Lacerta solar wedge (2"/M54) for white light observing

[Gemineyes]

OH! BTW gang - I'll post revised photos of my fully complete moded wedge once that extension tube arrives. 

[Gemineyes]

I should have my TS Optics 15mm extension tube July 22. Crossing fingers! 

Meanwhile, I decided to take out my ST120 (don't laugh!) f/5 Achromat for a jaunt today (July 21) on Sol. Temps here in Edmonton were in the mid 30s C and a bit of smoke haze from N. Canadian forest fires have been plaguing us a bit lately.  Today was pretty good - best day in the past 3-4 for sure. 

I did have some fun mid-morning, around 10:00 local (16:00UT), but the REAL fun came later in the day- the skies cleared a bit more, we had a nice light breeze, and WOW... I am still processing what I saw - esp. mid-disk: I have included a few shots of the setup today, again with TR3 and AZ5 head. What a fun combination for getting setup and observing - I live in a condo, so that is a nice way to go! 😎

Now - I KNOW this is NO Apo. But I have to say that my sample of this scope is very, VERY sharp optically. Maybe I got lucky with my sample (?)... Only major mod on the ST120 is to changeout the focuser from stock to a 2-speed TS Optics Monorail. It is a good focuser for this scope, but a tiny bit finicky on heavier loads, like the Lac-2s, but I can achieve perfect focus on any object, and use an APM 2" prism diagonal and some custom MV filtering for lunar/planetary and it does a dandy job, when I am not using one of my Apos. Also, ultrafine details on the sun with it seem routinely visible with no worries. It is not a fancy scope, but I think it is very nifty one when executed carefully with additions, and an incredibly fun scope to play with sometimes! 

Well, today was one of those days! As most folks know a non-Apo scope is a bit more susceptible to seeing conditions, and afternoon had arc second level stability. My setup was the ST120 f/5, with Lac-2s, and internally I had the ND3.0 (Baader), a Baader SA (semi-Apo) filter, stacked, and used my TS UWAN 13mm (46.1X) with a Celestron Linear 1.25" Polarizer, one of the Vixen types from pre-2000, which were made in Japan. To fit the UWAN barrel and polarizer on it, I had a 10mm extension tube to allow clearance in the 1.25" Click lock adapter (inside my 2" Click lock on the wedge), so I could rotate the EP for brightness and contrast tuning. 

I have included some Helioviewer images during the time I did my observations; from 23:00 to 00:20 UT was my observing time - had to cool off before inner here, and that heat was pretty demanding, and took lots of "shady breaks" as well... Nonetheless, it was worth every second at the EP! 

Referring to the images below, in the ST120 at 46X, once optimized for contrast (not at all difficult in the Lac-2s!), I was seeing (refer to full disk view first) VERY close to this level of detail in the EP. I am not embellishing! The views were THAT good. Only difference between the Helioviewer photo and my optical system during the best seeing was a very pale straw-yellow tint to the disk, with a very thin sliver of blue on the limb when not centered on that portion. It disappears if one centers their eye over the limb - gone. Some field curvature (expected) is present due to the short f-ratio, but it is easy to compensate for once you get used to it. Using any of my binocular telescopes or refractors with the Baader wedge in the past, I have used a technique I call "holding focus"; this is just that - sort of locking your eye focus deliberately while panning about a region. What it resembles is sort of a screen magnifier effect in a way - though not by adding bigger size to the view, but what I can only describe as an ultrafine "window" which moves with one's eye. It is hard to explain ideally and I hope some of our more seasoned observers know what I mean - it is a way to concentrate very fine details as you pan about. With most general targets, like the moon, and planets it is not as big a deal, as your eye grabs a detail by autofocusing again when going to another area of the object. But in solar continuum observing, some of the details are very subtle contrast and brightness variants, which to the less experienced, may go unnoticed in general. I hope that I do not sound like a wing-nut here! 😵‍💫 50+ years at the eyepiece has allowed me to develop, practice and verify this over the years. I am fortunate to have very good visual acuity still, being just shy of 60! 

Anyway I digress, sorry...

