Don Pensack

The Altair Astro version of the UFF is heavier because of a stainless steel lower barrel, but I don't see why the Celestron would be heavier by 57g than the APM. It's a mystery unless the barrel is a larger outside diameter to accommodate the orange rings.

My comment was for RWilkey, though, now that you mention it, the Castor mount looks a bit light for a 4" refractor. A lot of mounts, though, work OK as long as there is no wind.

I'm surprised you don't use the 4" refractor on the SkyTee mount. It is far more stable. I had issues with shimmy using an 80mm f/6 refractor on the Porta-II. Are you using the heavier tripod?

Looking for improvements? At 30mm, a UFF eyepiece. Heavier than the Panaview, but sharper to the edge and with a flatter field. At f/7, you can use eyepieces down to 3.5mm. Certainly a 5mm would be useful. I use a 5mm every time I use my 102mm f/7. But, let's look at the series. With a 30mm as a low power (24x), your next power up can be a 14-15mm easily. The jump to a 14mm is only 27x, to 51x. And a great 14mm could be a 14mm Morpheus or a 14mm StellaLyra 80°. Then to a 9-10mm, where there are a lot of choices, but the two 14mm choices would be fine. You really don't need the 12.5mm XF. Your 8,8mm would be fine here. Then to a 7mm, where you can stay with the 80mm SL or something narrower if you prefer, but a 7mm is a prime Moon eyepiece, so wider is better, I think. If you spring from the 8.8mm, though, a 6.5mm Morpheus would fit in well, too, or a 7mm, so you have choices. Then to a 4.8-5mm There are a lot of possibilities there. The sequences for exit pupil are a little different: 30mm>>21mm>>15mm>>11mm>>8mm>>6mm>>4mm>>3mm In the other direction: 3.5mm>>5mm>>7mm>>10mm>>13mm>>19mm>>26mm>>37mm This sequence works well, too, and uses a smaller number of eyepieces in the set: 22mm>>16mm>>11mm>>8mm>>6mm>>4mm And, in practice, a set with eyepieces at every 30x works fine in the 102mm: 30/60/90/120/150x, or 24mm, 12mm, 8mm, 6mm, 4.7-4.8mm Given what you have, you could simply ditch the 16mm and add a 6mm and a 4.7-4.8mm and have a nice set. No right or wrong answers. My own set is shared with a scope that is a different f/ratio and focal length, so I have a lot more eyepieces. But in the 4" refractor, I tend to use 22mm, then 14mm, 9mm, 6.5mm, 4.5mm, and 3.7mm. My other eyepieces get used more in the other scope. In practice, I often skip from the 22mm to the 9mm to get around the light pollution.

Well, that just it. The small scope yields views at low power and with wide fields not possible in a larger scope. It's the reason I still have a 4" refractor to accompany the 12.5" newtonian. Two completely different views. BTW, the reason you saw any SAEP/Blackouts with the 13mm T6 Nagler were likely the fact that that eyepiece requires that you hover above the eye lens. The eyecup is a bit too short to allow it to touch the face, so it's quite possible to get too close to the lens, inside the exit pupil, despite having only 12mm of eye relief. That would make it nearly impossible to use standing, as well. But, sitting, and holding the eye in the right place, it's free of SAEP and blackouts, at least as far as I can tell. The entire T6 series took a little getting used to. [In contrast, the 14mm Vixen SSW was a very difficult eyepiece to use and exhibited quite noticeable SAEP]

People write that all the time, but unless there is something terribly wrong with your vision, the edge of an 82° field should we WELL within your peripheral vision which, in most people, extends to 145° laterally and 125° vertically. You can see this as well simply by moving a bright star over to right next to the field stop and then looking at the center of the field. The bright star is still there in your peripheral vision. It's the same with the 100° of an Ethos as well. I think what you mean, and what most people mean when they say they can't see the entire FOV is that they cannot look directly at the edge of the field with the center of vision by merely averting your eye to do so. You have to hold the pupil steady and slightly roll the head while looking through the eyepiece at an angle. And some people simply cannot adapt to that method of observing (arthritis in the neck?). The other possibility is that, for some reason, you simply didn't get close enough to the eyepiece to see the entire field. I'm not certain what my ideal apparent field is. I've used eyepieces of 30-120° over the years. 78° seems *just* wide enough I don't feel like I have blinders on or are looking at space through a tube. 110° seems a bit too wide simply because when looking at the upper end of the apparent field my peripheral vision sees too much sky. I've used a few eyepieces of 84-85°, and that seems to be a comfortable apparent field. Maybe 90° would be optimum? Personally, I find the 13mm Nagler is an excellent eyepiece in every way. It's really only 79°, but it is superbly sharp and has excellent contrast.

I didn't see any noticeable SAEP in the 14mm (unlike the 14mm Vixen SSW, which had it in abundance), but I did notice EOFB (edge of field brightening). Otherwise, it was quite sharp. I had to change the eyecup to use it with glasses.

There haven't been many reviews because they haven't been in circulation long enough to have that many of them out there. I used the 14mm and was disappointed that the eyecup ate up 8mm of the 20mm of eye relief, making it impossible to use with glasses. If you are looking at these because you wear glasses, then you will need to look into changing the eyecups, and the 50mm inner diameter of the eyecup makes finding traditional rubber eyecups nearly impossible. They are from Long Perng in Taiwan, and available under these labels: Founder Optics Marvel Long Perng 80° Series LER Orion (US) LHD Stella Lyra (FLO) 80° LER UWA

No, I meant Meoptex, which is a cheap Chinese brand like Svbony. I cannot find anyone still selling the Meopta zoom with a telescope adapter. That is also why I didn't include Zeiss and Nikon in the list of Zooms. People who custom make adapters for a telescope can buy a Zeiss, Nikon, or Meopta zoom, but the average purchaser cannot get them that way right now.

