Planetary cameras and equipment for 2016

2016-03-07

Every year I try to summarise the hardware, camera market for Solar System imaging. This year I was holding this article back a bit to see what will happen with the new cooled ZWO cameras.

So what happened in 2015, and what interesting things await us in 2016? What are the best camera options?

2015 events

New generation of Sony CMOS sensors

At the start of 2015 the top shelf was occupied by IMX174 based cameras while the lower ones were held by ASI120 and QHY5L-II. Quite quickly we got AS224, a color camera that likely wasn't a hot topic before it actual performance was tested on planets. Record breaking low read noise combined with high sensitivity made it not only number one among color cameras but also number one for Uranus and Neptune imaging in infrared. Monochrome sensors were beaten, aside of maybe UV imaging. It was ASI224 that gave us a lot of Uranus and Neptune images with bright storms or cloud bands visible.

Uranus and Neptune imaging are hardware limited - the features contrast increases in infrared while amount of light we can get with deeper and deeper IR filters decreases. Low read noise and quite high IR sensitivity of IMX224 allowed to push the limit way further than with previous sensors. Other new cameras, like IMX174-based were used too.

Later on we got new mono sensors - IMX178 and soon IMX290 (mono version listed by QHY) as well as successor to IMX174: IMX265, IMX250 and IMX252 in Point Grey cameras. All of those sensors offer lower read noise than predecessors as well as high sensitivity.

Affordable cameras

ASI120MM and QHYL-II prices varied around 230-280 EUR with occasional discounts. The Micron/Aptina sensors are still pretty good, especially for that money. Compared to newer Sony sensors we have more fixed pattern noise (FPN) which may be easily noticeable if we use longer exposures and higher gain (like for methane band or UV imaging).

Success of those cameras brought the attention of other vendors, like Touptek Photonics that made a QHY-alike clone camera that is now available as Altair Astro GPCAM, Opticstar PX-125C or Mallincam AG. In general those clone cameras were cheaper than ZWO/QHY cameras by like 20-40EUR at start. The disadvantage is that Touptek cameras aren't supported by FireCapture (but are supported by SharpCap and its own custom software).

In 2016 we will see new cameras fro alternative vendors that will try to squeeze in on the market with better pricing. There may be some older sensors on a discount giving many options for cheap planetary cameras.

The dawn of CCD

When Sony announced discontinuation of CCDs the Solar System cameras were already on CMOS chips. Even ICX639 and ICX692 in cheap Blackfly cameras, successors to ICX618, got little to no attention from planetary photographers. Modern CMOS sensors are just faster, usually cheaper and offer lower read noise than a CCD. This was a perfect match for Solar System imaging, however DS imaging won't do it so quickly.

In 2016 and maybe even in the next years we may still see some CCDs. Sensor stocks may be cleared which may open a path to short batches of CCD-based planetary cameras. Such cameras will rather target low prices, similar to ASI120MM or QHY5L-II to be viable (ICX618, ICX445 and alike).

What awaits in 2016

Smaller and smaller pixels

IMX178 has 2.4 micrometer pixels. IMX290 has 2.9 pixels, while 3.75 is becoming a big pixel size. As mass markets usually want more pixels on a smaller sensor we will see more and more small pixels. Some big pixels will still be there from time to time, but it may happen that the best technology and performance will got to the small pixels that are high on demand.

Small pixels aren't bad but they can be a problem to use with some telescopes. ASI178 will be at optimal f/ratio with a f/14 Maksutov and likely will be often use without a Barlow with a f/10 SCT. Even smaller pixels will require either focal reducers or Newtonians with fast f/ratio.

A small pixel and a big pixel, both at their optimal f/ratio will in general behave in the same way. The seeing, mount shaking and other factors like that will have the same impact on the image. There is no difference. What does change is the well depth that is smaller for a small pixel which may indicate a smaller dynamic range, but that may not be the case as smaller pixels also have smaller read noise. IMX178 has so small read noise that his dynamic range is higher than that of IMX174.

Universal cooled cameras

QHY has cooled miniCAM5s and miniCAM5f while ZWO has several models based on IMX174, IMX178, IMX185 and IMX224. Those cameras are meant to be universal - for DS and Solar System imaging. Before cooled IMX174 came out it was speculated it will be better than for example ICX285AL in Atik 314L+. When it came out it turned out that CMOS sensors are very different from CCD. Existing cooled ZWO cameras with Sony CMOS sensors are limited by amp glow and they can't do few-minute exposures without severe amp glow noise. It may be hardware limited in QHY cameras and future ZWO cameras but at the moment it's not feasible to do long exposures with CMOS based cameras.

On the other hand very low read noise makes very short exposures work for DS imaging, eve one-few seconds exposures and many hundreds or thousands of frames. This also can allow skipping guiding setup for DS imaging so it makes everything cheaper.

