Quote:
Originally Posted by astro744
... not possible to get all eyepieces par focal
|
Not true, though rare.
Some examples of sets that are fully parfocal across the series are Vixen LVW and SLV and SSW, and Masuyama. The vixen LVW series were unique in spanninga 10:1 range of focal lengths 42 down to 3.5mm, and also have an aspect which is unique - they all weigh roughly the same so those with refractors or newtonians don't need to rebalance the scope between low and high power. Someone really thought about all aspects of the design of those, not just the lenses.
Another series that are precisely parfocal across the set are Brandon's...