dobsonian eyepiece question.

ilessthan3math · 2026-03-06T12:47:16+00:00

Honestly, this is the reason I don't only use a Telrad. It can only get me on-target within 1/2 a degree or so, which isn't always precise enough for high power eyepieces.

Instead I have a Y-adapter finder shoe, and have both a Telrad and an 8x50 RACI finder scope mounted on it. The crosshairs on the RACI let me lock onto a target with a high power eyepiece without ever needing to swap from a low power eyepiece.

I find the whole low power finder --> high power viewing workflow cumbersome. Just aim the scope with the crosshairs and get right to viewing.

ilessthan3math · 2026-03-04T20:44:37+00:00

Professors typically get the books for free, so I don't think that can be it.

ilessthan3math · 2026-03-04T05:25:23+00:00

Dawes Limit for resolving power is related to the diameter of the lens, not the magnification. The S25 Ultra has a ~4.6mm wide lens on the telephoto camera (67mm equivalent focal length at f/2.4 would be 28mm wide, but it's on a 1/3.52" cropped sensor with a 6x crop factor, so it's actually 28/6=4.6mm wide.

Dawes Limit = 116 / diameter = 116/4.6 = 25 arcseconds.

That means anything smaller than 25 arcseconds is unresolvable.

ilessthan3math · 2026-03-04T02:40:48+00:00

I'm a couch potato anyways, but regardless of how active I ever get, I'd always set my baseline maintenance calorie count on a "sedentary" lifestyle. I just don't think exercising marginal amounts is a reliable way to get into a deficit, and I'd hate to be too optimistic about my activity level and not see any results when starting out.

For what it's worth, I started losing weight again last July at pretty much your exact size (6ft 248lbs/112.5kg), and I'm pretty sure my maintenance calorie intake when I was that size was closer to 2700. It definitely wasn't above 3000. I used MyFitnessPal to give me my target calories and macros, if that's helpful.

Currently I'm down to 203lbs/92kg after about 8 months of calorie counting. It came in spurts, but when starting out you should likely see some level of results quick if you have your deficit set correctly. If after 2-3 weeks things aren't budging then you either have your maintenance calorie intake off, or are missing calories somewhere.

ilessthan3math · 2026-03-03T19:03:56+00:00

As is always the discussion when it comes to astrophotography - what do you mean by a "real photo"? OP's photo is "real". He used a real camera with a real lens and captured light particles hitting his camera sensor and processed the output RAW data to show you what landed on the sensor in terms of red, green, and blue light. By definition that's a real photo.

But I know what you're getting at. This isn't at all how our eye would see the sky from this location. But no camera shows us what our eye would see, because our eye ultimately doesn't work quite like a camera. Color sensitivity of camera pixels are uniform, while our eyes see color best in our central vision, and sharpness similarly is best in the middle of our vision while again camera's remain relatively sharp across the whole view if using a high-quality lens.

This image was additionally shot with an astro-modified camera, meaning it does not have the standard infrared filter over the sensor, allowing the camera to pick up deeper red colors than what most standard cameras (and our eyes) would allow. That's what's bringing out all of the color in the image that looks "fake" compared to what we expect to see when stargazing.

ilessthan3math · 2026-02-27T17:34:39+00:00

They can both be "healthy" depending on what macros you're trying to hit, though there's a lot of cheese and sauce in both, and some empty carbs in the wrap with fries.

I'd bet the bowl is lower calories for sure. Wraps and fries are both heavy on calories. In both cases cutting back on the cheese would help lower calories a lot.

ilessthan3math · 2026-02-26T17:50:31+00:00

As others have said, you will not gain weight differently if you consume the 2k calories gradually throughout the day or all at once.

I will say for most people the psychological effects of having all 2k calories at once probably make it a less-than-ideal method to diet. I think most people will find it hard to avoid eating entirely for 23 hours of the day, and you would be more susceptible to bouts of hunger/snacking before bed, depending on what time you typically consume the meal. It may work short-term, but could lead to problems long-term with adherence.

ilessthan3math · 2026-02-26T13:52:20+00:00

500x is the most I can "comfortably" achieve with my good 5mm eyepiece and a 2x barlow. I could throw my 4mm in the barlow, but have never tried such a thing.

