DSLR vs ZWO 120?

[Jojo204]

Hi all,

until now I have been using my DSLR to do astrophotography with some pleasing results. But now I’ve decided to have my go with the planets, which I find just as interesting as DSO’s!

Jupiter and Saturn look good observing through my 6SE! I get nice detail and moons visible. When I connect my DSLR, in live view, the detail shows up and is quite nice. However when I take a photo, the result is just a sandy coloured blob with no detail and considerable noise.

This led me to recently purchase a ZWO ASI 120MC which I believe is a CCD Camera? I was just wanting to know the main differences in between DSLR imaging and CCD imaging in terms of results. I understand that their will be lesser noise but what about resolution?

Thanks!

[Mr niall]

The 120 is a cmos not a ccd but yes you're on the right lines.

DSLR and CCD imaging are fundamentally identical - but if I'm reading your post right I'm assuming you are taking ccd imaging to mean planetary imaging.

Planets are bright - so they don't need long exposures. But they're small so they're more sensitive to atmospheric wobble and fuzziness; just as when you look through the eyepiece and see planets change shape, colour, contrast, clarity and sort of wobble around. So, because they are small you don't need a large DSLR sensor as 99% of the sensor is looking at nothing, a smaller one is better. In the same way that a small eyepiece creates a more zoomed image, the same is true for camera sensors - so a smaller sensor is a double plus in that regard. Additionally one that is extremely sensitive is a plus. And that's fundamentally the difference between a DSLR and Planetary camera (not CCD - they can have sensors that are all the way up to full frame in size) a good planetary camera has a very small, very sensitive sensor. Resolution is largely irrelevant; as above - Jupiter at its biggest is only 49 arc seconds across so that's only going to take up a couple of hundred pixels at most; there's literally no point having a 24mp dslr sensor pointing at it as 99% of the pixels will see nothing.

The other reason that this is a plus is the fact that you don't actually photograph planets, you video them. Because of the wobbliness described above you have to take many many short exposures of a fraction of a second. Really at least 200, but as many as 5000 through a video recording. From that you review every single frame if possible, discard the poor ones and keep the good ones.

You have a choice of processing these through something like Autostakkert!2 or Registax (both free) and it stacks these all together as with traditional DSLR photography and voila! 

That is a very very short explanation but should give you the idea. There are lots of guides on google. 

(all that being said, you can take good planetary images on a DSLR, especially if it has a 1:1 crop on lower res videos (which few have these days sadly) but the main point here is that planetary imaging is a different discipline to long exposure short focal length astrophotography)

Hope that helps

edit: here is a pretty good guide that does a better job of explaining it than me http://www.star-hunter.ru/en/planetary-imaging/

 

Edited July 17, 2019 by Mr niall

[Jojo204]

1 hour ago, Mr niall said:

The 120 is a cmos not a ccd but yes you're on the right lines.

Thank you so much for the quick explanation! Really helpful! Yes the sensor size makes sense now! I’ve been doing the entire videoing and stacking process but with a dslr and frankly I haven’t had the chance to actually have some good clips. Mainly just short 2-5 second clips to ‘document’ my first time seeing them! So yes these are insufficient and I’m looking forward to improve!

thanks once again!

[cletrac1922]

5 hours ago, Jojo204 said:

Hi all,

until now I have been using my DSLR to do astrophotography with some pleasing results. But now I’ve decided to have my go with the planets, which I find just as interesting as DSO’s!

Jupiter and Saturn look good observing through my 6SE! I get nice detail and moons visible. When I connect my DSLR, in live view, the detail shows up and is quite nice. However when I take a photo, the result is just a sandy coloured blob with no detail and considerable noise.

This led me to recently purchase a ZWO ASI 120MC which I believe is a CCD Camera? I was just wanting to know the main differences in between DSLR imaging and CCD imaging in terms of results. I understand that their will be lesser noise but what about resolution?

Thanks!

 

Jo

There is also an App for ZWO's

I am also looking at the ZWO ASI 290MC, for imaging, and the ZWO ASI290MM Mini autoguider to use with PHD2

John 

[Starwiz]

I bought the ASI120mc myself to start planetary imaging and was using this before I got a DSLR.

