James and others: I'm sure there is an explanation, since I know nothing about the topic... Why is it we don't hear concern about multilayer coatings on larger...
Refractor optics are lenses, not mirrors. They have their own coatings, as well as being constructed from two and sometimes three different types of glass....
Yes lenses refract... And yes multilayer coatings on lenses decrease reflection. But in both cases the wavefront strikes these surfaces (and shifts in wave ...
I am new here and am pleased with the great threads and people!! I am fairly new to astronomy and jumped in with a used Meade 12 1/2 Starfinder f 4.8, mirrors...
Hi David, I strongly advice against a focal length greater than 30mm. With a 40mm the exit pupil would be 40 / 4.8 = 8.3mm. Personally I would keep the exit...
Hi Andre, I am glad you pointed out the exit pupil. It really makes sense to keep it to around 30mm. Would it be fair to say that because the 31 Nagler has an...
Hi David, I'm fairly new to short f ratio scopes, having just recently purchased a 12.5" F5 scope in March. (Before that I observed with an 8" Meade LX200...
Hi David, Yes, and the 31 Nagler compared to the Panoptic 41 gives you more magnification and a darker background with about the same apparent field of view...
Hi Tim, that was really terrific info. I just ordered the 26 nagler as a starting point. I find that I use my 32 plossl quite a bit so I think I will like it....
Personally, I can't imagine regularly using an eyepiece with a FOV over 1 degree. I find .75 deg FOV (45') more than adequate for most DSO's and the higher...
Everyone has brought up really good points and explanations for their preferences. Thank you all again. I was just outside looking at Jupiter through my Orion...
Hi David, You made a wise choice with the 26t5. Some people like it better than the 31mm. For one the 26mm is much smaller and not as likely to cause balance...
David, A barlow increases the magnification. A 2x barlow increases the magnification 2 times; a 3x barlow, 3 times. So, since FOV = AFOV / Magnification, the...
The addition of a barlow does reduce the exit pupil. Example: If the exit pupil is 6mm the addition of a 2x barlow will reduce the exit pupil to 3mm. Joel...
... I learned in 4th year university optics 15 years ago. My guess is that the exit pupil remains unaltered by the addition of the barlow (same as a barlow...
... check balance issues. ... uses so check them out as well. ... permantly add a 2 lb weight to the bottom of the scope. I also discovered that as I drop the...
Dave & Tim, It probably makes all the mental calculations easier to think of the Barlow as increasing the focal length of the telescope by what ever times the...
Thanks. Yes, you are right. I just did the math.... In the formula for exit pupil (Exit Pupil = Eyepiece Focal length / telescope f ratio) you can substitute...
If you want to use a large eyepiece, then by all means do so. If it introduces a balance issue, then add a counterweight to the other end to offset it. A...
The TV Panoptics and Naglers are great. I'm sure that you'd be happy with any of them. See if you can try them before you buy. Or if you get one that doesn't...
Joe: I think the main reason is that refractor objectives are smaller and hence the concern over non-uniformity is less. They are still subject to the same ...
Hi, In the last few observing sessions I've noticed something about the sharpness of the images I'm viewing, especially with Jupiter. As usual, the clarity of...
... I think it has to do with the way the brain processes images. An old trick for trying to see very faint DSOs barely brighter than the background sky glow...
I have learned so much from this thread. Thankyou all so much!! I didn't realize how much a barlow can compromise your view. It is a good way to "double" your...
A good Barlow will not compromise your view. I use a 2.4X Dakin Barlow and it does not compromise the view at all. Low quality Barlows can spoil the view. ...
Andre, thanks for the filter adapter hint. I will do just that. The eye relief is a very attractive feature. I was thinking about the wider FOV the Nagler...
Your field of view is cut in half because your power is doubled (assuming a 2X Barlow). If you used an eyepiece of the same design but half the focal length to...
