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100 vs 140mm

Started by Michael Koons, 06/29/2005 11:59PM
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Posted 06/29/2005 11:59PM Opening Post
Michael Koons
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Join Date: Oct 2001

Location: Danville PA, US

Posts: 260

For planetary viewing from an suburban location with street lights, what would be the difference between a 100/f8 and 140/f7 be for planetary viewing only. Would it be close, would seeing measurably affect the 140 more. Both would be premium APO's.
Thanks in advance for your input!
Mike
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Posted 06/30/2005 12:09AM #1
Roland Christen
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Join Date: Mar 2004

Location: Rockford IL, US

Posts: 1441

The difference is huge. Planetary viewing is not affected by local light pollution. Seeing is the only criteria. The seeing in front of my house, in the middle of Rockford, is superb for planets, even though I can only see a few bright stars due to the car dealerships, Walmart/Kmart/Target/Mega malls, etc. right down the street.

Roland Christen
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Posted 06/30/2005 04:05AM #2
Chester Flaxmayer
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Join Date: Oct 2003

Location: Scottsdale AZ, US

Posts: 16

I have a TMB 115/850.
I just bought a TMB 175/1400

The improved detail and light grasp increase is, in a word, HUGE and I live 24 miles north from Phoenix and my skys suck.

The 140 all the way.

CF
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Posted 06/30/2005 05:36AM #3
Stu Travelbee
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Join Date: Apr 2002

Location: Columbia City IN, US

Posts: 36

Mike,
I did a comparison between my TEC140 and NP101 here in the city. Both Jupiter and Saturn images were extremely sharp in both scopes with the TEC140 being slightly brighter, but the back ground too. With twice the aperture the TEC140 gave a sightly better view. As far as a "grab and go", I would take the NP101.
Stu

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Posted 07/02/2005 11:33PM #4
Patrick Kelly
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Join Date: Jul 2001

Location: Centreville MD, US

Posts: 45

Aperature rules here...and not affected by streetlights at all so by all means do the 140. Seeing conditions will be your only limitation. I used to observe with my 102 Tak from a city townhouse backyard with 60 neighbors with lights, spots, a nearby steel plant and seeing was superb. Moved to the dark sticks, and the coast, with Milky Way to die for and seeing sucks most of the time.

Pat
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Pat Kelly in Centreville (Delmarva), Maryland. Retired but working second career.
Telescope - 8" f/12 classic achromat refractor by D&G Optical; Manheim, Pennsylvania;
Mount - 1200DA metric black classic equatorial mount circa 1992 by Astro-Physics; Machesney Park, IL;
BlueStar Observatory 13 x 13 roll off  by Backyard Observatories; Lodi, Ohio;
Previous telescopes A-Z: Astro-Physics to Zeiss...D&G Optical Aficionado; The Classic Refractor - The telescope everyone wants to have used but no one wants to own.
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