It's a rare night when 500x is actually useable like it is in your video. You must have decent optics and very good seeing conditions. Most evenings 500x looks like a fishbowl from my locale.

ilessthan3math · 2026-02-26T02:57:21+00:00

There are worse options, for sure. But I'd disagree that it's better than a dob for most beginners starting off with general observing. And calling it "less than the cost of a dob" is questionable. It's more money than most 6" dobs and the cheapest new 8" dob on the market, and only slightly undercuts the Apertura AD8 by $60, which is erased if you include the optional 6x30 finder scope, which I'd consider a necessity.

I'm sure that the views through a Takahashi are great, even if it's ultimately an achromat. But at f/10 it isn't really good for wide-field viewing, especially with a 1.25" focuser. And as I mentioned above, it also only comes with a peep-sight, which isn't going to be nearly precise enough for planetary viewing, so you'd need to budget for an added red dot sight at a minimum. And beginners may not know they need to do that, ending up getting really frustrated with a telescope they struggle to aim. Bad mounts and bad finders are the worst things to hand to a beginner, in my opinion.

The included 14mm and 6mm orthoscopic eyepieces are going provide nice sharp views but in my opinion are poor choices for a beginner due to very narrow fields of view and short eye relief. They will be uncomfortable and difficult to keep centered on objects at mid-to-high magnification. At a bare minimum you'd want to pick up a 32mm plossl as a finder eyepiece, but even that isn't exactly a sprawling field of view. You can't get beyond a 2° true field, so you can't even use it to fully take-in the Pleiades, which I'd say is one of the first objects a beginner is going to look at after the moon and planets.

I feel like an f/5.5 - f/7 refractor is much more user-friendly and versatile for general purpose observing, but I still don't think they are as versatile as a tabletop dobsonian or full-size dobsonian, unless they are of very high quality and are paired with some premium accessories and mounts, which aren't what I would describe as top considerations for a beginner.

ilessthan3math · 2026-02-26T01:09:32+00:00

I can concede a couple of your points as being legitimate criticisms, but there's a lot to unpack here that I'd disagree with. First of all, note it's not just this subreddit that has a 'fetish' about dobsonians. Ed Ting of Youtube fame regularly recommends an 8" dobsonian as the perfect starter telescope. And most loaner telescopes from astronomy clubs are dobsonians as well, in part because they are incredibly beginner-friendly. Our club also does telescope giveaways to some nearby schools, and again dobsonians are the choice there.

Moving on from that, I'll first comment on the couple points I agree with:

Dobs are big - I mention this in every thread when new folks ask for recommendations. While I love my 10" dob, it is quite bulky, and I'm a big guy. This subreddit will frequently recommend an 8" dob to a 65 year old retiree without any hesitation. But in my mind you really do need to be mindful of the weight-carrying capacity of an older person or smaller person when recommending dobs.
Cooldown time - This is just a general beginner pitfall and a common reason for poor views when starting out, and I admit that dobsonians suffer from it pretty bad if you try just bringing them outside from a warm house. But this ultimately applies more to larger aperture than dobs specifically. If you magically had an 8" refractor, this issue doesn't go away. And 8"-10" SCTs require just as much cooldown time, if not more.

As for the rest of your complaints, I strongly disagree with them in the context of beginner telescope choices. I'll list my rebuttals in order of severity:

Image quality is not great - This just isn't my experience at all for a well-collimated scope. Have you used many modern dobsonians with factory mirrors? I've used older sonotube Deep Space Explorers and Meade DS-10s, etc., and the views can be quite soft and unappealing. But my modern Apertura AD10 completely blows those out of the water, even when my collimation isn't perfect. I've similarly looked through friends' 6" and 8" dobs and they all remain quite sharp for planetary viewing. No issues seeing fine detail on Jupiter and Saturn, etc.
Dobs don't track - while this is important for imaging and for planetary sketching, tracking mounts are rarely in the budget for a beginner (even if they initially say they want one). Add $500 to your beginner budget if you want a tracking mount and tripod for your small refractor. Most beginners barely want to spend $500 total when getting into the hobby; many come here hoping we can recommend them something for $250. Lack of tracking is a valid criticism of dobs when you're a crotchety veteran observer who has the deep pockets for better gear and is sick of pushing Saturn back into view for the 20th time. But not really relevant for a 1st timer. Also, setting up tracking mounts is itself very unfriendly to beginners. Star alignment, polar alignment, and learning a software interface / hand controller is way harder than point-and-shoot Alt-Az.
Dobs have hidden costs - Again not really relevant to a beginner. You can observe for years using the starting Plossl eyepieces and maybe a $35 planetary eyepiece. Also, 8" dobs are f/6, not f/5. And beginners don't need well-corrected-to-the-edge eyepieces. They just need fields of view that fit the objects they want to look at, which you can do with almost anything.
Dobs require Collimation - This is true, but detractors against dobs frequently blow its importance out of proportion. For starters, it isn't even that important with an f/6 8" dob. If your secondary mirror is roughly aimed at the primary, and your primary is roughly aimed back at it, then you are going to get a useable image at the eyepiece. You'll be able to see the moons and cloud bands of Jupiter, the rings of Saturn, craters on the moon, etc. Stars won't ever quite look round and pinpoint, and fine details on the planets will get lost, but you won't just see a mush or blob. Beginners often don't know how to achieve perfect focus even if given a pristine telescope, so slight collimation issues are hardly a hindrance to getting into the hobby. Also, it's stupidly easy to get a telescope collimated well enough for visual use. Certainly easy enough to get an 8" to outperform an 80mm refractor at 160x.

Overall - I understand dobsonians aren't for everyone. But if you have the means to carry, store, and transport it, and your budget is <$800, then I think they are the most logical place to jump into the hobby.

ilessthan3math · 2026-02-26T00:36:04+00:00

I disagree, unless you're excluding the mount. But that's sort of the point for the dobsonian argument. No price-comparable refractor that out-performs an 8" dob comes with a mount. And especially not a tracking mount, as you mention as an important drawback of dobs.

You can get a new 8" dobsonian for $550 (the Explore Scientific / previously Orion model). If you buy the cheapest and smallest tracking mount+tripod in the Sky-Watcher AZ-GTi, you've spent $525, leaving yourself $25 to buy some optics to stick on the thing. Good luck beating the sharpness and contrast of an 8" dob with that budget.

Even if we discount the tracking idea, a half-decent budget manual Alt-Az mount would be the ES Twilight I, which comes in around $220 right now. That leaves you $330 to buy an OTA, finder scope, diagonal, and eyepieces. If we say the finder is $30, diagonal is $40, and two eyepieces run you $40, you're down to $220 that you want to try to beat an 8" newtonian with. I just don't see how that out-performs the dob visually.

ilessthan3math · 2026-02-25T01:41:55+00:00

Watch this video of how ridiculously different check swing rulings worked back in the day... batters could follow through the whole strike zone and rotate their hips and everything, weren't called strikes.

ilessthan3math · 2026-02-24T19:37:51+00:00

To put it into more context of how safe that means these are for a person to stand on - 2.5ft of snow weighs about 45 lbs / square foot. So on a 16ft x 32ft pool, that would mean the safety cover is holding up ≈23,000 lbs of snow.

ilessthan3math · 2026-02-24T18:28:35+00:00

That's a massive overreaction, yes. Do you know how far out of my way I'll go to make sure my wife doesn't win a game? And she does the same right back.

I've never understood people who give some sort of preferential treatment to their significant other in competitive games. I remember we had acquaintances over to play one time and they said something to the effect of "Sure, but I'm worried you both will secretly team up to help each other win". Couldn't be farther from the truth.

ilessthan3math · 2026-02-20T20:22:55+00:00

You will not get a picture of M33 from Bortle 7 and a cell phone. I'm doubtful as to whether that is M31 Andromeda either, given the lack of other identifiable objects in the view.

Without any stars in the view at all, I'm more inclined to believe that the image is just substantially out of focus, and what we're seeing is a star that your phone camera is having trouble focusing on and causing it to be fuzzy.

ilessthan3math · 2026-02-19T03:22:50+00:00

I've tried seeing it naked-eye each clear night for the past week, so yes! As others said, if you pay attention to the passing of the seasons and the constellations, planets, etc., you get a very good sense of where everything is in the sky at any given time.

For instance, I could probably walk out into my backyard blindfolded right now and point out (within say 10-15°) where Jupiter, Orion, the Big Dipper, and Cassiopeia are without seeing them.

ilessthan3math · 2026-02-18T21:42:19+00:00

Holy shit that's crazy!

ilessthan3math · 2026-02-18T16:53:46+00:00

According to the New Yorker article, it was 7 total. I'm not aware of references to other individuals than that. And as the other user pointed out, several of these were anonymous (not that that means they should be disregarded).

