Louis D

I keep my eyepieces stored upright in the case with only the top above the foam. I've never had trouble with the XL caps in this orientation over the last 22 years because gravity keeps them in place for the most part. Sure, they don't lock on, but short of a gale wind, they don't come off of their own accord between uses. I just toss the cap down the empty hole when I go to use the eyepiece and then grab it back out of the hole and put it back on when I'm done. The annoying caps are those packaged with the AstroTech AF70 and similar lines. The cap fits so snugly on the rigid eye cup that you have to work your finger around the edge of the cup to push it all up into the cap. It's such a pain that I just unscrew the eye cup and use it sans-cup with eyeglasses. That way, the cap stays on the cup between uses. I just place the cup/cap combo loosely over the top of the eyepiece between uses.

You should be able to see the Pleiades (M45) and the Orion nebula (M42) at the least. You might need to pan around a bit to see M45 due to its size and your scope's long focal length. They trail Mars by several hours in a similar region of the sky, so you might need to stay up late enough for them to be visible. Uranus, though tiny, should also be visible between Mars and the Pleiades as a tiny green dot once magnified enough. The Andromeda galaxy (M31) should at least show its cigar shaped core and possibly its two companion dwarf galaxies' cores. The Double Cluster (NGC884 and NGC889) should also be obvious once you can see M45. Once the moon is back in the evening sky, take an evening to tour around it. On each successive night, note how the terminator line changes as different features are side lit. My point is, not every object is easy to see. There are certain showpiece objects that are large and bright enough to be visible under just about any conditions. Learn what these are, use planetarium software to determine when they will be visible and where on the sky to make sure you have an unobstructed view, and then use the software on your scope to go after them. Much of the joy of astronomy is hunting down objects and confirming you at least detected them. That's how I approach comet hunting in particular since they mostly tend to hang out in the twilight murk near the sun. You may need to manually slew your scope back and forth a bit to detect faint fuzzy patches once the computer puts you on target. Your brain's ability to pick out a moving target is much better than its ability to pick out a static target. Ever notice how much easier it is to see a camouflaged animal when it moves or at least flinches?

Invest in an entry level binoviewer. I also couldn't adjust to viewing Mars at opposition without heavy filtration using monovision. However, once I switched to my binoviewers, I had no issues with brightness and could see loads of details with ease. It has something to do with splitting the brightness in half, presenting the same view to both eyes, and allowing your brain to image process as it was intended to do, from two eyes.

I'm pretty sure they fit the 32mm Plossl, but you should contact a TV vendor for confirmation.

You're already maxed out on true field width in a 1.25" barrel with the 32mm Plossl. Many of the Chinese made 32mm Plossls have the eye lens recessed much more than the TV version, so they have less eye relief as a result. If you want to go wider, you'll need to add a Mak to SCT thread adapter, a 2" visual back, and a 2" diagonal. Bright stars do exhibit a weird oval reflection as they pass the edge of the rear port and there is 30%+ vignetting of the edges, but works really well to bring in wider views. The 24mm APM UFF has roughly the same TFOV as your 32mm Plossl. Notice how much more field is visible below with only moderate vignetting? That's a massive 2", 35mm eyepiece on my 127 Mak below: Don't try to mount an SCT threaded 2" diagonal directly to the rear threads. It won't fit next to the focus knob.

Buy a large Dobsonian. In my second year of observing 21 years ago, I bought a second hand 15" Dob to get increased image scale without sacrificing detail or contrast.

This is even an issue with smaller refractors. I have an adjustable height stool so that I can sit mere inches above the ground with my legs straight out when the scope is pointed near zenith. It makes me wonder why people complain about the "contortions" it takes to view through a Dobsonian by comparison.

To add to that: Quality of lens polish Quality of lens coatings Quality of lens cell design and execution Quality of factory collimation and lens cell's ability to hold it Quality of stray light control (baffling, etc.)

Don't despair too much about the 6mm Delos. It will prove very useful in an f/7 or faster scope. I use my 5.2mm Pentax XL all the time in my ~f/6 scopes, so a 6mm would also find a good home in such a scope. I mention this because I'm sure you'll be wanting to invest in a 72mm to 100mm ED refractor in the f/6 to f/7 range in the next year or two just so you can get to lower powers with their concomitant wider fields of view.

