jetstream

The more observations and opinions on these objects the better. Some seem unique in their wants ie the filaments in the Eskimo disappear (my eyes) with a filter and yet these filters are supposed to be optically good. One of the very best views of the Eskimo was with the 15"/Docter UWA/VIP under superb transparency and seeing- a sight that will never be forgotten. I'm very interested in your reports with the 20" Mark.

I've had many many boots over the years- as a kid Sorels were king and are very good and have used the excellent ones @Ships and Stars mentioned. A lot of warm boots are bulky, but some are VG for walking such as hunting/hiking boots. I just use the Baffin Titan rubber boots for everything these days and are great on the ice or if having sled issues in the cat tails (slush, water). I do have a light set of cheap Walmart "Sorel" type knockoff boots rated for -30c and are no where near that rating. I had them on the other night observing and should have worn the other ones. They are really light though. Another VG resource will be @scarp15 an accomplished trekker. I've had hypothermia onset numerous times observing and normally the feet are not the contributing factor for me- its the hands,neck and head. A hat seems to aggravate eyepiece frosting, a real issue in the cold. One rule of thumb- good boots are not cheap.

I'm re visiting many objects with the larger dob and finding some nice surprises doing so. I like seeing faint objects but like viewing brighter ones with detail more. NGC 891 was really rewarding to see and the Swan nebula was incredible.

Sorels are good, I like Baffin better. There are huge differences in boots that can keep you warm when stationary vs walking IMHO. https://www.baffin.com/collections/winter/products/epicm005

Another quick report from the other night using the 24" dob under dark skies. M1 has always been a bit of ho hum object to observe for me, easy to see but detail lacking- until the other night. Flipping back and forth from no filter, UHC OIII revealed a startling difference- with the OIII. The UHC enhanced its "brightness" but no real structure seen. Going to the OIII I was shocked- a large "spike" of nebulosity appeared along with a shorter attached spur. There was also some intermittent finer detail in the body. I was far from optimized on this object- using 8.7mm EP- I think a hair lower mag will preserve the spikes and brighten it up so to speak. All I know is this is now a goto object for me and once the 17.3 Delos and Docter 12.5mm adapter issues are solved I think there's more to come. M1 is well worth spending time on IMHO and I cant wait to get on M97, the Owl nebula with this telescope.

Without the extender available I would not own this eyepiece personally as I too dislike floating eye relief. With it though it is superb.

maybe they just put it together with what they had laying around... maybe an H130 sec

well, maybe a nice 63mm sec?

Is this an imaging scope? sometimes they push the focus out using shorter tubes etc. OOUK does this on their VX's unfortunately. 10.5 inches is excessive IMHO. It should be 1/2 dia of tube + focuser height +.5" roughly

what is the actual measured distance from the centre of the sec to the focal plane? I ask because I've done these numbers many times same as you. One thing that the calcul;ator thankfully shows is the relationship between aperture, f ratio and central obstruction vs illumination. ie my 24" runs 19% CO at F4.1.

What is the measured distance to the focal plane? I guessed 180mm.

Here is a guestimate of your scope with the stock 58mm minor axis secondary Remember that illumination may drop to 70 % for visual use. Off-Axis Illum. Light Loss 0.00 mm 100.0% 0.00 mag 2.00 mm 100.0% 0.00 mag 4.00 mm 100.0% 0.00 mag 6.00 mm 100.0% 0.00 mag 8.00 mm 100.0% 0.00 mag 10.0 mm 100.0% 0.00 mag 12.0 mm 100.0% 0.00 mag 14.0 mm 99.58% 0.00 mag 16.0 mm 96.38% 0.03 mag 18.0 mm 91.96% 0.09 mag 20.0 mm 86.91% 0.15 mag 22.0 mm 81.50% 0.22 mag 24.0 mm 75.87% 0.29 mag 26.0 mm 70.12% 0.38 mag Max field for visual use with 68 deg eyepiece and 7mm exit pupil = 20.76 mm radius. offset = -2.43 mm parallel to focal plane

Magnus, the primary does need a bit of room to move, all my reflectors are like this- my truss dobs can move at least 1/8" laterally in any direction. Have you checked out secondary sizing vs illumination with Bartels excellent calculator? It gives insight with respect to central obstruction size vs illumination. http://www2.arnes.si/~gljsentvid10/diagonal.htm

A quick report on one of my favorite objects, the Eskimo nebula, NGC 2392. This object takes mag well and filters can enhance brightness, however the fine radial filaments tend to disappear when using them. Last night in the 24"/PCII/10Delos this exactly happened. With no filter those fantastic filaments in green appeared as well as a new to me feature- a bright green,not quite round inner ring was observed around the central star. It also had a couple of shades of green now. I need to get the 8mm Delos for more mag, 287x was just not quite enough. A great view but there is more there. The UHC/OIII killed the filaments and inner ring oddly, not sure why. This object is a showpiece, gift of the sky IMHO and well worth spending time on. Many scopes do a really great job showing it, try upping the mag and with no filter. NGC 891 showed as a bright edge on galaxy with a massive dust lane cut through it, again at 287x @ 2mm exit pupil, but I like more eye illumination, next time I'll try lower mag on it, maybe a 15mm effective fl eyepiece. So much to see out there.

