Louis D

I'm picturing $800+ APOs sent from Europe to the US as tube, lens cell, and focuser all separately on different days to legitimately keep the cost below $800 per individual per day (the letter of the law here). Some minor assembly required.

I've often wondered why there are four beginners forums, but only one Scopes/Whole setups forum. Why aren't scopes split out by type as on CN? A refractors forum would have been the natural place for this thread, but it doesn't exist on SGL for unknown reasons.

Indefinitely on that point. It was raised from $200 in March 2016 under Obama, and Trump left it alone during his four years, and since Biden is basically Obama v2.0, I don't foresee it being changed any time soon.

We're starting to see the 25% import tariff in the US on goods labelled as made in China. It's not clear how diligent customs is being on items like APM UFFs marked as Germany instead of China. US customs has been applying the 25% tariff very inconsistently even when items are clearly labelled as made in China. I may be buying more Chinese made goods from the UK/EU since personal imports under $800 are duty free and not checked for the 25% made in China tariff and individual retailers are not collecting the appropriate US state sales taxes because they have no nexus of business in the US. On net, these tax/duty/tariff savings easily pay for the additional shipping charges.

Correct. It's not like viewing a monitor screen where alignment is irrelevant. Your eye's entrance pupil has to be exactly aligned with the eyepiece's exit pupil, not only in the left/right and up/down sense, but also the in/out sense as well. It's a learned skill like riding a bike. After some time, it just comes naturally and you don't think about it any longer. That is, until you meet up with an eyepiece with loads of spherical aberration of the exit pupil (SAEP) or kidney beaning. In this case, it's a fault with the design of the eyepiece that no matter how careful you are, you cannot take in the entire field of view at once. The best remedy for this is to not buy such an eyepiece in the first place. That's where the SGL community comes in handy. We can steer you clear of eyepieces with known design issues such as SAEP. As far I know, your current eyepieces are not known to have such design issues. I'm 9 years your junior, and I can't hold myself steady for more than a few minutes before fatigue sets in while standing and observing. You need to be relaxed and comfortable to get the most out of astronomical observing.

If by barreling you mean seeing blacks or shadows as you move your head around; then yes, you're inside the exit pupil and are too close to the eye lens of the eyepiece. There are eyecup extenders or tall eyecups that might help with the 32mm Plossl by giving you a frame of reference for where to keep your eye relative to the eyepiece. Are sitting while observing? It's just about impossible to remain still enough while standing to successfully hover above an eyepiece. There are adjustable observing chairs of all sorts that can help with this.

Then the 8x42 bins will work great for that. I have a Meade Safari Pro 8x42 from the late 90s that still puts up great views and is eyeglasses friendly with a 65 degree apparent field of view. The Diamondbacks should be lighter being roof prisms instead of porro prisms, so probably even easier to use handheld.

Once you have the binocular section focused, hopefully you can move the trinocular eyepiece up and down to reach parfocality and then lock it down as well. You should also be able to focus the trinocular eyepiece using live view from the camera to a monitor screen.

I was thinking of a single one for the trinocular tube to take low distortion, afocal images. Distortion isn't all that important visually at the binocular viewer.

Moving up in aperture at a similar f-ratio with the same objective design will naturally result in poorer color correction. Replacing FPL-53 with FPL-51 at a given aperture will reduce color correction further. An FPL-51 triplet has similar color correction to an FPL-53 doublet, but with longer acclimation times. This is all theoretical, though. Visually, you'd be hard pressed to notice the difference except on the brightest objects at the highest powers. Photographically, you get more blue/violet halos around bright stars from what I've read.

I've had my $69 Galileo 15x70s for over a decade and have traveled extensively with them and have yet to have them go out of collimation. Sure, they only have 65mm of clear aperture, but they've given me and my family many great views both terrestrially as well as astronomically. You can always rig up a reclining lawn chair for binocular observing like this guy on CN did to get better comfort and stability.

Now you just need to trick out your recliner like this guy did on CN.

You have to watch out for that floating in space feeling. It can be unnerving 🤣:

Actually, the rubber cup part just pulls straight off with very little effort compared to the Aspheric's eyecup. The twist up/down part stays resident on the eyepiece. It is possible to unscrew the bottom barrel(s) and eventually get the twist up/down part off by sliding it downward from what I've read on CN, but I can't replicate it with my copies. The upper colored barrel won't budge on mine. I think they're thread-locked.

I've updated the comparison image with the addition of a 25mm Abbe ortho eyepiece. Notice the lower distortion and narrower field of view. Your best bet would be a 32mm Tak Abbe orthoscopic costing £189.00 (with 20% VAT) new for pristine images edge to edge. This would nearly double the cost of your microscope, though.

