Oscar23

"computers not communicating with each other" If true, that is an amazingly poetic failure mode, I couldn't come up with that if I tried!

Cheers! I looked around everywhere but couldn't find it, only an off-hand mention that the strength had been calculated or approximated. That's a big'un. If I recall correctly, most or all of the (scarce) electrical lines of the time were destroyed, junction boxes and such going up in smoke, telegraph equipment damaged with operators able to send messages without energising because the lines were already sufficiently energised by the induced current. Makes you wonder what would happen if we got hit by something like that now.

I think I've got whatever the opposite of that is called! I like my telescope, but it's a bulky and heavy Dob in the end, I increasingly find myself turning down a clear night because I just can't be bothered hauling it outside. I think I want a 100-120mm binoscope... ideally one with Matsumoto-EMS diagonals. Something that still has good light-gathering, but lighter and can be taken off the tripod for easier transport, maybe even carried around in a backpack. I wonder if Moonraker could make one? Being poor and instinctively frugal with expensive taste is a bad combo...

Re: anti-CA filters, I have some helpful material for comparison...

I personally still wouldn't trust it, even if it looks right... maybe I'm paranoid? But you just never know with eBay. You're technically not supposed to look through the film without a telescope, there is some minor residual UV/IR pass-through that the telescope's optics (be it reflective or refractive) and eyepiece glass absorb/scatter.

See if eBay will grant you a return or refund for the item not being as described. That definitely looks like counterfeit film. DON'T use it for anything. I wouldn't buy something as critical as solar film from a site as dodgy as eBay. Stick with FLO. Having a little extra isn't a bad problem.

Being able to fully illuminate the sensor is assumed; using a sensor too physically large for the telescope to illuminate it would obviously be a configuration error. I didn't think about it because it makes no sense to consider in this context. The question is not whether using the wrong gear together is better. Bivanus, I suspect the reason there's little talk about medium format cameras is because they are huge, extremely expensive, not astro-specialised, and the sensor size exceeds what's practical to fit using available hardware; full-frame sensors are already slightly too big for the standard T-2 thread and vignette slightly when used as such. Conversely, I would say that, if bigger were NOT better, modern medium-format cameras would not exist! And, evidently, the results of actually getting one hooked up to a telescope speak for themselves - the website you linked has many absolutely fantastic photos on it that were taken with a medium-format camera, so I wonder what point you were trying to make with it. It seems to me that bigger really IS better.

I almost forgot... No worries here - I haven't the stones to test it directly myself, but AstroSolar specifically is fairly tough stuff. Not identical, but similar, to Mylar - thus moderately puncture-resistant. Not "I stabbed it with a screwdriver and it didn't go through"-resistant, but more "I had to stab it with a screwdriver to puncture it"-resistant, i.e. unlikely to be damaged as long as you don't do anything stupid. No risk of shattering like glass if you drop it either To elaborate on the DIY, I found a blog post where a fella made some very sleek-looking solar filters in actual threaded filter cells just like the OEM units by cutting and sandwiching the film in-between the glass filter and the filter cell. https://www.dpreview.com/forums/thread/4194474 Note that he's mistaken about getting the film as smooth and flat as possible, it's supposed to have a loose "wavy" fit - Baader's recommendation, not just mine. I don't know if that could be achieved following this design but might be possible. I think he may have also made the mistake of removing the protective layers from the film before cutting... you're supposed to keep that on until you're ready to mount it in the cell.

Transmission = 10^(-OD) x 100 OD = -log (T / 100) Courtesy of Edmund Optics - https://www.edmundoptics.com/knowledge-center/application-notes/optics/understanding-neutral-density-filters/ So, spot-on, Paz Dwarflab says their filter is 1/1000000 which would be OD 8. I don't think I believe that's really necessary, though. I also don't think I believe it's actually OD 8, but that's unrelated. Baader indicates that their film is good to go on any and all "photographic camera- and tele-lenses", which of course your Dwarf II is just a miniature version of. So, I'll echo what Steve said - fashion your own from AstroSolar and if you must have an (inauthentic) yellow or orange tint, add it in post or, since you do have the 1.25" filter mounts, put some colour filters over the lenses, if you don't want to mess around in post. Not only will it work, it will most likely work better. That said, I did find one webstore with the OEM filters in stock. They are in America, but, for your consideration: https://astronomyhaven.com/products/dwarflab-nd-telescope-solar-filter-for-dwarf-ii

Steve, that's a very dubious and possibly disingenuous article (or, at least, article section) - Mr. Clark did not adjust ISO or focal length to compensate for the increased light sensitivity; you can actually see that the 6D image is over-exposed in his own example! The stars are blown out, and the nebulosity is brighter. Signal-to-noise is "extremely close to equal" because ISO is equal. Cropping is not a good way to take advantage of a larger sensor... you are literally throwing away the extra working area!

Can't say I'm aware of any, no... but what's to stop you from fashioning your own out of say AstroSolar film? This would probably be optically superior to the OEM filters actually. A yellow Sun means you ditch all the information in the other wavelengths... the Sun is a broad-band target. An aside, ND 1000000 is a very amusing if technically correct way of describing a solar filter! The usual way of grading extremely dark filters such as solar filters and laser goggles is OD, not ND. I guess Dwarflab likes the big numbers... there's a height joke in there somewhere.

Yes, bokeh and other depth-of-field effects are of no concern here - to a camera, the cosmos are flat

My knowledge on this one is somewhat surface-level but I will explain as best I can. Increasing sensor size, all else being equal, will also increase the field of view. So, you'll be imaging a larger patch of sky, and any subjects within that patch will look smaller, i.e. covering fewer pixels. But, you can get that back by increasing focal length, using a barlow (or a stronger barlow), etc. So you're back at the same field of view, but with a larger sensor. If that sensor is the same resolution, every pixel will be physically bigger and thus more sensitive to light, so you can get a brighter image or reduce ISO for the same brightness and thus reduce noise. Conversely, if the pixel size is unchanged, there will of course be more pixels in the larger sensor, so while it won't be any more sensitive to light, now any subject in the field will cover more pixels, which should in theory yield greater detail. And of course if it's somewhere in the middle you can get a combination of both benefits, to proportionately lesser degrees. I understand "better" is rather subjective in this case, but, as I see it, assuming you can achieve your desired FOV with both, without sacrificing optical quality, a larger sensor should make for a better picture by some metric, yes. That's no problem for non-astro applications which is why the best and most expensive "flagship" DSLRs/MILCs (Canon 5D, Sony Alpha-7, Nikon Z 5, etc) are usually full-frame. The main reasons to not go full-frame in photography are size, weight, and cost. You don't get better pictures for it. But, it can be challenging to get a narrow enough FOV in AP, especially if the scope doesn't have a very long focal length. Conversely, it can also be hard to get a wide enough FOV for large DSOs if your scope does have a long focal length... sensor size has some obvious parallels with eyepiece field stop size here. Hopefully not too wordy, I tried to explain as straight-forward-ly as I could

Does anyone remember off-hand what strength the Carrington Event flare was estimated at? I believe the one that knocked out Quebec's power in '89 was an X15.

Me too; that is a very impressive image! In fact, I think it's the best image I've seen of that nebula, period. Including the actual Hubble image. And from Bortle 9, no less. Very cool.