Go Back   IceInSpace > Images > Solar System

Reply
 
Thread Tools Rate Thread
  #1  
Old 31-08-2020, 03:10 PM
Fox's Avatar
Fox
Registered User

Fox is offline
 
Join Date: Jun 2006
Location: Camberwell, Vic
Posts: 319
Jupiter, my First Ever Astrophoto!

Dear all IIS's

Here is my very first astrophoto I have ever taken (not counting my goofing around with an iPhone at the eyepiece).

Date 29/9/2020
Scope NP127is
Camera ASI224MC
Mount LXD75
2.5x Powermate, therefore at f/13.2
About 4,000 frames stacked with Autostakker 3, tweeked with RegiStax 6.

I am really stoked, albeit I know it’s pretty crappy compared to what you experts come up with much bigger scopes. I know I can do much better, it’s was pretty windy on Saturday night, PLUS I was using my crappy Meade LXD75 Mount (for familiarity), not my new SW AZEQ-6 because I am having real difficulty to polar align that mount yet (waiting for my iPolar to arrive).

The biggest headache I am finding is trying to locate the planet on the frakking sensor chip as I change from eyepiece to Powermate + Camera. I tried my Powermate 5x but it’s finding the planet after the swap that is the problem. Now, much of this issue is probably because I am not (yet) using my far superior AZEQ-6, ie. the old LXD75 has terrible slop in the worms and gears, no wonder it loses the plot - literally ! Can’t wait until I start using my AZEQ-6 now.

Fox
Attached Thumbnails
Click for full-size image (Jupiter.png)
29.8 KB109 views
Reply With Quote
  #2  
Old 31-08-2020, 03:50 PM
PeterM
Registered User

PeterM is offline
 
Join Date: Jun 2006
Posts: 1,997
Well done Fox, your happy and we are happy you shared. Thank you, it looks like a nice Jupiter to me. Bravo I say!
Reply With Quote
  #3  
Old 31-08-2020, 03:52 PM
Tulloch's Avatar
Tulloch (Andrew)
Registered User

Tulloch is offline
 
Join Date: Sep 2019
Location: Melbourne
Posts: 488
Hi Fox, that's really good image for a first attempt (much better than my first try ), well done. Saturday night in Melbourne was not a good night for imaging anything, it will get easier than that!

The 224MC sensor is really small, and changing over from an eyepiece will not help (usually), especially since the focus point is so different. If you focus with your eyepiece all you will see on the screen when you change over is an ultra-dim, ultra-large donut which is almost impossible to see. These days, once I have focused for my camera I don't change it, and instead align the scope using the out-of-focus donuts through the eyepiece. Once aligned, I point it at my last alignment star and adjust my 8x50 RACI finder to be as accurate as I can be on the star. Then when I slew to the planet, I change over to the camera, point it with the finder and then just hunt around a bit until the planet appears on the screen. It will be in focus and once centered, I re-adjust my finder to point where the camera points.

For optimal resolution, the focal ratio of your setup should be around 5x the pixel size of your camera, so about f/19 for the ASI224MC. Therefore, leave the 5x PM in the bag, the 2.5x should be ok but you might want to investigate a 3x in the long term.

You can image for 3 minutes on Jupiter, 5 min for Saturn and Mars without having to worry about planetary rotation effects. If you are new to planetary, then these tutorial videos will be quite helpful.
http://planetaryimagingtutorials.com/

Andrew
Reply With Quote
  #4  
Old 31-08-2020, 06:19 PM
Fox's Avatar
Fox
Registered User

Fox is offline
 
Join Date: Jun 2006
Location: Camberwell, Vic
Posts: 319
Thanks Andrew, however with the TV127is, I don’t have a finder. I am hoping that once I’ve become more conversant with the AZEQ-6, it should help a lot.