Other regions throughout the disk had deep plage well into the disk - especially the eastern edge to the western edge through the lone group in the northern portion of the solar disk - it was VERY visible as an almost "Valles Marineris" type feature, with tendrils of plage and snaking directions as seen in the HMI SOD shot from helioviewer. It was hard to not see it this afternoon, to be honest. Lots of micropores popping up, and visible, many seen in the HV photos below. I estimate at least 1 arsec seeing this afternoon at my location, and estimate even at 46X, I was in the 1.5" regime for sure. 

The main two really nice treats were the big group in the central southern portion with the "Aleutian island" appearance - wow - so many spots!! I lost count several times. The other more interesting one for me was the lone central spot group, which I have zoomed in on for reference. Just off the bigger spot was a squared "horseshoe" feature that actually grew, darkened, and then changed shape slightly with extensions to it toward the upper portion of the big spot. It changed from 23:38-23:52UT - I could see changes over minutes - during 1 minute runs at the EP, followed by 1-2 minute breaks to absorb the detail in my eye-brain system, shading and micropores came and went, in real time. I have seen this before many times on other features, but this was a bit different: I THINK that the feature was a transition between hot solar photospheric plasma and cooler material, and I have included the 1700A channel off the SDO at the same time showing this where the edge was. It may have been a photospheric mini-flare, I am checking into this. Not sure. 

I added the scales as they offer interesting insight to detail size. Today during my session, Sol was 1888(.32)" across, and using its diameter, I calculate 737.3km/arcsec. So even if I'm at ~1.5" range most of the time today, that's ~1100km features (at 46x no less!) detectable on the sun. Holy Smokes. The scale can be divided by 40 for 1100km size range, or 20 for the more zoomed in one showing 22000km. That is why I included them. 😉

The long and short of it is that this was a VERY fun session... I was very tempted to up the magnification (probably should have!), but my experience when seeing this level of fine detail has taught me to not fix something not broken. Seeing on occasion for 10-30s at times went a bit turbulent, but only a bit - maybe a slight undulation of the limb edge once in a while. 

I think this Lac-2s can definitely hold its own against pretty much any good wedge - I am seeing just a bit deeper contrast in it I think, than the Baader. As mentioned before it is close. I think part of the benefit of having unipolarized views during smoke aerosol haze helped me DIG into the image a but more effectively, providing consistent details. I was tempted to change out the wedges, but man, I just could not tear myself away long enough to do that, especially in the heat! 

Oh! one final thing: even with the +35C temperatures, the backside of the heat baffle/radiator plate was maybe (?) a warm cup of coffee. I could easily hold my back side of my hand to it with no issues. Excellent heat control, IMO. 

Clear Skies, thanks for reading, and I hope that you all have excellent solar views! 

Darren

 

 

 

 

[Gemineyes]

Okay! Process for fixing the ND3.0 filter in the wedge to begin! 

TS Optics M54 15mm extension ring arrived - the last one they had until mid-August - phew! 

Only issue with mine is it is UNcoated at the nose inside end. Likely due to a mistake or that they feel a focal reducer will be used there, so no issue. It likely is minor, but I just do not want any glints, or residual likely reflections at all when using this. I am a bit of a perfectionist at times and pretty picky when it comes to this sort of thing, so before mounting the filter in it, I will mask it off and hit the bare metal insides of the nose piece of this ring with BBQ matte paint. That will avoid ANY issues, and will be able to handle the heat internally without issue. The paint is rated to 550-600C, plenty for the scopes I am using. 😎

Two light paint coat hits, and then overnight dry/curing, then installing. I'll grab some shots of the task as I do it when the paint and masking arrives tomorrow. Also will (may as well!) touch up the prism topside with IPA and a Sensor cleaning swab. Then its mint and ready to go! 

I will shoot before and after shots of the job for those wanting it as an idea or reference, if okay with everyone here... 😊

Darren 

Edited Wednesday at 17:21 by Gemineyes

[Gemineyes]

Ring is DONE! I will let it finish curing overnight, and then assemble the ND3 onto the wedge! 

The TREMCLAD high temperature BBQ Flat paint worked very well. I masked the tube where no paint was to go, and gave it one light hit, waited 10-15mins, and a second main coat. Left for 1h then removed mask to leave overnight. Came out very well:

Darren

[Rusted]

I just hope the HT paint doesn't off-gas over time and do any damage. Give the ring plenty of air and warmth before sealing it in anywhere.

