astro cams - low res?

[b16707]

Is it me or as i look at astro cams by companies like ZWO, they start to remind me of web cam tech back in 1998? Do people use this cameras just to show off on little phone screens and not print poster sized art to hang on walls? This is just speaking resolution-wise and not so much the other tech that goes into these things. I must be missing something here with my newbie-ness

[Anthonyexmouth]

they are based on webcam tech. its all do do with the size of the object being imaged. large format sensors like DSLRs are good for big nebula and wider field long exposure, the video cam stuff is for planetary where you take a short video and then stack the frames to bring out detail and scrub the unwanted data. 

[Stub Mandrel]

The resolution is limited by the optics, which needs to be matched to the pixel scale of the sensopr

For planetary imaging, there's no point going bigger than webcam size because even at the largest practical focal length the planet will still fit on a small chip.

Similarly, for deep space images, a sensor size larger than APS-C will be vignetted badly on all but a few special scopes. Using super resolution (like the most recent 48 megapixel sensors) is pointless because (a) the image is resolution limited by the optics not the sensor and (b) you want the biggest pixels that suit your available resolution to maximise light capturing ability for faint objects.

It';s not unusual to 'bin' groups of four (or more) pixels into super-pixels to get better light gathering with a better signal to noise ratio.

[cuivenion]

Hi, these companies also have larger format dslr type sensors as well. 

[Alien 13]

Although it might seem that the resolution is small it does work, the big advantage of a "web cam" type of camera is that you can get many more FPS exactly whats needed for Planetary imaging. I do believe though that pixel sizes need to get much smaller for DSLRs  and I am talking by a factor of 4 or more.

Alan

[Uranium235]

Poster size projects arent just made up of one image - but a series of them all stitched together as a mosaic. So if you have a small chip, but need to cover a large object - just mosaic it.

Bigger sensors with more (or more and larger) pixels produce a wider field of view if used on the same optics, and cuts down the need for mosaics. For instance, on the same optics - an camera with a resolution of 1040x960 is roughly A4 if printed out. While an APS-C type sensor or CCD like the 383L+ which has roughly 3300x2500 pixels (just smaller that APS-C) will produce an image that would just about print on A2.

Going further than that, if you use the large sensor and mosaic it - you end up with images that if printed at pixel scale would easily fill an entire wall.

[johninderby]

Also don’t forget the increase in sensitivity of the newer cameras. It’s not just as simple as resolution. An old Phillips SPC900 was 1.3mp whereas many of the new cameras are much higher.

[pete_l]

1 hour ago, b16707 said:

Do people use this cameras just to show off on little phone screens and not print poster sized art to hang on walls?

The trick is not to get sucked in to the mega-giga-pixel numbers game. 100 DPI is a perfectly usable print density or screen resolution and that will give even a "webcam" type camera a 6x4 postcard.
While there are plenty of big astrophoto targets, there are even more small ones. Something like 75% of messier objects are under 20 arc-minutes in size.

[tooth_dr]

59 minutes ago, johninderby said:

Also don’t forget the increase in sensitivity of the newer cameras. It’s not just as simple as resolution. An old Phillips SPC900 was 1.3mp whereas many of the new cameras are much higher.

And I thought 0.3MP was generous for the webcam ?

I was getting around 2-3 FPS with my Philips webcam, now I get 60+ with these new generation webcam type cameras. 

[sharkmelley]

2 hours ago, b16707 said:

Is it me or as i look at astro cams by companies like ZWO, they start to remind me of web cam tech back in 1998?

For planetary imaging, give me a modern low read noise, high QE (quantum efficiency), high frame rate sensor instead of a 1998 webcam.   Any day of the week!

The read noise is so low they are almost counting individual photons and the QE is so high that we're almost hitting the bounds of Physics. 

Mark

[DaveS]

CCD, CMOS cameras run up from about 6mp to 24 or so mp and pixels from 2.4 to 12 microns. They also have higher quantum efficiancy than DSLR sensors and have two-stage peltier cooling to ~40C below ambient and in the case of SX cameras dry argon filled sensor chambers behind fused silica windows.

As a reference the 2m Liverpool Telescope on La Palma has a camera with 4mp when binned 2x2, and 30 micron pixels. I don't hear many professional astronomers complaining.

Oh, BTW I print A4 from my images, but only because my walls aren't big enough to take many A3+ prints.

[DaveS]

I'll also add, that when people post images on here they expect them to be viewed on full size hi-res monitors.

[Stub Mandrel]

What many 'ground-based' photographers don't realise is that when you have something like the new 48 megapixel cameras, these are great for supa-dupa hi resolution images with short lenses, but are just wasting chip space with telescope focal lengths.

Look here:

https://gizmodo.com/new-super-crisp-images-of-neptune-show-how-far-our-tele-1827683475

This is the highest resolution image of Neptune ever taken from Earth. It required four 8.2 metre telescopes with adaptive optics, and the final image still fits on a webcam chip...

[Stu]

52 minutes ago, Stub Mandrel said:

What many 'ground-based' photographers don't realise is that when you have something like the new 48 megapixel cameras, these are great for supa-dupa hi resolution images with short lenses, but are just wasting chip space with telescope focal lengths.

Look here:

https://gizmodo.com/new-super-crisp-images-of-neptune-show-how-far-our-tele-1827683475

This is the highest resolution image of Neptune ever taken from Earth. It required four 8.2 metre telescopes with adaptive optics, and the final image still fits on a webcam chip...

Impressive stuff! Amazing difference the AO makes. How you correct so well for all the layers in the atmosphere I can't get my head around.

[Alien 13]

1 hour ago, Stub Mandrel said:

What many 'ground-based' photographers don't realise is that when you have something like the new 48 megapixel cameras, these are great for supa-dupa hi resolution images with short lenses, but are just wasting chip space with telescope focal lengths.

Look here:

https://gizmodo.com/new-super-crisp-images-of-neptune-show-how-far-our-tele-1827683475

This is the highest resolution image of Neptune ever taken from Earth. It required four 8.2 metre telescopes with adaptive optics, and the final image still fits on a webcam chip...

There are a lot of people that do use short focal lengths on tracking mounts like the SA, my previous comment about more megapixels was related to this as the current batch of DSLRs/CMOS and CCD have pixel sizes that are too big once you get below 300 mm fl.

Alan

[DaveS]

https://www.firstlightoptics.com/zwo-cameras/page/2/

These are not '98 web-cam tech.

The 2.4 micron pixels of the ASI183 arr a good match for short fl 'scopes and camera lenses.

[JonC]

Probably not trolling, but its an interesting question. It does seem odd if you have been away from the hobby a while that the resolution of some cameras is low, especially if you got caught up with the pixel count race of normal photography. Interesting that some of the latest DLSRs have lower resolutions than the previous generation. I think marketing departments like a single figure that they can wave at the competition, turn it up to 11.

 

PS great thread, the article on Neptune is great.