Regarding F/ number, I thought that 5x pixel size is a ‘recommendation/guide’, and I think I’ve read somewhere that up to 6x pixel size is still OK (I could be wrong...). Since the ASI224MC is 3.75microns, then say 5 to 6 will be around f/20, so the 5x Powermate gives f/26 - or am, I just pushing it over the top with ‘empty’ magnification ?

So I have a stoopid question now - can a larger sensor camera like the ASI294MC be used for planetary, or is a “planetary ZWO” best for planets only and a “DeepSky wide field ZWO” best for deep sky only? Is there some fundamental difference in the chip, the noise, the exposure range, etc. between the two types of camera (notwithstanding cost !) such that you ideally should exclusively use one for planetary and the other for DSO ? Would it be any easier to place the planet on the ASI294MC chip because the sensor area is significantly larger ?

How do people photograph the whole moon - my ASI224MC barely covers one-half the moon, don’t you need a bigger sensor ie. like the ASI294MC ? If so, then can’t you use that camera for planets, ie. it’s more versatile, but at a cost...?

As I said, my stoopid questions...
Cheers, Fox

Last edited by Fox; 31-08-2020 at 06:48 PM.
Reply With Quote
  #5  
Old 31-08-2020, 07:10 PM
Tulloch's Avatar
Tulloch (Andrew)
Registered User

Tulloch is offline
 
Join Date: Sep 2019
Location: Melbourne
Posts: 488
Hi Fox, I calculate you are imaging at about f/12.3 right now, based on the size of the planet (44.6 arcsec), the maximum width of Jupiter in your image in pixels (90 pixels), the diameter of your OTA (127mm) and the equation shown below (from here).

I also use a 2.5x PM, and it is pretty unique when it comes to barlows in that it decreases its magnification the further away from the back of the barlow, while most barlows increase their magnification (including the 5x). The 5x PM might be giving you much greater than 5x magnification.
http://www.televue.com/engine/TV3b_p...id=53&Tab=_app

From what I know about other cameras (which isn't much), the key requirement for a "planetary" camera is low read noise and fast capture speeds. The 294MC has a low read noise value (the 224 is lower, but not by too much) and fast transfer rates in 8-bit mode (but not as fast as the 224), so should be good for planetary with the added bonus of being excellent for DSO and the moon. DSO cameras are not my thing, so I can't really help you there.

That being said, if I want to capture the full moon in one shot, I use my DSLR or capture lots of images with the 224MC and use a Photostitching program like Microsoft's Image Composite Editor which does an excellent job (yes, really!).

I would highly recommend getting a finder, I use the Bintel (rebranded GSO) 8x50 RACI.

Andrew
Attached Thumbnails
Click for full-size image (Focal length calcs.PNG)
3.7 KB15 views
Reply With Quote
  #6  
Old 31-08-2020, 09:12 PM
Fox's Avatar
Fox
Registered User

Fox is offline
 
Join Date: Jun 2006
Location: Camberwell, Vic
Posts: 319
Thanks Andrew, I did a search for ASI294MC and Planetary photography, and the comments mirrored your assertions, yeah it can be used, a smidgen less optimal compared to the ASI224MC, but still more than capable and hardly rate limiting. I do plan to try my hand at DSO because the NP127is was born for this, but obviously that's down the road.

Yeah, I know, I'm spending money quite a bit at the moment, but what the heck - to be honest, I'm deliberately spoiling myself; compensation for stress & exhaustion working in public health and clinical trial Covid research.
Reply With Quote
  #7  
Old 01-09-2020, 08:33 PM
Fox's Avatar
Fox
Registered User

Fox is offline
 
Join Date: Jun 2006
Location: Camberwell, Vic
Posts: 319
Quote:
Originally Posted by Tulloch View Post
Hi Fox, that's really good image for a first attempt (much better than my first try ), well done. Saturday night in Melbourne was not a good night for imaging anything, it will get easier than that!

