Dom543

DoctorD, Your post suggests that the Atik Infinity has a better sensitivity than the SX Ultrastar and more comparable to the sensitivity of the Lodestar. Is this the general concensus about the Atik Infinity? Based on the fact that the Infinity and the Ultrastar are using the same ICX825 sensor, I thought that their sensitivities were comparable. Does the Infinity have additional gain circuitry or is it known how does Atik bring out more sensitivity from the same sensor? I wasn't able to log in frequently and follow these forums in the past few months. If there was a discussion of this, then I apologize for asking this question again but I have missed that discussion. Thank you, --Dom

Great job Don and great service to the community! --Dom

After some more use of the SX-825, I would like to qualify some of my earlier statements about the sensitivity of the camera. This update is not a departure from my earlier assessments, just makes them more precise. Based on my personal experience with the SX-825 and Lodestar x2 cameras by using them for real-time electronically observing out under the skies (i.e. NOT in a scientific laboratory with an optical bench), I assess that the sensitivity of the cameras compares as follows. 1.The sensitivity difference between the SX-825 mono and the Lodestar x2color corresponds to approximately 2/3 of photographic stops. This means that, with all other things equal, exposure times for the SX-825 should be increased by a factor of 1.6 from those used with the Lodester x2c. 2.The sensitivity difference between the SX-825 mono and the Lodestar x2mono corresponds to approximately one photographic stop. This means that with all other things equal, exposure times for the SX-825 should be increased by a factor of 2 from those used with the Lodester x2m. As said, this statements are not based on scientific grade laboratory measurements. Just on about one month's of personal experience of one amateur. Clear Skies! --Dom P.s. By the way, this thread continues with more SX-825 captures posted here http://stargazerslounge.com/topic/250718-wide-fields-and-tiny-stars-with-sx-825/.

Hi All, Thank you for the positive comments and likes. Unfortunately no clear nights since the last images taken. Rob: Unfortunately, in Seattle with a straight view of downtown, a narrowband filter is a must. I wish, I could go to a dark site but that's over 100 miles here and work keeps me in the city. Chris/Macavity: 16 bit is standard for imaging and the SX-825 is meant to be an imaging camera. By the way the Lodestar also has 16 bit data paths. LodestarLive saves FITS files in their original 16bit format but the png files are 8 bit, I believe. I state the 16bit feature because some vendors are marketing (possibly modified) Chinese microscope cameras for EAA/video astronomy and they are only 12 bit. 12 bit electronics is cheaper and downloads are faster. But I don't feel the 16bit downloads to be a bottleneck at the SX cameras. Karl: Unfortunately, I am not set up for broadcasting or being video recorded. I am also in a crunch as I will have resettle to the East coast for the next 4 months at the end of August. So I am trying to do as much observing as possible on the few clear nights that we have here in Seattle and keep my life and setup as simple as possible. By the way, there is not much difference between using the Lodestar or the SX-825 with LodestarLive. This was one of the main reasons I was interested to have another SX camera. Atik may do a good job of imitating LL but it will still be a different interface. Regarding the lines, they are vertical and only look horizontal on rotated images. I haven't had enough observing opportunities to recreate them and hence I don't know their cause. They seem to appear only randomly. The next thing I will try is to use darks. Initially I was happy that darks were not a must for stacking to work and that hot pixels were so few and tiny. But darks may correct also other sensor anomalies, if that's the cause. Martin: I don't have quantitative information on read noise. I am sure that one could find some info on the SX website or user groups or on the Sony datasheet. I take a somewhat fatalistic view of numbers: What would I do, if I knew the read noise was 4e-7? Would I snob the camera? I don't try to second guess the good people at SX if one could do better with the same sensor. I certainly couldn't. But I could see that this info may be of interest, if one stacks many short exposures. Finally, I would like to acknowledge and thank for Paul's foresight of incorporating the progressive scan code into v.012 and having built LL in such a way from the beginning that it is not hard wired to the Lodestar sensor and output. Will the new version, that works with virtually all SX cameras be called StarlightLive? SX should pay for that! Clear Skies! --Dom

