ok, i stand corrected, i withdraw the word "significant" :-)
i still believe the series 4000 is superior though, just bought a 14mm series 4k UWA myself.
Arief
Putting FOV aside, how good is Nagler?
-
Canopus Lim
- Posts: 1144
- Joined: Fri Jun 03, 2005 12:46 pm
- Location: Macpherson
Here is a review that compares the old T1 Nagler with the 'modern' T6 Nagler.
http://www.company7.com/library/televue/orrtv5mmN.html
About the distortion of the Nagler. I observerd Saturn for a short while with my C5 last night and observe the edge. The planet changed shape slightly at the extreme edge. I do not find it objectionable because from a circle globe it did not become an ellipse. It was slightly less than a circle globe; slightly elongated which probably was about 20 percent or less distortion. Within 70 degree AFOV, there is no problem with the shape at all and actually that is the area where I would look as the eyepiece performs always better towards centre. For DSOs, it is more important to be sharp at the edge the and the T6 Nagler retains the sharpness albeit very slight distortion which for stars is not noticeable easily.
Anyway, distortion always increases from the centre to the edge and how visible depends on the amount. The larger the AFOV, the harder it is to correct for distortion and in the case of 82 degree AFOV, it is really large. I am sure till now there is no 82 degree eyepiece that has less than 5 percent distortion at the edge. If you look at projectors, for example the star projector in the Griffith Observatory's Planetarium when I visited, the distortion is very significant. In comparison, the Nagler's distortion at the extreme edge is really much less. However for the Panoptic, it is a different case. My Pan35 has significant distortion and the moon literally changed shape obviously. Therefore, I would recommend the Pan35 for DSOs only.
http://www.company7.com/library/televue/orrtv5mmN.html
About the distortion of the Nagler. I observerd Saturn for a short while with my C5 last night and observe the edge. The planet changed shape slightly at the extreme edge. I do not find it objectionable because from a circle globe it did not become an ellipse. It was slightly less than a circle globe; slightly elongated which probably was about 20 percent or less distortion. Within 70 degree AFOV, there is no problem with the shape at all and actually that is the area where I would look as the eyepiece performs always better towards centre. For DSOs, it is more important to be sharp at the edge the and the T6 Nagler retains the sharpness albeit very slight distortion which for stars is not noticeable easily.
Anyway, distortion always increases from the centre to the edge and how visible depends on the amount. The larger the AFOV, the harder it is to correct for distortion and in the case of 82 degree AFOV, it is really large. I am sure till now there is no 82 degree eyepiece that has less than 5 percent distortion at the edge. If you look at projectors, for example the star projector in the Griffith Observatory's Planetarium when I visited, the distortion is very significant. In comparison, the Nagler's distortion at the extreme edge is really much less. However for the Panoptic, it is a different case. My Pan35 has significant distortion and the moon literally changed shape obviously. Therefore, I would recommend the Pan35 for DSOs only.
AstroDuck
Which is the ortho that you have? May I know what's the scope that you are using? I was considering TMB Burgess Planetary 7mm eyepiece.VinSnr wrote:Talking about the Burgess/Planetary eyepieces, don't ever use that to star test and collimate your scope. Especially if you use SCT. You will find that once the star is "off-center", your collimation seems out, but when you put it at the center, the collimation is dead on.rlow wrote:I have compared an 7 ortho with a nagler 7 type 1 on-axis, and the ortho beats the nagler in terms of light throughput, contrast and sharpness. From my EP testing, the humble ortho also beats a TMB/Burgess Planetary series (of the same focal length) in terms of sharpness, contrast and less light scattering, viewed on-axis. The Pentax XW is slightly better than the ortho in terms of light throughput, contrast and sharpness, and it has wider field and is more comfortable than the ortho, and hence the XWs are my all-time favourite series of eyepieces for deepsky and non-tracking planetary use. The image quality of the ortho and plossl are quite similar, but I prefer the volcano-top ortho over the flat-top TV plossl due to the comfort factor.
Off-center for the TMB/Burgess is really bad.
Clear skies,
Robin.
Cyclops Optics - QHYCCD, William Optics, Televue, STC & Optolong filters
Free shipping for purchases above SG$250
Robin.
Cyclops Optics - QHYCCD, William Optics, Televue, STC & Optolong filters
Free shipping for purchases above SG$250
-
Canopus Lim
- Posts: 1144
- Joined: Fri Jun 03, 2005 12:46 pm
- Location: Macpherson
He was refering to the 'standard' volcano top ortho from UO, Circle T etc. I have the 5mm BO/TMB eyepiece and would rate it good for the price. It has wide 60 degree field and the eye relief is quite alright. However, if you are critical in observing, the BO/TMB is not that good optically especially in the contrast department.
I have compared my barlowed 11mm Nagler T6 compared with the 5mm BO/TMB and the BO/TMB lost quite a large margin. The barlowed 11mm Nagler T6 showed belts better on Saturn's globe. It showed one belt that was split in 2 and another faint belt. Also the belt had some 'granulation' details on it. The 5mm BO/TMB does not show all these and it was noticeable. Few months back I have compared the same barlowed 11mm Nagler T6 at 300x with a 6mm BO/TMB on Jupiter at 260x. The difference was more pronounced on Jupiter with the Nagler T6 showing more details and having better contrast despite at a higher magnification which is more subjected to seeing conditions. Why did I buy the BO/TMB? Basically, I do not want to spend so much money on eyepiece so I got that. The 5mm BO/TMB is the 'new' production version and mechanically it works well and optics is quite alright. It is good for looking at the moon and DSOs because of the wider field but for critical observation, I do not think it is the best.
The cheap volcano top ortho would probably be better than it as the performance is rather close with the Nagler T6. The 7mm Nagler T6 has better transmission/contrast than my 7mm ortho, as I managed to pick out Saturn's moon near to it more easily than the ortho. The performance is more or less the same though. Hard to really tell which is really better as with good seeing the 7mm Nagler T6 was slightly better but with poorer seeing, somehow the 7mm Nagler T6 lost by a touch (slightly less sharp and contrasty but does not affect the details at all).
I have compared my barlowed 11mm Nagler T6 compared with the 5mm BO/TMB and the BO/TMB lost quite a large margin. The barlowed 11mm Nagler T6 showed belts better on Saturn's globe. It showed one belt that was split in 2 and another faint belt. Also the belt had some 'granulation' details on it. The 5mm BO/TMB does not show all these and it was noticeable. Few months back I have compared the same barlowed 11mm Nagler T6 at 300x with a 6mm BO/TMB on Jupiter at 260x. The difference was more pronounced on Jupiter with the Nagler T6 showing more details and having better contrast despite at a higher magnification which is more subjected to seeing conditions. Why did I buy the BO/TMB? Basically, I do not want to spend so much money on eyepiece so I got that. The 5mm BO/TMB is the 'new' production version and mechanically it works well and optics is quite alright. It is good for looking at the moon and DSOs because of the wider field but for critical observation, I do not think it is the best.
The cheap volcano top ortho would probably be better than it as the performance is rather close with the Nagler T6. The 7mm Nagler T6 has better transmission/contrast than my 7mm ortho, as I managed to pick out Saturn's moon near to it more easily than the ortho. The performance is more or less the same though. Hard to really tell which is really better as with good seeing the 7mm Nagler T6 was slightly better but with poorer seeing, somehow the 7mm Nagler T6 lost by a touch (slightly less sharp and contrasty but does not affect the details at all).
AstroDuck