers that implemented a built-in guiding system.

 

The first - and best known - was SBIG, as mentioned by others already in this thread.  The SBIG system used two separate physical sensors, a bit one for the main image and a second, smaller one off axis.

 

My memory is fuzzy on the other one, and I'm not finding any supporting documentation right now.  I believe that it was Starlight Xpress, and their system worked with an interline CCD.  If I remember right, they had a way use ever other column as a guide image.  Think of it like an interlaced monitor, where they could read out every other column independent of the rest of the columns.  In that way, they used a single sensor.  I'm not sure why this system never seemed to catch on.

 

Moving forward, I believe that there are plans for CMOS cameras that can non-destructively read out the pixel data.  Once those are available, it could be a game changer.  You could do frequent non-destructive downloads for the guide images, and then do a final download at the end of the exposure for the main image.  The presumes that the non-destructive reads don't affect the read noise of the final readout.



#9 rgsalinger

rgsalinger

    Hubble

  • *****
  • Posts: 12,979
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 05 October 2022 - 11:26 AM

The later versions of the SBIG system had the guide chip in front of the wheel in some configurations which eliminated the NB issue with guiding. Of course this is not the same as using the same camera chip for imaging and guiding. That's going to be a tricky thing to accomplish. So, as far as I know you need two cameras if you are going to guide when imaging. 

 

I think that you'd need a chip that somehow had two accessible areas that you could read independently. I would not put it past Sony to build such a chip if it had widespread use in other contexts.  We have the DSLR world to thank for the current wonderful SONY chips.

 

Rgrds-Ross



#10 dx_ron

dx_ron

    Surveyor 1

  • *****
  • Posts: 1,573
  • Joined: 10 Sep 2020
  • Loc: SW Ohio

Posted 05 October 2022 - 12:45 PM

Arthur, we so easily get distracted by bringing up old specialized cameras. I hope you understood the real reason why 99.99% of us use a separate guide camera from main camera.

 

The main camera is taking long exposures. During that time (a minute, 5 minutes, whatever) the mount is not perfectly tracking the target (unless you spend a boatload of money on a mount).

 

The guide camera is taking very short exposures (1-5 seconds each).

 

And Ross (to stay appropriately off-topic smile.gif) I would think we have the market for low-light security cameras to thank for the current generation of Sony chips. Have any of the new chips made it into consumer cameras?



#11 solaryellow

solaryellow

    Mariner 2

  • *****
  • Posts: 285
  • Joined: 27 Sep 2009
  • Loc: New Milford CT

Posted 05 October 2022 - 03:20 PM

Yes it was SBIG. They had a line of 'self guided' cameras that contained two imaging chips, several sizes of main imaging chips and a smaller chip placed right next to the main ccd. The reason it didn't catch on is what I said in my post above. The minute you throw a filter, especially narrowband, on the camera the guide chip became worthless.

Never had one myself but I imagine for taking unfiltered monochrome images only they were the cat's...uuh, meow. smile.gif


I remember that cam
We used ST-7 8 and 10 and were looking at the dual chip. I believe it was a Texas Instruments 245 or 255 chip.
Possible the same as the one in the Cookbook CCD that I also never built.
Oh the good old days!!

#12 dciobota

dciobota

    Mercury-Atlas

  • *****
  • Posts: 2,875
  • Joined: 07 Aug 2007
  • Loc: Sitting in a corner in southeast Arizona

Posted 06 October 2022 - 10:56 AM

I wish I could find the post again, but there was someone on here that wrote their own software that would guide and stack the guide images at the same time.  His test results looked very promising actually.  

 

Theoretically, it is possible with software given current cameras, if you use guide exposures of several seconds successfully.   Your only enemy is read noise per frame, but that is eventually swamped by longer total integration time.

 

I have seen an image once of Rho Ophiuchi taken on a static tripod with 1 sec exposures from a modded dslr and it looked pretty decent actually.  With read noise ever decreasing nowadays with cooled cameras, I don't see why this technique won't be popular eventually.  It will require longer total integration times, but it will simplify the equipment needed considerably.

 

Just thought of another drawback though, and that is narrowband imaging.  In that case stars are a lot dimmer and signal is greatly reduced.  Not sure if a few sec exposures will give enough stars to guide by.

 

Worth a thought though.  I wish the guy who wrote that software would report back on further progress.



#13 michael8554

michael8554

    Vanguard

  • *****
  • Posts: 2,495
  • Joined: 19 Aug 2020
  • Loc: Wiltshire UK

Posted 06 October 2022 - 12:43 PM

Daniel, what you are describing is called "Live Stacking".

 

I believe Deep Sky Stacker (DSS) and SharpCap among others will do Live Stacking



#14 dciobota

dciobota

    Mercury-Atlas

  • *****
  • Posts: 2,875
  • Joined: 07 Aug 2007
  • Loc: Sitting in a corner in southeast Arizona

Posted 06 October 2022 - 12:49 PM

Yup, but they don't do guiding at the same time.  Although the stacking part would certainly be very similar.  I think all the software is there, just haven't seen a product that puts it all together.  It does have some drawbacks as I mentioned, but I think it would be attractive enough for some folks to use it.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics