John

14 minutes ago, John said:

Thin cloud masks deep sky objects rather effectively as does a bight moon. I have these issues here tonight as well. Unless it clears I'm going to stick to the moon and binary stars. Galaxies and nebulae, if visible at all, will be far from their best.

On a dark, transparent night, a 100mm aperture can show Messier 42 very nicely.

 

I've just had a look at M42 with my 120mm refractor. I can see a little nebulosity around the Trapezium stars and the contrast of that gets stronger with more magnification but the extended "wings" of nebulosity are really not showing tonight. The thin cloud seems to have eased but the moon is not far away from Orion (Taurus tonight) so that is drowning out the fainter parts of the nebula.

In compensation, the seeing seems really steady tonight with E & F Trapezium showing well in the 120mm at around 130x.

Thin cloud masks deep sky objects rather effectively as does a bight moon. I have these issues here tonight as well. Unless it clears I'm going to stick to the moon and binary stars. Galaxies and nebulae, if visible at all, will be far from their best.

On a dark, transparent night, a 100mm aperture can show Messier 42 very nicely.

120mm refractor out tonight. Moon looks very nice again though thin high cloud is scrubbing a little off the ultimate sharpness I feel. Unless that clears later it won't be much of a deep sky night here. Binary stars should be OK though.

The Hadley Rille looked sharp earlier at 257x and 300x. Catena Davy showed slightly more craters than the 100mm managed last night. Such an interesting feature 

With a refractor the Pup star is to the East of Sirius A so that it trails in an undriven field of view. This was the view with my 120mm refractor when I spotted it last year:

I agree. I've never had any dew issues with my 130mm F/9.2 even when the exterior of the tube has been running with moisture the objective has remained completely clear.

3 hours ago, Voyager 3 said:

Were you able to split the tougher AB pair John ? This pair is riiiiight at the Dawes limit for a 4" scope but is relatively bright with only a little ∆mag . Perfect choice for your 4" refractor . 

During the moments of best seeing, I did see a split at 257x.

Just finished a good session with Zeta Cancri / Tegmine. A challenging but rewarding triple star with a 100mm aperture.

The seeing seems to have become highly variable though - fine for a few seconds then all blurry then fine again. Don't know whats going on up there

We had a cottage in Hexworthy last summer. Darkest skies that I've seen for a long time in that valley. No mobile signal or wi fi though. But VERY dark skies

E & F Trap, the Pup, Rimae Birt, The Hell H crater chain and Catena Davy, a couple of comets and assorted other gems. All with my 100mm refractor.

Interesting that the 63mm F/13.5 should show noticeable false colour. According to that chart that we post quite a bit an achromat of that spec should be practically colour free 

It's probably very nicely figured and polished though.

5 minutes ago, Nigella Bryant said:

Yeah, mine still had the original sticker on the side of the mirror stating ref number, year of manufacture, 2006 and 1/6PV . Forgot nearly 16 yrs now, lol. I bought mine second hand, changed the focuser with a moonlite, added a rear 12v fan, secondary heater, new losmandy plates top and bottom and internal temperature gauge. 

That's looking great

My OO 12 inch F/5.3 is a 2006 vintage as well.

Sub-$150 eyepieces can be very high performers (eg: Baader 10mm and 18mm classic orthos) although the mediocre seeing conditions and sky transparency will certainly blunt their edge.

A few years ago I was comparing one of the very best planetary eyepieces around, a 5mm TMB Supermonocentric with a University Optics HD 5mm orthoscopic over a few weeks and found that the only differences that I could see in the planetary (Jupiter and Saturn) views were very subtle and only visible on the nights of best seeing, which here are perhaps 10% of the time, maybe ?

At that time the TMB Supermonocentric retailed for around 4x as much as the UO ortho did.

I have an Astronomik UHC (2 inch) and I'm quite happy with it. I use an O-III when I want a more substantial impact though. I've tried some less expensive UHC filters that have been very modest in their performance - the Astronomik is a noticeable step above these.

Of course you need to pick a receptive target and use an appropriate exit pupil to get the best out of these narrowband and line filters.

My skies are around Bortle 5.

There are other letters available

I could just about see the Owl Nebula and M108 with my 120mm refractor last night without a filter. They were both in the same 1.8 degree field of view, on either side of it.

The challenge is that using a filter such as a UHC or O-III, while doing wonders for the visibility of the Owl Neb, causes the galaxy to become virtually impossible to spot.

I've owned a couple of Baader Neodymium filters over the years but didn't keep them for long because they didn't seem to do much, at least to my eye

When I use a filter to observe a nebula (I prefer not to mostly) I want it to make a really noticeable difference and for that I've found the good quality O-III and UHC tick that box for me.

I had a Nirvana 4mm for a while and found that to be a pretty good high power / wide field eyepiece.

Nice comparison @Stu.

Interesting regarding the Panoptic vs Morpheus views as well.

Comet Atlas does look quite nice at the moment, even in smaller apertures. Well worth a look and nice and high in the sky too.

That is a lovely shot - nicely done !

Some of the early TAL's had an eyepiece size that was neither 1.25 inch or .965 inch. It was a little smaller than 1.25 inch I seem to recall.

If yours is one of those then it could be tricky to find eyepieces that will fit.

Good stability as well tonight. Got some regular glimpses of the Pup star with the 120 a short while ago.

As well as Comet Atlas I found comet 67P/Churyumov–Gerasimenko again in Cancer. A little fainter than Atlas I thought.

Nice night but a gusty wind would have played havoc with my 12 inch dob so I'm glad I chose to use a refractor tonight.

10 minutes ago, sonicninja said:

Thanks John. Could you just eloborate a bit for me? Why would you need them in the car? Do these screws stop the  primary mirror from moving whilst in transit?

 

They stop the inner section of the primary mirror cell from moving during transit. The mirror is held into that inner cell with 3 clips so it won't move around itself. What it might mean if the locking screws are not there is that more collimation adjustments might be needed after transit than might otherwise be the case. The mirror won't become detached from the cell or anything horrible like that !

The ones missing are the locking screws. I don't use them on my scope unless taking it somewhere in the car. You collimation screws look to have been upgraded from the stock ones so perhaps the previous owner decided to dispense with the locking screws altogether ?

You should be OK without them but if you feel the need to replace them, any screw that fits the thread and is long enough to bear against the inner section of the cell would do. Many folks, like me, don't use these though.

I have the Astronomik UHC in the 2 inch format and it is pretty good. I've read that the Castell UHC is a decent performer as well but I've not used that one. I've tried a few lower cost UHC's that were not all that effective though. One surprise filter has been an older Meade 4000 Narrowband Nebular (spelt like that !) which is a UHC type and works rather well. I think that cost around £25.00 used.

The Orion Ultrablock was another decent one that I used to own. I've heard that the quality of those can be variable though. I must have had a good one !

I have to add that I did have an Explore Scientific UHC for a while recently and found it rather mediocre in terms of contrast enhancement.

It's decently clear again tonight. E & F Trapezium are showing quite nicely with my 120mm refractor at 112x. Comet C/2019 L2 Atlas is also showing quite well up in Gemini, close the radiant of the Geminid meteor shower.