Dragon Man
Carpal Tunnel
Reged: 03/07/06
Loc: Snake Valley, Australia
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Re: SCB 2000 accessories?
[Re: Amith]
#5254177 - 06/04/12 02:02 AM
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I see that mclewis1 mentioned that I would not be able to get quite a bit of DSO's. Is this because the camera is not sensitive enough or simply because of the F ratio only. Im sure I can save up eventually for the lower number focal reducers if that is the case. I also wouldn't mind getting an 80mm refractor if that works out cheaper in the long run.
Look forward to those images Kim.
Kim, it is because of the limited sens-up time your camera has. 8 seconds for an NTSC model and 10 seconds for a PAL.
Many faint nebula and Galaxies don't show up well until about 30 seconds or more.
But, this can be helped along by using fast optics and a good focal reducer. The wider the FOV the better the chance of picking up fainter objects 
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: Dragon Man]
#5254423 - 06/04/12 09:38 AM
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Thank you Dragon,
Right now I think I would only be able to afford the f6.3 reducer. I dont even know how to calculate the sens up time but on a f6.3 focal reducer how many seconds do you think I would get using the scb2000 and the 6SE (f10) scope?
I see that the scb2000 has a sens up function.. what would be the purpose of that if anyone knows?
Thank you again everyone for the feedback so far.
Regards,
Amith
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Dragon Man
Carpal Tunnel
Reged: 03/07/06
Loc: Snake Valley, Australia
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Re: SCB 2000 accessories?
[Re: Amith]
#5254438 - 06/04/12 09:51 AM
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Amith, the sens-up function in the camera is the length of integrated exposure.
Sens-up has nothing to do with focal reducers or the scope.
It is purely the length of the exposure in the camera
If you have an NTSC version of the SCB-2000 then it's maximum Sens-up is x512, which is 8 seconds.
But by using fast optics and a Focal reducer you will get smaller but brighter objects within that 8 seconds.
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: Dragon Man]
#5254504 - 06/04/12 10:41 AM
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That seems to clear a small part of it up for me with the exception of the "fast optics" part.. what do you mean by fast optics? I thought that the focal reducer will increase the capture speed.
Please forgive my ignorance but I am a noob when it comes to this... (I promise you that when you guys have any questions about the pc/software/IT related side of it.. i will more than likely have the answers for you  )
Thank you again in advance.
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mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
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Re: SCB 2000 accessories?
[Re: Amith]
#5254550 - 06/04/12 11:16 AM
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Amith,
Asking good questions (and reading about the silly ones many of us have asked over the years) is the best way to learn.
The "faster" optics are those with a lower number f ratio. For example if you start with an f10 C6 and add the f6.3 or .5x focal reducer then you will have a faster scope running at f6.3 or f5. It takes more extreme or aggressive optics to further reduce the f ratio of a scope and there are always trade offs. When you are imaging (or using a video camera) you will see more from a given exposure with a faster scope than with a slower scope. The image will be a bit smaller with the faster scope than with the slower one (assuming the same aperture) but it will be brighter.
So in general it's better to have a faster scope for video observing.
For an example of the trade offs, the Celestron f6.3 reducer/corrector has a clear aperture of around 38mm and will provide a relatively flat field (optically correct) that will cover up to a DSLR camera but it's around $130. A .5x 1.25" reducer (from GSO, OPT or Antares) has a much smaller amount of clear aperture and would only cover a smaller sensor with a good optically correct field. These .5x reducers are generally under $50. Since you are planning to use a SCB2000 camera with it's 1/3" sensor you can take advantage of the smaller focal reducer without worrying about optical quality issues that would show up if your camera had a larger sensor.
If you have a camera that has a limit on it's exposure capabilities (like the 8/10 second limit on the Samsungs) one way of increasing the sensitivity (to see fainter objects) is to reduce the f ratio of your scope (making it "faster"). Since most telescope are built to a fixed f ratio you need to add some optics (the focal reducer) to change the f ratio and make a scope "faster".
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: mclewis1]
#5256055 - 06/05/12 11:43 AM
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Thank you for not making me feel stupid as I believed I sounded.. I actually understood what you said there.
One last thing, will I need to remove my IR filter when I get my SCB2000.
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claws
member
Reged: 02/27/12
Loc: rio vista, CA
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Re: SCB 2000 accessories?