I have the 10mm Delos and really like it. I also looked through one in an 8" EdgeHD at a star party. It was showing incredible detail on Jupiter, so I know it does well when coupled with an 8" SCT. I also find 200x in an 8" a particular sweet spot for observing planets and planetary nebula when conditions allow it and for resolving large globular clusters like M13 and M22. Going to higher powers doesn't usually yield much improvement in resolution and often degrades low contrast features.

Corrected all values. Thanks, I had clicked 3032 into my computer's calculator and stored it in memory. I never caught it. I was wondering why all the powers seemed too high. I'm a bit off today what with our election turmoil.

Look at the size of the taking lens on most cell phone cameras. They're very similar in size to the human eye and react very similarly to eyepiece exit pupils. Once I realized this, I decided to embark on my AFOV imaging odyssey.

Let's work the numbers here. You've got a 2032mm FL scope. That equates to 66x, 92x, and 120x for the 31mm, 22mm, and 17mm Naglers. That's actually not a bad progression of ~30x per jump. Most nights, around 250x or so will be the upper limit due to seeing conditions. Your 6mm Delos at 339x is unlikely to ever see much use except to split doubles. The 0.6mm exit pupil will also be at the limit of comfort. You might battle with floaters in your eye at that tiny exit pupil. I would have gone with a 10mm or 12mm Delos instead. They would be much more likely to see extensive use at 203x and 169x, respectively.

I just threw that out there in case the OP hadn't considered non-TV options. I'm pretty constrained in my choices due to my astigmatism, but perhaps the OP is not.

With the extremely long focal length of a C11 (2800mm), adding a tele-extender doesn't make much sense. You'll already be working at powers that may be too high for typical UK seeing conditions with that 9mm. You might also want to investigate the APM XWA HDC eyepieces. Reports here and on CN generally regard them as slightly sharper, lighter, and less costly than their ES-100 counterparts. At the other end of the power spectrum, you might want to consider a 56mm Meade 4000 Plossl or similar to get to a 5.6mm exit pupil for OIII filter usage at 50x.

Only if they had at least 18mm of usable eye relief. I am toying with the idea of getting a 40mm Pentax XW for Christmas at the current sale price. I'd mostly be comparing it to my decloaked 40mm Meade 5000 SWA. What do you think, @Don Pensack, should I do it? Worst case, I figure I can resell it for $500 or more in 5 to 10 years once they're discontinued and become sought after on the secondary market again. 😁 After all, I only paid $125 for my 40mm Meade SWA in 2012 or thereabouts and could probably get around $150 for it today. With inflation, I'd at least be close to breaking even.

Because the return on trying to sell them is so much less than keeping them around for reference purposes. The only exceptions I can think of right off hand are the 12mm/17mm Naglers and 27mm Panoptic. Those are tying up over $700 of funds. I'm thinking of donating them to my daughter someday if her interest in astronomy grows more.

More of a theoretical question. Someone could probably use a scanning electron microscope to move atoms into the desired positions to empirically check this. I figured that once the slits are too narrow, the waves wouldn't be able to pass through. At that point, they're either going to be absorbed or reflected.

It will definitely be much lighter and more compact than either a 35mm or 41mm Panoptic, so there is that.

That's what I was thinking it reminded me of. However, what happens when the line width is narrower than the wavelength of visible light? For instance, say, greater than 10000 lines per mm? Do you just get a really good spectral analyzer or does something else start to happen?

Reminds me a bit of my home brew apodizing mask made from black window screen. That mask causes some really wild spectral artifacts in the outer field.

