ZWOI174 versus DMK41AU02.as

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solarmax2016
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ZWOI174 versus DMK41AU02.as

Post by solarmax2016 » Wed Feb 10, 2016 3:23 am

I just lost operation on my DMK41AU02.as (presumably burned out from over-heating in direct sunlight) - a good reason to always baffle video cameras from sunlight! I'm forced to buy a new
camera unless someone can fix it (Imaging Source is reluctant to do so). The sensor size in the
ZWO is nearly as large as the DMK41 but its pixel size is less 5.86 micromm versus 4.65 micromm
in the DMK. The ZWO has a better heat sink arrangement (its finned) whereas the solid body of the DMK has no heat sink (mine got hot to touch at times). Also the CCD (in the DMK) is always better
than a CMOS sensor (in the ZWO). The price is nearly equivalent.
In addition the ZWO is reported to be subject to Newton Interference Fringes - I never noticed any with my DMK as long as I stayed away from a normal Barlow (a 2X nosepiece Barlow in front of the DMK seemed to avoid this). Comments on this would be appreciated..........

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Re: ZWOI174 versus DMK41AU02.as

Post by _Zakalwe » Wed Feb 10, 2016 4:30 pm

Im not sure that it's fair to say that CCD will always be better than CMOS. Many planetary imagers felt the same way when the newer CMOS sensors came on the market, but the majority are now using CMOS.

Yes, there can be Newton Rings with the ZWO, and banding. I found them to be very troublesome when using a Quark and non-existent when using my Lunt L60. I cured them by using a Rowan Astronomy tilt adapter: http://www.rowanastronomy.com/productsa4.htm#adaptors
Image

Flat before the tilt adapter:
Image

Flat after the tilt adapter:
Image

One thing to consider is your USB and hard disk sub-systems. The ZWO 174 camera requires USB3 and can be a bit sensitive to cable lengths. USB2 will throttle the speeds massively. You will also need a SSD to get the top frame-rates. I tested mine on a 7200 RPM HDD and found that it stuttered and caused Firecapture to drop frames and crash. I also tried a 7200RPM external USB3 hard disk connected to the same USB3 card and that couldn't keep up.

You will be very pleased with the massive increase in frame-rates as long as your PC sub-systems can keep up with the camera. The large sensor size and high rates makes Lunar mosaics almost too easy, if that's your thing. It also makes solar work a joy....you will be getting about 100 FPS using the full sensor area.

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Re: ZWOI174 versus DMK41AU02.as

Post by solarmax2016 » Wed Feb 10, 2016 5:36 pm

Thanks for your good assistance. I use my Solar imaging equipment in a full dome observatory ( I design them for clients). because of this, the ambient air temp is really high (reflection inside the dome) and any camera I've ever used gets hot - too hot - even if shielded. I would like to try the Orion StarShoot G3 that
is on sale now but they cannot tell me if it performs well in H-alpha solar work. It is a TEC cooled camera.
I'm not going to use an un-cooled camera any more - burning out a really good DMK41! - I also use a Skyris247 that performs well but it too gets a little warm - I wrap a gel cooled small balloon around it in a tennis band that keeps it cooler. Is there a good design for a home-built heat sink or cooler that would be suitable for the Skyris 274?
I would like to get the cooled ZWO174 mono but as you say it won't perform well on a USB 2.0 connection. I refuse to budge from my Windows XP Professional for camera operation - I don't like any of the newer
Windows programs and I still use a Skynyx 2.0 which is super-sharp that only operates up to Windows XP.
Have you any ideas on the Orion Star Shoot G3 - it looks well-made and its a deal right now.

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Re: ZWOI174 versus DMK41AU02.as

Post by _Zakalwe » Wed Feb 10, 2016 5:49 pm

John,

No, Ive no experience of the Orion at all.

To be honest, you are really limiting your choices if you are sticking with USB2. Unnecessarily so, in my opinion. XP is a dog of an OS and it's nearly 16 years old.

You might want to consider the new range of cooled ZWO cameras?:
http://astronomy-imaging-camera.com/pro ... d-cameras/

http://www.cloudynights.com/topic/519359-asi174mm-cool/

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Re: ZWOI174 versus DMK41AU02.as

Post by marktownley » Thu Feb 11, 2016 7:04 am

If you don't want to update the pc side of things with connections you are going to struggle with the modern cameras.

Have you thought about the PGR GigE cameras?
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Re: ZWOI174 versus DMK41AU02.as

Post by _Zakalwe » Thu Feb 11, 2016 9:15 am

The Orion is a pretty old design (at least 4 years old). That's not to say that it's a bad camera, but things do move pretty fast in this area, so there are definitely better options available now.

I'd really recommend addressing the PC side, if for nothing else, to get access to large avi file sizes and NTFS.

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Re: ZWOI174 versus DMK41AU02.as

Post by marktownley » Thu Feb 11, 2016 10:00 am

I have to add that comparing my DMK to my PGR, the DMK is really, really noisy compared to the PGR, DMK is old technology now and it shows IMHO...
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Re: ZWOI174 versus DMK41AU02.as

Post by Astrograph » Thu Feb 11, 2016 11:47 am

Just to add,


The IMX174 chip used in the ASI174 is a very good chip and to use it at its full 1920x1200 resolution will require USB3.

Using a small ROI you might get away with USB2 but I doubt it. Even with a modern Laptop and USB3, you will find that for solar capture, programs like Firecapture have difficulty with 16 bit imaging and a non SSD HDD will not keep up with the data stream from the camera. My laptop has an upper limit of about 500 frames flat out with an IMX174 at full resolution before the memory buffer calls time.

USB3 is also a bit variable when it comes to power and cable length. 3m or even 2m is really the maximum with 'normal' cables unless you opt for a high end industrial cable.

We have also found that the power available on USB3 sockets may not be enough to run the camera properly. As such when we supply a PGR camera, we supply a USB cable with a second 'power only' USB plug so this can take extra power from the PC. The PGR cameras also have a GPIO connector which allows a clean separate power source to be connected. Apart from anything else this clean power improves camera performance still further.

The high frame rate and need to preferably capture in 16bit really does place a lot of demands on the capture software. Because of this we bundle PGR Mono cameras with Genika Astro. This is designed specifically for high speed 16bit applications. It is normally 70€ to buy this software.

If you are using a laptop with WinXP then although the OS is fine, it is likely the hardware of your PC will not support any of the latest chipsets. Obviously you don't have USB3 but I imagine if you have a wired ethernet port then this is not gigabit, and if it was, would not support Jumbo frames. Gigabit ethernet is a halfway house in terms of data speeds compared to USB2 and 3 and many cameras use it. The PGR Blackfly with IMX249 sensor effectively has an identical sensor to the IMX174 but it is designed to run slower, so its max frame rate at 1920 x 1200 is 1/4 of the IMX174. However this is still fast for such a big sensor and faster than any USB2 camera can offer.

In brief, replacing your Imaging Source camera with either a ZWO or PGR (which I think are far superior) USB2 camera would offer you an upgrade, but choosing a USB3 camera, even though it will run, will be restrictive and you won't realise all the benefits the camera has to offer.

Personally I would opt for the USB2 version of the ZWO ASI120 which is £160.00. This represents excellent value and will work well on your PC

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Re: ZWOI174 versus DMK41AU02.as

Post by christian viladrich » Sat Feb 20, 2016 2:33 pm

Hi,
Just a quick input, there is no need to use 12 bit-acquisition on the sun, and also on most on the usual targets (moon, planets).

The two only cases I know where we can make a difference between 12 and 8 bit acquisition is moon earshine :
http://www.astrosurf.com/viladrich/astr ... ndree.html
and corona imaging during solar eclipse.

This been said, the IMX174 is really an excellent sensor for solar imaging, but requires USB3 and a SSD.
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Re: ZWOI174 versus DMK41AU02.as

Post by Astrograph » Sat Feb 20, 2016 4:05 pm

Dear Christian

I have to disagree about the 12 bit acquisition on the Sun. One area where 8 bit shows up is around the limb where banding effects can be easily seen. For planets the benefit is debatable because of the low brightness but for solar, it does improve image quality.

Regards

Rupert
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Re: ZWOI174 versus DMK41AU02.as

Post by christian viladrich » Sat Feb 20, 2016 10:04 pm

Dear Rupert,
It is very strange you've found differences between 8 and 12 bits acquisitions. What camera did you use ? It is in Ha ? Do you have an exemple of this banding effect ?
I've made extensive tests with a number of cameras (Skynyx 2.1M, IDS3370, Lumenera LT435, AVT Manta283, Basler 640, Basler 1920-155, Basler 1400), I've never seen any hint of difference between 8 and 12 bits, even on solar prominences.
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Re: ZWOI174 versus DMK41AU02.as

Post by Astrograph » Sat Feb 20, 2016 11:38 pm

Hi Christian

I will try to dig out some examples. Failing that I will take some new test images as I don't normally shoot 8 and 16bit and keep the bad stuff! These days I only image using PGR cameras which in terms of noise and dynamic range I just find a lot superior. Maybe the low noise contributes to the banding being visible.

It may take some time to post. The weather is not looking good here for the next week at least!

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Re: ZWOI174 versus DMK41AU02.as

Post by marktownley » Sun Feb 21, 2016 10:20 am

I've seen the banding you're talking about Rupert when the gamma is adjusted from neutral on the PGRs. Doesn't bother me at all as I never adjust the gamma! :D
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Re: ZWOI174 versus DMK41AU02.as

Post by Astrograph » Sun Feb 21, 2016 12:40 pm

I find adjusting gamma a way to extract a bit more from different features. As a rule lower gamma tends to make the chromosphere pop a bit more and higher gamma teases out a bit more from a prom.

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Re: ZWOI174 versus DMK41AU02.as

Post by GuillermoBarrancos » Mon Feb 22, 2016 7:49 am

Astrograph wrote:I find adjusting gamma a way to extract a bit more from different features. As a rule lower gamma tends to make the chromosphere pop a bit more and higher gamma teases out a bit more from a prom.
I have the exact same with my QHY5L-IIc camera. That is exactly my workflow.

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