All Sky Camera

mikeinlehigh

Have been contemplating building a permanent all sky camera. I've used an ZWO Color planetary camera in the past just to do a night of imaging. Then i sped it up and had a time lapse video. Now I want to build something permanent to mount on my observatory. Building it and the software is no problem. The question is can a ZWO planetary camera take the direct Florida sunlight on a daily basis? Will the brightness and heat of the sun ruin the sensor? Complete Allsky cameras are available but the cost is outrageous. I can build one myself for a third. I've seen ones online build their own with good success but don't know if it's exposed to the punishing Florida sun. What do you think? Even if I set it up to only work during the dark hours, it's still exposed to the suns rays during the day.

Thanks, Mike

w7ay

mikeinlehigh The question is can a ZWO planetary camera take the direct Florida sunlight on a daily basis? Will the brightness and heat of the sun ruin the sensor?

Mike, I have been using an ASI178MC with a f/1.7 C-mount lens, and have had no burn in problem, even when running exposures in the daytime. The camera is mounted right the the roofline for the past two years now.

(I have a background project to bring up another All Sky camera using a spare ASI294MC and a Samyang fisheye (EOS mount), with a home-grown INDIGO program to control it. Powered by Ethernet PoE. But don't have any data to give you from the larger lens.)

The caveat is that I am in Portland Oregon, and the sun angle never reaches directly overhead like it does in Florida. A friend in Slovenia ("deepskydad") had also told me he had no problems (but didn't say what camera and lens).

You can mitigate the problem somewhat by not taking exposures in the daytime, although that lens is directly focusing the Sun's rays right on the sensor.

With C mount lenses, you could look for ones with adjustable iris, and close that down in the daytime.

This could be why commercial All Sky Camera are expensive (I am sure they also gouge from folks who are appliance operators and don't build their own).

By the way, you may also need something to mitigate the dew, especially in Florida. Often, the heat generated by the electronics in the enclosure is enough to warm the dome, but not so in deepskydad's case -- he had to add a bunch of resistors as heating elements, if I recall.

You won't have this problem in Florida, but in my case, I often had to reach it to clear the snow that accumulate on the acrylic dome (the house is at 900 ft over sea level, so we do get snow even when Portland city itself is just raining). So, don't mount it in a place that is too hard to get to :-).

Chen

mikeinlehigh

Thanks Chen, i found another guy online who says his camera is still going after six years with no "burn in." Can you tell me the manufacturer of the f/1.7 C-mount lens you used? Or, if you have a link? I heard the lens that comes with the camera leaves a lot to be desired.

w7ay

mikeinlehigh Can you tell me the manufacturer of the f/1.7 C-mount lens you used?

Hi Mike,

I use this one:

https://www.amazon.com/gp/product/B08GLYR572

Depending on your situation, it may not be wide enough for you. But I don't have a very wide clearance (trees in Oregon, you know. Plenty of 100 foot firs in the property.)

The fisheye lens that comes with any ZWO cameras (there are two versions of the crap) is at most useful as a dust protector for the sensor. And that is being kind. It has utterly horrid MTF and completely unsuitable even for cameras with larger pixels.

My assembled camera, with dome removed, looks like this:

The Raspberry Pi 3 is an unused ASIAIR version 1. The purple board is a PCB that I made up to easily mount one of the ubiquitous buck/boost convertors from Amazon; it drops 12V to 5V, and wired directly to the 5V pins on the Rasberry Pi GPIO connector. You see the pigtail of a PowerPole connector, which I use to distribute 12V everywhere.

Camera is a ASI178MC, with said lens. The lens is substantially higher resolution that the free ones that ZWO ships, but much worse than the Fujinon C mount lenses that I use for my "lab" experiments; but I could not find a good wide enough Fujunon. My next one will use DSLR lens, since this lens' image circle will not cover the sensor size of an ASI294 camera.

This is the angle of view it gives me (also gives you a sense of the Sun (notice the internal reflection of the red camera body off of the acrylic dome at the bottom right of the picture):

North is up, east to the left. Polaris is just off of top center at night.

The box is a weatherproof ABS box and this is what it looks like buttoned up (RTV applied to the lip of the dome before bolting the dome to the box with stainless steel [a must] screws) :

The next one I am building will be using a pancake version of the ASI294MC (have a spare one), with a Samyang 8mm Fisheye. And much bigger enclosure and dome, with Raspberry Pi 4 running INDIGO Sky instead of ASIAIR. I will probably also go to a PoE ethernet to supply the power, and use for data. The above one uses WiFi, which works reasonably well, given that the enclosure is plastic, and within perhaps 5 to 6 meters from two different eero mesh routers

Chen

mikeinlehigh

Like this? https://www.walmart.com/ip/35Mm-F1-7-Television-Tv-Fixed-Lens-Cctv-Lens-for-C-Mount-Mirrorless-Cameras-Black/938195491?wmlspartner=wlpa&selectedSellerId=101114713

w7ay

mikeinlehigh Like this?

The focal length of that one is way too long, Mike.

The one I use has a focal length of 3.2mm and even that is not short enough if you want horizon-to-horizon coverage with an IMX178 sized sensor. (And does not have sufficient image circle to cover larger sensors.)

C mount lenses often have two specifications: one is the resolving power (often stated in megapixels) and the other one is the image circle (for example, 1/1.7" format, in the case of the sensor I used; sensor format refers to the equivalent diameter of a vidicon tube that were used in old television cameras).

Make sure (1) the image circle is large enough for the diagonal of the sensor, and (2) the resolving power is enough to match the pixel size of the sensor.

Chen

Stars2962

Anyone have a link for a currently available fisheye that is appropriate for the ASI224MC since the one everyone recommended a year or so ago is no longer available?

mikeinlehigh

I think i'll order the lens you have Chen. The price is certainly right. I currently have a ASI385MC that I bought on sale and was going to use for planetary imaging. Deep Sky stuff always seems to take precedence so it hasn't been used yet. It does have a much small sensor than your ASI178, which is onsale right now. ASI178 - 6.4mb 3096 x 2080 to ASI385 - 2.1mb 1936 x 1096. Nice job on the enclosure Chen. Well engineered 🙂

Edit: When the stock ZWO lens is removed the adapter comes with it. Is that able to be separated from the lens? Obviously the threads on the camera are too wide to accomadate a C thread. If so, that adapter is really on the stock lens. Going to take some force to separate it.

w7ay

mikeinlehigh Is that able to be separated from the lens? Obviously the threads on the camera are too wide to accomadate a C thread. If so, that adapter is really on the stock lens. Going to take some force to separate it.

If your camera originally came with a ZWO lens, you already have a Cs-to-T2 adapter sitting around. Otherwise, there are also plenty of them around (even ScopeStuff) and ZWO even sells one:

https://astronomy-imaging-camera.com/product/m42-to-cs-adapter

If memory serves, that Amazon lens is a Cs lens (sometimes written CS), and not a C lens. Same thread size, but the flange focal distance is 5mm shorter (12.5 mm instead of 17.5 mm for C). I don't remember if the ZWO lens was a C or Cs, so you may need to do some literature digging, or simply experiment.

The barrel shaped ZWO camera do come with a 5mm C mount spacer, I think -- so if you have one of those, you already have a 5mm spacer, in case you need one. Otherwise, lots of places have them, ditto ScopeStuff. I am sure you can find them at Amazon or EBay too.

Be mindful that with your smaller sensor, you would have an even smaller FOV that I have with an ASI178. It is not directly proportional (because of FishEye geometry) but you can use the sensor size difference as a rough guess of what your FOV would be with that same lens. I think you might be better off looking for something like a 1.6mm to 2mm Fisheye.

Have fun.

Chen

w7ay

mikeinlehigh ASI178, which is onsale right now. ASI178 - 6.4mb 3096 x 2080

By the way, MIke, the only reason ithe ASI178MC is on sale is that it has been superceeded by the ASI678MC (uses Sony IMX678 sensor). The lower price is just to clear the existing inventory.

The IMX678 sensor has the same pixel count as the IMX178, but the pixel size is smaller (2 µm vs 2.4 µm), and the read noise is substantially lower, and has more near-IR sensitivity (IR sensitivity probably not a big deal for an all sky camera). Because of the smaller pixel, the sensor itself is also smaller (thus requires even shorter focal length length when all else is equal).

You might want to factor this (obsolete camera) in your decisions. You might not want to throw good money on something that now has very low resale value, if that is part of your purchasing equation.

I myself found that the IMX178 already has insufficiently large sensor. So, a ASI678 will be a worse match for my needs, although I have one on order with my dealer (but for use in a guide scope).

An ASI178MC at gain of 270 (max setting in ASIAIR unfortunately; INDIGO should do better) already requires a 10 second exposure to register the Milky Way. At that point, the stars are already trailing (yes, even on a fisheye FOV :-). That is why I am going to a DSLR lens (larger aperture for the same f/number to catch more photons) and compensate for the longer focal length with an even larger sensor -- a spare ASI294MC for now).

Just do everything on paper first before buying anything.

Chen

w7ay

mikeinlehigh

Oh, I forgot to mention, get yourself a bottle of Rain-X rain repellant glass cleaner (the one that you use on windwhield of cars). I have not seen it mentioned for an All SKy camera, but I have found that It is a bit better than Windex, which in turn is better than water.

Chen

mikeinlehigh

Thanks for the great input Chen. I bought the ASI385 on sale only to find it's been replaced but that was several months ago. Oh well, I'll find a use for it. So I agree on the 178. I'd rather spring for the newer camera. So, smaller pixel size is going to be better on an All sky camera? I guess the "formula" for pixel size along with focal length applies here? Also, great idea for using Rain X. Most of my time is spent on deep sky stuff using the ASI294MC Pro. I used to be really into planetary photography a few years ago using a C14. However the lengthy cool down times and the constantly changing sky conditions, by the hour, in here Southwest Florida made me give up. Although deep sky does depend on sky conditions it's not nearly as risky. So, I just planetary image on occasion now with a Meade 8" LX200 ACF . So, I'm thinking about the newer ASI585MC for that. Oh I've gotten way off topic now. My apologies to the moderators 😁.

w7ay

mikeinlehigh Oh I've gotten way off topic now.

Heh, you started this thread; it is not as if you have hijacked someone else's thread :-).

Keep in mind that although a smaller pixel is better matched as far as plate scale, for the same number of total pixels (like the IMX178 vs IMX678 case), the sensor dimension will be smaller, and you need to compensate with a shorter focal length lens if you want the same FOV. Secondly, the sensitivity will also drop, but in the case of the IMX678 vs IMX178, it is actually better because the read noise is lower -- but that is not always the case. And with such a short focal length, plate scale is on your side.

Have fun, Mike.

It is surprising how many people are building all sky cameras. With that many people, you would think someone would be enterprising enough to market an affordable and attractive turn-key package by now.

Chen

mikeinlehigh

As a serious astrophotographer I accept the fact that I've spent several thousand dollars on equipment. It's a lifelong passion. Good equipment is expensive. Fine optics are expensive. They always have been. An allsky camera is a luxury. Sure many have plunked down a grand for theirs. I might spend a lot but I do it wisely. A thousand dollars for one? I just can't justify it especially if one can be built in a few hours for a third of the price 😁. Thanks again for your help and insight.

w7ay

mikeinlehigh A thousand dollars for one? I just can't justify it especially if one can be built in a few hours for a third of the price

Me neither. I can afford it, but don't want to support people who gouge.

