Re: Interesting reading

["Lee John Droege" <leejohndroege@hotmail.com>]

from brother Lee John Droege

In the 1960's leica lenses were very over rated for use in transistor mask 
fabrication where uniform illumination was critical.

Emitters in a transistor mask can vary horribly in size even though at 400x 
the dots are sharp.

The only company who could be made to worry about such things was Wray of 
London.  Given the conjugates and frequency, (green mercury line for us) 
they would hand make a lens that had uniform focus AND illumination edge to 
edge over a 1.2 inch square.  We paid $600 to $1000 for such lenses in 1962. 
  They were called "UNILITE".  The variations in illumination that would 
kill us when exposing high resolution. plate(asa.05)were not apparant when 
we used such lenses in film cameras.

Since the 60's I have been manufacturing earrings where things are not so 
critical but it is the same technology.  Still I will bet that the lens 
people who still worry about such things---speak english


>From: Tom Droege <tdroege2@earthlink.net>
>To: Chris Albertson <chrisalbertson90278@yahoo.com>,tass@listserv.wwa.com
>Subject: Re: Interesting reading
>Date: Fri, 08 Mar 2002 13:28:56 -0600
>
>Chris and all,
>
>We shall see.  I am having lunch with him April 24 when he gives a talk at
>Fermilab.  I think I posted that here.  If anyone here wants to get to the
>talk, I will check on what has to be done with security.  It has been a
>pain since 911.
>
>I wrote him about what we were doing, but he did not write back.  I think
>we are competition.
>
>As for camera lenses.  I tried a few.  They do not have very flat
>fields.  The one I tried drooped about 50% at the edges.  Elliot's design
>looks like a few percent.  I don't know about the particular Leica lens,
>but ROTSE used the best camera lenses that they could find, I think from
>Canon, and they have a big variation across the field.  They paid a similar
>amount.  The field was much less flat (5x?) then we achieve with the Elliot
>Burke design.  The field flatness goes as some high power of the bandwidth
>when you try to optimize it.  So Elliot and I made use of this when the
>lenses were designed.  The history is that I discovered this from talking
>to lens designers.  Then I just kept hunting until I found someone willing
>to have a go at it.  It was an awful experience, getting the lenses right,
>but now I am glad we did it since we now have a bragging point.  Not sure
>it really matters for the result.  I should have worried more about lens
>baffling.
>
>I think the life of tass depends on using filters.  I would not encourage
>the competition to use filters.  ;^).  The economics of these surveys is
>such that they don't work at big observatories.  It is too costly to pay
>astronomers to sit at the observatory many months of the year.  Sure!  They
>will be run remotely for months without requiring attention.
>
>The more I look at Michael's software the more impressed I am with it.  It
>is well documented.  Once we run a lot of data through it and have
>problems, it will be easy to make changes.  We shall see if we can say the
>same about Dr. Charbeneau.  I will try to get his software, but we shall
>see what he makes available.
>
>He seems to be getting a lot of publicity.  You can't both do work and give
>talks everywhere.  My goal is to let the results do the talking.  We are
>pretty close.
>
>Below is the note I wrote him.
>
>Tom Droege
>
>Hello,
>
>I am looking forward to meeting you when you come to Fermilab in April.  I
>have started an amateur group called The Amateur Sky Survey (tass).  I am
>building a number of 400mm fl f/4 dual camera systems with 2k CCDs to
>perform an all sky survey.  At least one of our group intends to use a
>system for a planet search.  While we cannot do photometry at your level,
>we hope to provide candidates for projects such as yours.  See
>http://www.tass-survey.org for more information about tass.  TN-81 is one
>example of the data analysis work.  I did not have much luck getting
>through your web site to an actual paper.  Possibly you can direct me.
>
>Tom Droege
>
>At 09:35 AM 3/8/02 -0800, you wrote:
>>I like the part where it says
>>
>>   "An amateur astronomer could do this, except maybe for
>>    the debugging of the software, which requires several
>>    people working 10 hours a day,"
>>
>>I'm sure most of us would agree.
>>
>>The project sounds almost identical to the Mark IV except they
>>are using a shorter focal length lens but a much higher quality
>>Leica makes a 280mm f/4.0 lens.  They don't make a 300 so I assume
>>someone rounded up.  Lenses don't get much better quality then
>>Leica.  It sells for $4600. Being such a sharp lens their stars
>>are even more under sampled then TASS'.  Maybe a one pixel PSF?
>>They are likely using a very sturdy computer controlled mount too.
>>
>>The Dollar figure on the CCD says they may even be using the same
>>CCD as the Mark IV, just the #1 grade.
>>
>>They don't talk about filters but then this is a press release for
>>the general public.
>>
>>I would be very much be interested in finding out about their
>>software.  Whatever they use would be directly applicable to TASS
>>as it is clear TASS and this system are a lot a like.
>>
>>
>>
>>=====
>>Chris Albertson
>>   Home:   310-376-1029  chrisalbertson90278@yahoo.com
>>   Cell:   310-990-7550
>>   Office: 310-336-5189  Christopher.J.Albertson@aero.org
>>
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>
>




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