markse68

It’s gotta be just polished glass as you can see the whole cork supporting pad in the reflection. I guess if the blanks have such perfect finish why do they bother frosting them? Maybe that’s the question they asked themselves also  

“2. High definition: high brightness, the effect is more shocking! The observation is very comfortable.” 🤔

Its strange that my first Tal came with one of these- great optics and serious build but were  they not aware how dangerous these can be?!? It had a projection screen too which makes it stranger still- unless they thought you’d only use it to dim the projection  🤷‍♂️

There must be a better way than drilling holes- couldn’t you take it apart and fit circulating micro fans and then peltier  cool the outside shell?

1 hour ago, sploo said:

(and my non-existent metalwork experience),

😂

Loving this

Does the Mesu use harmonic reduction? Makes sense for zero backlash drive 👍 So then the friction drive stage is just to reduce the torque ripple?

following with great interest- top work Sploo!

33 minutes ago, F15Rules said:

That's ingenious Mark!

Well done!

I expect there will now be as rush of Telementor owners to eBay etc looking to replicate your ideas (not me, sadly, I don't have one now, but they are great scopes).

Thanks for sharing 😊

Dave

 

Cheers Dave, that would be funny 😄 Of course the good thing is there must be 100 old Zeiss/Lomo microscopes out there for every one Telementor in existence, so no shortage of parts  

I just had a thought - the strange lenses on either side of the prism effectively hermetically sealed it so despite a long hard life in a lab the prism itself is pristine  

Mark

Hoped this would have arrived in time to be included in the first post but I got bored waiting. Better late than never. Hermes 🤦‍♂️

It’s a Zeiss 60deg prism for microscope binoviewers- not as ideal as a 90 but it fits with the other bits and was v cheap 😉 Did I mention it’s Zeiss? 😁 (and nice)

For some reason it had lenses fitted on both sides- easily removed

I may have a go at opening the stops as it does vignette with the wider eps but seems to be perfect 20mm and under

Should make the scope a lot more comfortable to use with those low down and high up targets where you need to stand on tiptoes or be a contortionist! 

I thought I’d lost this it took so long- I couldn’t afford a Zeiss prism diagonal...

oh wait 😁

53 minutes ago, Chriske said:

I might have come up with a completely 'new' EQ-platform, First need to do some more brainstorming...🤔

I was thinking of making a shallow alt az platform with computer control to create a virtual polar axis. You could enter your latitude and use it anywhere in the world. At the pole it would just use the azimuth turntable and at the equator it’d use only the altitude rocker, side on, and in between a combination of the 2. I think it could work but a bit more complicated than a simple rocker platform...

I wonder if perversely we might have Elon Musk to thank for this- the starlink passes were trending on Twitter a few weeks back and I think a lot of people were looking up for something different to do with their kids in lockdown. That and ISS and the rocket launches of course. Or maybe the surreal existential threat of the virus is making people think a bit more deeply about life the universe and everything 🤷‍♂️

That’s a very fancy looking cap. Looks like the clearance is very small. Not sure what to suggest really as any tape will likely snag and end up peeling off. Can you maybe get some self adhesive silk ribbon from somewhere? That should be thinner than Elastoplast.  Or maybe clean it thoroughly with acetone  then run a thin line of superglue along the height of the rim and let it set hard, then repeat at 120 deg spacing? Not sure it wouldn’t just flake off as anodised aluminium is pretty non-stick though but it might work

16 minutes ago, John said:

http://www.ianmorison.com/the-maksutov-newtonian-telescope-discussion-survey-and-an-image-of-the-10-day-old-moon/

Like everything in astronomy, compromises.

 

Thanks John- that’s a good article that explains a lot.  An f6 with only 14% central obstruction sounds like it’s pretty dedicated to planetary indeed! I thought I was pushing the boundaries a bit with 18% with my f8

8 minutes ago, John said:

- Very small secondary and no secondary supports so very low diffraction.

- 30% the coma that a normal newtonian has.

- A "niche" design so expensive and made to high quality.

Despite all that, I don't have one now. I went for a refractor instead

 

How does it get away with the smaller secondary John? Is it because of the lens?

