markse68

14 minutes ago, DaveL59 said:

playing a bit with prisms, one from an old tasco 7-15x35mm bino which I removed earlier from the objective side of the bino

Does it matter that you’re using the prism the wrong way round? The side you’re using for reflection has a nice anti-reflection coating- might that cause it to not internally reflect like you want it to Dave? 🤷‍♂️

10 minutes ago, DaveL59 said:

playing a bit with prisms, one from an old tasco 7-15x35mm bino which I removed earlier from the objective side of the bino. Blacked the edges and made a folded card shield to improve reflection and reduce stray light.

hand held against the centre camera on the note-10 set to 1x, some vignetting and an odd effect in the top 1/3. Tho I've seen that in an older Prinz prism diagonal also when viewed without an eyepiece.

Camera set to x1.2 to x1.5 gave a better result in terms of the corners

In this test the phone is still fitted to its case which means a 1-1.5mm gap between camera flat glass cover and the prism surface. So far it looks like a mirror may be a better option but will try a bigger prism from a 10x50 at some stage. Pity I can't test against the night sky with no unlock code but a prism may be a workable solution, after all they are used in some diagonals, albeit with a narrower light path going through it 🙂 

 

Didn’t i read that the unlock code is good for 5 devices? 😉 Anyone up for a group buy? 

16 minutes ago, DaveL59 said:

I wonder how these folks are managing to do this...
https://www.all-startelescope.com/sales/product_info.php?cPath=21&currency=USD&products_id=2076

Perhaps they've bulk purchased the LT70 and stripped off the bracket and resell it with code and adaptors.

edit - yep seems that's exactly what they are offering, a removed bracket and codes. No adaptors.

Maybe that’s why Celestron dropped the cheapest model...

But that doesn’t fit with the wikipedia’s animation which suggests it’s moving quite a way from the arrow of stars past a triangle of stars somewhere up there?

Not sure- just a simple cup form

17 minutes ago, heliumstar said:

Did you cutout the eyecup on BCOs?

I printed new ones- the flap is ~useful but annoying! 

16 minutes ago, JeremyS said:

On some occasions, the detail was approaching that in some recent images I’ve seen. And almost as good as what is shown in @mikeDnight's  carefully executed drawings.

Amazing last night wasn’t it Jeremy!I had the same feeling- getting toward some of the images I’ve seen! And so true about sitting comfortably- I’m lugging a directors chair around with me just for Mars- need to sort out something lighter/more compact but it makes such a difference to comfort and staying power!

Mark

I’ve been getting custom size ep caps 3d printed in nylon- reasonably flexible but very tough. If you can measure the diameter accurately I could maybe get you one made but I can’t promise when as i’d have to fit it in with another bigger work order- the minimum order price is £40! The actual per piece price is pennies. I went for white as it’s easier to see in the dark but black and primary colours are also available

Mark

They sound very decent if you can split doubles with them! I never tried tripod mounting and can’t handhold steady enough so can’t comment on comparisons but I think i’ll keep an eye out for a bargain pair of these- thanks 😉 Centre field sharpness is everything as far as i’m concerned

Nice Nick! Oh I wish i’d got out a bit earlier for Saturn- it’d gone behind trees. But the seeing- amazing wasn’t it! I was down in Surrey bortle 4/5 and it was a bit strange- there was so much moisture in the air that the light dome from London to the north obliterated the big dipper! Yet looking toward the zenith i could make out the milky way glow horizon to horizon and to the south the skies were pitch black 🤷‍♂️ Air was dead still but as predicted by 1:30 everything fogged up to point of unusability.

BUT- best view of Mars yet- there were fleeting moments when I felt I could almost make out surface topology and there was sharp outline detail in the dark markings below the sharply defined but very small polar ice cap. I was able to push magnification to a crazy 640x without significant degradation for a nice sized disk and a light orange filter helped with contrast. Amazing view!

My other target the Veil was a bit of a washout though- strange given it was clear/dark enough to see the melkveg!

Mark

That’s very interesting- what is it about the suns position that causes this flash?  Quick google suggests this sodium layer and other metals up there are from meteors burning up! And it’s used by astronomers as an artificial star excited by lasers to enable atmospheric distortion correction! Very cool

After seeing @johninderby’s post in what the postman brought thread and having never seen this before it looks very interesting. The idea of having fairly accurate push-to location of objects without all the paraphernalia of encoders/dsc or actual setting circles appeals and it would be very useful under my poor skies but I had a quick flick through the CN thread on this and one jumped out at me:

”The past 3 nights the seeing was so bad where I live that the camera could not find enough stars to plate solve but I'll keep trying. I'm afraid that the poor seeing will limit the benefit this system is to me but, only time will tell.”

Obvious really but it kinda renders it a bit pointless for me unfortunately as if I can see the stars I can better find things by star hopping and where it might have been useful it will suffer the same problem i have- not being able to see the stars to navigate by! Oh well- was quite excited by it initially

Interested to hear how others get in with it though. I wonder if it can use long exposures?

24 minutes ago, johninderby said:

When you turn it on point the  scope to a bright star then centre the star on the phone screen in the crosshairs on the screen.by swiping your finger across the screen..You just have to align the image with the scope rather than aligning the phone holder with the scope. The more accurately you align the image the more accurate the push to will be.

