vlaiv

Yes - probably series of vortices that sort of blends into a single feature at this resolution. Here is something similar on one of high resolution Jupiter images: at smaller scale it simply looks like gap in cloud belt:

Nice image. Your image is probably correct. Jovian cloud and belt system is very dynamic system and you can't expect application to give you correct view of the planet unless it is streamed live from a telescope. Most applications that show Jupiter "as is" - just have one set of images recorded at particular time and use those to give you illumination, moons and GRS position information. Belts and clouds in the image don't reflect reality at that given time.

I'm a bit confused by that page as it does not mention anything about raw video being recorded. It mentions MOV video format which is mostly mp4 compressed. Have you tried recording with DSLR like that? What sort of file size do you get? For reference, 60fps, 640x480px at 8bit - one minute raw video would end up being about 1.03GB of data.

Apparently quarks make just 1% of mass of nucleus - rest is down to gluon-quark dynamic (quarks moving, gluons moving and some other strange things). It is probably down to geometry - takes more gluons to hold quarks in protons and neutrons when they are free particles than it does when they are "lumped together". https://physics.aps.org/articles/v11/118

We could say that energy of atomic and molecular bonds is stored in gluon and photon quantum fields? Gluons and photons don't really have rest mass, so all of that extra mass is due to relativistic effects of them whizzing about in nucleus and between electrons and nucleus.

It weighs more after charging it. It has the same mass after charging it. Weight of object is defined by acceleration in earths gravitation field. Acceleration depends on space time curvature. Energy and mass curve the space. You increase energy content - but not mass. That is why object weights more - not because it gained mass. Rest mass remained the same.

Hi and welcome to SGL

Two things really limit DSLR usability as planetary camera. First is ability to crop sensor to smaller size when shooting video. Second is ability to record raw video. If DSLR can do these two things, then it is not different to planetary camera. Most DSLRs can't do that. If you for example have 6000x4000px sensor and you shoot 1920x1080 video - that does not mean it has been cropped! It is still same FOV that has been binned / resampled in video - which changes effective pixel size. Another issue is compression in video recording. Most DSLRs shoot mp4 video. Compression messes up detail in recording and you want raw video without compression (at least not lossy compression). If you want to get decent planetary images - then planetary camera, or even modified web camera will be better choice (for web cam - same things apply - need to be able to record raw and to crop).

I could not resist posting this: https://www.skyatnightmagazine.com/advice/make-a-50mm-eyepiece/ That is actually amazing stuff. I have old Helios 44-2 58mm lens and 3d printer - might give it a go for my Mak102

That won't work very well. 25mm plossl has field stop of ~21mm. If you add x0.5 reducer - you'll want to provide 42mm of illumination to reducer element in order to fully illuminate field. Neither 1.25" reducer can accept that large field having less than about 28mm of clear aperture - nor Mak can provide that much fully illuminated field given that rear port of 127mm mak is only about 25mm wide: Best thing one can do if they want to maximize exit pupil is to take 1.25" eyepiece with long focal length and narrow field of view - like 40mm plossl in 1.25" variant (about 40 degrees of AFOV). There will still be issues with such setup as very large eye relief - so it won't be very comfortable to use (might be for someone wearing glasses who can keep their head still on optical axis ).

No. Filters are flat optical elements and they can't change magnification. There are some special cases where they can alter magnification produced by other optical elements - because they add (minimal) optical path and very small physical path to light. If you use them with barlow or reducer - then they would alter barlow / reducer element to eyepiece distance and change magnification / reduction factor of these elements - but you'd be hard pressed to tell the difference visually. You can get the same effect by slightly pulling eyepiece ~5 mm back in focuser and clamping it there - instead of pushing it all the way in. If you do that - it won't change magnification (again - with exception of above cases, barlow or focal reducer).

Actually you are quite close to good collimation. It needs to be touched up a bit, but it is pretty good as is. There is some astigmatism and distortion in outer stars that need to be addressed. Defocused image of Vega is only good for checking secondary collimation. And it is just a bit off as well. Here is an old trick that shows well if you have defocused image that is not concentric: It is same image in two frames - one normal, other rotated by 180 degrees. Now you can clearly see that there is a bit of "squish" on one side and that circles are not concentric.

Not sure myself, but it does sound like short for "If I recall correctly" - so I assume that is the meaning of that abbreviation

Hi and welcome to SGL. Use raw format and SER file in SharpCap. You'll need x1.5 barlow to match ASI120 to your C9.25. Any x2 barlow can be made to operate at x1.5 - by adjusting barlow element to sensor distance. You can do it during daytime on any far object that you can measure on your screen. First use just camera without barlow and record size of object (church tower, high building, bridge, wall - whatever you can comfortably measure in pixels). Then add barlow and tweak sensor / barlow element distance until you get x1.5 larger image. Don't debayer in PIPP. AutoStakkert will do it for you using bayer drizzle algorithm which is best for this type of imaging. Just tell it your camera is color and select bayer matrix order (there is menu option for that): Don't worry too much about polar alignment. As long as you have it in the ball park - planets will stay in FOV for the duration of capture. Remember, Jupiter rotates and if you don't want to use derotation (in WinJupos) - limit your runs to about 3-4 minutes. Use very short exposures - about 5ms. Don't try to get good histogram. That is not sound advice for planetary imaging. Histogram plays no part (except to tell you if you are over exposed and clipping - but that rarely, if ever, happens with proper exposure lengths).