I had a look for it tonight once the clouds had cleared but the seeing wasn’t good. Has it dimmed now? I could only make out that there was something there- even averted vision wasn’t clear what but if it was brighter than the 2 other stars near it then I might have detected it’s photons  😉 On the plus side while locating it, isn’t Almach a beautiful double! Rivalling Albireo for colour but nice difference in sizes and low altitude giving them a pleasing fireyness

Hi John, what makes a mak newt like that a better planetary scope than a regular newt? It’s quite a “fast” scope which isn’t normally associated with being a planet killer? I understand that mak newts have lower (possibly zero?) coma- an advantage in a faster scope and it seems to have a smaller secondary so better contrast (why can it have a smaller secondary?) And no spider so no diffraction spikes- is that an advantage for the planets? Or is it just that it’s easier to make a more perfect spherical primary? But then the lens has to be good too. Just wondering

1 hour ago, Stardaze said:

So... I’ve butchered my first eyepiece section. What’s the secret to a nice clean cut that you've all managed in the foam? Have you all bought a laser cutter 😂 I will admit that I’ve jumped straight into it with a craft knife that could be sharper, so you’re going to tell me the obvious I fear..

You want a blade that can cut full thickness/depth of the foam for neatest cuts- bread knives are surprisingly good or for tight corners a long thin filetting knife

...with microscope parts!

There were a few things bothering me about my Telementor- the screw in extension piece for the eyepiece holder would wear the threads each time I used the scope as I didn't want to leave it attached, the plastic tube holder that the eps slide into was a bit loose and would get worse, I'd like to be able to use modern eps and microscope eps as well as the originals with it easily, and it really needed a prism diagonal for comfortable use.

Then on CN I saw this really cool original "micro-bayonet" or dovetail quick release system Zeiss made for the Telementor back in the day. Needless to say these are rare and fetch collectors price now.

I also saw that Baader made a similar looking quick change system- the Baader TQC-TCR.

I had also noticed that there were a lot of similar dovetail qr systems used in microscopes- could they be the same? I contacted Baader and they told me that yes indeed they had used the CZJ standard for their adapters- the Zeiss Micro-Bayonet!

So I bought a few bits of old microscope- turns out Lomo microscopes also used this standard- and they are much cheaper than Zeiss and almost as nice  

I tried to find the Baader steel micro-bayonet ring but everywhere was out of stock then I got lucky and found the complete set on Amazon for £1 more than just the ring- perfect.

This is what I ended up with

I'll leave the male dovetail on the scope then I can quick attach extension tube and adapters for any of my eps.

The 0.965 eyepiece clamp was originally part of a telescopic extension tube. It's a beast of a thing- hefty chunk of stainless steel  with the nicest QR clamp and a solid split band that clamps the ep all around- not just a screw and thin metal band.

It has a 25mm bore. It needed a single layer of mylar tape to work perfectly with the 0.965" eps. I made a sleeve for 23.2mm microscope eps.

I think I prefer the Lomo look- less fussy and it almost matches the OTA 

24 minutes ago, Nyctimene said:

I prefer the app LunarMap HD over the SkySafari Pro moon display for several reasons

LunarMap HD isn’t on iOS unfortunately though

maybe it’s different on the android SS but the terminator on mine shows in real time. It doesn’t show the effect of the terminator on crater contrast like real live view but it shows where it is

mark

Thanks Don for the first hand opinion

47 minutes ago, Don Pensack said:

This one is inexpensive enough you could buy one for every 1.25" eyepiece you have and make

your entire eyepiece set into 2" eyepieces.

I’d need a much bigger eyepiece box then though 🤔😉

Thanks for confirming that Kyle- I thought it was what you meant. Good to gradually learn the differences between the versions- the basic version only shows an image of the moon with no crater searching etc. It’s not very clear in their descriptions either- they might sell a few more pro copies if it were clearer. It does say the pro version has 8x the resolution of “any other version” for moon and Mars which sounds like what we’ve found at least! I bought the pro because it was on offer and I figured it’d maybe come in handy to have the expanded star database at some time in my new hobby (I’m far from a pro 😂) But had I known about this feature I’d have more positively gone for it anyway and glad I did and feel more willing to recommend everyone with any interest in the moon get it for this feature alone!

3 minutes ago, Louis D said:

How would you get your fingers in there to tighten it with fat 1.25" eyepieces that overhang quite a bit?  I had to swap out the short thumbscrew for a longer one on one of my adapters because it was so short and had such a wide knurled head that it kept some of my eyepieces from seating level.

Very good point there Louis- I think the Baader one has a lever sticking out to solve that problem

7 hours ago, Stardaze said:

I’m going to go nanuk I think. They do look to be very nice and still 40% cheaper than a peli. What size is yours?

It’s a 905 (had to check) it’s for my smaller eps- orthos, plossls etc. There’s a pic somewhere in this thread. The catches are nicer I think than the peli or hprc  ones- they lock open or closed 

mark

2 hours ago, Ricochet said:

The radius of curvature for a Newtonian is equal to its focal length. 

The radius of curvature for a doublet refractor is 1/3 of its focal length.

The higher the radius of curvature, the flatter the image. 

You will see it most obviously with stars. Focus the centre of the FoV exactly and then look at the stars at the edge. Refocus to see the difference. I can see it in my 14mm and 8" f6 (fl 1218mm), but it isn't really an issue. Focusing slightly off centre keeps everything quite tidy across the field for my eyes. If your scope has an even longer focal length than mine then you will see even less of this effect. In fact, if you look for it, you might notice that the predominant issue is actually astigmatism at the edge. This is also shown in the diagram below, where the amount that the two lines pull away from the centre is field curvature, and the difference between the two lines is astigmatism.

I can see why you would have had trouble with FC while using that scope. 

Thanks @Ricochet that’s interesting to know about different scope types differing fc. I may take a more critical look in an open cluster or something but tbh as it’s not bothering me or detectable now I’m slightly loath to go searching for something that might then upset me

Interesting to look at those graphs too as it looks like the shorter focal lengths should suffer as badly or worse from any astigmatism but as I’m not noticing that in any of my Pentax eps I’m guessing that this could just be a case of looking too closely at the details and like someone in the CN thread F15rules linked to said it was brave and perhaps unwise of Pentax to release those test results when not many other ep manufacturers do... I think Pentax must have really improved on the longer fl eps with the xws as the 30 and 40 graphs look the best of the lot- my 40xl as mention is far from flat fielded and suffers astigmatism too. It’s very compact and light though on the plus side (I think half the weight of the xw40!) 😉

@F15Rules it’s strange that one eyepiece can behave so differently for different people and scopes Dave! but yes I guess the shorter fl xws cancel out curvature and improve field flatness whereas the 14 and 20 can add to and make curvature more obvious. In my scope I’ve not noticed an issue. I do have other eps where I do- many plossls, the BCO 10mm which I think suffers because they opened the stop wider than is normal for that type of Abbe ortho design, erfles etc but not these. I like these xws very much 

Mark

1 hour ago, John said:

Maybe they suit a newtonian better ?

Is there a difference between a newt and a frac in terms of native fc John? Or could it be just focal ratio? Mind you @F15Rules must have been using a slower scope than my f8

it’s a different matter with my xl40- that does suffer quite noticeable loss of focus at edge but I wonder if it’s just an erfle - it seems to have a lot less glass than my other pentaxes- seems a simpler design but I only really use it for finding things and hopefully the veil at some point- it’s wide enough as to not really be an issue generally

mark

7 hours ago, Stardaze said:

What's the dimensions of yours please? I've been trying to work what size needed. Currently have 5 EP's, Barlow, Concentre and probably need to allow for a couple of filters and two more EP's.

Was looking at the Peli 1450 but wondering whether I can get away with something a touch smaller (HRPC 2250)?? 

 

Edit: Just found this which looks decent value https://casesuperstore.co.uk/product/nanuk-910-case/

 

I've got a nanuk case- they're super tough and look to be waterproof. Very high quality up there with Peli etc

Mark

I’m often alarmed at the sound of scraping metal when changing eyepieces in my moonlite focuser and upsettingly despite being quite careful some of them are showing signs of wear from use so I was wondering if there was such a thing as a delrin 2-1.25” adapter but there doesn’t seem to be- at least not easily available. Then I stumbled across the Skywatcher twistlock adapter that says it has a polypropylene gripping band so sounds almost as good. Anyone had experience of these- are they any good? Do they clamp the eyepiece nice and firmly or does it tend to rock in the clamping band? I read a damning review of the similar looking TS optics one.

Are there other options- maybe a Baader one would be better?