TPOD jan28,'11 Redshifts?

[jacmac]

I am familiar with H. Arp's work and have his book "Seeing Red".
The excuse given is that some of Arp's objects just seem to be linked but are really very far away, etc.
Here is my question.
When the human eye looks through a telescope objects will either seem to be in focus or not. The object seems clear rather than fuzzy etc. Would it be possible and/or worthwhile to find an object that seemed to be "in focus", then measure the red shift of its light. Next, scan for other light sources that seem to be "in focus" without changing the focus mechanism of the telescope(same focal length).
Would this be a way to estimate that different objects were close to the same distance away, and then of course measure the redshift of each and any objects found.?
Would this be useful in either supporting or falsifying red shift beliefs?
Would different sizes of objects make this not a viable test of red shift?
Does anybody know if this has been done?
Is this a reasonable idea?
Just a thought,
Jack

[nick c]

hi jacmac,

Would it be possible and/or worthwhile to find an object that seemed to be "in focus", then measure the red shift of its light. Next, scan for other light sources that seem to be "in focus" without changing the focus mechanism of the telescope(same focal length).

I would say no. While you could do that when you look at mailbox 50 meters distant and compare it to a telephone pole in the same line of sight at a km distant; astronomical objects in the eyepiece are all focused at infinity. Essentially this equals the focal length of the primary lens or mirror..... whether the Moon, a star, or a galaxy; from the telescope's point of view they are all effectively at the same distance.

Nick

[mharratsc]

Nice application of logic tho, jacmac... I like the way you think!