There are a lot of zooms available, and many are quite inexpensive. Let me know if I left any out. These are only ones available new. I don't want to include used. 1 Brand Model FL Diam. AFOV Wt. Eye Relief Undercuts? Coatings Edge black Elem. 365 Astronomy Aspheric Zoom 8-24 1.25/2.00 43-66 410 15-20 Y FMC ? ? Agena Zoom 7-21 1.25 30-43 156 16-33 Y FC ? 4 Agena Zoom 8-24 1.25 40-60 217 18-15 Y MC Y 6 Altair Astro (UK) Lightwave Zoom Premium 8-24 1.25 40-60 18.0 Y FMC Y 9 Angeleyes (eBay/Ali Express) Zoom 7.5-22.5 1.25 42-66 255 18-19.5 Y FMC ? 8 Apertura Zoom 9-27 1.25 40-60 250 18.0 Y FMC Y 7 APM Super Zoom 7.7-15.4 1.25/2.00 64.7-66 520 17.0 N FMC ? 10 Artesky Aspherical Zoom 8-24 1.25/2.00 43-66 410 15-20 Y FMC ? ? Artesky Zoom 7.2-21.5 1.25 40-60 ? ? Y ? ? ? Astromania Zoom 7-21 1.25 30-43 156 16-33 Y FC ? 4 Astromania Zoom 8-24 1.25 40-60 15-18 Y FMC ? ? Auriga Zoom 9-27 1.25 40-60 250 18.0 Y FMC ? 7 Auriga Zoom 7.5-22.5 1.25 42-66 255 18-19.5 Y FMC ? 8 Baader Planetarium Mark IV Zoom w/click-stops 8-24 1.25 45-68 290 16-19 N FMC ? 7 Bresser LER Zoom 8-24 1.25 40-56 250 20.0 Y FMC Y 8 Bresser DLX LER Zoom 8-24 1.25 40-62 315 20.0 Y FMC Y 9 Celestron Zoom 8-24 1.25 39-63 15-18 Y FMC ? ? Datyson Gold Band Zoom 8-24 1.25 40-60 145 15-18 Y FMC ? ? Datyson silver band Zoom 8-24 1.25 40-66 15-18 Y FC ? ? Discovery Zoom 7-23 1.25 36-65 16.6-16.7 N ? ? 7 Discovery Zoom 8-24 1.25 33-54 10.4-11.4 N ? ? 6 Hercules Plano Zoom 8-24 1.25 50-70 ? Y FMC ? ? Leica Aspherical Zoom (needs adapter) 8.9-17.8 1.25/2.00 57-78 18.0 N FMC ? 8 Long Perng Zoom 8-24 1.25 40-60 20.0 Y FMC ? 8 Long Perng Zoom 8-24 1.25 40-60 17.0 Y FMC ? 9 Long Perng Zoom 8.2-24.2 1.25 29.8-? 25.2 Y FMC ? 8 Lunt "Solar Eyepieces" Zoom 7.2-21.5 1.25 38.3-56.5 15.0 Y FMC Y 7 Meade Zoom 8-24 1.25 40-55 ? N FMC ? 7 Meade Series 4000 Zoom 8-24 1.25 40-60 206 15-18 Y FMC ? 6 Meade Acouto Zoom 8-24 1.25 40-66 168 15-18 Y FMC ? ? Meoptex Zoom 7-21 1.25 30-43 156 16-33 Y FC ? 4 Meoptex Zoom 8-24 1.25 40-60 15-18 Y FMC ? 6 Omegon Super Plossl Zoom 7-21 1.25 30-43 16-33 Y FMC ? 5 Omegon Magnum Zoom 8-24 1.25 34-51 15-18 Y FMC ? 4 Omegon Premium Zoom 7.2-21.5 1.25 38.3-56.5 ?-15 Y FMC Y 7 Omegon Premium Zoom 7.5-22.5 1.25 42-66 255 18.5-19 Y FMC Y 8 OpticStar (Opticstar Brand) Zoom 7.2-21.5 1.25 38.3-56.5 155 15.0 Y FMC Y 7 OpticStar (Opticstar Brand) Zoom 7.5-22.5 1.25 42-66 255 18-19.5 Y FMC Y 8 Orion E-Series Zoom 7-21 1.25 40-57 142 16.3-18 Y FMC N 6 Orion Lanthanum Zoom 8-24 1.25 40-60 20.0 Y FMC N 8 Orion Zoom 7.2-21.6 1.25 42-65 18-20 ? FMC Y 7 OVL (First Light Optics) Hyperflex Zoom 9-27 1.25 40-60 18.0 Y FMC Y 7 OVL (First Light Optics) Hyperflex Zoom 7.2-21.5 1.25 38.3-56.5 155 15.0 Y FMC Y 7 Pentax XL Zoom 8-24 1.25 39.2-56.5 12-18 Y FMC Y 6 Pentax XF ZOOM 6.5-19.5 1.25 58-41 11-15 Y FMC N 6 Saxon Australia Zoom 7-21 1.25 30-43 ? Y FC Y ? Saxon Australia Zoom 8-24 1.25 40-60 ? Y FC y ? Seben Super Zoom 8-24 1.25 40-60 20.0 Y FMC Y 6 Seben Zoom 7.5-22.5 1.25 42-66 255 18-19.5 Y FMC Y 8 Sky Mentor (Khan Scope, Canada) Zoom 7-21 1.25 29-42 16-32 Y FMC ? ? Sky Mentor (Khan Scope, Canada) Zoom 8-24 1.25 40-60 15-18 Y FMC ? ? Sky Optic (France) Hyperflex Zoom 7.2-21.5 1.25 38.3-56.5 15.0 Y FMC Y 7 Sky Rover Super Zoom 7.7-15.4 1.25/2.00 64.7-66 520 17.0 N FMC ? 10 Skywatcher Zoom 7-21 1.25 30-43 16-33 Y FMC ? ? Skywatcher Zoom 8-24 1.25 40-60 15-18 Y FMC ? ? Skywatcher Hyperflex Zoom 9-27 1.25 40-60 18.0 Y FMC Y 7 Skywatcher Hyperflex Zoom 7.2-21.5 1.25 38.3-56.5 155 15.0 Y FMC Y 7 Stella Lyra (FLO) Zoom 8-24 1.25 40-60 20.0 Y FMC Y 8 Svbony Zoom 3-8 1.25 56.9-59.8 10 Y FMC Y 6 Svbony Zoom 7-21 1.25 37.6-53.5 133 16.3-18 Y FMC Y 6 Svbony Zoom 8-24 1.25 38-56 18-19.5 Y FMC Y 7 Svbony Zoom 9-27 1.25 40-60 230 17.5 N FMC Y 7 Svbony Zoom 10-30 1.25 33-51 17-18.5 Y FMC Y 5 Svbony Zoom 7.2-21.5 1.25 42-65 167 18-20 N FMC Y 7 Tecnosky Zoom 7-21 1.25 40-57 16.3-18 Y ? ? ? Tecnosky Zoom 8-24 1.25 40-60 15-18 Y ? ? 7 Tecnosky Aspheric Zoom 8-24 1.25/2.00 43-66 15-20 Y FMC ? ? Tecnosky Zoom 9-27 1.25 40-60 250 18.0 Y FMC ? 7 Tecnosky Zoom 7.2-21.5 1.25 40-60 15 Y FMC ? 7 Telescope Service Deluxe Zoom 7-21 1.25 40-50 20.0 Y FMC ? 6 Telescope Service Zoom 7-21 1.25 40-50 20.0 Y MC ? 5 Telescope Service Premium Zoom 7.2-21.5 1.25 38.3-56.5 15.0 Y FMC Y 7 TeleVue Nagler Zoom 3-6 1.25 49 150 10.0 Y FMC Y 5

