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Equipment Discussions >> Video and Electronically Assisted Astronomy

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Atl
professor emeritus
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Reged: 04/13/12

Interested in video astronomy - what equipment?
      #5668732 - 02/08/13 11:07 AM

I have been playing around with a home made 12.5" dob for 4 months now and I have been learning about the sky and the scope. Initially I wanted to try astrophotography, but saw that semi-live video seemed to be a good compromise between optical astronomy and astrophotography. I can view and take a snapshot if it makes me happy.

Now my question. Which direction to go for equipment? Do I go with an 8 to 10" reflector...or is this (like astrophotography) suited to a small refractor. Is there a compromise between the extremes or am I off base. What type of scope and mount do I need?


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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Interested in video astronomy - what equipment? new [Re: Atl]
      #5668949 - 02/08/13 12:44 PM

What types of objects interest you?

The object size determines the focal length of the telescope. Large nebulae and star clusters require a shorter focal length, in the range of, say, 400mm. A tiny planetary nebula requires a focal length of at least 2,000mm.

The object surface brightness suggests a suitable fical ratio. The bright Moon and planets allow long f/ratios to f/30 or so, when going fir high detail. Dim nebulosities hardly brighter than a dark sky require short f/ratios no longer than f/4-5.

There is no one perfect telescope. Each has its strengths. And do not discount the power of a small instrument, if you wish to start out simply and at lower cost. Search this Forum (or Google) for a thread I started called, "Results from Starfest", to see what an 80mm achromat on a $500 mount can do.


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mpgxsvcd
Carpal Tunnel


Reged: 12/21/11

Loc: Raleigh, North Carolina
Re: Interested in video astronomy - what equipment? new [Re: GlennLeDrew]
      #5669067 - 02/08/13 01:37 PM

What do you want to achieve with this? Do you want to replace the eyepiece with a camera? What objects would you like to see(Solar Sytem planets? Deep Space Objects? Really Dark DSOs?)? Do you want to share those images with anyone else or just see them yourself?

The reason I asked is that a traditional video is not the only solution if you want to replace the eyepiece. Video is definitely one of the solutions. However, it is not necessarily the only way to go.

Live view cameras are essentially the exact same thing as what is typically referred to as a video camera. They can output video over any type of connection whereas almost all of the traditional video cameras are limited to standard definition rca or svideo.

There are also wireless solutions with standard cameras that actually work extremely well. Do you have a smart phone or iPad. Some of the cameras can now stream a live view directly to your tablet’s or phone without the need for wires.

Really it all comes down to what is the ideal solution for you and what is your budget.

Edited by mpgxsvcd (02/08/13 02:35 PM)


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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: Interested in video astronomy - what equipment? new [Re: Atl]
      #5669137 - 02/08/13 02:02 PM

Quote:

Which direction to go for equipment? Do I go with an 8 to 10" reflector...or is this (like astrophotography) suited to a small refractor. Is there a compromise between the extremes or am I off base. What type of scope and mount do I need?





It's all about the camera and how much you are willing to spend on one. A webcam is good enough for Lunar and planetary viewing. There are security cameras in the several hundred dollar range that will do an adequate job of the brighter deep sky objects. A Mallincam is the most expensive but it will give you the best view of any of the video cameras available.

An 8" SCT is more than adequate for video. It can be used with focal reduces or barlows for wide or narrow field of views. If you want to do longer exposure an equatorial mount is best.

If you are primarily interested in visual astronomy and willing to spend enough you won't be sorry.

Last night I was picking up 30th magnitude objects in the field of view. Think about how many objects there are between M42 and those. More than enough to keep the average visual observer busy for a while


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: Interested in video astronomy - what equipment? new [Re: Lorence]
      #5669566 - 02/08/13 06:28 PM

My primary interest is in visual and the light gathering power I have seen demonstrated by video cameras is awe inspiring, but the ability to grab a screen occasionally to show to somebody or to compare to a later screen grab is a huge plus. I want to initially invest about $2000 over the next 6 months. The camera I was thinking of starting out with is the Mallincam Jr., then spend about $1500 on the scope and mount. I want to get a mount that tracks...not necessarily a goto. Two telescopes I had looked at were the Astro Tech 8" imaging reflector and the AT72ED 72mm Doublet they sell. I am thinking this is a good starting point. Which telescope is more suited to video? I am not so interested in planetary as deep sky.

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Dwight J
scholastic sledgehammer
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Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: Interested in video astronomy - what equipment? new [Re: Atl]
      #5669762 - 02/08/13 09:02 PM

I would consider a Samsung camera over a Mallincam Jr. as the Sammy can go up to 8 sec/integration and the Jr. only 4 seconds. 4 seconds will show the brighter deepsky objects well (like M 57, 27, 42) but not long enough for dimmer objects. The Samsung goes for around $100 or so but some mods are needed. If you have a fast focal ratio you could get more out of what ever camera you get. Longer ratios can be had using a barlow lens.

