Rusted

More of a heads up than an image to write home about: I have been fighting a solid overcast for hours.

The Moon does not seem to mind filters as long as they don't slow frame rate exorbitantly. I use my 6" f/10 H-a solar scope for lunar imaging when the Moon is cooperative. Leaving the D-ERF, UV and IR filters in place seems not to spoil the results when using a mono camera. The one no-no is the Baader Solar Continuum, a popular, green, lunar filter. When used with red filters it turns all the lights out. It had me completely baffled for a couple of minutes.

If that was your first go at lunar imaging then you put my poor efforts to shame. Your first image has amazing scale! I like close-ups.

I should have added that my "messing about" with your image should not remotely be seen as criticism of your skills. Your images are excellent, are very natural, well exposed and have a lot of detail.

A more gentle approach avoiding burning out the highlights: Reduced contrast and then some darkening with Histogram in PhotoFiltre. [Free]

I can't be certain but I think I'm seeing more surface detail in Plato. This is very much a matter of taste and some will argue I have overcooked your image. I just darkened your image and applied a touch of contrast. Central crater and some streaking?

Beautifully processed. I was advised [here] to reduce my video frames to 500 and stack only 75. I found it very useful advice. Experimentation with frame numbers and stacking may find you a happy medium. The theory is that large frame numbers and stacking lots of them merely adds to the overall noise. You are processing a lot of average images rather than working on only the best. Besides the arguments above, it greatly reduces the need for huge file storage. SSDs aren't cheap. You can capture a lot of short videos in a much shorter time frame. Which reduces tracking issues, cloud intervention, vibration, subject and wind movement. You also get to choose between multiple videos for processing. Which should automatically help to increase your success rate. I like to think that multiple short captures provides far more practice than far fewer long ones.

I have been setting up for imaging in the dome, scanning the disk and limb on the monitor and then just walking away. There was nothing interesting to be seen yesterday. A couple of small filaments and a few tiny proms. I captured this on the SE quadrant to check etalon and focus adjustment after my latest changes: Just the usual thermal shaking and light "simmering" to spoil the show.

Wait until you see two objects together moving in unison. You'll swear there is intelligent life on Earth.

It would be handy if somebody could report on the effectiveness of the interlocking sponge flooring. Can one isolate the movements of those present using this material over floorboards or plywood? It would certainly solve all sorts of potentially costly problems. I have no experience of this matting, myself, so simply offer the idea for discussion. Going back to the supporting structure: Deeper joists will really stiffen up the observatory floor compared with standard joist depths. For the cost of a couple of extra inches/cm depth you gain enormously. Your architect/structural engineer will confirm. Width of joist has relatively little effect.

Thanks.

Darken a close-up, H-a image enough and it turns into dark petals. Being darker at the limb makes it look as if it curving away like the flower of the same name.

Limb darkening is more of a white light thing. Though it certainly exists in H-a and possibly Ca. It's most noticeable when teasing detail out of a poor image. It darkens the edge first as you move the sliders in ImPPG. The limb easily vanishes completely during clumsy processing. Sometimes ending with the "Dahlia effect."

Never mind the quality.. feel the width?

The seeing was awful. The wind was gusting. The cloud teased endlessly. Well, that's my excuse for these dreadful "snaps!"

Excellent images!

I suppose it makes sense to work on a small surface first rather than a very large one. No doubt there is far more information online now. Than there ever was in the local reference library of 50+ years ago. Do I vaguely remember mention of figuring the Cass convex secondary in ATM Vols 1-3? Ring star, pitch polishing tools seem to pop into my false memory module noddle. That was after first achieving a nice convex sphere of course. They'd use a concave spherical test plate [perfectly matching glass surface] to monitor progress. Such a small surface really demands a simple polishing machine. The strokes are so short it would feel like you were polishing a spectacle lens. Have a look for YT videos on optical fabrication in these small sizes for more ideas.

I had to look that one up. We still have a few, ancient individuals fighting a losing battle against time while nursing old wounds.

I'm 100% with Peter on this one. The weights don't have to be exactly opposite the focuser + finder in the radial sense. "Underneath" the lower tube would be 95% while still almost compensating for radial imbalance as well. Moment = Mass x Distance. So the lower they are placed, the lighter the weights can be. Less to carry about. No reason for them to hit the uprights if placed correctly. I wouldn't want a reflector with a nose heavy balance! Forget to add the weights when you are tired and preoccupied and in the dark and you may well regret it! I've seen primary mirrors miss inadequate restraining clips Then roll edge over edge right down the tube at high speed and straight into the secondary! Having a heavy camera doing a nose dive as well could be an expensive mistake.

"I'm a tree!"

You captured a big one too! Gong-Ha is going to have to smarten up its act: They need a new label for their solar disks: "Here be dragons!"

Thanks. I don't think you will get away with anything cantilevered from the house structure. Anti-vibration damping is not easily achieved and you could be building a springboard! Overall sponge packing under a pier will just flatten to solid material under load. Tried it! Don't bother. I have even tried car valve springs under concrete slabs. If they don't flatten under the load the pier will have its own, very undamped, low frequency resonance!! I have concrete blocks buried in deep gravel supporting my 5 meter tall, isolated, pyramidal pier. These have adjustable height brackets which are bolted to the 100x100mm sloping pier timbers. An unlikely and very bulky design for most situations but it suited me fine as a lone observer/imager. I climb up inside my pier via a stepladder from the ground floor and a trapdoor. Not recommended for anyone else! Too dangerous to have a hole in the floor! What is immediately below your intended observatory site? An occupied domestic room? Can you tolerate a free standing, block "chimney" in the middle of that room? Very unlikely. If there is a structural wall below the middle the observatory you could build a pier off that. A hole in a ceiling would never get past building regs in an occupied room. A garage below would be seen as a serious fire risk! A further difficulty is your SCT will need a very tall pier for comfortable viewing. Much more seriously though: The interlocking "jigsaw puzzle" sponge floors are popular for observatories. Double the thickness with non-coinciding joints? You now have fair, footfall isolation. It would feel weird to walk on but you might get away with it. Your pier would be mounted on a large and heavy steel plate. With four conical spikes in the corners to isolate right down through the carpeting. Hifi speaker style. You could lay sponge industrial grade carpet underlay on top of your "jigsaw" sponge floor. Add a nice pile carpet? This is easily tested out for isolation before you build anything at all.

As the builder of a second storey 3m/10' dome I agree with Peter & others here. Domes are never big enough and you have no corners to place the inevitable fidgets. You can't insist on people remaining still. Particularly children waiting for a view. People move about. Any movement is catastrophic to image stability. Even the wind will be conducted through the structure. Any pier resting on a raised floor will shake the image violently. Guaranteed! You need a solid, isolated pier built off solid ground and clear of the obs. floor. Pre-cast chimney blocks are good being solid, strong and compact. My solution was a massive pyramidal pier built on widely spaced concrete footings. All it takes to short circuit the floor isolation is a trapped cable between the pier and desk. In all other respects the timber and plywood pier has been a "huge" success. If you really want to impress then buy an astro camera and good quality, 27" or larger monitor. Place it where everybody can see it easily. Seeing a razor sharp Moon or the Sun, the equivalent of three feet across, is mind blowing. Far more fun than staring at dim things. Which an educated eye cannot eve see in the few seconds in impatient queues. Unless your house is white don't choose a white observatory dome. It will stand out like a sore thumb from miles away. Pulsar do a mid, sage green. Not the earlier dark grass green. A green dome will vanish against a green or dark building backdrop. It will look more like a round bush or conifer which the eye will pass over without pause.

The seeing may have gone off but the 150/1500 produced very inferior surface detail with the Lunt prism compared to the 90mm. The first image is with no D-ERF. The second image is with the D-ERF in place.

Thanks Freddie. I can just as easily use the 150mm 6" f/10 iStar. I'll give that a go. Just a matter of exchanging the PST etalon + filter stack for empty extension tubes. I have used the iStar for lunar without removing the D-ERF and protective UV/IR filters.