See if they'll price match and refund the difference. 😉

Reposting detailed description from another thread of how I captured these images so I can find it more easily in the future: I taped some rulers and yardsticks together on their back sides with packing tape and then wedged them under the edge of one of my kitchen cabinets, but hanging off to the side. I always align the 17 inch yardstick mark with the edge of the door for consistency. I turn on every light in the kitchen/dinette area and open all the blinds to maximize the available light. I put my AstroTech 72ED telescope on its leveled alt-az mount at the other end of our rather open plan house, about 35 feet away and close to level with the yardstick and close to perpendicular with it. I put a 2" GSO dielectric diagonal in the focuser with a TSFLAT2 field flattener spaced 15mm in front of the diagonal body on the scope side. This pretty effectively flattens the otherwise severely curved focal plane of the scope. Luckily, I don't need to add any extension tubes to reach focus, unlike when I try this with a 127mm Synta Mak. I put each eyepiece in the diagonal and focus the image with my eyeglasses on so the afocal image is focused close to infinity for the camera. This allows the field stop to be at its sharpest if it was correctly positioned during assembly and allows the camera to focus at infinity. I then center the yardstick in the field of view and lock the altitude clutch. Next, I nudge the mount left/right to put the edge of the ruler at the edge of the visible field stop, or at least the edge of the field for those without field stops. This can be a judgement call for eyepieces that use the barrel for the field edge as the edge will fuzz out. Also, you can move your eye off center and see more of the field with them by peeking "around the corner" of them, so to speak. That's why some don't show the edge when the camera is centered. I'll sometimes take an image with the camera way off to the edge looking at the other edge at an angle to get a clearer image of this effect, just like your eye would be doing in this situation. I use the high resolution, normal wide angle rear facing cell phone camera for most of my images. In my case, a Galaxy S7. I cup my thumb and forefinger around the top of the eyepiece to make a landing pad for the phone. I start well away from the eyepiece and move the camera in toward the afocal image using the screen to guide my movements. It's important to keep the camera level and centered. That's where your thumb and forefinger come into play. With practice, you can get it down to a fraction of a millimeter. You can roll your fingers get fine height adjustment. I've tried using adjustable height eye cups on eyepieces that have them to do this, but I couldn't get them to work very well. Now, you have to move the camera phone in and out until the edge of field or field stop just pops into view. You're at the correct exit pupil distance for that camera at that point. Any further out, and you miss some of the field. Any closer, and you start to get blackouts. If there is spherical aberration of the exit pupil (SAEP or kidney-beaning), you're going to be fighting a dark shadow all around the field. If you are perfectly centered, you will get a dark circle with a bright center and a bright edge ring. This cannot be helped as it a defect of the eyepiece and not the camera or scope. In this situation, you may need to turn down exposure to -1.5 to -2 to avoid the autoexposure circuit trying to make the shadow 18% gray while blowing out the bright areas. Make sure to use the camera's diagonal to get the widest image possible for super wide angle and wider eyepieces. You'll have to rotate the image in image processing software later. I then proceed to take a series of 3 to 5 images to later pick out the best of the bunch on a large computer screen. I've found that it's impossible to critically judge these images on the phone's screen. I then take an angled image of the edge for super wide angle or wider eyepieces since the edge of field of even the best camera lenses is not as well corrected as the center. It may also be cropped off for ultra wide field and wider eyepieces, so this is a necessity for them. If your phone has an ultra wide angle camera, use it to take all-at-once images of ultra wide field and wider eyepieces. I bought a second hand LG G5 phone for $25 off ebay just for its ultra wide angle camera since my S7 doesn't have one. That's what I use to take my "full view" images. I scale them up to match the scale in the center 20% of the S7 images. Differences in angular magnification across each camera's field of view accounts for the slight width difference in the final images when using the same eyepiece. Unfortunately, the G5's a 5 megapixel camera compared to the 12 megapixel S7 camera. When combined with the smaller image scale, these "full view" images are pretty low resolution by comparison. I'd love to acquire a 24 megapixel or higher ultra wide camera for this purpose. Anyone know of used ones that sell for cheap on ebay? In post-processing, I do not do any exposure adjustments or sharpening. I just rotate and flip them to be more readable. I also crop and composite them for comparison images.

This is what I ordered and will wait to see how it is. The Aero ED 35mm will be pretty good at f/4.7, but not Panoptic sharp in the last 25% of the field, so temper your expectations, and you should be happy with it. Here's how it looks at f/6 in a field flattened 72mm ED scope:

If you are trying to block sky glow, I'd probably recommend a UHC filter. If you're already in dark skies but want to go after faint outer tendrils, I usually go with an OIII. Both filters make the Trapezium look really odd, so remove them for enjoying views of it.