By the way, I just pointed one of my Amazon Blink cameras straight up (yep, 100% overcast -- i.e., normal, in Portland). Located close to my All Sky camera whose images I posed earlier. "Borrowed" from the Blink that I use to point to our garden, thus the name :-).

Looks almost as wide length wise, but not as tall in height as my all sky camera (which is not horizon-to-horizon).

I'll see if it can pick up any stars at night (it might be "clear" tonight but with terrible transparancy). Will report back.

I am sure it will go into "monochrome" mode at night (same kind of near IR sensitivity of the IMX678, where the R, G and B sensitivities all bunch together to form a monochrome image at the 850 nm region.

So, no star colors for sure (not that the IMX178 could pick up that much star colors anyway :-).

But if it is actualy sensitive enough to see stars (it picks up deer at night :-), we can add some optics to it to get a wider angle (perhaps even the cheap "wide angle" attachments for smartphones).

If the darn thing is sensitive enough, it can be the "turnkey" all sky camera for the masses (especially the masses that already have the Blink system at home, since it does need a Blink hub in addition to the camera module. At least it can warn you of clouds directly overhead (rain!), even with its existing camera angle. At least the wireless range is fantastic to the hub, and the hub just has to see the home WiFi system. I also have the third party solar panels to go with each of my Blinks, although I doubt it will last more than a few dozen pictures, so this will need a microUSB cable to feed 5V to it.

Chen

mikeinlehigh

I'll probably go a lot more simple Chen. Camera in a good enclosure of course but a 30' long powered usb cable coming inside to a spare laptop running "AllSkyEyePro" software by Michael Poelzl. I have weather instruments so hole already drilled through the concrete block for cables. Camera enclosure can be mounted right outside on the roof. I've already tested the whole setup on a tripod and it performed perfectly. Software is easy to use and highly programmable. Honestly, this is more of a novelty for me. Can check at a glance to sky conditions before going out to open the observatory roof. I can control my whole imaging setup from my office, once the roof is open and scopes uncapped. I like to periodically check my imaging progress once it's up and running. The allsky cam will let me check the sky conditions at the same time. I often set up another scope on my patio to observe while the imaging scope in the obsy is running. But if it's late night and I'm tired it's nice to have an eye to the sky from inside the house 😁. So you can see why I'm budget minded on this project. I do enjoy taking the video from last night and converting it to a time lapse. Fun to look for meteors etc.

w7ay

mikeinlehigh

Mike, the Blink does not work out anyway.

When it got dark, the Blink went into low resolution Mono binning, and even so has very low sensitvity compared to the ASI178MC with the 3.2mm/1.7 lens. I could currently (just left civil twilight for nautical twilight) see Vega easily with a 1sec exposure, Bin 1 and gain of 92 on the ASI178MC, while nothing appears on the Blink's mono-binned auto exposure frame.

Fun to look for meteors etc.

I have yet to see one meteor on my all sky camera (even tried a sequence of 1 minute back to back exposures just last year on August 13th). But have multiple occasions seen sporadic meteors (and one case, possibly a bright Perseid crossing Cygnus a couple of years ago) when I doing long exposures. I think a large camera lens will be better as a meteor camera (perhaps even the Samyang I will be using with my next generation all sky camera). Perhaps a couple of them, pointing to different parts of the sky.

I still remember in my youth lusting for an Aero-Ektar with a 4x5" plate holder, but could not afford to build a meteor camera like that. Those lenses are really rare nowadays (radioactive lens coating? I believe). But nowadays, a 50mm/1.4 camera lens with a cooled full frame sensor should beat the Aero-Ektar with 4x5" film anyway (so no more lusting :-).

Chen

mikeinlehigh

I'll be looking forward to your next project using a regular camera lens and the 294. I use the ASI294MC Pro for all my regular astrophotography.