It is my observation over the years that 100mm is about the minimum visual instrument size for astronomy use (smaller works fine for terrestrial use). I think 50-90mm scopes are fine for astrophotography, but simply don't have enough light grasp for deep sky, visually. Nor do they have sufficient resolution to show small details on planets or moon well. The question is, how can you make a 102mm scope a "Grab'n'Go". I did it by putting it on a Stellarvue M2C mount on a wooden tripod with pier extension. I define grab'n'go as when a scope can be lifted while still on the mount and carried outdoors for a near-instant setup. And, at 71, I have no problem lifting 20kg and carrying it 20 meters to the yard. I would never define my larger scope as a "grab'n'go"--maybe a "drive'n'go", LOL.

The 24mm UFF has the distinction of being glasses-friendly, which is not the case for the TV Panoptic or ES 24x68. And, it is optically better than the 24mm Hyperion. Other than that, it is not in the same class as the 30mm. The 30mm is a better eyepiece in every way, and rubs shoulders with eyepieces costing 2x-3x as much. The 24mm is about average for its price point. More to the point is that the magnifications provided might be a bit too close together anyway. At 1000mm focal length, they are 33x and 42x, too close together to be a useful change. At 2000mm focal length, they are 67x and 83x, still too close together to be a useful change. The difference finally becomes useful in a scope of 4000mm focal length, but there are very few scopes out there with focal lengths that long. Even my friend's 32' only has a 2800mm focal length. If you have a scope of 2000mm focal length, the next logical step is to a 17.5mm Baader Morpheus. That is a jump of 47x, which is a very useful step up from the lowest power that yields a larger image and a significantly darker background sky. I admit to having an eyepiece in between the 30mm and 17.5mm, but it is skipped over 90% of the time.

Needs to at least have the dust blown off. Lots of debris on that lens.

They had a blem dead center in the image that looked like someone had put grease on the lens. if you don't see that, you didn't get one of the bad ones. I think that was confined to only one batch, anyway.

