CN FORUMS ARCHIVE Telescope Reviews: Nagler 17 mm T4 17mm ER & glasses yes/no?

Hi Mike,

I have been using specially made glasses for astronomy use for many years. This was based on the advice of my optometrist who said my night time prescription would be slightly stonger than my daytime prescription.

The only way to do this properly is to go visit your optometrist and tell him exactly what you are trying to achieve and the reasons for it. He should then leave you in the room with the lights out for about 15 minutes to allow your pupils to properly dillate, then come in and do the eye test under a red light. It isn't much good IMO estimating your night time adjutment as it can be different for each individual. In my case my prescription in my right eye changes by .5 diopter for short sighted correction and .25 diopters for astigmatism correction with a minor change in the astigmatism axis. You can't guess at this, you have to test for it properly. By going and ordering a pair of glasses .25 diopters overcorrected will likely help a little in every case, but it is not necessarily the ideal result for each individual. You then need to consider the quality of the glasses and how much you want to spend. I strive for every photon. In this regard it is important to get high quality lenses with very good coatings when you order these glasses. I have previously had glass lenses from Zeiss, Rodenstock and Hoya which all worked very well and are recommended if you can handle the weight. I currently have Nikon lenses made from a special high transmission plastic, with an anti reflective coating called Crizal Alize. These glasses are absolutely outstanding and the equal of glass with a lot less weight. At a price seriously in excess of the cost of a new Ethos eyepiece, they would want to be

I can go at least .3 mag deeper naked eye with these glasses over my standard glasses under good conditions and most importantly the stars appear a little tighter and better defined. They are worth every cent if you have a spare $AUS 1,000 lying around, with the prospect they will be useless in less than 2 years time as my prescription changes. You could probably spend 1/4 of that amount and still realise 90% of the gain I realise. Under that scenario it is a very worthwhile exercise.

Hi Patrick,

I wear glasses to observe. Have a case full of Pentax XW's, 12mm and 17mm Nagler T4's, a 31mm Nagler T5 and a 13mm Ethos. Whilst the T4 Naglers are not quite as comfortable to use with eyeglasses as the Pentax XW's, they are very user friendly for eyeglass wearers and the 17mm Nagler T4 is an excellent choice at this focal length. Very highly recommended.

Cheers,

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John Bambury
AS of NSW
AS of Hunter Valley
18"/F4.5 Obsession #1333 (fully loaded with OMI optics)
14"/F4.5 SDM #33 (fully loaded with Zambuto Optics)
10"/F5.3 SDM #50 (fully loaded with Suchting Optics)
Pentax XW's, Nagler T4's, T5's, DELOS & ETHOS. TV Paracorr, 1.8X TV Barlow and 2.5X TV Powermate