Altair Hypercam 294C Pro Tec Review
As another astro season descends upon us I have moved onto a new camera! The latest addition to my astrophotography set up is the Altair Hypercam 294C Pro Tec. I have been using this camera a little while now and with various scopes and let me just say it has been a very welcome addition to my kit. Those that have followed me previously will know that I used to use an Altair Hypercam 183C Pro Tec camera, this is a fantastic camera and my reasons for upgrade to the 294 is that I needed a more versatile camera to be a good match with the various telescopes that I use.
First things first though, lets discuss the vital statistics of the Altair 294C ProTec.
The 294C is a colour camera (that is what the 'c' stands for), unlike some other models this one is not available in a mono version. Altair do sell two versions of the 294C though, there is the 'Pro' version which is fan cooled and retails for £675 and the 'Pro Tec' version which is both fan and peltier tec cooled (can cool to -45 degrees below ambient) and retails for £1025.
So for £1025, what do you get in the box?
An Altair Hypercam 294C Pro Tec
A spare desiccant cartridge, Altair state that this shouldn't need to be used in normal use.
USB 3 cable, though I prefer to use my USB 2 cable (more stable!)
2 inch nosepiece
Dust cap for the camera
Armoured case (it looks a lot like a pelican case!)
A power supply for the camera ( I run mine via the pegasus pocket powerbox though)
Personally I went for the Pro Tec version as you can specify a sensor temperature, this is great if you want to shoot your dark calibration frames during the day. The fan cooled version would certainly be a step up from DSLR though, as the sensor inside is attached to a heat sink, with cooler air drawn in to cool it down. A fan helps to keep the temperature more stable and this helps reduce the noise levels in the sensor and would be a help in summer and an even bigger help during winter. However with the fan cooled version there is no way of controlling the sensor temperature and thus dark frames would need to be shot just after your light frames, to ensure they were at the same or similar temperature to your light frames. Most dark frames are ok when they are within 5 degrees of the light frame and as such a fan cooled camera is a definite upgrade from a DSLR.
The Altair Hypercam Pro and Pro Tec cameras both carry 4gb of on board RAM, this is useful when running your camera on something like a mini PC. I personally use a mini PC and connect the hypercam to it via USB2. My Mini PC isn't anything special and thus if my frame transfer speed drops I know that I have got plenty of on camera buffer memory to prevent any dropped frames. I can honestly say that it is a rarity that I get any dropped frames at all, I keep my mini PC bare bones (with only the software that i need on there) and it has had no problems running any of my hypercams.
The 294C uses the Sony IMX294C CMOS sensor, this is a 11.6 Megapixel Back illuminated sensor and carries the Exmoor-R and STARVIS ratings (basically this means it's great in low light, which is what astrophotography is all about right?!). But what does 'back illuminated' mean? Here's a diagram I did earlier:
In short, these back illuminated sensors move all the circuitry to behind the pixel thus incoming light isn't blocked by any sensor circuitry and you get a more sensitive sensor!
The 294C is a 4/3rds size sensor (23.2mm diagonal) and so with my Altair 72EDF Deluxe telescope it gives a much larger field of view than with the 183C.
This means with our rubbish UK weather I'll have to spend less time with doing mosaics of targets. The trade off for this though is that as the 294C has much larger pixels (4.63microns) it is more suited to telescopes of a longer focal length (think 750mm and above). When the 294C is used with the 72EDF images are under sampled, though I haven't noticed any particular negative effects of that in any of my images! Though in the (near) future I will be using the 294C Pro Tec with my Altair Ascent 102ED telescope...so the pixel size will be much more suited to this scope.
I've been using this camera a little while now and one of the positive things I noted is the lack of amp glow, however there is a characteristic sensor glow on this sensor. Different CMOS sensors show different types of glow and on the 294 there is a starburst towards the top right of the image. The starburst gets larger as the exposure time gets longer, however is easily removed with correct calibration frames. I use Astro Pixel Processor and its adaptive pedestal feature to ensure that any glows are removed as much as possible.
