markse68

33 minutes ago, Alan White said:

Only if you ordered from Saturday onwards though Mark, unsure on the odd discounts.

 

Trying not to think about it lol- bought the 7 last month and just got the 10 to complete the set at the weekend 🤦‍♂️ Lovely eps and it’s only money. Lovely eps and it’s only money. repeat....😂

50 minutes ago, Alan White said:

From 365 Astronomy, special offer too

Dang - I didn’t even check just went with Flo. serves me right- could have saved myself a small fortune ! 

Lovely ep though

A Zeiss 0.965” O-16 ortho like the ones for the telementor but to my pleasant surprise it has blackened barrel and field stop- most didn’t as they were to be used with a cross hair insert

Had a quick look just now as the moon and Mars were pretty clear of clouds and Mars is getting really quite high now! I remembered I’d bought this filter a while back so thought i’d give it a try- well it is called a Mars type B filter so why not! Well it definitely makes for a properly red planet! Even the ice cap... But it did most definitely increase the contrast and make the dark features stand out better. I don’t think it’s available anymore but there maybe something similar? it’s an orange colour to look through with dichroic reflective coatings on each surface. Seeing was terrible tonight though- really shimmering most of the time. I’ll definitely use it again in better seeing. Oddly the moon which was lower suffered less from the poor seeing 🤷‍♂️

Mark

Why is it so important to get it perfectly circular? I’ve often wondered this. What if your secondary isn’t a perfect ellipse? If its “in the middle” then when you tilt it to get the whole primary in view you’re going to get a more sensitive and accurate 45degrees aren’t you? Not knocking the technique btw- it looks excellent and useful- just wondering what’s so magical about it being perfectly circular 🤷‍♂️

It’s just easier to get to the eccentric rings with it removed Dave- the outer ones slot is pretty well covered by the clamp ring.

The ross binos would be tricky to hold that way 😬

I had to wait for clouds to clear but just checked my russian BNU4s and they’re pretty good so i’ll leave them alone

Mark

Thanks to @DaveL59 for his link to this technique and in preparation for re-cementing the doublets in my ancient Ross binos I had a go at this today and i’m glad i did!

I jerry rigged a collimation stand using my stepperised Tal-1 mount so that it would follow the sun a bit better. The rig is just a long beam strapped to the mount with a target screen at the bottom end and a small mounting platform for the binos. I need to think about it more and find a better way to mount them more rigidly as they move about too much while making adjustments. 

I drew up a target of concentric rings spaced for my ipd ~ 66mm

The binos are just lashed to the mounting plate and a welding rod resting on the ep cups gives a horizontal reference to align the target.

I measured the height of the centre of the eps for each bino I wanted to check and put an offset horizontal line for each. 

IPD was set accurately using callipers 

The idea is that the sun projects an effectively collimated beam of light down through the objectives which should be projected parallel from the eps onto the target.

First test was my Jenoptems. They’d never felt right and i now wonder if it was because of this- collimation was way off!

Adjusting the objectives is tricky and a bit just trial and error. First i removed the aluminium beauty cover- it just unscrews from the cell. Then I removed the locking rings from the cells using a screwdriver blade- very carefully! a special tool would have been better. Then you have to adjust the 2 eccentric rings holding the lens elements. I found it easiest to move them both together after slackening the side grub screw (which was missing from mine!) then locking the outer ring with the grub screw and adjusting the inner ring. 

Eventually I got somewhere much better looking. Locking the outer ring again with the grub screw the locking ring was refitted and tightened. Tested them on distant buildings and they’re certainly no worse than before Job done

Well worth the effort if just to check your binos I think 👍

Mark

Thanks Vinyard- bookmarked

Mark

Sky Safari pro has them all integrated in the app along with an excellent searchable moon. SS Plus might too but not sure- maybe not the searchable moon map- you’d need to check. Nice to have them in one app.

4 hours ago, iPeace said:

I now recall that one of these mounts I used worked as close to perfection as one could hope for - but only when two particular scopes were deployed in a particular configuration. It was a real 'wow' moment for me. The only useful explanation must concern weight and balance. In your situation, I suppose I would be trying to determine whether this 'perfect point' exists, with the scope on one side and the empty counterweight bar on the other, gradually applying downward force by hand until the mount (almost) starts moving by itself; if that point exists, then it's a matter of re-creating it with counterweights, adjusting one millimetre at a time.

I'm sure the above reflects at least in spirit your efforts so far.

Does the Gyro use PTFE thrust bearing for the AZ? Interestingly ptfe coefficient of friction reduces with load up to a point. So if it does, a couple of thoughts- you could try a heavier counterbalance weight closer to the pivot point to try to reduce that cof. Or maybe a lighter weight further from the pivot to increase the rotational inertia (it increases by square of distance from pivot) which might help smooth out the motion and make the stiction less noticeable? Worth an experiment perhaps.

V nice scopes! I like your skeletal dob mount- is it diy Stuy?

57 minutes ago, AdeKing said:

Distance to center of Counterweight to the AZ axis centre is the same as the distance from the centre of the axis to the centre of the OTA.

Is the counterbalance weight the exact same weight as the ota? If not then it shouldn’t be the same distance to get perfect balance. you may find you’re pinching one side of the az bearing surface which might improve with more even weight distribution through better balancing?

edit: sorry you did say it was equal so ignore this

1 hour ago, CraigT82 said:

Thanks Mark, is that 3am UTC or BST?

 

my bad- utc does align with your image 😬

lovely image Craig. Was this last night? Maybe the dark patch is Ascraeus Mons- according to SS Olympus Mons was further to left at 3

On 06/07/2020 at 13:53, andrew s said:

I may have misunderstood but if the laser in on the spacecraft as is the light sail how does it overcome Newtons 3rd law, action and reaction are equal and opposite?

Regards Andrew 

Yes could you answer this @alberto91 as it doesn’t seem to make sense? Also what’s the difference between laser propulsion and photon propulsion?

Perfect evening had here too- warm still air (so important with my dob) and incredible clarity on the gas giants. So clear in fact i was still getting a very detailed and pleasing sharp image at 400x at times! One of those balmy summers evenings where you could just relax into hopping from random target to random target. Could have stayed at it for hours. Alas cut short by a need to be up now- much too early 🤦‍♂️

On 05/08/2020 at 11:48, CraigT82 said:

Snap! Well not quite. I recieved a 2 pack of space blankets today (would have cost more than my scope did to get the window film). Have just used one of them to wrap my plastic fullerscope tube. Its looks snazzy if nothing else! 

Is it going into orbit Craig? Adc not doing a good enough job?

31 minutes ago, DaveL59 said:

I think the aim is to improve the aim rather than velocity, since the shell would lose some of the impulse energy in gaining spin, albeit a small fraction. I've not looked down the TAL-1 tubes but can say the TAL-M I have isn't rifled. Maybe it did happen on early ones tho, if they simply repurposed tooling or processing methods at the start. I doubt they'd have been real armoury barrels given the material, ally wouldn't take the heat very well for rapid fire nor last many rounds of occasional use I'd think. Kinda adds to the mystique of these old Russian gizzmos tho huh 😉 

Sounds like the story a mate once tried to get me to believe that kenwood chefs started out as surplus spitfire starter motors or some such. You’re probably going to tell me that’s true now aren’t you😂

ooh you found an honest ebay seller! Interesting patterns there- I have a couple of “perfect” (🤦‍♂️) tal plossls that are separating too - this could become a handy skill to have! 

I found it on ebay Dave- hope it’s decent quality.

Ill do some reading up on the collimation thing- thanks

It’s done! 🤦‍♂️ no turning back now 😂

So what’s the goal of collimation? Presumably it’s to adjust so that the entrance and exit beams are parallel? If I use a laser cross projected  through each side of the binos and adjust the objectives to align the crosses with correctly spaced marks on a distant wall ?

Mark

It took quite a while but i’m certain i found the flying V asterism and with averted vision could make out some fainter objects in the vicinity. So i’m pretty sure some photons from the nova did enter my eye. Does that count? 😬

Nova hunting with Jupiter, Saturn and the moon behind a pretty cloud

Does this look right?

54 minutes ago, bomberbaz said:

has anyone got a more detailed chart of the location of this please, maybe something that shows where it is in relation to a bright star for star hopping purposes?

Would be nice if you could search in Sky Safari using coordinate input 

incredible!