New imaging makes DS stacking with DS imaging applications harder. Some photographers have problem with for example DeepSkyStacker, that isn't always able to align under-exposed frames or handle random horizontal noise. However planetary photographers have come with their own software for that - Autostakkert2 can stack as well as remove horizontal banding.

Small pixels limit telescopes that can be effectively used for DS imaging. With 2.4 pixels (or even smaller) you should be looking at very short refractors or lenses, for example cheap M42 lenses at 100-300 focal length. Such setup will give nice field of view and should even work without guiding. On the other hand very short exposures at high resolution are way less affected by seeing than typical DS imaging on long exposures. So DS lucky imaging on high resolution is also possible.

If you are thinking about DS imaging with such cameras just take into account that it's still a compromise camera. Maybe newer cameras will be better, time will tell. If you are looking for DS images take with such cameras check cloudynights, astrobin or Emil gallery - he has the most extreme lucky imaging examples (note that he is processing master and to get such results you will have to practice a lot and get a lot of good data).

Atmospheric dispersion correctors

When ZWO announced cheap ADC they likely didn't expect the demand for it that hit them. I looks like that every batch they make gets sold out quickly. This corrector got good reviews and is on par with other correctors, aside maybe for the fused silica ADC from ASH that is better in UV spectrum. If you are new to atmospheric dispersion, read this article.

Cheap dispersion corrector and big demand for it is good as many photographers will use it and they will get better and better planetary images. This is especially important for north hemisphere where planets will be lower and lower.

ADC were an exotic and rare accessory like two years ago. New revisions of ASH ADC as well as Pierro Astro ADC gave a bit of fresh air last year and now with the addition of ZWO ADC the market is very hot. There is even atmospheric-dispersion-corrector.com site with ASH correctors.

Best cameras for 2016

Among entry level ASI120, QHY5L-II as well as Point Grey Blackfly cameras will be the best choice. For Blackfly there are various sensors and only some of them are good (note that most of them is for the GigE interface). For color cameras it's likely worth it to invest in ASI224 as it's way better than anything else. Also if you are looking hard for low prices - keep an eye for alternative vendors that may bring some interesting cameras in lower prices (like Altair Astro and other with Touptek). They may not be the newest but they still should be good for the price.

As for best color camera the ASI224MC is still the king, however it may be challenged by QHY5III290, which should hit the market soon. According to Sony comparisons IMX290 will be close to IMX224 in terms of image quality. SNR1s may not tell the whole story. The pixel size is different and the IMX290 is backside illuminated so it ought to have less amp glow and maybe even less noise patterns in general. Only planetary tests will tell how good the new sensor will be.

In case of best mono cameras then we have IMX178, IMX265, IMX250 and IMX252. It's hard to tell which is best. All of them showcase very good performance - wherever it's a PGR or ZWO/QHY camera. QHY also lists mono IMX290 so this sensors may be also a good option.

By the end of 2016 the list will be different, likely one or more sensors further. Don't expect drastic changes, there likely will be incremental, so you can skip a generation or two before upgrading the camera again. Only a new technology could provide a bigger change.

Other, less popular and older cameras

We still have TIS cameras, Celestron Skyris cameras with older or newer sensors. Some got bit to old for their price so be sure to check what you are buying. The old Neximage (without the 5) may have problems working with newer Windows versions (like Windows 10), and they are very very old USB 1.1 webcams. Neximage 5 is different but still based on bit to old CMOS sensor to be hot. If you are looking for a very cheap guider with ST4 then likely QHY5R-II-C is the cheapest for around 130 EUR. It's color and I can't tell much about it. It likely will be entry-level image quality, but still it should work for guiding with for example finderguide scopes. French iNova cameras are also available, and they offer optional cooling too.

Be sure to look out for older Orion cameras as those aren't supported by FireCapture or SharpCap (not to mention that the old ones are really old in terms of performance). Also be sure not to pick a 16-bit low gain DS camera with small sensor advertised as a guider and planetary camera (like sometimes Atik Titan or SX guiders). 16-bit and low gain plus slow framerate is a bad combination when imaging planets. Those cameras are excellent guiders, but they are very inefficient at Solar System imaging. As an exception there is Atik GP which is a Point Grey Chameleon rebrand/repackage.

In general you can find from time to time a good option among less popular or older cameras. Last few lines were full of warning and you should read them carefully. Even a good camera at a very low price won't be useful if you don't have any application that can use it, or there are no drivers for your modern Windows system.

My wishlist for 2016

I'm always for new things - wherever it's a new hardware improving imaging or new type of imaging.

One of things that could get more popular is petrographic lunar imaging, which requires some narrowband filters. Aside from cherry-picking filters from OmegaOptical on ebay, Thorlabs or Edmund Optics two optics companies - Optolong and Chroma should be able to provide full sets of filters for this type of imaging, while ASI224 or monochrome Sony BSI mono cameras should be quite efficient in this type of imaging.

Planetary Coronagraph would be a awesome thing to try out - catching faint Jupiter and Mars inner moons, catching Uranus rings and maybe more. However at the moment such device is around 1500 EUR.