I’ll be using a reticle eyepiece to centre the star in the scope first.

This is very exciting technology- I hope they bring out a stand-alone version or better still someone does something that’ll work with sky safari etc- a little standalone wifi/bluetooth linked camera would be even better so you could hold the phone in your hand

On 10/09/2020 at 22:55, johninderby said:

The next generation of push to. Instead of having to align the mount and of course needing encoders. You just point the scope at a star and it takes a photo and uses plate solving to workout where it is pointing to and that’s it. Then select something using the plantarium app that you  want to look at and it guides you to  the target using arrows on the screen and tells you when you have reached the target. 

Push to made easy.

 

this is very interesting!

Do you have to accurately align the phone/holder to your scope like a finder or can you use the software to select your optical alignment by clicking on the target you see through scope? 

amazing detail and great animation. Have you got more frames to have io leaving the disk? 

That’s very cool- the movement really makes the surface topography stand out well

49 minutes ago, Barry-W-Fenner said:

Great news Mark, Glad you managed to find it from home. I am yet to see this wonderful target. Hopefully this winter.

Was you using your OIII filter when you located it from home?

Baz

Hi Baz, yes I could only see it with the oii- uhc didn’t show it. And I don’t think i’d have seen it had i not already seen it under less polluted skies- weird but i think like faces your brain remembers the image and makes it easier to pick out from the background- it was ever so faint and i couldn’t see any detail- just a faint greyness that was very slightly different to the grey (low mag) background. Good luck with the hunt and yes good to know it’s at least detectable from poor polluted skies with an 8” dob.

Mark

small update to this- last night i spent a good few hours on Mars etc (okish view) from my home bortle 8/9 skies and thought i’d have a quick look for the veil knowing full well it was impossible from here... This is quite interesting I think because it wasn’t there before- I tried so many times but i guess I didn’t look hard enough! Having now finally seen it (washed out by moon) from better skies and knowing what to look for, there it was! Very very faint and too easy to miss but with proper looking i could indeed just make out the eastern and western veil! 

Mark

On 13/08/2020 at 23:35, WJC said:

Eccentrics only?! GOOD MAN!!! When I talk about collimation vs conditional alignment—because of my “cut to the chase” manner—the Snowflakes take me to be a number of bad things. That’s okay; I chose that road. I learned years ago that if you desire to be taken seriously you have to be bold enough and loud enough to be heard over the din of the incessant speculators.

 

 

 

Bill  

 

hi bill @WJC I just read one of your papers on collimation/conditional alignment and it mentioned prism lean. I guess you’re familiar with the prism assemblies from old Rochester B&L Zephyrs? What a beautiful thing the Zephyr is and what an interesting method for holding/adjusting prism alignment! A bent/twisted piece of flat wire 😳 Ingenious. Thanks to your paper I will try the ruled paper method for adjusting the lean which i think is a little out now since i removed the prisms to clean them...

Mark

On 06/09/2020 at 21:16, Woodrow F Caul said:

I ordered Seamless Carbon Fiber tube material 5.8oz/yard to make it 1 layer thick, Very Strong and it's optimal size is 21" Diameter at 45° fiber angle. This Braided Sock has a +/- 20% diameter size depending on the braided strands intersect angle.

By my Calculations  this 6.8 ft X 22 in Diameter O.D. tube will weigh around 5lbs.

Next step is to build a Rotating Mandrel to put the Carbon Fiber Sock on to infuse the Epoxy resin into it.

Gonna be FUN !

 

 

 

Hi Woodrow, amazing scopes you’ve built already and this new project will be very interesting to follow i’m sure. Just out of curiosity, what made you choose a solid tube over the more common truss dob format?

Mark

That’s cheap!  Guess you could use a second one for alt or use a digital inclinometer (“wixey”)? Thanks for the heads up- very interesting. Not very high res but probably enough to get you in the ball park?

Incredible detail! (looks up orographic) yes looks like it! 😉

Lots of interesting points and I'm sure the answer is in there somewhere or maybe a mix of them all!

Thinking about it a bit more the obvious reason for some of the difference with Jupiter and Mars at least is that although Jupiter is about 9x further away from us it is about 20x larger diameter than Mars so it's about twice the angular size if I got my maths right (?), and of course the features we see like the GRS are themselves unimaginably huge- it could swallow 3 or 4 Mars sideways!

And to be fair to Mars like Stu rightly pointed out the ice caps have been well defined in good seeing and other than those its features are low contrast and it does have an obscuring atmosphere particularly when there's a dust storm

Thanks for all the input

Mark

It struck me probably the first time I saw them that it was odd that Saturn often appears sharper than Jupiter under similar magnification. How could that be when Saturn is twice as far away? Is it just that it is smaller in the ep or perhaps the strangeness of the geometric rings kidding the eye that it’s sharper when it isn’t really? But then what about Mars? It’s much much closer yet rarely does it seem as sharp as Jupiter, it’s features less defined. Is that just because it has a fuzzying atmosphere? Similarly Venus?

Or could this be something to do with the distances- the furthest Saturn must be casting closer to a collimated beam of an image than the closer planets and those closer planets more of a divergent image. Could that collimated image beam somehow interact less with atmospheric disturbance? Just wondering out loud- likely nonsense

Thanks John