posted a report on observing with contact lens.
Cheers,
Chris
Televue Dioptrix Review
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Canopus Lim
- Posts: 1144
- Joined: Fri Jun 03, 2005 12:46 pm
- Location: Macpherson
I have read somewhere that the BO/TMB planetary eyepiece can fit the Dioptrix. Having the BO/TMB eyepiece, I removed the eye cap and tried the screwing on the Dioptrix. It works! Therefore, it is not only long eye relief TV eyepieces that benefit from it. I think there could be more eyepieces that can fit as long it has a T-shape top like TV eyepieces. The BO/TMB T-shape top is smaller, but still allows the Dioptrix to catch onto it and rotate.
I did a transmission test that Roland Christien of Astro Physics demonstrated in an article. In this test, he would cap the bottom (telescope end) of the eyepiece and place the eyepiece out in the open and let the sunlight reflect onto the surface. The darker the lens (seen from the business end of the eyepiece) and darker the reflections of the surroundings (including myself), it means the better the transmission. However, this test is not that good as the eyepiece cap at the bottom are of different gray shades.
So, I used flocking paper as the base for all the eyepieces and put the eyepieces standing on it to observe the reflections. I was glad to see that my multi-elements widefield eyepieces have good transmission and was better than all my plossl except for my TV plossl which had the best transmission. It shows that it does not mean that less elements means better transmission as it depends on the coating process and internal baffling of the eyepiece too. An improperly coated or lacking of coating of simple eyepiece design can have poorer transmission than a multi element eyepiece.
I did the same transmission test on the Dioptrix and it has really good transmission. ZERO reflection. I placed my Nikon frameless spectacle onto the flocking paper to test and it does have noticeable reflection although it is supposed to be multi coated Nikon/Essilor spectacle. I could see my reflection but at least I could not see the sky reflection. Therefore, the last time I said that the Dioptrix has less throughput was wrong (I based it on stars only so it was not that accurate test). It actually gave a darker background but the so-called nebulous kind of effect round the stars disappeared so I think it was better contrast instead of lower transmission. Therefore the Dioptrix has better throughput and higer contrast (due to zero reflections) compared to multicoated spectacles. But of course if you don't need to use spectacles that would be the best.
The TV eyepiece Nagler Type 4 and Radians have a pupil guide (sort of a plastic aperture placed over the business end of the eyepiece to help guide novice in finding the exit pupil) and I used it on the dioptrix. It further improves it as it will prevent bright light sources (like lamps) from reflection of the business end. The main benefit is that it makes it very easy to locate the exit pupil and prevents the dioptrix lens from getting scratched.
Anybody has eyepieces that has a cross section T-shape at the business end? You would have to remove the rubber eyeguard first.
I did a transmission test that Roland Christien of Astro Physics demonstrated in an article. In this test, he would cap the bottom (telescope end) of the eyepiece and place the eyepiece out in the open and let the sunlight reflect onto the surface. The darker the lens (seen from the business end of the eyepiece) and darker the reflections of the surroundings (including myself), it means the better the transmission. However, this test is not that good as the eyepiece cap at the bottom are of different gray shades.
So, I used flocking paper as the base for all the eyepieces and put the eyepieces standing on it to observe the reflections. I was glad to see that my multi-elements widefield eyepieces have good transmission and was better than all my plossl except for my TV plossl which had the best transmission. It shows that it does not mean that less elements means better transmission as it depends on the coating process and internal baffling of the eyepiece too. An improperly coated or lacking of coating of simple eyepiece design can have poorer transmission than a multi element eyepiece.
I did the same transmission test on the Dioptrix and it has really good transmission. ZERO reflection. I placed my Nikon frameless spectacle onto the flocking paper to test and it does have noticeable reflection although it is supposed to be multi coated Nikon/Essilor spectacle. I could see my reflection but at least I could not see the sky reflection. Therefore, the last time I said that the Dioptrix has less throughput was wrong (I based it on stars only so it was not that accurate test). It actually gave a darker background but the so-called nebulous kind of effect round the stars disappeared so I think it was better contrast instead of lower transmission. Therefore the Dioptrix has better throughput and higer contrast (due to zero reflections) compared to multicoated spectacles. But of course if you don't need to use spectacles that would be the best.
The TV eyepiece Nagler Type 4 and Radians have a pupil guide (sort of a plastic aperture placed over the business end of the eyepiece to help guide novice in finding the exit pupil) and I used it on the dioptrix. It further improves it as it will prevent bright light sources (like lamps) from reflection of the business end. The main benefit is that it makes it very easy to locate the exit pupil and prevents the dioptrix lens from getting scratched.
Anybody has eyepieces that has a cross section T-shape at the business end? You would have to remove the rubber eyeguard first.
AstroDuck