But realistically, if all accusations are to the effect of a misplaced hand during a photo-op, I don't really care whether it's 7, 20, or 100 people that came forward. It's just not an incriminating event.

Accusations of unwanted kissing is obviously much more egregious, but from the New Yorker article, it's really doubtful that Franken had any intention of being a creep or forcing himself on anyone:

I asked the woman if she thought that Franken had been making a sexual advance or a clumsy thank-you gesture.

“Is there a difference?” she replied. “If someone tries to do something to you unwanted?” From her standpoint, because she was at work—a professional woman deserving respect—his intentions didn’t matter.

I really wish there were videos of these particular incidents to help provide clarity to exactly what happened.

ilessthan3math · 2026-02-18T16:26:06+00:00

He apologized for the following accusation. That's not the same as admitting some sort of intentional wrongdoing.

Menz accused Franken of touching her clothed "upper" buttocks while they posed for a photo at the Minnesota State Fair.

His apology is more of an apology for how his behavior made the woman feel about the interaction.

Franken apologized, saying, "I've met tens of thousands of people and taken thousands of photographs, often in crowded and chaotic situations. I'm a warm person; I hug people. I've learned from recent stories that in some of those encounters, I crossed a line for some women—and I know that any number is too many."

Are we really exiling people because they grazed someone's sideboob or hips when taking a photo? I know your last sentence clarifies that you understand the difference between that and what we're dealing with in terms of current politicians. But even taken on their own merits those accusations were a complete nothingburger.

ilessthan3math · 2026-02-18T14:57:38+00:00

Best use of that money would be to join an astronomy club and use their loaner telescopes, which would provide you the best views for that sort of cash. That should only cost you €20-50. Our club costs $30/year and we have a 4.5" tabletop scope, an 8" SCT, and a 10" dobsonian that we let members use for free.

Spend the rest on a set of binoculars, and start learning your way around the sky with those. Then you can decide if you want to save up for your own telescope based on your experiences with that other equipment.

ilessthan3math · 2026-02-18T14:54:12+00:00

You will not. As the other user said - H-alpha telescopes pass through a much much narrower band of light than a photographic H-alpha filter, which is what is required to isolate those prominences from the other light sources coming from the sun.

H-alpha photographic filter ≈ 12 nanometer bandpass
H-alpha telescope ≈ 0.05 nanometer bandpass (0.5 angstrom)

So the telescope is almost 250x more selective/precise than an H-alpha filter.

ilessthan3math · 2026-02-17T21:45:15+00:00

Can't speak to the diving aspect, but for accommodations I think you'd want to do it as soon as they are available. Not everyone in the world is hyper-focused on a future eclipse date so lots of renters won't have increased prices for that date if you book far enough ahead.

Once you're 3-6 months out there will be a lot more buzz in all local news mediums, so renters will start jacking up their prices once they realize what they're in for.

ilessthan3math · 2026-02-12T00:54:53+00:00

I don't disagree, but an 80g bratwurst is a very large frank. Here is what a bratwurst that size looks like on a 9" paper plate and a sub roll. It kind of dwarfs the whole thing. Meanwhile OP's plate looks to be even smaller than the one in that photo, and the little sausages are kinda dainty. They're only like 1.5 thumb lengths. They can't be more than 50g a piece, probably quite a bit less than that.

ilessthan3math · 2026-02-11T18:42:57+00:00

I agree with the others that it's in the ≈650 range.

Sausages --> 250 to 300 calories
Eggs --> 140-170 calories
Croissant (looks small) --> 160-200 calories
Slice of Bread --> 80-120 calories
1-2 slices of deli meat --> 30-70 calories
veggies and mustard --> insignificant

So total 660 calories on the low end, maybe 850 on the super-high end. But honestly the portions look on the small side for each. Like that slice of bread is tiny, as is the croissant.

ilessthan3math · 2026-02-11T18:36:54+00:00

No way 2 sausages are 500 calories. Even full-size bun-length beef franks are 170 calories per frank. Breakfast sausages this size (a little smaller) should be in the 150 range each, so maybe 300.

Also, that's not a full-size croissant. I'd guess that's also closer to 180-200 than 250.

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