markse68

The weather forecast- particularly the met office one on my phone. Last night it predicted clouds, rain and  even had a thunderstorm warning! All night! At 11pm i looked out to perfectly clear skies- horizon to horizon. It was too late though to set out with scope so i missed a much needed session 😡 This happens regularly and often Clear Outside is no better- they often completely contradict each other! Where’s the best resource for live satellite views of the weather? I’ve downloaded an app but it’s a very tight view of UK- something wider would be useful to see the patterns

20 minutes ago, John said:

A barlow isn't mandatory is it ?

 

well if the scope is faster than f10 then it’s a good idea as the prisms can introduce other aberrations apparently. otherwise not but it could help with in- focus travel too? I’m using a 2x with my f8. gives my orthos a bit more er too which is nice. The ultra-ultra-expensive Gutekunst model (they do 2 versions)  has a built in barlow

8 minutes ago, John said:

On a practical note, how much inwards focuser travel do the ZWO and Altair ADC's eat up ?

I've seen a figure of 57mm for the ZWO but that sounds a lot to me

Thanks

it probably is about that- the optical part is ~30mm then add the displaced ep holder. Adding a barlow complicates things- shortening it somewhat i think

6 hours ago, chiltonstar said:

Anyone know where I can get spare scope front caps from??

I particularly need one for an SW 127 Mak, od 150mm, id 144 mm in order to mount some optical kit.

Many thanks,

Chris

someone once recommended these sort of nitrile blanking caps but they’re spec’d for their od- i guess you could ask them for the id? They’re steel shells coated in nitrile rubber- i think for sealing bores and pipes 🤷‍♂️

https://www.ebay.co.uk/itm/324238274862

Essential is a strong word but I was trying to draw attention to what I was witnessing I guess  It’s early days yet for me and my adc- maybe i’ll get bored of the extra hassle though it’s not really a hassle- I got bored of my motorised focuser so who knows. If i lost it or forgot to take it with me I’d of course not refuse to look at the planets 😂 I’d miss it though 

33 minutes ago, heliumstar said:

To my eyes it's better than 4mm and 5mm SLVs and 5mm XW - this one is close if not the same view but is just too big - comfortable though. Not sure what is going on there to be honest.....

I’m using the BCO 6mm barlowed for tight doubles too. It’s quite comfortable but a bit of extra fov would be useful with the dob- works though.

I think it’s long been recognised that the abbé ortho design for some reason gives an excellent balance of properties but is limited in its afov. More expensive eps possibly can’t improve on the sharpness or contrast (though that’s debatable) but can improve on afov and. comfort whist trying to maintain those properties.

Mark

57 minutes ago, fate187 said:

I did another test: I switched to view without ADC and what is easily noticeable is, that the moons are not defined spheres anymore, but washed out/elongated due to the AD. Also details on Jupiter were less defined and less sharp. Less sharpness was also very prevalent on Saturn without ADC.  

You probably need better quality optics or you lack experience in your observing or you should have been using a smaller scope.

Thanks John . I was thinking it was a shame i couldn’t use it with the adc on Jupiter as it’s the perfect power with my scope but I will try it without the barlow next time. The 14 barlowed with the adc has the dancing corneal reflections so not so great. I should try the 7 barlowed with the adc on antares next time too though - been using the bco 6mm but at ~500x and the small fov you don’t get long after it settles before you have to nudge it again. The wider fov would be useful.

3 minutes ago, fate187 said:

My experience comes from a ZWO ADC, which I sold because it introduced astigmatism. The view in focus was sharper compared to without the device, but overall color rendition was quite pale. Nowadays I don't observe without an ADC anymore.

Hi fate187, which adc are you using now?

At what focal ratio were you getting astigmatism? Did it affect planetary views?

Mark

It’s very green now isn’t it! I had a bit of an embarrassment yesterday evening trying to show it to some curious passers by. I found it in my binoculars easy enough but just couldn’t pinpoint it with the scope 😞 Tonight the clouds rolled in from that direction before I had a chance and forecast is poor for foreseeable so i guess it’s bye bye Neowise- was great while it lasted though 

Good news!

I sent the 7XW back for a full refund unhappy with a few things apart from this issue- namely that it had been advertised as unused for which i paid a premium but it had quite obviously been used... 

Anyway I just received a brand new one from FLO and have tried it tonight on Jupiter and there is no evidence of this issue at all 👍 In fact Jupiter looked great apart from AD smearing which i’m super sensitive to now 🤦‍♂️😂

The one with the issue was the original series in a Pentax rather than Ricoh/Pentax box so I can’t be sure that they haven’t just improved the coatings but it’s sorted now whatever so that’s nice and I’m much happier

3 hours ago, DaveL59 said:

Hi Mark, they do seem to vary between makers and models even. The there's matching the threads, not sure if those would be imperial and the japanese ones metric, for example, tho a german sounding make could be metric too. I've a few spare zenith 10x ZCF's kicking around spare in various condition so its possible and eyecup from one of those may work, post up the various dimensions and I can take a look at some stage, could be a bit slow on that tho...

