Tv 26mm smoothside plossl versus TAL 25mm plossl.

[Chaz2b]

Not an in-depth comparison, just a quicky from my daylight observations.

I’ve just recieved the Tv plossl so I wanted to compare against something similar of that era.

The TAL eyepiece is an excellent ocular, with which I purchased another to make a Bino pair, so, as they are of the nineties era I put them into my recently acquired Televue Ranger, also nineties era.

This comparison is done during daylight hours and the target is not too far away, 6.8 miles to be exact.

This is a farm I use as it has lots of fine/ slim poles and fencing plus sheep grazing and trees on the horizon.

The TAL will get a good focus with a fair degree of back focus, the sharpness falls off in the last ten percent around the perimeter but not greatly.

Switching to the Tv plossl and…wow! What a difference! The viewing is much brighter and the sharpness IS to the edge!

The range of focusing range is what I describe as far in the TAL and close in the Tv, meaning it doesn’t need much movement either side of focus to be out of focus , snap focus comes to mind.

Bearing in mind what the cost difference of these two eyepieces and you can understand that the Tv would win this one.

This motivates me to now considering buying another Tv smoothside 26mm to pair for Bino viewing, oh! This is going to be fun!

chaz

Edited May 4 by Chaz2b

[John]

Interesting report 🙂

Smoothside TV plossls were the 1st 1.25 inch eyepieces that I ever bought - when I migrated from .965" ones way back in the late 1980's

The TAL 25mm is no slouch though so it shows that TV was doing something right with their version of the plossl design.

 

[Louis D]

My understanding of the TV Plossl design is that Al Nagler made the two outer elements slightly concave to improve edge sharpness.  The success of his Plossl design's sales gave him the financial wherewithal to bring the 13mm Nagler Type 1 to market.

[John]

6 hours ago, Louis D said:

My understanding of the TV Plossl design is that Al Nagler made the two outer elements slightly concave to improve edge sharpness.  The success of his Plossl design's sales gave him the financial wherewithal to bring the 13mm Nagler Type 1 to market.

I agree. This is from the original Tele Vue patent documentation:

[Highburymark]

Nice comparison.
The world is split into two different types of people. The first compares a TeleVue plossl with that of another brand and exclaims “wow”! The second performs the same act and goes “meh”. I have always belonged to the first group, but some respected observers rate other Plossls just as highly.