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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: Interested in video astronomy - what equipment? new [Re: Atl]
      #5669777 - 02/08/13 09:12 PM

Quote:

Two telescopes I had looked at were the Astro Tech 8" imaging reflector and the AT72ED 72mm Doublet they sell. I am thinking this is a good starting point. Which telescope is more suited to video? I am not so interested in planetary as deep sky.




Rock Mallin sells a telescope very similar to the Astro Tech f8 8"

They're called the VRC Series of Optical Tubes

http://mallincam.tripod.com/id43.html

To my way of thinking that's one good recommendation for a video telescope.

If you are primarily interested in deep sky you might want to consider going to a used VSS instead of a new Jr. It would be well worth the extra cost.

I have a VSS+. It has a nicer image than my Xtremes up to it's two minute exposure limit. Two minutes buys you a lot of deep sky viewing.


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: Interested in video astronomy - what equipment? new [Re: Dwight J]
      #5669887 - 02/08/13 10:20 PM

Quote:

I would consider a Samsung camera over a Mallincam Jr. as the Sammy can go up to 8 sec/integration and the Jr. only 4 seconds. 4 seconds will show the brighter deepsky objects well (like M 57, 27, 42) but not long enough for dimmer objects. The Samsung goes for around $100 or so but some mods are needed. If you have a fast focal ratio you could get more out of what ever camera you get. Longer ratios can be had using a barlow lens.




Which Samsung camera model are you referencing?


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mclewis1
Thread Killer
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Reged: 02/25/06

Loc: New Brunswick, Canada
Re: Interested in video astronomy - what equipment? new [Re: Atl]
      #5669900 - 02/08/13 10:27 PM

The inexpensive Samsung models that work well for astro video work are the SDC-435 or SCB-2000, these have 1/3" sensors. You'll also see reference to the 1/2" models (SCB-4000, A2333) these are in the $300-400 range.

To use any of these cameras you'll need a few accessories ...
- a C mount to 1.25" barrel adapter ($20-30)
- a 12v 300-500ma power supply ($10-15)

It's highly recommended that you physically remove the IR filter that's mounted over the CCD sensor. This is a bit tricky unless you follow the instructions from someone who's done it before (there are good instructions in a few older threads in this forum).

A focal reducer is also highly recommended, the model depends on your scope and budget. You're shooting to get your final f ratio down to f4 or faster. Simple focal reducers thread onto the 1.25" adapter and start in the $30-40 range, other models can also go up into the $300 range.

Many folks with these Samsung cameras will also build simple remote control boxes, these are simply extensions of the 5 buttons that control the onscreen menu (OSD) that are on the back of the camera.

Edited by mclewis1 (02/08/13 10:38 PM)


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Interested in video astronomy - what equipment? new [Re: mclewis1]
      #5670050 - 02/09/13 01:50 AM

For deep sky work, a camera which offers longer integration times and has cooling for noise reduction is *highly* recommended. A lesser camera will end up being replaced quite soon. Make the right video camera purchase out of the gate. It will serve well with most any instrument.

Then if your (stretched) budget allows, a mount such as the Skywatcher EQ5 Synscan GPS is a nice mount which includes the two (or three, to be pedantic) important extras which for most less expensive mounts require to purchase separately; drive motors (two axes here), controller and polar alignment bore scope. And also important extras; periodic error correction (PEC) and an Autoguider port. And don't forget the GoTo capability! This is a lightweight mount rated to carry 24 pounds, which can be used for long exposure/long focal length imaging, and which represents excellent value.

To start off, you could mount a low cost scope such as, say, a 130mm (5.1") f/5 reflector (with an inexpensive 0.5X focal reducer, optionally.) This will keep you busy exploring a great many objects while you also become proficient.

As it's the video observation of DSOs which you emphasize, a suitable camera is a must. Only if you still harbor doubts about any long term interest should you start with a more 'intermediate' camera.

And there's no substitute for a decent mount. Of course, you could plunk down $2000+ for a very capable one. But the Skywatcher model I suggested above, while not high end, is quite capable for its size and price, with features that will ensure its long utility. And it forms the heart of a very portable system if you take trips to dark skies.

Or... You can search the used market. I stumbled on a great deal at my local astro shop, where a very good condition, fork-mounted C-8 Ultima SCT was had for $600 (including the tripod and equatorial wedge.) This was obtained for my own video work, and to that end I purchased a Meade f/3.3 focal reducer. This combo is very nice.

Keep you eyes and options open, and continue researching...


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Atl
professor emeritus
*****

Reged: 04/13/12

Re: Interested in video astronomy - what equipment? new [Re: GlennLeDrew]
      #5670101 - 02/09/13 03:17 AM

Got it...the scope is secondary. Mount and camera come first. OTAs are actually cheap do aquirinq a large astrograph later should be no problem.

