josefk

21 hours ago, MalcolmM said:

This is really difficult for me as I love them all, but if you twisted my arm till it really hurt I would choose this one (but don't tell the others 🙂). It accompanies me on weekends away. It accompanies me abroad. It fits in a very small rucksack, mount, tripod and all. I can get a 5° FOV with a 28mm Erfle (over 7° if I use a 2" eyepiece). I can get a razer sharp x140 with a 2.5mm TOE (I feel it could go further but I've no shorter FL eyepiece or Barlow). And to boot, it's lovely to look at sitting in the corner of the lounge ready for instant use. Even my partner calls it a cutie 😀

Malcolm 

Those fluid damped Manfrotto video heads seem to make lovely astro mounts for scopes within their weight range don't they Malcom? i love mine - a quick lock in Alt or Az with one finger and thumb and nicely damped when not locked. And light to boot...

7 hours ago, Whistlin Bob said:

Here's mine.

We name stuff in our family- so this is Henrietta - named for the astronomer who first enabled us to measure the distance to galaxies. She's at least third hand: the previous owner bought her to strip the DSCs for an atm project he was working on- not a problem for me as I like star hopping. He thought the previous owner was a London cabbie. She's been with me for five years now, and I very much hope for many more. She fits me perfectly: at zenith, the eyepiece is nicely level with my eyes, at 80kg she's not light, but will fit happily into a medium sized hatchback with the back seats still up.

I've seen things with her that make me sound like Rutger Hauer. Moonrise over Jupiter. The pup of Sirius. The fossil light of galaxies dancing in the Permian period. If there really are attack ships on fire off the shoulder of Orion, then I'm pretty sure she's gonna get them too. And then share it with anyone fortunate enough to be nearby at the time. 

Here she is doing her stuff at Castlerigg stone circle a few years ago, the first night I saw the Horsehead

Never mind the scope - what a fantastically cool spot to be set up observing!

…actually really nice scope too  🙂

Thanks for the heads up Agnes. i made a point of catching up with Ceres last night - a total first for me. At Mag. 7.0 I found it to be the brightest thing in what seemed to me to be quite a sparse spot in Coma Berenices. A dull cream in colour though only a stellar looking point source dull cream at 200x. Fantastic to contemplate what i was looking at while looking at it. Cheers

I'm loving the Venus sketches @mikeDnight and extremely inspired by them to get a good observation of Venus in these weeks. I made a schoolboy error last night. Observing Venus was on the list (it was the main thing on the list) but i couldn't get out with my 5" refractor till late (21:30 ish). I didn't want to swing onto Venus till the scope had cooled and got carried away with other things in the meanwhile. By the time i did remember Venus was a blue/yellow/red kaleidoscope about to go into the tree line. Doh!

I will probably order a Wratten 80A Blue filter today - have you had experience of good and bad ones? i will only buy once.

Cheers

A low contrast twilight full portrait from yesterday. A 95mm APO and right way up right way round erect image at 70x.

I enjoyed two bites of the cherry last night and this morning. A first early evening session with GnG kit to attempt a low contrast full Luna sketch then later a for a close up attempt on an eye-catching twin crater arrangement seen while making the full sketch (little did i know)...

i'm quite happy with this one:

The eye-catching craters are those in Oceanus Procellarum - newbie alert - I sketched the below later without knowing what it was at the time. I'm not happy with the "sketch" (ahem) but it has helped me identify Valles Shroteri, Aristarchus, Aristarchus B, Aristarchus Z, Herodotus, Herodotus N, & Vaisala "after the fact" oh dear oh dear oh dear:

I was super happy with the TOA and AZ100 at 400x using a Tak 5LE and TV 2x PM. All balanced and quickly settling. It was all flying by with just an 8' FOV though!

The TOA pointing at Vallis Schroteri in the early hours of this morning. The blur is cold hands...

