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

Focal Reducer

Astrophotography
  • Please log in to reply
11 replies to this topic

#1 DaRkPluto

DaRkPluto

    Lift Off

  • -----
  • topic starter
  • Posts: 3
  • Joined: 13 Sep 2022

Posted 01 October 2022 - 10:54 PM

I have a Celestron 127slt at f/12

1500mm focal length

127mm aperture

My camera is an ASI120MC-S

 

I was trying to video the moon but it was zoomed in too much. Do I need to buy a focal reducer and if so what size to fit the full moon?



#2 FRANKVSTAR

FRANKVSTAR

    Ranger 4

  • *****
  • Posts: 322
  • Joined: 14 Nov 2015
  • Loc: GASTON S.C

Posted 01 October 2022 - 11:28 PM

 Good question. I would feel you could use Stellarium  or pull up Astronomy -tools on the web, on either you can tell it what scope you have and change various different reducers and it will show you how much the moon will fit your frame/camera/eyepiece . I really don't have much to do so I may look it up myself and message you back.



#3 FRANKVSTAR

FRANKVSTAR

    Ranger 4

  • *****
  • Posts: 322
  • Joined: 14 Nov 2015
  • Loc: GASTON S.C

Posted 01 October 2022 - 11:40 PM

 I looked it up and with you scope and camera combo you can only get a little over half of the moon and that's with a .5 reducer, .63 reducer and you see even less. Do  you have a DSLR camera they have a much larger sensor and that will get the entire moon and a little more.

 There may be other options from others, but I cant think of one...


  • CharLakeAstro likes this

#4 LukaszLu

LukaszLu

    Apollo

  • -----
  • Posts: 1,309
  • Joined: 28 Sep 2020
  • Loc: Poland

Posted 02 October 2022 - 12:37 PM

I have a Celestron 127slt at f/12

1500mm focal length

127mm aperture

My camera is an ASI120MC-S

 

I was trying to video the moon but it was zoomed in too much. Do I need to buy a focal reducer and if so what size to fit the full moon?

No - you should even extend the focal length to reach the optimal relations resulting from aperture and camera pixel size. Please visit http://www.wilmslowa...tm#CCD_Sampling



#5 wavefront

wavefront

    Viking 1

  • *****
  • Posts: 643
  • Joined: 15 Jul 2005
  • Loc: Colorado

Posted 02 October 2022 - 05:30 PM

I've got an 8" f/5 Newtonian and no fancy camera. A good used one will probably do (suggestions ?).  When I finally get the camera will I have to move the mirror forward a bit to do lunar and planetary ? Not worried about deep sky pics. Just look on line. Thanks 



#6 Michael Covington

Michael Covington

    Author

  • *****
  • Posts: 8,282
  • Joined: 13 May 2014
  • Loc: Athens, Georgia, USA

Posted 02 October 2022 - 06:16 PM

The ASI120MC-S has a very small sensor.  To get the full face of the moon on it, you need a very short focal length, more like a telephoto lens than a telescope.  You can easily video areas of the moon (groups of craters, etc.), which is what I do with my ASI120MC-S and Celestron 5.



#7 DaRkPluto

DaRkPluto

    Lift Off

  • -----
  • topic starter
  • Posts: 3
  • Joined: 13 Sep 2022

Posted 02 October 2022 - 06:39 PM

 I looked it up and with you scope and camera combo you can only get a little over half of the moon and that's with a .5 reducer, .63 reducer and you see even less. Do  you have a DSLR camera they have a much larger sensor and that will get the entire moon and a little more.

 There may be other options from others, but I cant think of one...

No other camera besides the ASI and an iphone6s



#8 wavefront

wavefront

    Viking 1

  • *****
  • Posts: 643
  • Joined: 15 Jul 2005
  • Loc: Colorado

Posted 02 October 2022 - 07:44 PM

My camera is an old Olympus. Just a cheap little pocket job. I don't have a cell phone of any kind.



#9 maroubra_boy

maroubra_boy

    Vanguard

  • -----
  • Posts: 2,367
  • Joined: 08 Sep 2009
  • Loc: Sydney, Australia

Posted 03 October 2022 - 03:35 PM

DaRKPluto,

 

As you have a smartphone (like your iPhone), you can do afocal photography to capture the whole of the Moon with your scope.  Afocal photography means taking a pic pointing the camera into the eyepiece of a scope.  I use a smartphone adapter to hold the camera steady over the eyepiece which makes the process far easier and more productive.

 

I have the same scope as you do (the Skywatcher version, exact same scope as Skywatcher makes both scopes & owns Celestron), and I use my smartphone to regularly take pics of the Moon.  You will need a long focal length eyepiece around 40mm to 30mm 1.25" to achieve the whole of the Moon in the eyepiece.  A 2" eyepiece of the same focal length will make things easier as these provide a wider AFOV at this focal length.

