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what specs should i be looking?

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#1 prefetch

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Posted 06 May 2013 - 10:22 AM

hi. i'm looking to get into live video astrophotography.

i'm looking at different security camera options, and i'm curious which specs are the most important for live viewing?

for example, what is a "good" lux value? 0.1? 0.0017??

what is sens-up and is it important?

s/n ratio?

tv lines?

sorry if some of these are dumb questions. i've been doing a lot of reading, and i'd just like some clarification.

#2 mclewis1

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Posted 06 May 2013 - 12:56 PM

Not dumb questions at all. Real video has quite a bit of different nomenclature. Great first post ... welcome to CN.

Lux - smaller is better. .001 and smaller is the area where the cameras start to be effective for DSO viewing.

Sens-up - This is the multiplier for extending the exposure times. 2x, 4x ... up to 128x, 256x, 512x, or 1024x depending on the camera. The multiplier is off of the frame rate and the math is a bit convoluted but for an NTSC type of camera 128x =2.1 seconds, 256x = 4.2s, 512x = 8.4s, and 1024x = 16.8s. Generally longer is better but you also have to watch how the camera handles the longer exposures. You really want a completely manual gain to go with the longer exposures but so far it seems that for the 1024x cameras the gain is still automatic and seems to not be optimal for really faint DSOs.

s/n ratio - larger number is better

tv lines - larger number is better. In general you're looking for 500+ lines of resolution.

#3 jchaller

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Posted 06 May 2013 - 01:07 PM

First, Welcome to Cloudy Nights.

Second, you can't go wrong by selecting the Samsung SCB-2000, as it is has a successful track record in this endeavour.
(SCB-2000 is equivalent to the SDC-435)
For info. on this camera see this link: http://www.cloudynig...ber/4379862/...

Last, I'll leave it up to the folks with more skill and knowledge than myself to answer your individual questions.

#4 Lorence

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Posted 06 May 2013 - 02:54 PM

i'm looking at different security camera options, and i'm curious which specs are the most important for live viewing?


That's like asking what sort of telescope should a I buy. Specs published by the manufacturers are about as reliable as a politician's promises. You are better off asking what equipment others are using and what they can view with it.

The camera on most video astronomers wish list is the Mallincam Xtreme. If you have $1500.00 to spend then it's the one to buy.

If you just want to get your feet wet for a few hundred $'s then look at the Samsung or one of the astro friendly webcams.

#5 Pharquart

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Posted 07 May 2013 - 11:55 AM

Hi and welcome!

I just started in live video astrophotography. My goals were very specifically NOT to create or capture images for processing, but just to put stuff on a screen for others to view live. A Mallincam seems to be like the Televue of eyepieces: a wonderful camera that works really well, but comes with a premium price. I'm not in that price range (at least not yet!)

I dabbled with webcams, but found their image chip too small so I ended up with really high magnifications. I also didn't have good enough software to let me control the gain, so planets were totally washed out blobs due to the auto gain control.

I ended up buying a used Samsung SCB-2000 for $100 (plus $25 for a 1.25" eyepiece adapter, plus $25 for a 0.5 focal reducer, plus $10 in cables to convert from BNC to RCA) and so far, 1 night out, absolutely love it. I got great images of Saturn and Jupiter. I haven't tried the moon yet, as I've only owned the camera for less than a week.

I made one attempt at a DSO (M51) and could see the core, but that was about it. I was also at the end of my driveway under a street light with a F/10 8" SCT. I was running out of battery power, so I couldn't tinker with a different scope.

Best part: they seem to hold resale value. So rather than struggle to figure out specifications, I recommend you get one and get your feet wet. Sell it if it doesn;t meet your needs.

Brian

#6 mclewis1

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Posted 07 May 2013 - 01:01 PM

Brian,

Good choice on the Sammy ... they are great bang for your buck. You'll find that the focal reducer will make the world of difference on DSOs. f5 is good, f4 is better and between f4 and f3 is the real sweet spot (real color and lots of details).

In addition to all the solar system objects, M51, M82, and a few other bright galaxies will be fun. A lot of globulars are great targets with your setup (M13, M3, M5, etc.), as are the brighter planetaries (M57, etc.). In a few months some of the brighter extended nebulae will also be good targets (M7, M8, M20, etc.).

Depending on your sky conditions (light pollution, moisture, etc.) and with a little experience you might also be able to go beyond the brightest objects mentioned above and start exploring all kinds of stuff ... but you'll really have to pick your nights, the conditions will really dictate how successful you'll be.

#7 prefetch

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Posted 08 May 2013 - 06:22 PM

thanks for all the advice. i really appreciate it.

i ended up getting an samsung SNB-7001. it was only a few hundred dollars, and it'll do 1080p which i'm excited to try out.

now i just have to figure out how to attach it to my telescope!

#8 jchaller

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Posted 08 May 2013 - 06:41 PM

I'm afraid that isn't a good fit - it doesn't look like a good low-light camera. Different chip than the SCB2000 and max integration 60x.

#9 prefetch

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Posted 08 May 2013 - 10:15 PM

>I'm afraid that isn't a good fit - it doesn't look like a good low-light camera. Different chip than the SCB2000 and max integration 60x.

the lux rating is pretty darn low at 0.4 and then sens-up the lux is .007.

is lux not how you determine "low light"? are these numbers not good?

#10 ccs_hello

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Posted 08 May 2013 - 10:35 PM

Do not trust the Lux rating! Period!

#11 jchaller

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Posted 08 May 2013 - 10:48 PM

Lux ratings are not the best gauge as there doesn't seem to be a set standard to arrive at them. I've noticed the same manufactures literature on the same camera give differet lux ratings.

Lux ratings are high compared to the SCB-2000
0.05Lux / 0.0001Lux

Integration of 1 sec compared to 8.5 sec.
Also this camera is using a cmos chip as compared to the ccd chips in the SCB2000.

The Samsung cameras that I know of that have been used are 2000 and 4000 series.

#12 jchaller

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Posted 08 May 2013 - 11:03 PM

Before I went to the Samsung SDC-435 I used a Polaris camera that claimed lux ratings of 0.0001 to 0.00005 Lux. It had a maximum itegration time of about 2 seconds. While it worked on planets and globs, that was the limit.

And I paid $300.00 bucks for the Polaris vs. about $80.00 for the Samsung.

#13 prefetch

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Posted 08 May 2013 - 11:19 PM

maybe i made my first of many mistakes by buying that camera!

the one thing that really attracted me to this camera was the 1080p. my interest is in live viewing with a group of people, and i have a large tv, and the idea of having a resolution of 400 or 500 lines seemed really awful to me.

i guess if it turns out that it's crummy, then i'll see about getting a different one.

#14 Spacetravelerx

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Posted 09 May 2013 - 02:17 AM

Prefetch,

I am new to this hobby, however I can tell you when I do the video astronomy thing via a laptop and larger LCD (24") even with the 400 to 500 lines the images were not only adequate, it was VERY clear what we were looking at on the screen. Needless to say, the groups who viewed with me were very excited what they saw - some commented the images looked like they were out of a book! My guess is those with the security monitors made for this resolution have even better views.

Still, I am more than happy with what I see and the images captured are better than I would have expected. Trust me - the 400 to 500 lines are not awful.

#15 prefetch

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Posted 09 May 2013 - 08:43 AM

Still, I am more than happy with what I see and the images captured are better than I would have expected. Trust me - the 400 to 500 lines are not awful.


that's encouraging. i've got a really really big (90") screen that i'm going to send the video to, so it's a primary concern. if this camera i have turns out to be a disaster, then of course i'll try another one. it sounds like the ultimate is the mallincam, but i run a mac and there isn't software for the signature series (the higher resolution one) http://mallincam.tripod.com/id55.html

anyway, i'll report back on how this one goes. part of the fun of the hobby is to mess up and learn from experience.

#16 Stew57

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Posted 09 May 2013 - 09:00 AM

The signature series cameras are designed for planetary/solar observing. If you are wanting to view deep space objects (nebula etc..) that is not the camera you want. You will have to ignore the output resolution in choosing a camera for now.

#17 Spacetravelerx

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Posted 09 May 2013 - 10:11 AM

Prefetch,

I am running right now a MallinCam X2 on a Macintosh without any problems. I am using the MallinCam Control Miloslick software which is a great tool.

Basically here is the break down:
* For stars and DSO - MallinCam
* For the Sun (a star, lol), Moon, Jupiter, Saturn, Mars and Venus - Canon 60Da and its Mac based control software with "Live View". We do view the Moon, Jupiter and Saturn on the MallinCam, however the Canon 60Da does take prettier live images.

