[Chaos-l] Image from Little River

[Mark Montazer]

Most wider camera lenses suffer from chromatic aberration in the same
fashion as achromat scopes. Due to the extreme curvature from one side of
the lens to the other not all colors are focused at the same point. When we
do focus, our eyes tend to defer to the green wavelengths leaving
blue/violet out of focus.

This is rarely an issue in daylight photography, though you may be able to
see evidence of it when looking at pictures that have strong contrast in
the (e.g., branches against a bright sky, etc.) At night it becomes more
noticeable because there is less to distract our eye from it.

The edge of the lens contributes most to the aberration as it refracts the
light most strongly. Stopping down the aperture will reduce the amount of
light coming in from the edge of the lens, at the cost of increasing your
exposure time. It's a trade off and you've got to find your comfort zone
there.

I've got a great low-light lens (Canon FD 50mm f/1.4.) If I shoot it wide
open every star in the sky is blue, so usually I'll stop it down to f/4 or
f/5.6 or so.

Mark



On Sat, Apr 6, 2013 at 9:21 AM, Jayme Hanzak <spacenuut at gmail.com> wrote:

> There is a lot of color out there that our eyes can't make our. The colors
> that you see in your RAW images Steven are probably fairly accurate.
>
> I have a Canon 10D and yeah, it is difficult to focus. I try to find a
> bright star like Sirius, get a good focus and hope that I don't bump it
> again. My biggest issue is that I am not patient enough to take the
> numerous images that is required to make a great picture.
>
> Steven this is a great early image. You'll be surprised at how much you'll
> learn and your images will improve. You will look back at this image and
> say to yourself, Wow, I've come long way. It won't take long and we all
> look forward to seeing more images.
>
> Great job and thanks for sharing.
>
> Jayme
>
>
> On Sat, Apr 6, 2013 at 5:46 AM, Steven Christensen <steve at smc.vnet.net>wrote:
>
>> Had a good time at Little River Friday night.  Nice folks and skies.   I
>> also played with my new Vixen Polarie star tracker and took this
>>
>> http://smc.vnet.net/orion2.jpg
>>
>> 12 20 second exposures stacked with Deep Sky Stacker software.  I am
>> happy with the Vixen as it is easy to use and seems to do fine.   My Canon
>> DSLR is quite old and not high resolution and kind of hard to focus.  The
>> lens is the stock one that came with it.  But I did get Sirus, Orion, and
>> Jupiter along with some ground light.
>>
>> I plan to get a much better Canon soon and hope to do better.
>>
>> Steve C.
>>
>>
>>
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