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zwo asi 174

sooot

By sooot
in Discussions - Cameras

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michael.h.f.wilkinson

michael.h.f.wilkinson

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What often happens is that machine with fast CPUs also have other fast components. This correllation might be one of the causes for your observation. One other point is compression. I am not sure if USB3.0 does this natively, but the camera might have a compression chip on board, and the driver software might have a decompressor. If the decompression is done by the software, then the CPU load will go up considerably.

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JamesF

JamesF

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What often happens is that machine with fast CPUs also have other fast components. This correllation might be one of the causes for your observation. One other point is compression. I am not sure if USB3.0 does this natively, but the camera might have a compression chip on board, and the driver software might have a decompressor. If the decompression is done by the software, then the CPU load will go up considerably.

The data rate for the USB connection may well exceed the throughput to the disk too, and be exacerbated by the disk running at lower speeds (as they often do in laptops).

My suspicion is that the disk will become a bottleneck for many people and act as a limit on capture rate.  Heaps of RAM used as a virtual disk would probably help with that, but you've still got to shift it to disk at some point (hence my desire for large, cheap SSDs :)

James

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rwg

rwg

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I'm fairly sure there is no compression/decompression involved, but the raw data rate is quite enormous - about 450 megabytes per second (or 3.6 gigabits if you prefer it that way). 

If you are capturing raw and just saving to file, there isn't too much data processing - just shuffling bytes from the USB to memory and to disk. Of course only SSDs are going to have a chance keep up with that data rate...

Of course, most people like to actually see what they are capturing, so your capture program will be displaying at least some of the frames that come in on the screen - this might involve de-bayering (for a colour camera), converting to bitmaps, etc. SharpCap 2.5 (beta out real soon now...) has an adaptive algorithm for what fraction of frames are displayed - it will try to pick a fraction that means the display thread is busy at most 80% of the time. This means you get to see a decent frame rate on the display, but it shouldn't lock up the app or make the system unresponsive. I should have an ASI174 incoming in the next few days, so will be able to do any final tweaking when it arrives :)

SharpCap will also buffer up to 50 frames in memory, waiting to be written out to disk. I might need to increase that or make it configurable perhaps.

cheers,

Robin

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Astroboffin

Astroboffin

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Does anybody know what this new. Camera will be like for DSO long exposure work, I realise it is not cooled, but even so, what are your thoughts as an introduction to long exposure, do you think it would out perform a DSLR, apart from the sensor size of course.

:)

AB

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michael.h.f.wilkinson

michael.h.f.wilkinson

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Does anybody know what this new. Camera will be like for DSO long exposure work, I realise it is not cooled, but even so, what are your thoughts as an introduction to long exposure, do you think it would out perform a DSLR, apart from the sensor size of course.

:)

AB

I intend to find out :)

I have seen some pretty nice efforts with planetary cameras on e.g. M57 (OK, planetary nebula, so fitting :D), so it is well worthwhile to give it a shot

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long_arms

long_arms

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I already have the ASI120MC-S and with my relatively new USB 3.0 laptop I have gotten some pretty great frame rates. The bottleneck imo is the Hard disk though. 

At the end of the day would I get this camera if it was USB2.0? Yes. Definitely glad its USB 3.0 though for those ISS chasing moments :smiley: ! 

With regard to deep sky. I took this with my ASI120MM+colour filters. Unguided. Lots of short frames. Through my 200p/heq5. I think it worked quite well. Guided would be better but my guide camera was taking the light frames  :p 
I reckon the ASI174 will be much better for deep sky so I'll no doubt give it a go.  

post-26081-0-46022900-1423503235_thumb.p

Dan 

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Astroboffin

Astroboffin

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£13 duty think ive got lucky

very luck, pay it quick, they obviously have not recorded the true value of the camera, well done ZWOPTICAL....

i have bought stuff before from abroad, for a few hundred pounds, and on the package it said £50 value, wish all suppliers would do that.

AB

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rwg

rwg

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For those wishing to use this camera with SharpCap, I'd recommend updating to the newest build available, which will improve performance and stability.

Right now, the newest build is here : https://drive.google.com/uc?export=download&id=0B7cWKVXZzvOESGNnQ1J4dUFRS0k, which is build 2.5.1311. This contains the latest bug fixes in the SDK from ZWO and a much faster debayer algorithm (so far 8 bit only) which increases frame rates when you have chosen Raw + Debayer preview.