Next step is tying a headless MacMini to the MallinCam. Then I will wirelessly connect to our main network which will repeat the desktop to an AppleTV connected to a 65" Samsung Plasma (or other display). Additionally I am looking at NSN, but this seems VERY hard to join. Either way, my business runs a set of servers and we will also be feeding to all users globally from our new observatory. People will be able to right to the website to get a live feed. This should be operational in August.

Oh, wifi control of the telescope is via SkyFi and SkySafari Pro on the iPad, iPhone and Macintosh. This works wonderfully with my LX200. We will be testing next week with the LX850.

Bottom line - you can control your MallinCam (and most other cameras) from a Macintosh.

#18 nytecam

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Posted 09 May 2013 - 10:53 AM

maybe i made my first of many mistakes by buying that camera! the one thing that really attracted me to this camera was the 1080p. my interest is in live viewing with a group of people, and i have a large tv, and the idea of having a resolution of 400 or 500 lines seemed really awful to me.i guess if it turns out that it's crummy, then i'll see about getting a different one.

I'm surprised nobody picked up on your HD requirement - to my knowledge HD and cam night-time sensitivity, essential for DSO imaging in video exposures with sens-up, don't match :o

#19 mpgxsvcd

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Posted 09 May 2013 - 12:36 PM

Output resolution is rarely an issue for Astro Photography and observing. The telescopes we generally use are almost never able to resolve the detail that normal photography lenses would be able to. In addition the objects themselves rarely have that much detail that is small enough in apparent size to warrant a very high resolution output.

Even if you have an Ultra HD TV you won’t be able to capture detail anywhere near that resolution.

I have what is probably the only camera that can do video Astro Photography in near real time and output it at 1080p @ 60 FPS. That being said I usually output at 480i simply because there really isn’t that much detail that is that small in apparent size in these objects. Even with a large scope most cameras will out resolve the object, the sky conditions, and the scopes capabilities.

If you really are that worried about resolution then you should also be worried about diffraction. Diffraction decreases the resolution of the captured image more than anything else. Diffraction affects depend on the sensor size.

Therefore, smaller chip sensors are much more susceptible to diffraction affects than larger sensors.

However, in reality even diffraction doesn’t decrease your perceived resolution in deep space objects because they simply don’t have that much really fine and small apparent size detail. You can get outstanding images from small low resolution sensors and you can get similar results from large high resolution sensors.

#20 jchaller

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Posted 09 May 2013 - 01:45 PM

How will this high resolution camera perform on the moon and planets?

#21 Tom and Beth

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Posted 09 May 2013 - 07:01 PM

thanks for all the advice. i really appreciate it.

i ended up getting an samsung SNB-7001. it was only a few hundred dollars, and it'll do 1080p which i'm excited to try out.

now i just have to figure out how to attach it to my telescope!


While that Camera may not get you the "Astro" usage, it DOES have some nice features that lend itself to a DIY Weather cam mounted on top of your house. Just don't make it a lightning attractor. You will need an enclosure (circa $30 USD). An old TV rotator adds a bit of value to the installation.

Night time use, sadly...just isn't there.

#22 prefetch

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Posted 12 May 2013 - 09:43 AM

Night time use, sadly...just isn't there.


well, i tried it last night. mixed results. the primary enemy seemed to be atmospheric turbulence.

here's a screenshot from the 'live' view:

Posted Image

#23 prefetch

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Posted 12 May 2013 - 09:49 AM

and here is another screen shot with 60x sens-up active, but of course it's horribly over exposed and the software does not seem to be able to have controls to reduce it (or i can't figure them out.)

Posted Image

#24 jchaller

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Posted 12 May 2013 - 01:58 PM

Yeah, at that exposure it's going to be over exposed.

How is this connected to the computer?
Are you viewing on a seperate monitor?
How's the software?

#25 nytecam

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Posted 12 May 2013 - 02:10 PM

and here is another screen shot with 60x sens-up active, but of course it's horribly over exposed and the software does not seem to be able to have controls to reduce it (or i can't figure them out.)

I've never successfully recorded Saturn's sats and the disk in the same exposure :shocked: eg use ~1/500s for disk and 2s for sats and 10s for faintest sats. Then composite disk image onto sat image :rainbow:






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