The Delites and Delos vary by focal length. The 6mm Delos is sharper to my eye in a 12.5" coma-corrected scope than either the 7mm or 5mm Delite. However, the 18.2mm Delite is definitely better than the 17.3 Delos in both sharpness and contrast. Those differences are fairly subtle, though, and the eyeguard construction on the Delites, if not used all the way down, results in incredible contrast in the Delites. Personally, I prefer the larger apparent field (one reason I like the Morpheus eyepieces). I only briefly used the HRs when they were available because they were only usable in my refractor, but even there yielded exit pupils too small for the 'floater vision' in my eye. I cannot comment on them except to warn people about the 3.4mm--there are still a lot of defective 3.4s out there, even though Vixen called them back and replaced them with a new batch.

Caveat emptor! The 2X GPC that William Optics makes adds chromatic and spherical aberration to the images. The WO binoviewer is fine by itself, but you really need another GPC other than the WO one. And, IMO, the 20mm WO eyepieces are not good. I second Ricochet's remarks about the Baader. The GPC is FAR better.

It's important to learn where the images get compromised by floaters and simply stay away from there. I also have a 102mm f/7 apo refractor, and I learned I can use a 4.7mm eyepiece (152x, 0.67mm exit pupil) and a 4mm (179x, 0.57mm exit pupil), but not a 3.7mm (193x, 0.53mm exit pupil) or 3mm (238x, 0.43mm exit pupil) on the Moon. On planets, the 3.7mm becomes usable without floaters interfering, but not the 3mm. And on double stars, the 3mm becomes usable. For general viewing, though, I never go smaller than the 4.7mm's 0.67mm exit pupil. Perhaps your floater problem is worse than mine. If it is, I understand. I have a good friend about my age who can't go below a 1mm exit pupil on the moon without floaters being a problem. Shorter f/ratios yield larger exit pupils. In my upcoming 16", that 3.7mm will yield a 0.86mm exit pupil at 474x. in my 2.5" it yields a 0.64mm exit pupil at 493x. That's the advantage of larger, faster, scopes--a brighter image at higher powers.

TeleVue's vary from a warm tone (Plössls, Radians, T6 Naglers) to neutral (Delos) to a cool tone (18.2, 15mm Delite) in my tests. It depends on the glass makeup in the eyepiece.

Or a spectrophotometer, like the type that measure the responses of filters. Here are some graphs once on the web for Pentax transmission curves: https://web.archive.org/web/20141231092400/http://pentaxplus.jp/archives/tech/xo-xw/63.html

It's been 5 years since I saw a refractor at my observing sites that didn't have a camera attached. And Takahashis seem as rare as hen's teeth here. I see AstroPhysics, TEC, and a veritable see of Chinese and Taiwanese refractors. But it's been many years since I actually looked through a Takahashi refractor, and my memory of any tonality is gone. I've never seen an SV140, but if I did, I guarantee it would have a camera attached. So what you find in your comparison will be equal to anyone's opinion. Though I am certain there are many many refractors being used visually in backyards and on patios, those observers do not seem to bring them to my dark sites. I am in that category, too, because when I travel to a dark site, I take my 12.5", not the 4" apo. Most of my friends wouldn't even know I had a 4" refractor, as they've probably never seen it.

When looking at planets, how could you tell what is neutral, warm, or cool except by comparison with other eyepieces?