Flats will work, but problem is not with flats as much as light loss itself. If you get significant vignetting - you'll get much worse SNR in corners. Say you have 50% vignetting. That is like you exposed corners only for half of total time - SNR will be only ~70% of center. Here is quick diagram of vignetting based on specs that I managed to find online: This is for 150mm F/5 newtonian with 185mm distance between Focal plane and diagonal. I figured following: DSLR can reach focus on 150P, so we have at least 90mm from optical axis to tube edge (tube diameter is 180mm), then we have at least 50mm of focuser and 44mm of flange focal distance for DSLR giving total of 184mm. I used 185. At edge of the field - magnitude loss is 0.3mag which translates to about 75% illumination. Which is ok. I'd be more worried about field definition and vignetting depending on coma corrector. Here are some interesting examples of how CCs perform on 10" newtonian on 4/3 sensor: https://www.astrofotoblog.eu/?p=856

Yes, L will be problem and it will result in slightly bloated stars. If you are really on a tight budget - there is solution for bloated stars in L - Astronomik L3 as luminance filter. It removes a bit of spectrum on far ends that usually cause bloating. It will work with OSC as well, but even better with LRGB approach. As far as scope goes - here is a good one: https://www.teleskop-express.de/shop/product_info.php/info/p3881_TS-Optics-PHOTOLINE-80-mm-f-6-FPL53-Triplet-Apo---2-5--RAP-Focuser.html Not sure how much it will cost after import duty and tax - could be comparable in price to WO81? It is triplet though. Alternative is same scope from AA: https://www.altairastro.com/starwave-80-ed-r-triplet-apo-travel-refractor-465-p.asp (but currently out of stock)

SQM reading has nothing to do with local seeing. You can use Meteoblue for seeing forecast and they are usually right about high altitude seeing, but very important part is local seeing - that one you can't predict. It has to do with how well your scope is cooled down, what part of sky you are observing in (how close to horizon) - what thermal object you have around you like large concrete buildings or maybe large bodies of water. What sort of wind is blowing and what sort of terrain you are in. If you have rolling hills and you are on top of the small hill and there is nice smooth breeze blowing - local seeing is going to be good, but if you are observing over roof tops in winter time, or perhaps over lake in hot summer evening or there is mountain near by and wind blowing from that direction - you are probably going to have rather poor seeing. For what the software is asking - Meteoblue forecast rounded to nearest half FWHM (like if forecast is 1.89" set it to 2" and if it is 1.56" set it to 1.5") should be good enough since this is very arbitrary analysis given that it is using long exposure image of a real star. If you want to be precise about it and you want good analysis - take a telescope and look thru it at actual star and use Pickering scale to determine FWHM. see here for details: https://www.handprint.com/ASTRO/seeing2.html and here https://www.damianpeach.com/pickering.htm Do analysis on the night when star is mostly stationary with diffraction rings being visible and not broken (Pickering 6 and above)

They are terms that are of interest to astronomy enthusiasts? SQM and Bortle scale are measures of object brightness. SQM can measure both extended target and sky background (affected by light pollution), while Bortle scale is very crude measure often used in descriptive manner for sky brightness. Mostly used by visual astronomers. Bortle scale ranges from 1 to 9 (best sky to worst sky). SQM is abbreviation of "sky quality meter", but is often used as - magnitude per "square" element of sky / target (sq - square, m - magnitude) - be that arc second squared or arc minute squared - in any case, some surface. It is logarithm scale much like regular stellar magnitude - and has the same meaning - or rather, how bright patch of the sky / target would be if you took star of certain magnitude and "smeared" it over that surface (arc second squared or arc minute squared). It is measured and besides being more precise description of the sky for visual astronomers is very handy for exposure / SNR calculations for imagers. Here is conversion table between the two: (not very precise, as I was able to glimpse MW at zenith from red - white border - which was about SQM18.5) FWHM is measure of how good the seeing is at any given moment, but also - what is the resolution of long exposure image. It stands for full width of half maximum and is measure related to Gaussian (or other similar) profile created by star in a telescope. When we talk about seeing FWHM - then definition is - FWHM of recorded star using very large aperture telescope for 2 seconds (or perfect tracking mount). Seeing FWHM will not be equal to FWHM that you get in your image. FWHM in image is influenced in part by seeing FWHM, but mount performance and aperture size play a part. How precise is your focusing also plays a part and if telescope is diffraction limited or not (collimated well, or even optically degraded by choice - like inclusion of field flatteners / coma correctors that improve edge of the field but give away some of sharpness overall). Image scale is simply conversion factor between angular units in the sky and linear units in focal plane - often expressed in units of pixels instead of microns - so you get arc seconds per pixel or "/px. It depends on pixel size and focal length of telescope and formula is - image or pixel scale = pixel_size * 206.3 / focal length (where pixel size is in micro meters and focal length in millimeters). FWHM of the image and pixel scale are related like this - there is match between where pixels match what can be recorded in terms of sharpness. This is called optimum sampling. If you sample with less pixels per sky angle - this is called under sampling and is in itself not a bad thing. In general, there are artifacts associated with under sampling - but those artifacts never happen in astrophotography (due to nature of blur that is imparted on image by atmosphere, mount and telescope). If you read that "stars are square" due to under sampling - well that is simply not true (they can be square if one uses improper interpolation algorithm - but that is whole another story). If you sample with more pixels per sky angle than you need - you are over sampling. Over sampling is bad. It produces poor results when image is viewed at 100% zoom - being soft with bloated stars, but there is much more important aspect of over sampling and why it is bad. We always want to take "faster" images of the night sky and produce smoother better looking images with less noise in given amount of time. Over sampling prevents us from doing this - over sampled images have much lower SNR then they need to. This is because light is spread over more pixels (than it needs to be) - and signal per exposure is lower and hence signal to noise ratio is lower. This is very similar to using very high magnification visually - object just gets dimmer and you don't get to see additional detail. Proper sampling is when you properly match FWHM and pixel scale and it lets you capture most detail with having best SNR for given time.