 

Below are a couple of single frame uncropped pics I have taken using my smartphone with my 127mm Mak using 40mm & 30mm 1.25" plossls respectively.  Depending on the settings on your smartphone camera the size of field of view will be larger or smaller. The third was done using a 2" 38mm 70° eyepiece as a comparison, of course with the same scope & camera.

 

You won't fit the whole of the Moon using a generic 0.5X focal reducer with your 127mm Mak and your ASI camera.  The sensor size is just too small.  Again I have a camera with the same sensor size and also tried it not only with the 127mm Mak but also a scope with an even shorter native focal length and it was only with the 600mm focal length with the reducer that I could get the whole of the Moon on that sensor size.  The last pic is from my 1/3" sensor size camera (same size sensor as your camera) using a scope with a 600mm focal length so you can see that your scope and astro camera won't fit the whole of the Moon using a reducer.  Full frame pic, uncropped.

 

Alex.

Attached Thumbnails

  • Luna 15 July 2021 127 Mak 40mm Pl (1) - Copy-1.jpg
  • Luna 12th March 2022, 127 30mm Pl - Copy (2).jpg
  • 127mm Mak 38mm 70deg - Copy.jpg
  • ed80 neat LR.png

Edited by maroubra_boy, 03 October 2022 - 05:18 PM.

  • Michael Covington and Sarciness like this

#10 wavefront

wavefront

    Viking 1

  • *****
  • Posts: 643
  • Joined: 15 Jul 2005
  • Loc: Colorado

Posted 03 October 2022 - 05:42 PM

I don't have a cell phone of any kind.  I do understand afocal though. I can ask for camera recommendations on a photography forum which sends me a notice every couple of weeks.



#11 DaRkPluto

DaRkPluto

    Lift Off

  • -----
  • topic starter
  • Posts: 3
  • Joined: 13 Sep 2022

Posted 03 October 2022 - 08:56 PM

DaRKPluto,

 

As you have a smartphone (like your iPhone), you can do afocal photography to capture the whole of the Moon with your scope.  Afocal photography means taking a pic pointing the camera into the eyepiece of a scope.  I use a smartphone adapter to hold the camera steady over the eyepiece which makes the process far easier and more productive.

 

I have the same scope as you do (the Skywatcher version, exact same scope as Skywatcher makes both scopes & owns Celestron), and I use my smartphone to regularly take pics of the Moon.  You will need a long focal length eyepiece around 40mm to 30mm 1.25" to achieve the whole of the Moon in the eyepiece.  A 2" eyepiece of the same focal length will make things easier as these provide a wider AFOV at this focal length.

 

Below are a couple of single frame uncropped pics I have taken using my smartphone with my 127mm Mak using 40mm & 30mm 1.25" plossls respectively.  Depending on the settings on your smartphone camera the size of field of view will be larger or smaller. The third was done using a 2" 38mm 70° eyepiece as a comparison, of course with the same scope & camera.

 

You won't fit the whole of the Moon using a generic 0.5X focal reducer with your 127mm Mak and your ASI camera.  The sensor size is just too small.  Again I have a camera with the same sensor size and also tried it not only with the 127mm Mak but also a scope with an even shorter native focal length and it was only with the 600mm focal length with the reducer that I could get the whole of the Moon on that sensor size.  The last pic is from my 1/3" sensor size camera (same size sensor as your camera) using a scope with a 600mm focal length so you can see that your scope and astro camera won't fit the whole of the Moon using a reducer.  Full frame pic, uncropped.

 

Alex.

Don't know why I didn't think to use my phone with a 25mm eyepiece. I looked it up on astronomy.tools and it will easily fit. Guess I had a brain fart. Also, what smartphone do you have and what adapter do you have?


Edited by DaRkPluto, 03 October 2022 - 08:57 PM.


#12 maroubra_boy

maroubra_boy

    Vanguard

  • -----
  • Posts: 2,367
  • Joined: 08 Sep 2009
  • Loc: Sydney, Australia

Posted 04 October 2022 - 04:19 AM

Mine is an Oppo A9 2020 phone.

 

The adapter I use is in the pic below.  Brand - I have no idea as it doesn't have a label.

 

A smartphone can be used to do the same work as with an astro camera, that is taking an AV file and then stacking the video file.  This is for lunar, planetary and DSO's.  There is some amazing work being done with smartphones.

 

My own use is very basic taking only single frames.  But the adapter makes taking dozens of shots very easy, and then I just go through the pics to select the best images and delete the rest.

 

The second pic I also took with my 127mm Mak.  The third was done using my 9" Mak. 

 

 

Alex.

Attached Thumbnails

  • phone adapter.jpg
  • IMG20210812212837 - Copy.jpg
  • IMG20200721233411 - Copy.jpg



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





Also tagged with one or more of these keywords: Astrophotography



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics