FYI Here's Jupiter + 4 m00ns
Another example of knowing how to calculate exposure for Io, Ganymede, Europa & Callisto in relation to each other & Jupiter from magnitude could be helpful as starting point in getting each exposed optimally?

I am prepping to return to Ft.Collins, Colorado & cutting back on Asto time, but have a few ?s.
Your big dipper foto w/Tamron 24mm/1.4 clearly registered Alcor @ magnitude,~ 4. Shot wide open? Time & ISO available?? I am thinking that's only 3 stops to f4 or 1 stop to some of my Oly-Zuiko lenses. Another project for me is making navigation star maps w/ ther constellation's limited to +4 magnitude for that grandson to learn the nite sky. HARey's book was what I used w/ my 3 sons, but we marked it up too much to be useful.
Lonely Spec put to rest my project to panorama Milky Way w/ C-5 as it took 58k+ frames & I doubt I have that many years left to shoot & process them, tho that grandson will inherit the C-5 & Who knows ? Like @2yo he flushed a potato that was pure Yukon gold for the plumber
Attached are 2 fotos of Jupiter/ Saturn 21Dec21 conjunction taken on old Linhof ball mount screwed to table. Exif data N/A but taken @ 600mm (A6300 = 900mm) f6.3 Sony 200-600 telly. Surprised me 4 moons of Jupiter registered + w/a gob of imagination also Saturn. Used GIMP 10.2 to crop & scale for post to FaceBk. Sadly only FaceBk screenshot is image available now. The Saturn solo foto shows horrible CA of the Sony lens, but it does show it is possible to capture a single shot image using A6300 auto focus (✓'d w/ peaking) & auto exposure w/ bracketing! I use this to gather Exposure vs Moon magnitude data to eventually develop a Multiple Regression equation if no one can solve that w/ algebra!
Thanks for your patience readung this far, but if you prefer I can limit future queries to haiku's 5-7-5/three lline format?
Ernie
Ooops I cant find Jupiter+ 4 moons screen shot. Try, try again later.

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I just typed a rather long reply buTT Nature called & when I returned had lost the page looking for Jup/Sat foto AND now can't get back to original msg.
Is ther a way to save an incolete msg on UHH & return to it later? Or need I type all in Libre Word Processor to Cut&Paste?? TIA

THANK YOU, Jim for a detailed & informative reply.
AND for the link to Ian Norman's website. It is a treasure trove. His article on Star Trail Calculator is worth a donation. I love that he took the time to detail its working replete w/ the math so now I can build my own spread sheet for this Fon. I plan to ask him to help w/ my Star Magnitude/Exposure dilemma.
I am putting off the Tamron vs Sony wide zoom til after return to Colorado. I have discovered from my days as a film fotografer several Olympus Zuiko lenses (16mm rectilinear 3.5, 24mm 2.8, 40mm 2, as well as 35mm 2 Nikkor & 60mm 2.8 macro Nikkor) which once I complete great great grandson's animation may along w/ Lonely Speck tutorials to try Milky Way & Orion shoots.
Again thank you so much. My summer nites are going to be full of new experiences. I may even clean the mirror of my C-5 Schmidt Cassegrain. I wonder if I can do a panorama using its FOV in arc-minutes to take a series of overlapping shots a stitch them togethr? WhaddaYaThink??
Ernie (notBert), my 3 sons loved Sesame St!

THANK YOU, Jim for a detailed & informative reply.
AND for the link to Ian Norman's website. It is a treasure trove. His article on Star Trail Calculator is worth my donating. I love that he took the time to detail its working replete w/ the math so now I can build my own spread sheet for this Fon. I plan to ask him to help w/ my Star Magnitude/Exposure dilemma.
I am putting off the Tamron vs Sony wide zoom til after return to Colorado.

Thanx, once more. I am in the midst of my semiannual commute to Colorado and will not decide until I return, meanwhile here in Florida I just bought a Sony 70-350 f 4.5-6.3 for moon, bird & moose, etc fotos. I am trying to put together one of those flip animation cartoon like mini-books for my great great grandson who was fascinated by clips I seńt of full moon and waning, but it is slow going as clouds, etc do not make for shoots every day of the ~ 28 day cycle. Also, after New moon after sunseet when its magnitude goes from -4.8 on 1 May to -9.3 on the 6th is most challenging. I know about the looney f/11 rule, which works around full moon nites, tho my A6300 spot reading works @ -2stops compensation to tame hilites w/ bracketing usuallly 5 exposures @ ½stop intervals. Crescents are not that easy being spot is too large. I once asked this group if anyone knew how to calculate shutter speed (say @ f stop @8 at ISO 800)to no avail. There is an app Photographer's Companion which suggests exposurs,, but my French is nil and not sure where to send question how calculated. Do you have any better ideas? TIA

Thanx bwa. I am still leaning towards the Sony f4 w/ OSS for other than astro-pics which are on tripod or EQ mount. Good to hear that f/ 3.5to4.5 is adequate for exposure. Is that for a single shot or long exposure w/tracking? Obviously I am a novice @ this!

I prefer using zoom lenses and I am trying to decide between a Sony 10-18mm f4 & Tamron 11-20mm f2.8 for occasional Milky Way fotos which include foregrounds. At 88 yo I appreciate Sony's OSS on my 200-600mm telefoto lens for birding. So I think Sony's 16-20 is worth the 1 stop decrease as the Tamron is w/o OSS as is my Sony A6300 camera. Either lens will be used mostly for landscapes, etc.
But I am curious as to which is better for astro-fotos? TIA

Fantastic crater details. I am confused tho by :
"Sony A7R4, 100-400 5.6 at 400mm, ISO 100."
1.No shutter speed?
2.What is the "100-400" bracketing at ISOs 100,200,400 ?
Plz more info. TIA

Not sure this was sent to you on 1st try?
Yes more owl RA. TIA
Here's foto of Eastern screech owl yawning!

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Yes plz, thanx.
Attached is an Eastern screech owl yawning

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Answer is too simple DUH. SEARCH 'Rock Art Nine Mile Canyon'" Thanx. Looks like Horned owl? Any other owls? Read further "Yes there are" even a multicolored one. Have you posted it?

Got 'em. Toosimple DUH, "SEARCH 'Rock Art Nine Mile Canyon'" Thanx. Looks like Horned owl? Any other owls?

I would like to see more. Have you posted earlier fotos? Plz post links as I cannot figure out how to aee them. TIA

In 1997 I bought a Celestron C-5 Schmidt-Cassegrain telescope. Recently I noticed the corrector lens has some internal “fog” ( see foto) and have contacted Celestron for instructions to demount the corrector as I have followed the instructions in the original Owner’s Manual p.25, but after removing the retainer ring, etc. the corrector seems to be cemented to two narrow flanges in the tube (see foto).
Tech support at Celestron replied to my Help request:
“Good morning,
Thank you for contacting Celestron Technical Support.
The corrector is not cemented in, it is merely stuck with age. It has been in place for 45 [sic] years!
It may be necessary to gently pry on the edge of the corrector with a thin blade to pop it loose.
Good luck!
Celestron Technical Support”

My reply was I had tried prying most gently, as the corrector is thin, to no avail. And I would appreciate a technique that did not involve “good luck”
My questions are:
1. Have any Celestron, or other, owners run into a similar problem trying to remove the corrector lens?
2. Did gently prying “pop it loose”?
3. I also tried seeping isopropyl alcohol around the edge of the collector but capillary action did not draw it in?
4. Any suggestion appreciated. TIA