I have painted lots of DIY refractor baffles and components with water based, matt black, non-toxic, childproof, blackboard paint.

[Gemineyes]

Yes I did actually - Well, only 1 day. I posted today, but took these yesterday. I checked (left it in my garage at 33C overnight - total 30h actually) and no solvent smell at all. I am a chemist by trade/education and this paint is a quick dry type, but is not immune to solvent migration, so the extra time for curing is a good idea. However, the solvent is highly volatile petroleum based in this case. I chose it only since this is on the wedge EP side and I wanted extra temperature handling in case I ever use it on a larger scope - I am going on an astrofest with a few friends in two weeks, and one of them has a 10" scope. So if we use this on it, definitely want to use the better paint and I have a NIR block just in case. 

BTW great comments - I have used water-based acrylics to do general flat black recoating or repairs in the past so totally get your comment on that end. those DO take a bit more time to cure, due to water and the carrier co-solvent coming off. That IS an issue if not careful, as I remember many years ago getting a foggy film on one of my dielectrics after touching up something internally w/water-acrylics and not allowing it to air out enough. You get that "acryl smell" for a time before curing is complete on those. I was able to remove the residual film off the diagonal, but had I waited about 1-2 more days with that acrylic paint, I'd have been better off! 😵‍💫

So...UPDATE:

I am happy to report the job is done! The 4mm M54-M48 ring fit the Baader OD3.0 on the front end and fit into the (now) re-blackened front of the tube. The depth was maybe... 0.1mm beyond the tube (?) Almost flush. Putting it into the wedge, fit like a glove with ~0.4mm of body thread to spare before being fully through the body of the wedge. Perfect fit! 

With the Baader M54a Q-L on it, I get 35mm+10mm = 45mm internal clearance (to the ring, which acts as an internal stop) and an extra 4mm for 49-50mm depth to the filter rear surface. If I use my 1.25"-2" Q-L on top that gives an extra 9mm. Basically, the new tube is 1.5mm shorter (actually 1mm after measuring) than the ZWO 16.5mm tube, but now, where a stop would be in the ZWO tube (actually a bit lower than that stop by ~1mm now), I have the OD3.0 in the diagonal below it. 

So, the wedge will now be able to be used with the OD3.0 for visual installed. No extra checks on the OD3.0 in the filter chain. It basically is like stock, but with better EP mount fittings on it now. I just never liked the screw mounts and rotator assembly that came on it. Would leave my EPs hanging off of it. This just works and looks better, IMO. 

This gives me a lot of extra room, for longer 1.25" EPs, several of my 2" zooms; I may also use my custom made (did it up in 2015 made it from a 37mm unmounted into a 48mm adapter cell) my He-D line 8nm filter w/90%T as well. That one is around 7mm deep, and with the polarizer on front, will allow me to use it also, just as I can when wishing to in the Baader Herschel Wedge. Shows plage and some details like a Ca-filter but it is yellow, obviously. Will be interesting to play later with that! 

Thanks for reading and following. CS and good sun-gazing!

Darren

 

Edited Thursday at 05:44 by Gemineyes

[Gemineyes]

And a final note before gazing again (windy/rainy the past few days since coating the tube, so all good to get those things finished. 

I decided before final use I'd retouch the prism and clean it. In situ, and I used special high grade lab lens paper I have to do so, both sides. I started with Zeiss lens wipes, on the lower section - EEW - may have been smoke residue from the recent fires in the area, not sure. But after two Zeiss wipe runs and then IPA (Isopropyl alcohol, 99%) on lens paper the base portion of the wedge plate came very clean.

Then, same on both sides for the top business side of the prism; two (one for each side) left a significant residue, likely old from storage. Two careful hits with the lens paper with IPA, and clean as a whistle! So, now we are ready for the next sun day! Likely late tomorrow afternoon or Sunday - we have had T-storms coming through and lowering regional hazy smoke from the Jasper fires 400km away. Looking forward to running the final new/improved visual Brewster Wedge! 

 

Darren