Thanks Dave! Thinking about it even if the thread were the same, the outside design would likely be different. I’ll measure them  when i get home but i’ll probably 3d print something for them

I have an old boot sale pair of binoculars missing one eyecup. They’re Lieberman and Gortz 10x60 and theyre “highly coated” !😳😂

Actually theyre a bit pants in the contrast dept but I seem to remember collimating the prisms and freeing up the focussing mech which is lovely and smooth now and they seem to work ok but for the missing eyecup (and the ep focus diopter adjuster is seized but luckily in an ok position!) 

My question is are these eye cups fairly standard threaded fitting or as i suspect different across brands/models? concerning is the one that’s there unscrews but doesn’t fit the other 🤔

Figured they might be useful for astro with the 60mm aperture- shame not to use them for a missing eyecup.  they’re about same weight as current 10x50 offerings so that’s a positive.

edit: the cup does fit both sides after all- thought that a bit odd - the threads are a bit chewed and crossed though which had me fooled 

Thanks for the links Robin- I started watching the second and will definitely finish watching later when i have time- looks fascinating

Silly question but why do you have a light bulb fitted to the end of the scope Robin? is it for calibration? 

21 minutes ago, astro_al said:

Was that in your 8" dob @markse68? I was out with my 4" refractor and didn't see any colour smearing at about 140x. Are the effects of atmospheric dispersion more noticeable with larger scope due to their higher resolution?

Yes it was with the fullerscope astro_al. You may be into something there- I was using higher power too. Actually i spent most of the evening using the 18mm BCO barlowed to 9mm for 178x. Lower powers increase contrast on the planets I find but I didn’t do any comparisons at that magnification range. I swapped to the 10mm when Ganymede slithered behind the limb as the GRS rounded same limb- what a sight!. The distortion of the moons made it super obvious and Mars being a fair bit lower.  On the disk maybe smearing is too strong a word- the outline didn’t appear distorted  without the adc but the colour balance was very obviously. 

Magnification clearly amplifies the differences and aperture I think must have a role to play too- the big observatories take it very seriously.

Just back from another superb seeing evening with the planets and did a few comparisons of with and without the ADC. This is the last time i’ll do such a thing as there is really no point in looking at them at their current altitudes without. I had my 10mm BCO in the ADC barlowed to 5mm and swapped back and forth with the 6mm BCO on its own. Jupiter Saturn and Mars all had orange tops and bluish bottoms with the 6mm. There was detail to see but it was soft compared to with the ADC. Despite a bit more magnification with the ADC (320x vs 266x) the ADC view was sharper on all of them- there was just more definition. Easiest to see why was when observing Jupiter’s moons. With the 6mm the moon’s were elongated with strong colour smearing stretching their form. With ADC they were perfectly round disks. I know which i prefer.

Mark

missed this but will definitely watch the youtube catchup.

53 minutes ago, andrew s said:

If you can't see it no need to worry anyway.

😂

hi Thomas, I like your sketch very much. What do the numbers mean in the top one?

Back pain and tiredness meant i called it a night at 1:30am- what a whimp 🤦‍♂️

BUT the planets I did see were sublime- watching Io pimpling off the limb chased by the sharp dot of its shadow, then the GRS i’ve not seen sharper with clear detail of its churning of its belt and a hint of faint swirls within it. It just keeps getting better and better. Ditto Saturn- shading of its surface stripes and in the rings. Mars too- clearly defined polar ice cap and a triangle of dark markings

The comet though was barely visible at that time from these light polluted skies- glad I caught it last weekend

46 minutes ago, DaveL59 said:

just read a post of yours from way back re the motors and gearbox on these, so I thought it worth repeating the comment you made then too...

"Only manually control the mount when the motor is turned off so you don't damage the gearbox"

That shouldn’t be necessary Dave- there’s a clutch on the output worm gear and another between the clock drive and the worm but the clock drives are quite delicates do the clutches might be stiff with old grease and/or need adjusting.

Looks like a nice early one from the blue colour scheme and 2-part column. The really early ones had metal end caps but I’ve only seen one in a museum.

Be careful with the mains transformer and dew/dampness obviously! 

Welcome @Tabby !

Mark

Dang that’s a real bummer Dave  Have you had the objective out since the damage? Is it a doublet? Such a shame

No consolation I know but that Edmund Deluxe red finder I bought as an ebay bargain went in the bin the other day  The brass ep sliding focuser bit was corroded solid in the thick aluminium tube. I tried soaking in vinegar overnight and hot air gun but with nothing to get a decent purchase on all i managed was to shift in in a bit further 🤦‍♂️ Anyway the scientific application of targeted force (hammer and drift) resulted in the crosshairs glass shattering inside and at that point it was a waste of time going further. Shame as it was an unusual and nice thing but very heavy for a finder tbh...

Good to hear you’re not giving up on it and look forward to it’s resurrection

3 hours ago, DaveL59 said:

Still, on with the occulars and eyecups etc and you'd hardly know it'd been broken.

beautiful work Dave- like you say you’d never know they’d been repaired! 👏

On 15/07/2020 at 09:08, Captain Magenta said:

I've always been passively interested in astronomy, so am puzzled as to why I never got to see Hale-Bopp or Halley's when they were around.

Snap! I think i must have been giving my navel more than it’s fair share of my gazing at the time- or at least more than I usually am  odder still Hale Bopp was around the time i bought my first telescope- I remember first sights of Jupiter,Saturn and Moon, yet i can’t remember actually seeing the comet...🤔🤷‍♂️