Below are the only two higher power captures made with an SCT that I have at this time and that are, at least marginally, presentable. I am not proud of them because both tracking and focusing was lousy. But that was the first night with the camera and the fast moving 70% cloud cover was particularly annoying. Both are the Crescent Nebula taken with my Meade 10" SCT focally reduced to about f4 and with a 7nm H-alpha filter. The first one is 5x30sec exposures mean stacked and with the linear DR mapping option of LodestarLive. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_309233.jpg. The second capture is 4x60sec exposures again mean stacked but with the nonlinear x^0.25 DR mapping option. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_353719.jpg. I included both captures as they illustrate well the difference between linear and x^0.25 non-linear DR mapping. The linear is crisper but the non-linear is showing more faint detail. (The contrast is best seen on the full resolution images.) This is because the fourth root mapping (x^0.25 stands for the "square root of the square root" ) strongly enhances the graduation of faint detail and slightly suppresses bright areas. Compare this to the other non-linear mapping option used in post #2. Arsinh maps faint detail the same as linear but strongly suppresses the brightest areas. x^0.25 strongly enhances faint detail and reduces bright areas only slightly compared to the linear option. Clear Skies! --Dom

In this post I include a couple of upright images from areas North of the wings of Cygnus made with the SX-825 mono. All are taken from Seattle with the 300mm f2.8 old manual Nikkor lens, 7nm H-alpha filter and all are 5x60sec mean stacks. First the Pelican with its fluffy white feathers. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_617419.jpg Next the Elephant's Trunk from the huge Rose of the North IC1396 in Cepheus. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_6263.jpg I like the co-existence and intersaction of stars and nebulaosity on this images. It shows the stars on the shoulders of the trunk, whose radiation winds blew away the nebulosity and crated the trunk. The image could be used to demonstrate students how elephant's trunks are created. Finally, after all this heavy science stuff, the funny face of the Pacman with its cool hairdo. This is a crop from the full size image, so no links are needed. Clear Skies! --Dom

Here are a few captures with the SX-825. All images included on this tread are reduced to about 30% of their original size and resolution. To appreciate the benefits of the HD resolution offered by the camera, please look at the full-size captures at the included links. First two renderings of the Eastern Veil with the Witch's Boom flying at the top. The optics is a 300mm focal length Nikkor camera lens at f2.8 and using a 7nm Baader H-alpha filter. Both are 5x60sec exposures mean stacked. The first one is with linear dynamic range mapping and the second one with non-linear (arsinh) DR mapping. Here is the link to the full-resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_425472.jpg Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_752032.jpg The brightness was intentionally be kept muted as this shows the finer details better. In full resolution one can almost feel the light breeze blowing the thin lace of the veil. A side benefit of looking at these two images is that they demonstrate well the effect of non-linear DR mapping. Arsinh mapping renders faint detail similarly as linear mapping but compresses, and hence tones down, the brightest parts of the image. This is well demonstrated on the annoyingly bright star above the Witch's Broom and also on other brighter stars. If we are at the Veil, here is a capture of its Western part, also called the Network Nebula Same optics, filter and exposures but only with linear DR mapping. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_711731.jpg The Veil is also rich in other emission spectra. Here is the western Veil with an S-II filter from a different night http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_83532.jpg A nearby neighbor of the Veil is the Foxglow Nebula in Vulpecula. The same 300mm f2.8 optics with the same H-alpha filter and 5x60 sec exposures as for the captures above. Here is the link to the full resolution file http://stargazerslounge.com/uploads/gallery/album_3893/gallery_26379_3893_60508.jpg This capture illustrates well the benefits of the anti-blooming circuitry of the SX-825. Stars are nice tight and even though this nebula is in a star-rich area, the stars show but don't overpower the nebulosity. By the way, I didn't know that this nebula also had a large elephant's trunk. It might be worth revisiting it once with the higher power SCT. Clear Skies! --Dom