The camera also has a heated optical window to stop dew forming. However recently the conditions in the UK have been awful and when running the camera down at -15 I did have one night where the humidity was at 98% and I ended up getting dew on the outside of the camera optical window (I think the anti dew heated window was just totally overwhelmed). This presented itself as a dark round spot in the centre of the image. To cure this I simply warmed the camera up to -10 and the spot went away...I have now continued running my camera at -10 and I haven't had any problems with dew on the window since. That said this spot should never be confused with a frosty sensor, I've heard of other cameras from various other manufacturers getting ice on the sensor but thankfully I have never suffered that with any of my Altair cameras. This is because the cameras are assembled in a protected atmosphere and unless the sensor chamber is opened to the atmosphere (there's a sticker on the side of the camera that states “DO NOT UNSCREW”) there's no way that moisture can get in. In the unlikely event that something catastrophic does happen and moisture gets in, that's where that spare desiccant cartridge would be utilized, almost as a rescue solution...however Altair should always be consulted before resorting to using it.
I've used a few astro cameras now, and so i'm quire familiar with getting them setup for astrophotography with my equipment, but what if you're a new user? Here are a few of my tips to help you get up and running with the 294C.
First things first follow the setup procedure that altair provide with the camera, download the drivers and altair capture etc. Once that is done download yourself a copy of Sharpcap Pro. Altair cameras tend to come with a free one year license, you just activate it after plugging the camera in and starting up sharpcap. Then in sharpcap set the camera to RAW 14 and run a sensor analysis (in the tools menu), this will allow you to have a look at the characteristics of your particular camera. You'll end up with a graph and a table. So here's the graph for my camera, unity gain is around 391 (unity gain is where the e/ADU =1). I run my 294 at unity gain all of the time.
Then next time you're out imaging and all focused and ready to go with whatever filters takes your fancy in the imaging train...point your scope at a dark bit of sky ( I tend to use the area around polaris), open up the histogram tool and then click on the brain. This is the smart histogram tool and will give you the best settings for your camera and whatever set up (telescope, filter etc) you happen to be using on the night. My preferred imaging control software is Astrophotography Tool (APT) and so I just transfer the recommended settings from the smart histogram tool in Sharpcap to APT. There's also a HCG (high conversion gain) mode for the 294C sensor. HCG mode enables you to keep the read noise lower at higher gains whilst preserving high dynamic range. I tend to leave HCG mode disabled when running at unity gain, however I would enable it for the best results if I were to ever use the camera at 900 gain and above.
Calibration files are also a must with this camera, darks are not optional and should match the light frames exactly...so that means exposure time, gain, temperature and black level/offset. I also use flats that I create using the flats aid tool in APT (aim for around 8000ADU in APT or if using Sharpcap make sure the histogram is around 45-55%). I don't use bias frames with this camera and I would recommend the use of Dark Flat frames instead. Dark flats are simply flat frame exposures, but with the cap of your scope on instead. I use 30-50 of each calibration frame type.
I use a couple of filters with the 294C (and whilst I had it, the 183C) to great effect. I live in bortle 6-9 skies and I find the SkyTech L Pro Max is a great broadband filter for galaxies and reflection nebulas (such as the Pleiades) and I utilise the Altair Triband filter for emission nebulas. Obviously when using the triband filter my exposures need to be longer and the best exposure length for my setup plus the triband filter is acutally 248s.
To sum up my thoughts on the altair 294C camera:
Its a great all rounder camera for various focal lengths, though more suited to longer ones
The larger field of view is a bonus to me
There's little to no amp glow and even the star burst isn't massive.
I really like the TEC cooling and how it means I can shoot my darks whenever I like.
I like the camera a lot!
Here's a few images from the Altair 294C Pro Tec:
And if all of that is too much to read, check out my video below!