(meteorobs) Improving the contrast of all-sky camera &mirrorsystems. Chris?

[Larry]

Hi Leo.

I would say you have conquered all the issues. Great photo's and the circuit 
is worth bookmarking for any later need.

Absolutely outstanding is that focal plane shutter speed of 1600 and ISO 200 
fine grain film producing pictures like that your last one. That June 28th 
was a REALLY pretty double shot!!

As in most photogrraphy,  film cameras will continue to come out on top for 
resolution and color over digital cameras.

The UK does nice work old boy. Nice work indeed!

YCSentinel


----- Original Message ----- 
From: "Leo S" <l.stachowicz at btinternet.com>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2009/06/16 10:00
Subject: Re: (meteorobs) Improving the contrast of all-sky camera 
&mirrorsystems. Chris?


> Hi Larry,
>
> Larry wrote:
>> Hello Leo.
>>
>> It seems you are pursuing very challenging work in daylight lightning.
>>
> It's actually not too hard to do. Certainly no harder than trying to
> capture daylight meteors. At least lightning is fairly predictable
> compared to meteors. I think that apart from that, in essence, the
> problems of trying to capture daylight lightning and fireballs are more
> or less the same, the biggest problem being contrast between the event
> and the sky (once the triggering issue has been overcome).
>
>> There is a possibility that very large(not small) industrial IR domes 
>> where
>> the camera is distant from the surface of the dome itself at the radius
>> center might work for that. Those domes are used in Casino's but are a 
>> bit
>> "pricey".
>>
>> This would allow more latitude in sensitivity and threshold adjustment. I
>> lost a daylight fireball test camera using this method due to internal 
>> metal
>> or PVC sweating even though it was heated on a timer during the night and
>> was sealed from ambient moisture. The CCD substrate itself failed I 
>> believe
>> because slow oven treatment did not bring it back.
>>
> Yikes! Perhaps a small PC fan for ventilation might prevent this from
> happening again? The dome does sound like a good solution if you can
> overcome these problems though!
>
>
>> If you can post some lightning strikes or your personal research results 
>> I
>> think it would be quite interesting to the group. Certainly I would like 
>> to
>> see what you can image.
>>
> Previously I would just set up the camera so that the sky was slightly
> under exposed, and then rapid fire in the hope of catching the
> lightning. I got a few pics by doing this, but I wanted to avoid wearing
> out the shutter as much as possible. You can see previous attempts here:
> http://www.btinternet.com/%7El.stachowicz/pics/weather.htm
>
> Last year came across a blog detailing how to build a photo-sensitive
> trigger using a mini-computer (see:
> http://www.glacialwanderer.com/hobbyrobotics/?p=16 Scroll down for
> someone else's daylight lightning pics using the same device) which I
> built, and I did not get an opportunity to test it in a real storm until
> yesterday. This is the trigger I built:
> http://farm4.static.flickr.com/3205/2882095025_e9d564cdce_o.jpg
>
> Unfortunately, by the time I had set up the trigger yesterday, the storm
> had almost petered out, but I did manage to catch the last strike that I
> saw. It's not a great shot, but it proves the trigger works as it
> should. The exposure was 1/1600 of a second, ISO 200 @ F3.5
> http://www.btinternet.com/~l.stachowicz/pics/other/YX9J3301.jpg
>
>
>> Yes on the mechanical shielding. I will study that issue now. I do need 
>> to
>> keep certain fixed lights on my horizon as Azimuth alignment markers, 
>> which
>> assures me no changes have occured with the cameras North alignment 
>> during
>> my routine servicing.
>>
>> YCSentinel
>>
>
> I was thinking you might be able to get around this problem by cutting
> notches or drilling holes in the appropriate places in the shield, so
> that just the lights that you need shine through, but it might be a bit
> fiddly to get right, although you could always patch up a hole if it was
> not quite in the right place.
>
> I think a better idea might be to install a couple of small LEDs on the
> shield edge that you could then use to align the camera. You would have
> to make sure the shield was well and truly fixed in place though.
> Otherwise, it might be an even better idea to install LEDs on some other
> object that is fixed, and you have access to, or if there is none, you
> could fix a pole or two that would be just high enough to elevate an LED
> into your FOV.
>
> Leo
>
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