[Re: Amith]
#5256184 - 06/05/12 01:34 PM
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Quote:
Thank you for not making me feel stupid as I believed I sounded.. I actually understood what you said there.
One last thing, will I need to remove my IR filter when I get my SCB2000.
I believe that the consensus is that the filter has to go. There's at least one video out there on how this is done. Sorry I don't have a link right now but someone will come along with it.
Kim
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mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
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Re: SCB 2000 accessories?
[Re: claws]
#5256314 - 06/05/12 02:48 PM
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Links to CN threads on removing the IR filter. There's also a ton more info in the pinned thread at the top of this forum's list - The Best of QnA ...
link
link 2
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: SCB 2000 accessories?
[Re: claws]
#5256552 - 06/05/12 05:35 PM
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Image surface brightness scales as the inverse of the f/ratio squared. So if with a 0.5X refucer you reduce an f/10 to f/5, the image is 4X brighter, meaning you can obtain the same signal strength in 1/4 the time.
On an f/10 scope, a 0.33X reducer yields f/3.3, and the image is 9X brighter!
Of course, the effective focal length and hence image scale decreases accordingly. But when you have limited integration time, it's a necessary trade-off.
Incidentally, when exposure duration is limited and one cannot obtain rather fast f/ratios, some light pollution actually helps somewhat, in that it elevates the background level and so masks electronic noise. And the night sky always has some glow; artificially darkened backgrounds lead to clipping of fainter details.
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: GlennLeDrew]
#5257491 - 06/06/12 03:32 AM
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Thank you Kim, Mark and Glenn... you guys are absolutely awesome... IR filter will be gone... Im getting my scb2000p before this week is up.
Now all i need to do is get the BNC to USB converter, GSO 0.5 focal reducer, and 1.25" C-Mount adapter. ... Am I missing out anything? Oh is there a specific type of C-mount adapter for the SCB2000 that I would need to get?
Thank you guys... you are absolutely amazing.
Edited by Amith (06/06/12 03:44 AM)
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mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
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Re: SCB 2000 accessories?
[Re: Amith]
#5257856 - 06/06/12 10:22 AM
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Amith,
No the 1.25" C Mount adapter is a pretty standard part. You'll find two versions - one made from aluminum (bit more expensive), this type is necessary for Mallincam owners (they use the front of the camera as a heat sync so the adapter has to be able to dissipate heat from the internal cooler) and the less expensive Delrin models (a type of plastic). The Delrin type is fine for use with the Samsung cameras but it will wear and mark up a bit more than the aluminum ones. Generally you'll find the aluminum ones at the astronomy dealers and the Delrin models on Ebay.
There is also a short low profile model around, this is useful when you have interference problems inside a 1.25" diagonal or adapter. This could happen if you also stack a focal reducer and a few filters together ... but usually you don't have to worry about this as the stacked filters are just as robust a mounting point as the adapter is by itself. The other reason for this shorter adapter is for use with a 1.25" focal reducer that requires less than 37mm of spacing (rare).
Edited by mclewis1 (06/06/12 10:26 AM)
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: mclewis1]
#5258558 - 06/06/12 03:34 PM
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Hi Mark,
I am getting the .5x focal reducer (GSO 1.25" 0.5x/0.3x Focal Reducer w/ext). Not sure what the w/ext is or what it is for!
I have searched on ebay for the Delrin c mount adapter with no luck. I would like to get the short low profile model seeing that I will be using the star diagonal and focal reducer on my scope.
In all honesty.. I have searched most of the South African astronomy websites but am not sure which is the correct one.
Any further help will be appreciated!!!
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mclewis1
Thread Killer
Reged: 02/25/06
Loc: New Brunswick, Canada
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Re: SCB 2000 accessories?
[Re: Amith]
#5258668 - 06/06/12 04:51 PM
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The extension included with the reducer is a 25mm spacer (that uses the 1.25" filter threads on the front of the focal reducer) that when used with the focal reducer increases the reduction factor (the .5x to .3x for example). Most folks will use this reducer with a spacing of between 35 and 50mm. With a standard 1.25" Cmount adapter (which is also about 25mm long) on your camera and the reducer then threaded onto that you'll be in the 35-40mm area ... if you add the included spacer you may be in the 55-60mm area which will be very fast but I believe the optical quality won't be very good.
One source for the low profile version of the 1.25" Cmount adapter is from OWL
http://www.owlastronomy.com/barlows.htm (scroll down to the bottom of the page).
