Re: [APML] Lyra, N5128, N5139

[Wei-Hao Wang <whwang@gmail.com>]

Hi Glenn,

My refractor is Pentax 105 SDHF.  It's a doublet F6.7 APO using FK 05 ED
glass with a built-in field-flattener (so totally three lenses).  It
has a flat field
covering 88mm diameter.  It also has a 0.77x focal reducer which also 
produces an 88mm flat field.  It's optimized for median format prime-focus 
photography and is not that excellent for high power visual use.

This telescope is discontinued.  The current 4-in version is called 105 SDP.
This one is very similar to Takahashi FSQ106.  It has 4 lenses and two of 
them are ED (one is FK 05 and the other one is FK 03, I guess).  It also 
produces an 88mm flat field, both with and without the dedicated focal
reducer.
105 SDP has better color correction than 105 SDHF and is better for
visual use.
Pentax has another 4-in scope called 100 SDUF II.  This one is really an 
astrograph.  Its focal ratio is 4 and is optimized for 67 format, too.  Many 
people even use it on 4x5 film.

Pentas doesn't sell these telescopes in the US.  Perhaps they can only be 
bought in Japan or Europe.  They are widely available in Japan.  There is 
almost no waiting time for getting them, unlike some scopes in the US.  
The retail price of 105 SDP in Japan is 417900 Yen, corresponding to about 
$3.5k.  100 SDUF II (the F4 one) is a much cheaper 249800 Yen, about $2k.

This is the telescope website of Pentax Japan:
http://www.pentax.co.jp/japan/products/telescope/normal/
You can also find other telescopes made by Pentax.  Most of them are 
optimized for median format (at least 6x4.5) photography.

Please let me know if there is anything I can help.  I really enjoy using my
Pentax.  It's a pitty that they are not sold in the US.

Cheers,

Wei-Hao


On Thu, 05 Aug 2004 21:10:08 -0800, glenn shaw <glennshaw@alaska.net> wrote:
> Wei Hao:
> 
> Can you provide info on the Pentax refractor? Availability and prices? Its
> optics seem great!!
> 
> glenn shaw
> 

-- 
________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       
2680 Woodlawn Drive         Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
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