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jambi99
sage


Reged: 08/14/10

Loc: Québec, Canada
Re: Interested in video astronomy - what equipment? new [Re: GlennLeDrew]
      #5670404 - 02/09/13 09:52 AM

Personnaly i would have a look at the new celestron advanced vx. I dont have any argument for it presently, but think it should be a better overall mount. It has been designed for AP in mind . No gps i think, but this can be added later on. Personnaly i find it to be trivial.

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a__l
professor emeritus


Reged: 11/24/07

Re: Interested in video astronomy - what equipment? new [Re: mclewis1]
      #5671223 - 02/09/13 07:02 PM

Quote:

The inexpensive Samsung models that work well for astro video work are the SDC-435 or SCB-2000, these have 1/3" sensors. You'll also see reference to the 1/2" models (SCB-4000, A2333) these are in the $300-400 range.





I have read the specifications on the SCB-4000 and Mallincam.
I am interested in.

SCB-4000:
Color : 0.1Lux (50IRE@F1.2), 0.0002Lux (Sens-up, 512x)
Chip 1/2" SONY Exview
(Sens-up this Frame Integration; 0.1/0.0002 about 500)

Mallincam Color:
LUX at F/1.4 STANDARD MODE 0.00006 @5600K 30 IRE
LUX at F/1.4 HYPER MODE 0.0000000005 @5600K 30 IRE
LUX with PELTIER ON STANDARD MODE 0.00004 @5600K 30 IRE
LUX with PELTIER ON HYPER MODE 0.0000000002 @5600K 30 IRE
Chip 1/2" SONY No Exview

In what physical principles achieved difference of 1 million?

Ps.
Electronic Shutter Speed SCB-4000 1/60 - 1/10,000sec
Sens-up, 512x this 1/60*512=8.5 sec?
120 sec Max Mallincam /8.5sec=14

Hmm.... Where is my mistake?


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mclewis1
Thread Killer
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Reged: 02/25/06

Loc: New Brunswick, Canada
Re: Interested in video astronomy - what equipment? new [Re: a__l]
      #5671290 - 02/09/13 07:37 PM

Mallincam's are designed and built to be optimized for low light video work. They have a combination of a high quality CCD sensor, high gain read amplifiers and noise reduction circuitry as well as Peltier cooling. This enables much longer integration/exposure times to be used which makes them much more sensitive to low light levels.

If you want more specifics you could join the Mallincam Yahoo group and ask Rock (the guy behind the Mallincam) directly, he's usually very willing to discuss the details of his products (unless it gets into the some of the proprietary areas of his products).


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a__l
professor emeritus


Reged: 11/24/07

Re: Interested in video astronomy - what equipment? new [Re: mclewis1]
      #5671313 - 02/09/13 07:48 PM

CCD sensor from Samsung cam is more sensitive (1/2" SONY Exview)
Signal to Noise Ratio from Samsung - 52dB (AGC off, Weight on) - this is probably the maximum gain (without Peltier)?
Peltier adds (see above) = 0.00006/0.00004=1.5
Gain Malincam 62-52=10 dB =10*1.5=15
How to get a million?

Ps.
Information on Samsung SCB-4000
http://www.bhphotovideo.com/c/product/752335-REG/Samsung_SCB_4000_SCB_4000_Hi...
Mallincam
http://www.waningmoonii.com/Updates%20-%20July%202005/MallinCam%20Color%20HYP...

Edited by a__l (02/09/13 08:09 PM)


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mattflastro
Vendor - Astrovideo Systems


Reged: 07/31/09

Loc: Brevard County , FL
Re: Interested in video astronomy - what equipment? new [Re: a__l]
      #5671426 - 02/09/13 09:05 PM

Quote:

Quote:

The inexpensive Samsung models that work well for astro video work are the SDC-435 or SCB-2000, these have 1/3" sensors. You'll also see reference to the 1/2" models (SCB-4000, A2333) these are in the $300-400 range.





I have read the specifications on the SCB-4000 and Mallincam.
I am interested in.

SCB-4000:
Color : 0.1Lux (50IRE@F1.2), 0.0002Lux (Sens-up, 512x)
Chip 1/2" SONY Exview
(Sens-up this Frame Integration; 0.1/0.0002 about 500)

Mallincam Color:
LUX at F/1.4 STANDARD MODE 0.00006 @5600K 30 IRE
LUX at F/1.4 HYPER MODE 0.0000000005 @5600K 30 IRE
LUX with PELTIER ON STANDARD MODE 0.00004 @5600K 30 IRE
LUX with PELTIER ON HYPER MODE 0.0000000002 @5600K 30 IRE
Chip 1/2" SONY No Exview

In what physical principles achieved difference of 1 million?

