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Hi,
I have all 3 of the T4 Naglers (22mm, 17mm and 12mm) amongst about 20 other Televue, Pentax and other premium eyepieces. I use these in several different newtonians.
IMO the 17mm and 22mm Naglers don't perform all that well in an F5 newtonian unless used with a paracorr, which by itself is an expensive item. When used in combination with a paracorr these 2 eyepieces perform superbly.
Also be aware that if you have a 1.25" barlow you cannot use it with the 17mm Nagler, which has a 2" only barrel.
Further, I don't think these 3 eyepieces give a big enough range, nor utilise your barlow to it's maximum potential.
Understanding you want long eye relief and good comfort and assuming your barlow is 1.25" and you don't own a paracorr, I would consider going along the following lines.
26mm Televue Nagler
14mm Televue Delos barlows to 7mm
10mm Televue Delos barlows to 5mm
You can't barlow the 26mm Nagler but it gives you a much larger true field of view than the 17mm and doesn't need a paracorr to perform at it's best in an f5 newtonian.
This lineup gives you the following magnifications and exit pupils.
26mm = 38x with a 5mm exit pupil ideal bottom end
14mm = 70x with a 2.9mm exit pupil
10mm = 100x with a 2mm exit pupil
7mm = 140x with a 1.4mm exit pupil
5mm = 200x with a 1mm exit pupil
All of these will work well in your scope without a paracorr.
This gives you a good spread for both deep sky and planetary observing. If you wanted to add a 4th eyepiece into the range then I would do things a bit different to this.
Cheers,
John B
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