That one is also easy to solve. If we look at geometrical optics - then combination of the lens can usually be replaced with single lens. For monochromatic light there is really no difference in singlet, doublet or triplet telescope. They all act the same - as simple/singlet lens with given focal length. Additional lenses are there just to correct for optical aberrations that are "on deeper" level than simple geometrical optics (chromatic aberration, spherical, flattening the field with camera lens, etc ...).

I'm not sure I understand what you mean by x2 larger noise in red over green or blue with cooler turned on and temperature set to 0C. Is it thermal noise? Is it read noise? Is this subjective judgement of SNR when inspecting subs? ASI183 has rather small pixels and you should take this into account. It tends to over sample on most telescopes because of 2.4um pixel size. Given that it has rather small read noise - you can bin it in software without issues. I'd advise you to do the following if you want to get the maximum out of that camera: 1. Use super pixel mode or split debayering to get color information (don't use interpolation methods) 2. Bin resulting subs further x2 to increase effective pixel size and improve SNR (or bin x2 linear stacks prior to any further processing). Camera itself is 5496*3672, but above will reduce pixel count to effective 1374 x 918 px I know that this sounds too low in terms of mega pixels - but just think about it for a moment - it is low cost, small pixel sensor similar to say ATIK314/414 models - but with better QE and lower read noise at lower price. People get caught up in all the megapixel craze - and fail to see sensor for what it really is.

Doublets do have some residual color and I would not recommend them for serious imaging. If you don't mind having a bit more bloated stars in LRGB or some bluish halo here and there with OSC - then, sure, doublet can save some money, but for really tight stars - go with triplet.

That depends on how you use it. Since you have DSLR and plan on getting 2600 (or rather IMX571 in some shape and/or form), I'm going to assume following: APS-C sized sensor and 3.76um pixel size. You want middle ground, so both galaxies and nebulae - 1.8"/px is good place for that (and seeing conditions, and mount performance). Simple calculation gives us ~430mm of FL. Here is scope + flattener for you: https://www.teleskop-express.de/shop/product_info.php/info/p14015_TS-Optics-APO-Refractor-96-576-mm---FCD100-Triplet-Lens-from-Japan.html + https://www.teleskop-express.de/shop/product_info.php/info/p11122_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html Not sure what is current exchange rate so it could be a tad over your budget.

That one is simple. You have to look at chief ray for either lens or mirror - it does not bend (in case of lens). In above image it is ray passing thru point B. That ray is always straight. It does not bend - for lens. Similarly for reflector - it is also ray that "does not bend" - or rather one that is reflected like of ordinary mirror - look at this diagram: In above image - ray that hits center of the mirror - might as well hit flat mirror - it will be reflected at the same angle it came in - it will be symmetric to optical axis. Now that we know what chief ray behaves like - it is very easy to understand why FOV depends on focal length - if we examine this diagram: Here we have lens and chief ray that hits "edge of FOV". If our focal length is short - it will hit focal plane closer to center, and if focal length is long - it will hit it further away. In fact - there is relationship between focal length and height in focal plane for given angle - all those triangles are similar and have same angle. Now if you fix sensor size - following happens: If sensor is further away from lens because focal length is greater - then line connecting center of the lens and edge of sensor forms smaller angle - and again, angle is function of sensor size and focal length. Don't need any ray bending to explain this - chief ray that stays straight is enough to show this dependence.

What is the actual issue with that camera that you experienced?