Thanks. I shall put several dates in my phone then 👍🏼

Using this rainy Friday to mess about weighing eyepieces and fine tune balancing arrangements on the AZ100 - just dialling out minor irritations in my set-up basically to enjoy next time it's clear - anyway - here the TOA behaving itself with an EP at the heavier end of the scale.

You can tell its been cloudy 5 long weeks. Is there a term for astro cabin fever?

...so looking for satisfactions from little tweaks > I'm extremely happy with this new counterweight arrangement: 

I have 4.9kg of weight in the offside saddle here - all of it adjustable forward and back and 3kg behind and/or below the altitude pivot.

If i balance the scope at a good 45-50 degree angle using my lightest eyepiece then with only 10cm of fore and aft movement of my "counterweight sledge" i can balance everything from a 5mm ortho (110g) to a 31NT5 (924g) and MaxBright binoviewers with orthos or panoptics in the middle of that range too. 

No roll over even when deliberately unbalanced  - this pic below is deliberately unbalanced with BV - clutches fully off:

Now where's the clear sky?

That is absolutely lovely - the sketch that is. I am putting a reminder in my phone for the 26th July so thanks for the tip off!

Edit - i've just taken a look at the table on your link - what value is it in that table that gives the hint that the 26th July is good but not 29th April, 28th May etc. i am completely new to this level of "detail" in more ways than one.

Cheers

12 minutes ago, Mr Spock said:

Without following the can of worms some older Nikkors had poor correction for spherical aberration, like the 35mm f1.4. Use that wide open and you get a dreamy image 

That leads nicely into the topic at hand. As well as poor MTF, other aberrations can restrict detail and apparent contrast, such as the afore mentioned spherical aberration. Correction of all those aberrations is what you are paying a lot of money for 

and without being too philosophical about it the sum affect of these corrections (IMHO) may be more and more difficult to see positively (i don't know) but their absence on the other hand is profoundly difficult to unsee or see through if you care, if your expectations are elevated, and/or if your highly invested one way or another (this i do know).

52 minutes ago, Mr Spock said:

What's being discussed is edge contrast or MTF (Modulation Transfer Function). The closer you get to a perfect figure, the better the MTF. Here's an extreme example:

You can see how much sharper and 'contrasty' the top image is. This affects optical systems with a central obstruction more than refractors; the larger the obstruction, the worse the effect. With refractors the difference is only going to be small, but it can be noticeable.
To answer the question, yes, poor MTF can obscure fine detail.

Without opening a whole other can of worms - this is also one element in why you have  cameral lens A vs. B. vs. C differences and debates and obsessions even when comparing the same focal length from the same manufacturer. Thankfully with a camera lens comparison you can see differences in MTF for yourself relatively quickly and objectively in good AB set-ups. I had a "holy grail" Nikkor look disappointingly like the lower right diagram wide open (i know it wasn't only an artefact of MTF :-)). Burst that balloon pretty quickly.

Good effort - neat trick!

9 hours ago, Ratlet said:

As it's my first year, I've never known such good Stargazing.

Seriously though, I survived winter by being an astronomical scavenger.  Learning that the 20 minutes whilst the chips were in the oven was usually clear and taking every opportunity to cook dinner.

i also scavenge "here and there" with a life saving lightweight set-up. Strictly post chips though otherwise there's a good chance i would have burnt the house down by now! 😂

Nice one @Lurcher - this is on my sketching targets list this spring if ever the cloud clears off though I don't have quite so much aperture as you have been able to point at it. 🙂

Fabulous @mikeDnight especially the subtlety of Venus and the detail of Cyrillus - i recognise the rising panic re. sketching the moon. I sometimes (attempt to) sketch birds - I find attempting to sketch the moon is like trying to sketch wading birds in a moving flock - different every time you move your eye from view to page and back! A test of memory and speed. My own attempt on the terminator last night is well described as a "car crash" so won't be getting posted here 🙂.