Another benefit is the download speed of the images.  Because the sensor is quite small, the image size isn't very large, so frames can download to the computer much faster.  I was getting around 40 fps downloading, but it can vary depending on the image size you select.  I would capture around 1,500 - 2,000 frames, sometimes more, before stacking.

Now I mostly use the ASI120mc as a guide camera, but I could switch it back to planetary at any time if I want to.

John

[cletrac1922]

7 hours ago, Starwiz said:

I bought the ASI120mc myself to start planetary imaging and was using this before I got a DSLR.

Another benefit is the download speed of the images.  Because the sensor is quite small, the image size isn't very large, so frames can download to the computer much faster.  I was getting around 40 fps downloading, but it can vary depending on the image size you select.  I would capture around 1,500 - 2,000 frames, sometimes more, before stacking.

Now I mostly use the ASI120mc as a guide camera, but I could switch it back to planetary at any time if I want to.

John

 

John

Was looking at ZWO ASI 290MC

You saying can use single ZWO for imaging and guide camera

Was looking at getting ZWO ASI290MM Mini as a guide camera

I am also out couple times per month, with my club, doing presentation in primary schools and scout groups

Using the ZSO app, was also looking at projecting what viewing, using the ZWO ASI 290MC onto screen of tablet, for physically impaired students

Also when public viewing nights, do have people who turn up, wheel chair bound, use the ZWO ASI 290MC that as well

John

 

 

 

[Starwiz]

12 hours ago, cletrac1922 said:

Was looking at ZWO ASI 290MC

You saying can use single ZWO for imaging and guide camera

You can use a single camera as either a guide camera or for imaging, but not both at the same time with the same camera.

You could have the ASI290mm Mini being used for guiding and the ASI290mc used for imaging if you wanted.  I can't see a problem with that, and you could always swap them over if you wanted to try some mono imaging.

John

[cletrac1922]

On 19/07/2019 at 21:43, Starwiz said:

You can use a single camera as either a guide camera or for imaging, but not both at the same time with the same camera.

You could have the ASI290mm Mini being used for guiding and the ASI290mc used for imaging if you wanted.  I can't see a problem with that, and you could always swap them over if you wanted to try some mono imaging.

John

 

John

Last night was out doing Space Badge for one of my local Cubs groups

I like eventually get a android tablet, and project into the screen of tablet, using a ZWO camera

Occasionally have  kids who are physically impaired, and not able to stand with assistance, to view through the eyepiece

Last night was a beautiful viewing night

Using laser, pointed out Jupiter, Saturn, Scorpio, Southern Cross

One of the things kids have to do is locate South Celestial Pole using the Southern Cross

Unlike northern hemisphere, with has Polaris as northern star, do not have same Southern Hemisphere

4.5 times the length of the southern cross, gives you the south celestial pole

Viewed Jewel Box, Southern Cross, Omega Centauri, Jupiter and Saturn  

Demonstrate last night using laser pointer

John 

[Starwiz]

10 hours ago, cletrac1922 said:

 

John

Last night was out doing Space Badge for one of my local Cubs groups

I like eventually get a android tablet, and project into the screen of tablet, using a ZWO camera

Occasionally have  kids who are physically impaired, and not able to stand with assistance, to view through the eyepiece

Last night was a beautiful viewing night

Using laser, pointed out Jupiter, Saturn, Scorpio, Southern Cross

One of the things kids have to do is locate South Celestial Pole using the Southern Cross

Unlike northern hemisphere, with has Polaris as northern star, do not have same Southern Hemisphere

4.5 times the length of the southern cross, gives you the south celestial pole

Viewed Jewel Box, Southern Cross, Omega Centauri, Jupiter and Saturn  

Demonstrate last night using laser pointer

John 

That's great work you're doing!

John

[cletrac1922]

19 hours ago, Starwiz said:

That's great work you're doing!

John

If you ever make it down under

Take you along

I also speak in Indigenous Astronomy, which dates back over 40,000 years

Taught to me by elders, who lived on river bank, where grew up, northern Victoria, when in primary school

They also taught me to read rock art

Which areas are women's business, not allowed down there, and men's business

Some of the rock art also points towards permanent water holes, in arid Australia

Interesting stuff

John