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T2i....battery or AC Adapter for Astro use

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#1 zawijava

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Posted 12 February 2013 - 03:48 PM

Hi,

I've read here the recommendation that for astro use using a ac adapter instead of the battery in my T2i will reduce noise from battery heat...it does get warm. Is this for all exposure times ie long, short, HD Movie mode etc?

And does the ac adapter not get warm as well?

thanks! -Tim

camera is very new to me, it hasn't seen star light yet due to poor Wx

#2 RedLionNJ

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Posted 12 February 2013 - 03:53 PM

The AC adapter will actually eminate more heat than the battery - the difference is that the heat is not being emitted inside the camera, so the sensor is not affected by it.

For any astronomical purpose, I'd be trying to minimize the additional heat recorded by the sensor.

Grant

#3 zawijava

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Posted 12 February 2013 - 04:11 PM

Grant,

So the small ac adapter "brick" (not sure what it's called) that slips into the battery compartment on the T2i doesn't produce any heat? -Tim

The AC adapter will actually eminate more heat than the battery - the difference is that the heat is not being emitted inside the camera, so the sensor is not affected by it.

For any astronomical purpose, I'd be trying to minimize the additional heat recorded by the sensor.

Grant



#4 Falcon-

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Posted 12 February 2013 - 04:13 PM

To elaborate a bit on what Grant said in case you have not seen one of these AC adaptors yourself - the AC adaptor's power brick is outside the camera (on the other end of a 5ft cable in fact). That is why the head produced by the AC to DC circuitry does not effect the camera at all even though technically it ges warmer then a battery under load does.

Is this for all exposure times ie long, short, HD Movie mode etc?

Yep, any exposure mode/type/length will see a noise contribution due to heat. Long exposures see it most severely simply due to the length of time for the heat-induced noise to be added to your signal. That said, if you are doing video capture of the moon or any type of daylight photography I would not worry about it at all.

For what it is worth I do use AC adaptors instead of batteries for both my cameras when doing astro work.

#5 Tom and Beth

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Posted 12 February 2013 - 04:20 PM

With my XSi, a fully charged battery on a cold night will last somewhere around 2 hours.

So far, I've had the AC power suply and have noted:
1) No time limit.
2) No heat. The conversion is done in a box separate than the Dummy Battery Connector inside the camera.
3) A very slight reduction in weight at the focuser end, although now I have another cable to deal with.

For the cost (Amazon -$17, delivered) it was money well spent, IMO.

#6 piaras

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Posted 12 February 2013 - 04:21 PM

Another reason is you will likely only get about 2 hrs with the battery. That is what I got with my T3i, full charge on an August night.
Pierre

#7 zawijava

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Posted 12 February 2013 - 04:23 PM

So, it's sounding like I have a misunderstanding of how the ac adapter plugs into the camera :question: can someone enlighten me since I don't have an Owners Manual for reference :tonofbricks:

To elaborate a bit on what Grant said in case you have not seen one of these AC adaptors yourself - the AC adaptor's power brick is outside the camera (on the other end of a 5ft cable in fact). That is why the head produced by the AC to DC circuitry does not effect the camera at all even though technically it ges warmer then a battery under load does.



#8 Falcon-

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Posted 12 February 2013 - 04:27 PM

The ac adaptor goes like this:

AC outlet -> Wire -> AC/DC power brick -> wire -> battery "blank" -> camera

The battery blank is simply a connection that happens to be shaped like a battery, no active circuitry of any sort. All the power conversion goes on in the "AC/DC brick".

You can see all this (with cables coiled up) on this page: amazon.com link

#9 zawijava

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Posted 12 February 2013 - 04:44 PM

Thanks, that's the way I assumed it worked as I have another Canon Camera and Video cam. Unfortunately the plugs that come out of those power bricks are different than the T2i so looks like I'll have to spend the entire $69 bucks vs just getting the "battery blank" which is about half that. thanks for all the responses! -Tim

The ac adaptor goes like this:

AC outlet -> Wire -> AC/DC power brick -> wire -> battery "blank" -> camera

The battery blank is simply a connection that happens to be shaped like a battery, no active circuitry of any sort. All the power conversion goes on in the "AC/DC brick".

