(meteorobs) advice needed to shoot meteors

[stange34 at sbcglobal.net]

As Chris has mentioned, a simple "tracker" can be fabricated from a 24 hour 
timer (lamp or sprinkler) dial modified by hardware into a mounting platform 
for a camera, with the axis of the dial aimed in line with the North Pole.

The more robust timers, and those with large dials for outdoor use are 
better.

Larry
YCSentinel


----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2007/12/15 18:11
Subject: Re: (meteorobs) advice needed to shoot meteors


> Hi Jeremie-
>
> How bright a meteor appears is largely independent of exposure time,
> since the meteor sets its own exposure time by how long it spends on any
> one pixel. Longer exposures do slightly decrease the sensitivity by
> adding more noise, but the effect is small for typical camera exposures.
> So why limit yourself to 5 seconds? You're going to need to take an
> awful lot of images, and there is dead time between each while the data
> is saved. I'd consider something like 30-second exposures. That gives
> you a much better chance of catching a meteor, and a lower percentage of
> your time spent inactive. You're not going to see much sky movement in
> 30 seconds using a 50mm lens unguided. You might also consider a cheap
> tracker for the camera.
>
> You get some advantage with the smaller DSLR sensor, because it sits in
> the central region of the lens image plane, where the optics are better.
> Even so, very few lenses are capable of producing pinpoint images out to
> the edge of the chip unless you take them down one or two stops from
> wide open.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- 
> From: "vaubaill" <vaubaill at imcce.fr>
> To: <meteorobs at meteorobs.org>; "IMO-news" <imo-news at yahoogroups.com>
> Sent: Saturday, December 15, 2007 6:04 PM
> Subject: (meteorobs) advice needed to shoot meteors
>
>
>> Hi guys,
>>
>> Here is a kinda unusual request. Here is the thing: I would like to
>> shoot some meteors with my digital SLR (canon rebel XT). I do not want
>> a
>> too large FOV because in this case the tracks are so small they can
>> hardly be seen. So the focal length I am aiming to is around 50mm
>> EFFECTIVE, meaning a lens focal length around 35mm because of the
>> correction factor for digital SLR (1.6 for the Rebel XT).
>>
>> Now I really need a FAST lens, since I'll shoot 5sec max., so forget
>> about anything slower than f/2.0
>>
>> So you may think of the 35mm f/1.4 by canon, BUT for ~$1200, man
>> that's
>> kinda a stretch for my wallet!
>>
>> I saw the sigma 30mm f/1.4 for ~$400. Since I don't know wnything
>> about
>> this brand, my question is to know if anybody here has ever tried this
>> one for astro-photography please?
>>
>> Thanks for any advice ;-)
>>
>> Jeremie
>
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