Ps.
Electronic Shutter Speed SCB-4000 1/60 - 1/10,000sec
Sens-up, 512x this 1/60*512=8.5 sec?
120 sec Max Mallincam /8.5sec=14

Hmm.... Where is my mistake?



The mistake is that you trust the lux specifications from vendors.
They are bogus, first of all due to the fact that there is no standard lux or sensitivity test , no organization that measures all cameras , sets standards or validates vendor claims as far as lowest light long exposure sensitivity.
Each vendor defines their equipment sensitivity whichever way they want , then proceed to not disclose the measurement conditions and claim all sorts of meaningless numbers. You are simply not comparing apples to apples . You are more like comparing pigs in a poke .
Somewhat akin to the Strehl race of a few years ago between various opticians claiming knife edge test measurements of 0.99995 etc.
People were real unhappy that they got a bad mirror with a Strehl of only 0.94 !
I feel the claimed most sensitive lux value (although I could be wrong since I did not take the time for any calculations ) is so low the CCD would have to operate in individual photon counting mode , which is silly (meaning IMPOSSIBLE with a regular Sony CCD ) .
I don't say this as vendor bashing, please correct me with actual test conditions and numbers if anyone has actually measurement confirmation for the sensitivity for these cameras. I'd be happy to learn something new .
The specifications from Sony for the various CCD's used in the Samsung , Mallincam and others mostly don't differ by orders of magnitude. They differ by a LITTLE compared to the huge million fold improvement claimed by some cameras. No camera has gain in the millions , so view it just as marketing claims . Look up images taken with the various cameras, go to Nightskies network and see how they behave in real time , etc. Then you will be able to make an educated comparison. Not by silly misleading published numbers.


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a__l
professor emeritus


Reged: 11/24/07

Re: Interested in video astronomy - what equipment? new [Re: mattflastro]
      #5671457 - 02/09/13 09:32 PM

Ie Mallincam/Samsung about 5 magnitudes?
(same CCD sensors, 8.5 sec -> 50 sec, gain 52 -> 62 dB + add Peltier)
Unless of course specifications (gain + Peltier) - true.


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Lorence
scholastic sledgehammer


Reged: 09/15/08

Re: Interested in video astronomy - what equipment? new [Re: a__l]
      #5671461 - 02/09/13 09:34 PM

Quote:

[I have read the specifications on the SCB-4000 and Mallincam.
I am interested in.

SCB-4000:
Color : 0.1Lux (50IRE@F1.2), 0.0002Lux (Sens-up, 512x)
Chip 1/2" SONY Exview
(Sens-up this Frame Integration; 0.1/0.0002 about 500)

Mallincam Color:
LUX at F/1.4 STANDARD MODE 0.00006 @5600K 30 IRE
LUX at F/1.4 HYPER MODE 0.0000000005 @5600K 30 IRE
LUX with PELTIER ON STANDARD MODE 0.00004 @5600K 30 IRE
LUX with PELTIER ON HYPER MODE 0.0000000002 @5600K 30 IRE
Chip 1/2" SONY No Exview

In what physical principles achieved difference of 1 million?

Ps.
Electronic Shutter Speed SCB-4000 1/60 - 1/10,000sec
Sens-up, 512x this 1/60*512=8.5 sec?
120 sec Max Mallincam /8.5sec=14






In all honesty I don't recall anyone, including Rock, ever discussing those numbers.

As well as the Peltier cooling Rock uses research grade CCD's in his cameras. Those facts aren't evident in the numbers. Neither is the Hyper circuitry that allows exposures up to 1 hr and forty minutes.

I used a few off the shelf security cameras before buying the Mallincams. Those cameras use standard grade CCD's. When sense up was at maximum they showed as many hot pixels as stars. For some reason that fact doesn't show up in the numbers.

To make a comparison between an Xtreme and a Samsung serves no purpose other than to fuel the endless speculation around here. Mallincams are in a league by themselves.


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a__l
professor emeritus


Reged: 11/24/07

Re: Interested in video astronomy - what equipment? new [Re: Lorence]
      #5671466 - 02/09/13 09:41 PM

Quote:


To make a comparison between an Xtreme and a Samsung serves no purpose other than to fuel the endless speculation around here. Mallincams are in a league by themselves.




No speculations. I want to know the true advantage.


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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: Interested in video astronomy - what equipment? new [Re: a__l]
      #5671480 - 02/09/13 09:54 PM

The length of integration is important and one of the keys to the mallincam's success. The cooling is another. Keeping the hot pixels and noise down while doing a longer exposure will give a much better viewing experience. Now as to if it is worth the increase in cost, that is a personal choice. Night skies is a great suggestion as both cameras can be seen in use there. Just as a side note, my vss gives better views than my extreme, but it is limited to 112 seconds.

Edited by Stew57 (02/10/13 12:30 PM)


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