USB 3.0

[hunterknox]

One for the experts out there. I was just wondering whether USB 3.0 promises greater frame rate cameras, or whether chip sensitivity would become a limiting factor? I'm a solar imager myself, so the promise of something like a DMK41 with 150 fps sounds very sweet indeed.

[riklaunim]

CCDs in DMK31 or 41 can't actually be faster. 30 FPS for DMK31 is acutally more than they can do by public sheet (and doing so causes circular artifacts on planets). High framerate sensors at the moment are nearly only latest CMOS sensors like Sony Exmor line (IMX) or CMOSIS... and I doubt you would use more than 80-90 FPS due to exposure time limiting the framerate (or just use very low gain at lower framerates). Plus you would need a fast HDD to handle the load.

Point Grey - Imaging Products - Flea3 - USB 3.0 Camera - here are few USB 3.0 cameras (only two released). Note that they do have small pixels and rolling shutters (not good if the target is shaking a lot - like due to bad seeing).

As for CCDs there are also GigE ethernet cameras with ICX445 - Basler ace Flächenkameras (18 FPS if USB 2.0 used - PGR Chameleon). There will be also GigE CMOSIS Ace cameras - 2/3" and 1" sensors - 25 FPS for the 2048 x 2048 bigger sensor and 50 FPS for smaller 2048 x 1088 one

[x6gas]

So Rik, you're saying that data transfer isn't a limiting factor on planetary cams? I'd assumed that when image compression kicks in that was because of data transfer limitations...

[E621Keith]

Remember Imaging Sources also make DMK models with Firewire and Ethernet, but their frame rate remained the same, so frame rate limitation is not caused by USB2, but the camera itself.

[riklaunim]

So Rik, you're saying that data transfer isn't a limiting factor on planetary cams? I'd assumed that when image compression kicks in that was because of data transfer limitations...

For planetary imaging 60 FPS is ok. For lunar/solar bigger sensors get very slow on USB 2.0 and that's not ok. So USB 3, GigE is an improvement in that type of solar system imaging

If the CMOS has a global shutter and good performance - should be good at Solar System imaging. Rolling shutters won't like bad seeing. And it seems that USB 3 are only CMOS (as Sony CCDs can't be as fast and take the advantage of USB 3). CMOSIS and e2v sensors do look good

Remember Imaging Sources also make DMK models with Firewire and Ethernet, but their frame rate remained the same, so frame rate limitation is not caused by USB2, but the camera itself.

TIS has ethernet cameras but they aren't GigE cameras - they don't use high transfer rates. They could be faster (100 FPS via GigE for ICX618) but that isn't good for planetary imaging (artifacts).

[hunterknox]

Good points. Thanks Riklaunium!

[Parus major]

I'm going to ask a silly USB3 question - is it possible to fit a USB3 Interface card into a motherboard that only has USB2.0?

[riklaunim]

For laptops - via Smartcard/Expresscard adapter only.

[Parus major]

What about towers?

[riklaunim]

There are adapters you can mount. Check their descriptions.

[stoffe]

On a stationary computer, just buy a PCI-e USB3.0 card to add USB3.0 connectivity to your computer. Check on ebay, they are quite cheap and does the job. There are also combined SATA6 and USB3.0 PCI-e card if you also need SATA6 for a really fast SSD drive to save your data from your camera. It depends how old motherboard your computer have? Check with CPU-Z (downloadable free) what type of motherboard you have if you are unsure.

[Baffa]

I think ZWO are currently beta testing their ASI120MM/MC cameras for USB3. 1280*960 @ 60fps or 70fps in "overclock" mode... nice.. if it works.

[stoffe]

Yes I can confirm that they do that. The new camera will probably be named ASI120MM-S and be a USB3.0 device, I read about it on CN forums. There are already a few cameras out there and currently being tested by real amateur astronomers. But for planetary work, there is no difference with a USB3.0 camera and that already existing ASI120MM camera. It is only when doing lunar or solar photography that uses the whole sensor. In planetary photography I am always using region of interest mode, with 320x240 resolution or something like that.

[NickK]

Hmm exposure time and frame rate. It's possible to have a fast exposure time, resulting a a static image rather than a blurred mess - but - at a low frame rate. Only thing is you miss the interval steps.

The reality is that you *can* do fast FPS if you can grade and reject duff frames on the fly.. as most people's seeing is bad enough. Then you're down to how fast you can process