You can see all this (with cables coiled up) on this page: amazon.com link



#10 Sean13

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Posted 12 February 2013 - 06:05 PM

Here is an ebay link to much cheaper generic AC adapter kit for your camera if you don't feel like spending $70 on a branded one:

http://www.ebay.com/...-T2i-Kiss-X4...

#11 Falcon-

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Posted 12 February 2013 - 06:10 PM

Well.... there is a way to save money. There are some cheap clones of the Canon AC/DC adaptor, and they naturally come with a battery blank.

Now I own both a cheap clone and a canon official part and I have to say the quality on my clone is so low that I would not buy another..... I have already had to take it apart and re-solder the DC cable to the board. Still, they ARE inexpensive! A quick amazon search for "t2i ac adapter" showed the first result as $16.90. Just keep in mind you do get what you pay for ;)

#12 zawijava

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Posted 12 February 2013 - 07:13 PM

I think I'll steer clear of the cheap ones :bow: thanks for your insights!

-Tim

Well.... there is a way to save money. There are some cheap clones of the Canon AC/DC adaptor, and they naturally come with a battery blank.

Now I own both a cheap clone and a canon official part and I have to say the quality on my clone is so low that I would not buy another..... I have already had to take it apart and re-solder the DC cable to the board. Still, they ARE inexpensive! A quick amazon search for "t2i ac adapter" showed the first result as $16.90. Just keep in mind you do get what you pay for ;)



#13 avarakin

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Posted 12 February 2013 - 10:15 PM

Another thought is: if you expect to travel to darker sites for your imaging, instead of 110v model, you should buy 12v model which can be used directly from battery. Converting from battery to 110v and then to 7v camera needs wastes a lot of power.
Unfortunately such converters are rare and pricey. If you are into DIY then it is easy to build one out of parts found on ebay for 20 total.

Alex

#14 Mike Clemens

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Posted 12 February 2013 - 10:50 PM

I've been thinking to deliver only QUALITY 12V to the scope from the pier on 12 AWG ultraflex cables, and then put nice well filtered tiny homebuilt DC linear power supply(ies) out there that put out the Canon voltage, the USB hub voltage, the dew heater voltage. I could buy the T2i cheap power supply just to get the battery blank and feed it some stepped down DC.

#15 zawijava

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Posted 12 February 2013 - 10:59 PM

You can buy the battery blank separately, at least from Canon...not sure about the cheap version? But I guess the complete cheap power supply is less $$$ -Tim

I've been thinking to deliver only QUALITY 12V to the scope from the pier on 12 AWG ultraflex cables, and then put nice well filtered tiny homebuilt DC linear power supply(ies) out there that put out the Canon voltage, the USB hub voltage, the dew heater voltage. I could buy the T2i cheap power supply just to get the battery blank and feed it some stepped down DC.



#16 Falcon-

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Posted 12 February 2013 - 11:28 PM

Mike: Hmm... that is rather a good idea. If I ever get my but in gear for my synscan upgrade I should do the same and add in 7.whatever volt outputs for the cameras (and, as you say, 12v for the mount and 5v for USB)

#17 guangtou

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Posted 13 February 2013 - 12:51 AM

Wouldn't a battery grip also reduce noise since the batteries would then not be next to the sensor?

#18 Falcon-

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Posted 13 February 2013 - 03:17 AM

Wouldn't a battery grip also reduce noise since the batteries would then not be next to the sensor?


Yes it would, but it adds mass (important for those of us who overload our mounts) and only partially solves the running-out-of-power problem.

Still, for those imaging away from easy AC power....

#19 neptun2

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Posted 13 February 2013 - 03:28 AM

I also use AC adapter with my Nikon d90 and it is must have purchase for astronomy in my opinion. In the cold at -15 deg celsius the battery lasts for no more than 1.5 hours. The AC adapter allows me to work with the camera without worrying that it can shut down during the session.

#20 bilgebay

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Posted 13 February 2013 - 06:46 AM

I am using this to convert 12V to 7.5V for my Canon DSLRs. It's cheap, it's efficient, me happy :)






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