Many people think the XWs have a "cool" tone that tends to suppress the warmer colors. I've compared them directly in a triplet apo that lacks CA by using them to look at an arctic white building, where you can look directly at the building, then in the eyepiece, then directly at the building. Many, many eyepieces change the tone of the white, and very few see the white as the pure arctic white it is. There is a red wind sock on the top of the building that appears orange or even grey in some eyepieces because their responses fall off in the longer wavelengths. All of these color rendition issues tend to disappear at night except on the Moon or planets, but some show up when looking at carbon stars or red giants. Anyway, the XWs have a strong yellowish tone to them when looking at that white building. I am mystified some see the view as "cool". The red windsock is still red, but a bit less intensely red than the naked eye, which is consistent with the measured steep drop-off they have above 650nm. The TeleVue Delos, on the other hand, had a better color rendition, with the building still arctic white and the red windsock still the same as the naked eye. This can be seen at night when looking at Carbon stars and red giants. I think it may be the lack of fall-off in the red end of the spectrum that makes some observers describe them as "warm" in tone. Maybe that is true in comparison with the XWs, but I found them more neutral in my daylight test. So if you are looking for a 70° field eyepiece for planetary use, I think you would find planetary colors less suppressed by the Delos. You will find differing opinions from different observers. I think that is because color vision sensitivities in the violet and red vary all over the place among observers. However, you do have to pay attention to whether the diagonal is a mirror or prism, how low in the atmosphere you view, and chromatic issues in the scope. You have a reflector scope, which is free of chromatic aberration. Are you planning to get a new scope? Because these eyepieces are expensive and might be hard to justify in your current scope. I guess I should ask what it is about your current eyepieces that has you seeking out others. Because if they are not sharp on axis, it might not be the eyepiece at fault, but the cooling of the optics, or collimation, or simply the seeing conditions. What is it that you don't like in them?

The long f/ratio of your Maksutov means you can pretty much use any eyepiece you want. Chances are likely that there is nothing wrong with the 12mm BST, but that it is merely the magnification that is exceeding the quality of the scope's optics, or the seeing conditions due to the relative high magnification. Your refractor probably has a shorter focal length so the same 12mm yields a lower power in that scope. That the eyepiece works well in the refractor says there is nothing wrong with the eyepiece, the issue is with the magnification it yields in the Maksutov. There may be NO eyepiece at 12mm that will yield a good quality image in the Maksutov all the time. Assuming there is nothing wrong with the Maksutov's optics, then the issue is collimation, cooling, or sky conditions. Have you checked its collimation? Have you let the scope cool down outside for an hour before using it at such a high power? If your scope is an f/15, a 12mm eyepiece will be pushing the limits of the scope (collimation, cooling, optical quality) or seeing conditions. If your scope is f/12, it is still a high power, but not at the limit. Here is a way to look at it: magnification of 3.6 to 10x/inch of aperture is low power. Usable all of the time. magnification of 10-20x/inch of aperture is medium power. Usable most of the time. magnification of 20-30x/inch of aperture is high power. Usable sometimes, but not all or even most the time. magnification of 30-50x/inch of aperture is ultra high power. Usable a very small % of the time. Are there higher quality 12-13mm eyepieces? Yes. But if 12mm doesn't yield a good image quality, a 9mm will be worse. Now, assuming proper collimation, a cooled scope, and excellent seeing, a 12-13mm should work fine. A 13mm Nirvana would work fine, but might not be in your range. Have you considered an Omni Plössl in 12mm? It would have a slightly smaller field than the BST, and a little less eye relief, but you might find it adequate. I don't think it will really improve the image quality, though, because I don't think the problem is the eyepiece.

You are using the term 'backfocus' incorrectly. It may not be intuitive, but the term 'backfocus' refers to the ability to get closer to the scope for accessories requiring more in travel of the focuser (like a camera) by moving the focal plane farther away from the objective. The prism diagonal throws the focal plane farther back, which allows the diagonal to move farther into the light cone from the objective, allowing accessories that require more in-travel to come to focus. In other words, the prism diagonal provides MORE 'backfocus' than a mirror diagonal. An accessory that needs more in-travel of the focuser is said to need more backfocus. I find that understanding of the word very non-intuitive, so I think about back focus as meaning how far back away from the objective the focal plane is. And a prism diagonal moves it back, so an accessory that needs more in-travel can accomplish focus.

You will probably need an optical corrector (GPC) to come to focus. If you do, don't get the one from William Optics. I found it added chromatic and spherical aberration Big Time. There are several other brands that would throw the focal plane far enough back that don't add appreciable aberrations.