The 224MC sensor is really small, and changing over from an eyepiece will not help (usually), especially since the focus point is so different. If you focus with your eyepiece all you will see on the screen when you change over is an ultra-dim, ultra-large donut which is almost impossible to see. These days, once I have focused for my camera I don't change it, and instead align the scope using the out-of-focus donuts through the eyepiece. Once aligned, I point it at my last alignment star and adjust my 8x50 RACI finder to be as accurate as I can be on the star. Then when I slew to the planet, I change over to the camera, point it with the finder and then just hunt around a bit until the planet appears on the screen. It will be in focus and once centered, I re-adjust my finder to point where the camera points.

For optimal resolution, the focal ratio of your setup should be around 5x the pixel size of your camera, so about f/19 for the ASI224MC. Therefore, leave the 5x PM in the bag, the 2.5x should be ok but you might want to investigate a 3x in the long term.

You can image for 3 minutes on Jupiter, 5 min for Saturn and Mars without having to worry about planetary rotation effects. If you are new to planetary, then these tutorial videos will be quite helpful.
http://planetaryimagingtutorials.com/

Andrew
I had a look at 8x50 RACI finders on the Bintel site, I see what you mean in helping as a direct visual aid. When you 'adjust' the RACI finder, do they have spring loaded adjustment, or does the finder flop around loose in the rings when adjusting ?

Thanks for the link to the tutorials, I did in fact follow that guy's YouTube guide quite a bit for capturing, and stacking. It was with the RHS and LHS side Registax wavelet tutorials that I lost it a bit.

I realise that at the end of day, I am going to be limited by having only 127mm of aperture, but when I see Rigel003 posts of Jupiter, Mars and Saturn with a 175mm AP refractor and ASI224 camera - absolutely amazing! That really inspires me, ie. even with a 127mm refractor.

Thanks for the tips about planet rotation (I limited Jupiter to 2 mins), and about taking multiple moon images and Microsoft Image Composite Editor stitching, what a great idea !

Cheers,
Fox
Reply With Quote
  #8  
Old 01-09-2020, 10:12 PM
Fox's Avatar
Fox
Registered User

Fox is offline
 
Join Date: Jun 2006
Location: Camberwell, Vic
Posts: 319
I'm reading up about those RACI finders, sounds like often employ fine adjustment screws, cross hairs - ie. just made for image finding during computerised photography. Thanks for the valuable tips!

PS: another stoopid question... I believe the general rule of thumb for optimal f/ number is about 5 x the camera pixel size (microns). With the ASI224MC planetary camera (3.75 microns) that means ~ f/19. For the ASI294MC Deep Sky camera (4.63 microns) that means around ~f/23 is optimal. All other things being equal, does that also mean that the final image will/can be bigger with the ASI294MC camera?

Fox

Last edited by Fox; 01-09-2020 at 10:28 PM.
Reply With Quote
  #9  
Old 02-09-2020, 10:11 AM
Tulloch's Avatar
Tulloch (Andrew)
Registered User

Tulloch is offline
 
Join Date: Sep 2019
Location: Melbourne
Posts: 488
Hi Fox, the added advantage to the RACI finders is that the image is right side up - I used to have a straight through finder that was upside down and left to right. Trying to work out which way to slew in the dark was too much for me, these make it easier .

There are no stoopid questions, none of this information is intrinsic so ask away . The "5x rule" takes pixel size, focal length etc into account and means that the actual image size for a particular OTA should be the same, regardless of which camera you use if you stick with the 5x rule. A camera with a bigger pixel size needs a bigger image across its sensor (so a higher f/num) to give the same number of pixels "on target". The maths describing the relationship is attached.

The concept is better explained in Steve's video entitled "Which Barlow?" (scroll to the bottom of the page).
http://planetaryimagingtutorials.com/getting-started/

Hope this helps,

Andrew
Attached Thumbnails
Click for full-size image (Focal ratio 5x pixel size proof.jpg)
157.1 KB17 views
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 08:24 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Testar
Advertisement
Bintel
Advertisement