If you are using the camera with a USB3 port on a PCI-express add in card (like I do), you may only see frame rates of up to 80fps. This isn't a camera problem - it is because your USB3 card is almost certainly only using 1 lane of PCI express ('x1' as it is called) and the bandwidth of this is actually less than the bandwidth of USB3. If your USB3 ports are on a laptop or the PC motherboard you are not likely to see this problem. It's possible that this Startech USB3 card will fix the problem as it is advertised as 'x4 PCIe' and claims a full 5GB/channel bandwidth. At the moment, I'm not worried enough about it to spend £70 on a maybe - 80fps will do :)

cheers,

Robin

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Amra

Amra

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I've just received my camera (no duty, yay!) and put it to the test right away.

post-28221-0-51551400-1423762268_thumb.jpost-28221-0-09740300-1423762290_thumb.j

I followed all the software instructions here from ZWO Optical, using the latest FireCapture 2.4 Beta 7.

post-28221-0-84825600-1423762315_thumb.j

In just 35s I'm recording 10GB of data at full 1936x1216 resolution. Getting avg 125-126 FPS with default settings in FireCapture, I assume I'm recording in 12bit ADC so I'm very close to the limit of 128 fps as advertised in the spec sheet.

I've never used FireCapture particulary much, mainly used EzPlanetary for my QHY5L-IIc, so I need to check what I can/should modify in the settings.

Looking forward to putting this camera to a proper first light test when weather allows. ;)

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long_arms

long_arms

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My camera came today also :grin:  

No duty to pay either which was great. 

Works well with my laptop. 

It doesn't come with a suitable lens (presumably because of the larger sensor) so I have only been able to see a dark frame  :embarrassed: (The CS lens that comes with the ASI120's won't focus).

First impressions are extremely low noise even with the gain pushed to the max. Certainly seems better in this respect compared to the ASI120's. 

Finally however it does seem to get warm quite quickly regardless of settings. Sure its nothing to worry about just something I noticed. 

Dan

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Amra

Amra

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My laptop dont write fast enough for my liking. Will swapping the hard drive to a ssd sort that out? Im not too clever with computers, the fps is there but sucks that memory like no ones business

Yes it will if your computer is recent enough to have a SATA3 interface, if it has a USB3 port I'm going to assume it does. You need a decent SSD that has 300 MB/s write speed, preferably a bit more, normal hard drives have no chance getting that kind of throughput.
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Amra

Amra

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Toshiba satellite c855-1TF. it is usb3. Does the ssd replace the hd or is it external? Where would be the best place to get one

It's best to replace the HDD with the SSD and then reinstall the operating system & drivers (or clone the old disk onto the ssd, if you know how.) because your particular laptop only has 1 usb3 port, just like mine. I suppose it's possible to use an SSD externally, but then you need 2 or more USB3 ports and you lose the benefit of having a fast system running the OS of the SSD.

I find great offers on SSDs on ebay from time to time, Samsung EVO 840 are a nice brand that you sometimes find cheaply, I would get a 250GB sized one as a mininum.

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neil phillips

neil phillips

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what kind of exposures, would we be talking about,  at these lightening frame rates ?

 On planets, would the sensitivity be up to it, with scopes in the 10 to 12" Range,

it doesn't sound likely to me. 300 fps would be seriously fast exposure, Any thoughts anyone ?   The moon sounds interesting with this though, especially at slightly lower Focal lengths, and a large scope, those frame rates may well be used

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sooot

sooot

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what kind of exposures, would we be talking about,  at these lightening frame rates ?

 On planets, would the sensitivity be up to it, with scopes in the 10 to 12" Range,

it doesn't sound likely to me. 300 fps would be seriously fast exposure, Any thoughts anyone ?   The moon sounds interesting with this though, especially at slightly lower Focal lengths, and a large scope, those frame rates may well be used

with roi selected i was getting 300fps+ , with full res 126 fps im sure i set the exposure high only had a little tinker . Without upgrading my hdd i cant give exact numbers as it was sucking data like no tomorrow and the fps dropped when the laptop couldnt write fast enough. Ordering a 500gb ssd today so will have a better test when i recieve it tomorrow
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