RE: [APML] Epsilon 160 and 210 informations.

["Loke Tan" <tan@cox.net>]

Teiva,

 See:

http://astro.umsystem.edu/apml/ARCHIVES/NOV02/msg00006.html

We have discussed this before for the Epsilon 210. See the links to the
illumination. Use the graph on the lower right  to see illumination for the
ST10, a 14.9mmx10mm chip. The image showing image circle is exagerated. Here
it is again:

http://starryscapes.com/tmp/ST10_E210_hor_illum.jpg
http://starryscapes.com/tmp/ST10_E210_hor_illum_top.jpg

The images circles for the Epsilons are:

E160 - 49mm
E210 - 57mm
E250 - 69mm
E350 - 70mm

I go these numbers from Texas Nautical
http://www.lsstnr.com/default_scopes.htm

If you look at the Takahashi website in japan:

http://www.takahashijapan.com

Direct links:
http://www.takahashijapan.com/PURODUCT/tube/specks/EPS160.htm
http://www.takahashijapan.com/PURODUCT/tube/specks/EPS210.htm
http://www.takahashijapan.com/PURODUCT/tube/specks/EPS250C.htm
http://www.takahashijapan.com/PURODUCT/tube/specks/EPS350.htm

They state that the image circles are:
E160 - 42mm
E210 - 57mm
E250 - 69mm
E350 - 69mm
I hope I interpreted this correctly, if not please let me know.

None of these are large enough for 6x7 which requires 90mm. I am not sure
why the E160 and the E350 have different numbers from the USA website. I
believe Takahashi has a definition of illumination. From my CCD flatfield,
it is not defined as 100% illumination for the given image circles. That is
just because the stated image circles for the E210 is 57mm, it does not mean
that it is 100% illuminated at 57mm. For example, with the TOA130 (from
Takahashijapan.com)

-----------------------------
67??????(130F??)
?KA31583? ???? 1000mm
??? ?/7.7
???????? ?92mm???60???
?? ?5.3°
?? ?78,000?
------------------------------

The image circle is 92mm at 60% illumination for the TOA130 refractor. I do
not read Japanese so this is my guestimate of what this means. You might
want to ask someone who does. The percentage illumination for the Epsilons
was not stated at the Takahashi Japan website. Hope this helps.

Loke




-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Teïva Leroi
Sent: Saturday, March 15, 2003 10:00 AM
To: astro-photo@seds.org
Subject: Re: [APML] Epsilon 160 and 210 informations.


If the epsilon 210 has a 57mm dia image circle, it's not enough for 6x7
camera. Maybe the Ep250 will be better.
Bobby, somebody told me the Ep210 and the BRC250 have the same focuser.
Is yours very good and precise?
teiva
http://www.astrosurf.com/leroi

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