Fantastic! All of them!

thanks @Paz - it's tricky not being able to thumb through it but i can imagine it from how you describe it. I may take the leap anyway (to use standalone) because i can still see a few copies available new and that situation is probably time limited (when its gone its gone).

I have Sky Safari Pro so possibly do have all the info it provides but i prefer using books at the weekend after spending all week starting at a screen 🙂

Cheers

could  i ask a follow up question here to those who have the Uranometria Field Guide - in your opinion(s) is it useful as a standalone reference for the qualities and characteristics of DSO even without the Atlas volumes or is it laid out in such a way that it only comes into its own with the matching Atlas? Cheers

5 minutes ago, Franklin said:

Is it the convenience of having different configurations side by side? such as a widefield, low power scope next to something with a bit more focal length? Different views of the same target in a handy setup.

This is my motivation though i haven't had a whole lot of opportunity to exercise it this year through lack of clear nights justifying big set-up's. For me it's also mono/bino at the same time. I missed planet season last year w.r.t. dual scope capability but i'm looking forward to having mono/bino capability in parallel later this year. 

So far i haven't seen the glaring need for ultra precise alignment of saddles (because one side so far has anyway been at  low powers). That may change at higher power both sides but then again it takes a few moments for me to move sides and get back to the eyepiece anyway. I don't have a driven mount.

23 hours ago, TakMan said:

might be missing something, but this appears to be a retrograde step - like an updated version of the ole SkyCommander XP4/5 devices (I do have one somewhere that shipped with the Nova)….

Now Sergie’s old Nexus WiFi thingy, hooked up to an iPad offering a push to digital planetarium with corrected views, etc seams to be a much better way of doing things!!!!

Hi Damian - i also may be missing something but i believe you get the choice with the AZ100/Nexus combo including a choice of "best of both" - i have a Nexus PRO equipped AZ100 and regularly use both the Nexus "head unit"  for want of a better description with its catalogues  AND Wi-Fi linked Sky Safari Pro on an iPad next to the scope. It really is "best of both" not either/or in my user experience.

Love your dialled in set-up BTW. Brilliant. 👍

No worries at all.

It's also just occurred to me you could check for yourself on diffraction spikes and if they will be impactful or not for you by stretching some thin (but not too thin) wire crossing at 90 degrees in front of the objective of one of your refractors. You could then systematically target a few increasingly dim stars at a magnification that would be meaningful for your musings.  

I enjoyed that report -  it's been 2 1/2 weeks wall to wall cloud here in S Lincs now (at least in the evenings and nighttime) so your observations were a nice stop gap 🙂 - thanks!

I have the GSO 8" Classical Cassegrain @Moon-Monkey though its actually 185mm in reality. These are my ad hoc observations in case they're of any use.

Resolution for this aperture in theory is 0.62" (Dawes) and 0.74" (Rayleigh) while my "personal best" so far with this scope is 1.6" (with a 0.5 Mag. difference between components). I haven't deliberately tried to find my tightest possible split on the best nights but i assume it would be better than 1.6" if i did because on a couple of great nights i could have driven a bus through ~2" splits.

Limiting magnitude for this scope is in the range 13.8 to 14.05 depending on formula while my "personal best" dimmest companion so far with this scope is Mag. 11.9. I have a dodgy observation where the secondary was Mag. 14.0 but i this has a big asterix against it in my notes because i'm not at all positive of the observation and need to go back to it.

Yes you do get diffraction spikes on bright stars with a CC. I've never checked at what magnitude they are not visible. i have recent notes that they were quite strong (though not unpleasant or obstructive to the observation) on the primary of Beta Cephei at Mag. 3.2. I'm not conscious of them on the regularly observed double double at Mag. 5 so somewhere between Mag 3 and Mag 5 they must disappear.

The stock focuser on the GSO scope never had image shift though i have upgraded it for other reasons.

Cheers

Joe