In a change from the pre-announcement / speculation threads, I am reporting here about something that is available and proven to work. I received the SX-825 mono camera about two weeks ago for a 30 day no risk trial. As I am in Seattle, there were only four nights, when I could actually use it. Even in those cases I had to dodge fast moving clouds and look through low transparency, moisture filled air. I start with an overview of my experience and then include a few captures. When I make comparisons, the base is always my Lodestar x2c, which is also made by Starlight Xpress and which I have used for over a year. All assessments are my personal judgements based on my own limited experience. Any numbers included are approximates. Please note that due to file size limitations and disk space quotas, I had to reduce the file size of the images to less than 30%. At this reduction the resolution advantage of the camera disappears. To properly judge the capabilities of the camera, please look at the full-resolution images at the gallery links provided. Camera and Availability The full name of the camera is "Starlight Xpress Trius SX-825" monochrome version. The one in my hands is serial #006. This is a progressive scan CCD camera using the Sony ICX-825ALA ExView HAD sensor with TEC, binning capability, anti-blooming circuitry and full 16-bit data paths. This is the newest member of the company's SX-9 line of purpose-built astrophotography cameras. It can also be used as a guider and, as my current post purports to demonstrate, for near-real-time observation. For more information about the camera please peruse the SX website at http://www.sxccd.com/sx825 and http://www.sxccd.com/trius-sx9. The SX-825 mono is listed as "in-stock" by at least one US retailer for $1629 http://www.highpointscientific.com/telescope-accessories/astro-photography/ccd-cameras/starlight-xpress-trius-sx-825-mono-ccd-camera-usb-hub. The price is comparable to that os other TEC cooled cameras used in video astronomy and, on a $/MP basis, even cheaper than the Lodestar. The SX-825 is also sold as part of an astrophotography kit that also includes a Lodestar x2 and a USB mini filter wheel and OAG for $2268. At this package pricing the filter wheel is included for essentially free. I have not checked pricing and availability at other retailers. Software The camera comes with two software disks. One containing the drivers and the other the SX software for all Trius cameras. I have not had a chance yet to install and try out this software. I am using the SX-825 with Paul Shear's free LodestarLive software that I have also used for over a year now with my Lodestar x2c for electronically assisted real-time observing (a.k.a. "video astronomy"). I am happy to report that the popular LodestarLive works flawlessly with the SX-825 and provides all features that have been available for users of the Lodestar cameras. These include - Full and unlimited exposure control, - Histogram with brightness, contrast, black point, white point sliders and with linear or non-linear dynamic range mapping, - On-the-fly dark-frame subtraction, - Excellent registered real-time stacking in selectable sum, mean or median modes, - Synchronized or independent color channel control, color saturation and hue sliders for OSC cameras, - Alignment, framing and focusing tab with focus assist, that can be used while preserving and existing live stack, - Automatic saving of all captured frames in FITS format for possible post-processing. LodestarLive is a continually growing and expanding product that sets the standard and represents the leading edge of real-time (live) astronomical observing software. Progressive scan cameras require LodestarLive v.0.12 or higher and, at the current time, the use of command-line parameters to connect to the SX-825 camera. I am using a test build that Paul has sent me on a one-day turnover that also allows to log information that he can use for further development. Paul has posted on another thread that the automatic recognition of the various higher end SX cameras, including the Ultrastar and SX-825, will be included in the next release of LL. In that case no command-line arguments will be needed. Resolution and Field of View The ICX825 sensor includes a 1392x1040 array of 6.45 micron pixels on an 8.8x6.3mm area. For comparison, the ICX829 sensor of the Lodestar x2 has 752x580 pixels of 8.6 micron size on a 6.5x4.8mm surface area. Roughly, the ICX825 has four time more pixels on a sensor of 35% larger diagonal size (80% larger area wise), as compared to the ICX829. It offers near HD resolution with a 35% larger (angular) FOV (80% larger area), than the Lodestar and other 1/2" sensor cameras. On a practical example, this means that the SX-825 on a 11" SCT will provide approximatively the same FOV as the Lodestar on an 8" SCT at the same focal ratio. The HD resolution advantage is largely lost, when comparing images reduced to customary internet post / NSN broadcast sizes. To properly assess the difference please look carefully at the full size, full resolution captures linked to the reduced size images posted below. You can also compare them to the Lodestar captures in my "Lodestar Widefield" SGL gallery. There were taken with the same optics by the same person with the same skills. The difference is only in the cameras used. Sensitivity My personal judgement is that, in photographic terms, the sensitivity difference between the Lodestar x2 and the SX-825 is equivalent to about 2/3 of a stop. A 2/3 stop increment sequence in the range used for EAA is 2.0 - 2.5 - 3.2 - 4.0 - 5.0 - 6.3 - 8.0 - 10... What I am saying is that, based on my limited experience, at identical exposure times and other settings, the SX-825 yields an image of comparable brightness to that of the Lodestar used with optics that is one step slower on the above ladder. This is the same as saying that an additional x0.8 focal reducer would compensate for the sensitivity difference resulting from the smaller pixel size of the 825. To put it differently, using the same optics and settings, exposure times needed to be increased by a factor of 1.6 for the SX-825 to provide an image of the same brightness as the Lodestar x2. After torturing you with all these numbers, I have to say that, in my simplified world, I have almost always used 30sec or 60sec exposures with the NB H-alpha filters