Links to a couple of Ebay sourced adapters that are made from Delrin (some don't say specifically but from the prices and pictures are very likely not made of aluminum).
link
link
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: mclewis1]
#5258772 - 06/06/12 05:52 PM
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Surprisingly enough, I had stumbled across the very same two in your links moments before you posted. The one for $18 was the one I was looking at getting (worked out cheaper with shipping).
It is very unlikely that I will be using the spacer if it will reduce optical quality. I would rather sacrifice that little speed for the quality of the image.
The GSO I am looking to get costs approx R130(ZAR), I believe that is about 15USD. My life would have been so much easier if I could get a c mount here. I've just ordered the DVR to usb card today on ebay.. that may take a while to get.
Thank you for the quick response once again.
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: SCB 2000 accessories?
[Re: Amith]
#5258916 - 06/06/12 07:35 PM
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Note that the working f/ratio with a reducer depends on the distance between the reducer's lens and the detector. Those 1.25" thread-on reducers are really just a 25mm f/4 binocular objective with 100mm focal length. To work at 0.5X, this spacing must be 1/2 the reducer's focal length, or 50mm. If the spacing is less, the reduction factor decreases (e.g., 0.6X, 0.7X, etc.) Conversely, a larger spacing means greater reduction, such as 0.4X. However. No simple achromat is able to deliver a decent image when reduction is pushed much below 0.5X; certainly not 0.33X. But if you're forced to do this just to get something like a useable image, nothing says you can't get aggressive, as long as the cometic aberration off axis, and some spherical aberration on axis are to be expected.
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: GlennLeDrew]
#5259748 - 06/07/12 10:18 AM
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I have just received my SCB2000P. I need to cut the end of a 12V DC converter so that the wires can be attached onto the camera.
My problem is that I really don't know which is the positive and negative coming from the 12V adapter.
I have an old tester at home but its not digital so I cant see when it shows a negative reading.. Haven't used it in a while but I hope the needle will try and move backward if the polarity is incorrect.
Thanks for the additional info Glenn. I think I am going to buy the C-mount adapter from ebay and the focal reducer from SA. I will play around with the distance of the focal reducer and spacer to see what effect it will have as I go along.. It looks like it is going to be a while though before it all comes together from around the world.
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barbarosa
professor emeritus
Reged: 04/11/10
Loc: "lamorinda", CA
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Re: SCB 2000 accessories?
[Re: Amith]
#5261017 - 06/07/12 10:44 PM
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I need to cut the end of a 12V DC converter so that the wires can be attached onto the camera.
Before you make the cut you might want to look for (or make) a pigtail for the camera. A pigtail allows you to disconnect the power close to the camera.
The pigtail is a short length of wire, with bare wires at one end and a connector of some type at the other. You may be able to find one already made up to match the plug on your adapter. This one fits the Celestron adapter (5.5 x2.1) and is commonly used with security cameras.
You could also make one up with parts from Radio Shack but it would require some soldering.
Quote:
My problem is that I really don't know which is the positive and negative coming from the 12V adapter.
I have an old tester at home but its not digital so I cant see when it shows a negative reading.. Haven't used it in a while but I hope the needle will try and move backward if the polarity is incorrect.
Well, it won't swing to the right if unless it is positive. 
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: barbarosa]
#5261313 - 06/08/12 03:20 AM
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Haha, Thank you David. I managed to get it sorted. Tested the camera and it works perfectly.
I didn't do the Pigtail because it has positive/negative connectors one would find on a car amplifier (basically the wires are screwed onto the camera). All I did was used the connector for it and left them on as a permanent connection.
And yes, the incorrect polarity did make the meter want to go backward... lol.
Cant wait to get my 1.25' nosepiece adapter, focal reducer and DVR to USB converter and I'm all set to go.
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AussieAmature
member
Reged: 05/06/12
Loc: Sydney Australia
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Re: SCB 2000 accessories?
[Re: Amith]
#5279650 - 06/19/12 09:22 PM
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Then all you will need to do is come onto nightskiesnetwork and do some live broadcasting for us all to have a look and help out
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Amith
member
Reged: 06/03/12
Loc: Durban, South Africa
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Re: SCB 2000 accessories?
[Re: AussieAmature]
#5280029 - 06/20/12 01:51 AM
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Hey Aussie, I am registered on that site as well. Will do as soon as I get all components.
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