Clever woman you are. 👍 I tried a similar thing by slipping my 27mm Panoptic's 2" barrel over the 1.25" diagonal's eyepiece holder with the securing screw removed. It worked great with little to no vignetting. No wonder that it works so well. With a 30.5mm field stop over a 31.75mm opening, there shouldn't be any issues.

Remember to pull off the rubber eyecup if you need extra eye relief. It's on a plastic barrel, so no worries about scratching your eyeglasses on the bare top. The rubber eyecup can be quite difficult to work off the first time. You may need to get a butter knife in the gap under it and work it around to pry it upward.

For the binoviewer side of things, this won't matter as it is visual only. Louise is looking for two, low cost, yet decently performing eyepieces for this purpose. For the trinocular imaging side, she can probably stick with the BST she already has for now. It seems to have the least distortion of the three in my image. I don't think she's going to find a well corrected, budget, low distortion eyepiece that isn't a used Abbe orthoscopic. I just remembered I had an image for a 25mm Abbe ortho for comparison sake, so I added it to the image, replacing the original image. It does have lower distortion, but at the cost of a very narrow field of view. Louis would need about a 33mm ortho to maximize the true field of view in a 23.2mm barrel. The 32mm Tak Abbe orthoscopic costs £189.00 (with 20% VAT) new for reference.

There are many Chinese made, long eye relief, wide field (50 degrees in microscopy parlance) eyepieces on ebay for cheap that you might want to try. They come in either 23mm or 30mm barrels already.

Agreed. It's really only at very high powers on bright objects that false color can intrude. False color suppression also helps discern low contrast details on planets and nebula. For everyday viewing, though, it isn't much of an issue. I still remember being unimpressed with the views of Jupiter through a 4" Astro Physics APO at a Texas star party as compared to the view through a 15" Obsession Dob. It was simply no contest. Both cost the same with the mount included. That sealed the deal for me to get a Dob instead of an APO.

I think there's also the point that Chinese manufacturers seem to put more effort into getting a near perfect figure on their ED and APO scopes as compared to their achro scopes. My ST80 has bucket loads of spherical aberration in addition to chromatic aberration. So much so, that it makes it nearly useless for terrestrial or astro viewing. I'm sure an ST80 could be made with as fine a figure as my FPL-51 and FPL-53 based scopes, but at what cost? Would people be willing to pay a premium for a premium figured fast achromat?

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.

First, does your scope use 23mm or 30mm barrelled eyepieces? This is what ultimately limits the true field of view of any eyepiece in a microscope. You can't see what's beyond the barrel. Second, microscopes operate at high f-ratios (f/13+ as I understand it). As such, they're not very demanding on eyepieces at the edges. Third, I love my 23mm Aspherics in my binoviewer when barlowed to f/12 in my Dob or natively at f/12 in my 127 Mak. It's super easy to get my nose between them and sink them deep into my eye sockets thanks to their diminutive size. Being super light also makes scope balancing easy; although this isn't an issue for microscopy. I also remembered I have unprocessed/unreleased 127 f/12 Mak images for several of the eyepieces I've mentioned here. I whipped together a new composite image below for four of them. (Edit: I just added the Edscorp 25mm Abbe Ortho for reference). As you can see, all perform really well at f/12 which is comparable to a microscope as compared to with the f/6 flattened ED refractor in the earlier image.

Actually, you guessed more or less correctly. An SCT primary is about an f/2 and the f/5 secondary effectively slows it down to f/10 due to its curve. Varying the distance between them varies the resulting magnification. If the secondary were a simple flat, the focal length wouldn't change any more than it would on a Newtonian by moving the primary forward in its cell to get more back focus.

It also depends on the aperture as I pointed out with that achromat chart by f-ratio and aperture in one of these achro/ED/APO threads. Similar to achromats, an f/6.3 50mm with an FPL-53 doublet would probably be easily as color free as an f/6.3 FPL-53 triplet at 100mm, perhaps better. The next question becomes, at what aperture would an FPL-51 doublet look as good as a much larger FPL-53 triplet. I know of no equivalent chart for comparing FPL-51/53 doublets/triplets to each other across various combinations of f-ratio and aperture. I think it is informative that no premium frac companies make 150mm f/5 scopes, despite Skywatcher/Celestron making an achromat in this size/f-ratio. I'd like to know how good an FPL-53 triplet at this size/f-ratio could be. 750mm is a very manageable focal length on an alt-az mount.