Is it just me, or do others find it odd that a number of 155 owners are selling because they are getting a 160. I do not own an AP scope, and probably never will (a $ issue), but why would someone do this? Not challenging the action, just curious.
"Upgrade" from 155 to 160
Started by george_kiger, 10/27/2005 02:37PM
Posted 10/27/2005 02:37PM
Opening Post
Posted 10/27/2005 03:48PM
#1
George Kiger said:
Is it just me, or do others find it odd that a number of 155 owners are selling because they are getting a 160. I do not own an AP scope, and probably never will (a $ issue), but why would someone do this? Not challenging the action, just curious.
Because they can?
The 160 gathers a whopping 6.5% more light.
But it's an F7.5 instead of F7. So the focal length is 10.5% longer. That alone might be a good enough reason for a person who enjoys viewing planets.
I don't know how the two compare optically, but I think the 160 is the first air spaced design for AP.
Some folks might have the 2.7" focuser on their 155's and want the 4".
And some folks just probably want to own one of each.
Posted 10/27/2005 03:51PM
#2
I would not know about those who already have a 155 F7, I have one and have really no intention of signing up for a 160. Most people I know who got their 160's don't own a AP 155 F7. One person I'm aware of had a 6 inch F9 AP that was made in the early nineties He recently sold his F9 scope when he took delivery of his 160 but other than that I'm unaware that a lot of people are doing this.
Clear Skies
Dwight L Bogan
Clear Skies
Dwight L Bogan
. Afterall, there's some distinct advantage in this design 8O.
Posted 11/11/2005 08:26PM
#4
I recently star tested a 160 at 300x and cannot say it was in
any way dramatically different from the 155. Same nice wavefront;
same slight red / blue color fringing either side of best focus.
It was not a side-by-side test, which would have been more exacting,
but nonetheless any difference was non-dramatic. Perhaps there
is more differnce photographically, but visually it was not
apparent to me. I guess I vaugely thought the extra degrees
of freedom in the lens design would produce some immediately
noticable effect.
By contrast, comparing a Travler EDFS and a TMB 100 F8 star test
(also oiled vs. airspace) it is right away obvious they are
very different (also different F-ratios!); not so with
the 155 vs. 160.
If I had to decide between the two -- it is not obvious to me.
Anyway, my name is so far down the 160 list, it will be a
long time before I need to worry about it....
any way dramatically different from the 155. Same nice wavefront;
same slight red / blue color fringing either side of best focus.
It was not a side-by-side test, which would have been more exacting,
but nonetheless any difference was non-dramatic. Perhaps there
is more differnce photographically, but visually it was not
apparent to me. I guess I vaugely thought the extra degrees
of freedom in the lens design would produce some immediately
noticable effect.
By contrast, comparing a Travler EDFS and a TMB 100 F8 star test
(also oiled vs. airspace) it is right away obvious they are
very different (also different F-ratios!); not so with
the 155 vs. 160.
If I had to decide between the two -- it is not obvious to me.
Anyway, my name is so far down the 160 list, it will be a
long time before I need to worry about it....
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