for extended nebulae with my Lodestar x2c. And I keep using the same 30sec or 60sec exposures for the same objects with the SX-825 but I push up the contrast and brightness sliders a little bit. I was very pleasantly surprised that I can use the same exposure times and still get the higher resolution. (If 30 and 60 second exposures sound long, please keep in mind that I use 7nm narrow-band filters to fight the light pollution of my location. Well Depth and Anti-blooming The camera is equipped with sophisticated anti-blooming circuitry and the ICX825 sensor has greater well depth than the ICX829. The purpose of this is to prevent overexposed pixels to overflow into neighboring pixels and make from one overexposed pixel a whole blob of overflown pixels. Apart from the higher resolution, in my opinion, this is the second most significant improvement that we get from the SX-825. The reason is that to achieve sufficient brightness of images in near-real-time, we basically overexpose the sensor in EAA. (Grossly overexpose by standards of astrophotographers.) The SX-825 yields much tighter stars and prettier star fields than earlier generation cameras used for EAA. One can notice this especially well on the wider field captures made with the shorter focal length (<300mm) optics. Please feel free to compare these with the captures made with the Lodestar that can be found in my "Lodestar Widefield" gallery. Tandem Operation with Lodestar An SX-825 and a Lodestar can be operated simultaneously, each of them connected to separate copies of LodestarLive running on the same computer. This makes it possible to have a high detail view through the main telescope and a wide-field "context" view through a piggy-backed smaller scope and display the images side by side and the two cameras controlled by the same computer. The only thing to keep in mind is that each copy of LodestarLive stats up with the settings that were saved at the most recent shut-down of the program. E.g. in my case, if I shut down the SX-825 first and the Lodestar x2c later, then the next time, when LL starts, it will have the OSC box checked. The mono SX-825 would produce funny striped images until I uncheck the OSC box. But nothing gets harmed and, once all settings are made to correspond to the connected cameras, everything works fine. Defective pixels and Dark Frames This is an area, where I have not had the chance to do as much exploration as I wanted, due to the very limited observing opportunities. Starlight Xpress states that, when TEC cooled, this camera doesn't need dark frame subtraction. I have yet to turn the TEC on. But even uncooled, I noticed that there are very few hot pixels, less than 10 out of the 1.5 million. Moreover, the hot pixels are tiny and much less noticeable in the huge array then they were with the ICX829 based Lodestar. One of the consequences I noticed was that these tiny hot pixels are not confusing the stacking algorithm by being mistaken for stars. Hence stacking is possible even without dark frame subtraction. This made me lax and, in my hurry to use the quickly disappearing opportunities to shoot through swiftly moving windows through clouds, I skipped dark frame subtraction on several nights. This is not something I would recommend to do, as dark subtraction also corrects for sensor artifacts other than hot pixels. Astrophotography Option This current post is from the perspective of someone, who has used cameras only for electronically assisted real-time observing. But who has also looked with envy at the beautiful artwork created by astrophotographers. The SX-825 has been designed to be an astrophotography camera. As such, even if it is used primarly for real-time observing, it offers a readily available path for its owner to move in the direction of or experiment with astrophotography. In fact, LodestarLive can save all captures in FITS format. After the live observing session is over, one can just keep the camera running unattended and, after a few hours, have a substantial collection of subs ready for post processing. This possibility of moving between real-time observing and asrophotography is a option offered by the full-featured SX-825 but not to the same degree by its downscaled junior brothers. Physical Camera Attributes I left this to the end, as these are perhaps the least interesting details. The SX-825 comes in a ribbed cylindrical aluminum housing of 75mm (3") diameter and 70mm length. It has an internal fan and also an optionally engageable external fan. According to SX, the purpose of the external fan is to keep the temperature of the camera housing close to environment temp. The back of the camera has several connectors for guiding, active optics and all kinds of other options. I used only the main USB connector, which is a very solid full-size (not mini or micro) "Type-B" USB socket. Due to the built in TEC and the fans, the camera also needs 12v power. It is not powered solely through the USB connection. An AC adapter and all needed cables are included. The SX-825 attaches to the optics through a (female) T2 thread on a collimatable collar. The flange to sensor distance is about 16mm. Both of these are significant departures from the Lodestar's C-mount and 12.5mm flange to sensor distance and require different spacers and adapters. The camera comes with both 1.25" and 2" nosepieces threaded for corresponding filters. The 2" nosepiece also has an M42 screw mount thread and the correct length to achieve infinity focus with Pentax screw mount camera lenses. Summary - The SX-825 combined with the free LodestarLive software is a readily available and proven to work. - Offers all familiar and easy to use real-time live observing capabilities of the Lodestar with LodestarLive, - LodestarLive is an established, widely used and proven artwork of software to which new capabilities are continually added, - Has 1.5 MP near HD resolution, yielding detail not seen before in real-time EAA, - Has sensitivity allowing the same or only marginally (~1.6x) longer exposures (compared to the Lodestar), - Has anti-blooming feature yielding nice tight stars and star fields, - Offers transition path to post-processed astro-imaging, - Can be used simultaneously with a Lodestar operated from the same computer. Sample captures will follow in separate posts. Please feel free to ask any relevant questions. Clear Skies! --Dom