On 08/02/2018 17:37, Johnny B Good wrote:
On Thu, 08 Feb 2018 15:20:31 +0000, nothanks wrote:

On 08/02/2018 13:59, Johnny B Good wrote:
On Thu, 08 Feb 2018 08:06:43 +0000, Martin Brown wrote:

On 07/02/2018 17:45, Tim Streater wrote:
In article , Vortex13
wrote:

On 07/02/2018 14:02, T i m wrote:

Silly question for you ... why don't you see any stars in any of
the shots from the Roadster? Is it that it's too bright in general,
even though it looked pitch black in the background?

It's too bright in general. People asked the same Q about Apollo
moonshot pix from the Moon's surface.

Too bright for seeing any stars but Venus is doable from the ground
when it is at its brightest and maximum elongation close to midday.
You just need to stand out of direct sunlight and know exactly where
to look.

The hard part is focussing your eyes at infinity.

[snip]
However, when it comes to observing the "Morning" or "Evening" star,
namely Venus, that generally doesn't present any great difficulty with
naked eye observation since it is both very bright and discernible as a
tiny crescent, unlike the dimensionless points of light we call stars.

For the avoidance of doubt I was talking about seeing Venus with the
naked eye at or around midday in a clear blue sky with the sun well
above the horizon. You need a good clear day and to stand in shadow.

I have to admit that 'focussing on distance objects' relies not so much
on relaxed focussing muscles so much as on correct convergence which
almost always is a matter of some active muscle control and less about
total relaxation which usually only approximates the precise convergence
required for viewing distant objects. As you pointed out, my throw away
observation wasn't quite correct, merely just a small part of the whole
story.

The eye's default focus is as someone else has said is a few metres away
from you if you have normal vision. You have to make an effort to bring
the distant horizon into sharp focus assuming normal vision.

If you want a serious test of visual acuity try splitting the star
epsilon-Lyra naked eye soon after dark it is a 3' arc double star -
actually a double double in a small telescope it looks like:

... :

with much bigger gap between then.

--
Regards,
Martin Brown