Yes, UHC it is! for the Flaming star anyway- I flipped back and forth on it with the filter slide- the OIII killed it for me. You can also make it out no filter. I take filter recommendation with a grain of salt these days- I try them all ie IC1318, listed as hb I think but both the OIII/UHC are go tos. The Hb is top for Barnards Loop though, to my eyes, California neb too. For me the list of Hb targets is small. I dislike the Cocoon neb lol! not really a showcase object IMHO. If you can find a good DGM NPB filter, ours is, they can be a great lower cost option. They might show stars a bit differently but the Flaming Star/HH etc are no problem in it. Cold is cold! Last night just had the long johns on over jeans but no gloves... my bad. Those Al ladders will suck the life right out of bare hands. I hope your family member is OK and you can get out to obs. BTW your scope has potentially the best mirror support for cold weather IMHO.

What can be said is the excellent Televue plossls have great scatter control vs the other mentioned eyepieces. The TV plossls are my goto's for certain objects like Horse Head last night in the 24", both the 32mm TV and 25mm TV plossls are excellent for this and much more. Under the best of conditions here these eyepieces will pick out the HH with no filter. I'm glad you are now happy with these eyepieces Alan.

Excellent! Great report and also images S&S! Perfect description of the HH and other targets. You are now ready for a nice little challenge seeing as you were in the M52 area... the Bubble is not hard to see, but harder to get detail out of. This however is not the challenge. In your 20" SH2-157-the Lobster Claw will be readily visible as well as a nice LBN. This is the challenge. The Wizard also has more to offer- congrats for getting it straight away! You hit a couple of favorites- the beautiful Flaming Star- are you sure an OIII is your friend here? Again congrats for a fine cold weather session, I was out myself last night observing the HH etc with temps dipping below -15c. Some of the best conditions are in this weather, particularly if there is little or no snow. Eagerly waiting reports S&S!

Interesting discussion. I have never had a mirror in a truss dob go below ambient outside. My seacan, painted white is a very good stable environment for my scopes. I have extensively measured the internals temps with a Fluke IR gun and found that the top third gets colder than the bottom 2/3 when air temps are dropping. The flat grey interior is radiating heat out through the top.Unless very extreme temp changes the mirror is within 3c-4c warmer of the air temp. I had one night that the mirror was 8degc cooler than outside and bam., instant fogging. The temp spread overnight to the next afternoon was +10c down to -12c, with the fogging temp of -2c. My mirror was -10c at the time. I can see how it is possible for an aluminum tube dob to cause the mirror to go below ambient, from the temp gradient between the top of the tube and bottom. I have not however had a primary mirror in an Al tube dob fog up outside. Certain conditions and it could happen IMHO. The biggest problem is bringing the scope back inside after cold weather use, I don't do this anymore but when I did the scope was in an insulated case.

its all good

I find this too- the Delos are back and are top except for one small issue (for me). The 32mm TV plossl is an excellent eyepiece and I run a pair of them in the binoviewrs, both with eyeguard extenders.

What scope is it? How long is that gap and how many threads left on the center bolt? One more question- is the spider properly located?

This is the main issue IMHO, my 90mm scope shows it nicely, M33 that is. BTW M33 can be kind of hard IMHO.

Dark site trip?

Fantastic Mike! Eagerly waiting reports. The Sky Commander is "old school" I think but it is accurate and meets my needs. How accurate is the Nexus system Mike? Sorry to all for going off topic in my own thread

I'm using the Sky Commander but I hear Nexus might be better in some regards. I bought this one as it was recommended to me and the controller has heaters built in it so it works in the cold. Downside is the cables, but Astrosystems is going to make me some flexible silicon sheathed ones. Nexus uses the phone Mike? wireless? The Sky Commander is accurate to 1/10 deg and I can re find objects easily when using .3 deg TFOV using orthos. There are tricks to get this accuracy though. Are you running Nexus on your current scope?