turboscrew

I ordered the Microstage II. I realized that none of my eyepieces had any threads under the eye cup rubber.

Thanks, guys. Now I need to ponder. I'll go through the suggestions probably several times.

I could start from the fact that I did buy a 3.6 mm MA - very bad idea. My budget... well, rather less than 200€ per piece.

I'm a beginner from Finland, and I got my tube in the beginning of June = not much experience. I think it has been darker than civil twilight for about a month now...

Those more powerful eyepieces are mostly for planetary. I guess it's enough for me if the eyepieces work, and are not very hard to use (like 0.5 mm eye relief 😄 ). I think about 50° AFOV is good.

BTW, which is usually better? A 3 mm eyepiece or 9 mm eyepiece with 3xBarlow?

I'm a Finn that bought my first scope at the beginning of June. (Bought it second hand.)

https://www.timeanddate.com/worldclock/sunearth.html

I have a 300 mm / 1200 mm (F/4) scope, and I wonder what kind of eyepieces would be good for higher powers (<= 10 mm)?

I've heard that Plössls are good, but there doesn't seem to be a lot of them around with focal length of 2 mm to 5 mm.

What kind of eyepieces are "planetary eyepieces"?

I'm not familiar with SDI, but here's something about it: https://en.wikipedia.org/wiki/Serial_digital_interface

Maybe I should... I just wondered if I could attach the camera to the filter threads of the eyepieces.

Then again, that holder doesn't cost much more than the mostly useless tube adapter.

And easier to change the eyepiece.

Thanks.

I wonder how do people get a digital pocket camera attached for digiscoping?

I have Canon A590, and the lens adapter (with 52 mm filter thread) for it. I also bought a 52 mm -> T2 adapter ring, but how can I get the eyepiece between the telescope and the camera?

I bought this: https://www.omegon.eu/projection-adapter/omegon-camera-adapter-1-25-/p,1250 but only one of my eyepieces fit into it.

I've also tried to find a 1.25 mm filter thread -> male T2 adapter, but it seems that more often chickens have teeth than stores sell that kind of adapter.

To my understanding, the eyepiece should be as close to the camera lens than a human eye would be when visually observing.

I've been planning to get a goto-mount. Not really for the goto, but tracking. It just seems that there are very few mount that just track and without goto.

My reason is that low objects (if I even bother to try due to the atmospherical dispersion) pass my 12"/1200mm FOV in 48 secvonds if I use 333x magnification.

And my dobson is a bit sticky - quite hard to direct accurately.

Dobsons are not good for photographing except for planets, when the exposure times are short. Then again, for real AP, if you wand a bigger aperture, start from the mount. The OTA is much cheaper. I'd say, roughly,  1500 € for OTA, 3500 for the mount.

Just learned the hard way: when you plan of buying a scope, consider these:

- Weight and size: It's a different thing to carry a small tube in one hand and the mount in the other, than carry about 100 lbs of stuff.

If you plan of trying astrophotography later, with big tubes, the mount load capacity tends to cost 1€/ gram. A good enough mount for 16" scope costs probably about 10 000.

and then there's the "sail effect" if the tube is physically long and thick (lots of area the wind can hit).

- The eyepieces for fast scopes need to have shorter focal length then eyepieces for slower scopes, and the short focal length eyepieces tend to cost more.

- Fast reflectors have coma. Reflectors with focal ratio bigger than 8, have coma too, but it's so small, that you probably don't need a coma corrector.

- Refractors suffer from dispersion, and quality optics tends to be pricy - especially large optics.

- Dobsons are not good for taking pictures. Even if you can drive its altitude and azimuth, there is also the field rotation.

Just a couple of things to take into account...

Hmm, there doesn't seem to be threads left for a lock nut. Maybe the mistake was pushing the axle bearing too deep such that the outer rim of the bearing made contact with the nut. Let's see...

1 hour ago, michael8554 said:

Does your mount have metric or Imperial Allen screws ?

Michael

My mount is dobson (I think metric screws) and made by OrionOptics (UK). The telescope is OrionOptics VX12.

This far I haven't tampered with the mount, but those tools I mentioned, seem to be all I need for the OTA.

I'm only in the phase of figuring out which EQ mount I'll get.

[edit]

Yep. the dobson and dove tail / support wheel screws are 5 mm Allen.

On 01/08/2020 at 16:21, Stu said:

First thing, forget Pluto, I’ve yet to see it after 20 years in the hobby; tiny and very faint so you need a big scope and dark skies to see it, plus bags of patience.

There are some good value beginner scopes out there. The Heritage 130p and 150P are excellent value and also excellent quality scopes. They have sturdy Dobsonian mounts which are so much better that the flimsy EQ mounts on offer, and which you have. Wobbly scopes are frustrating enough to put people off.

There are things you can do to reduce vibration on the scope, and I would just recommend you take your time and be patient. Astronomy is a life long hobby and you are always learning, that’s what makes it so interesting.

BTW, the angular size of Pluto is about the same as the angular size of Betelgeuze. No wonder it's hard to observe.

My secondary has #3 phillips screws, so I got a screw driver with a hole at the end of the handle. I tied about 120 cm chord in a loop through the hole. Now when I ajdust the secondary, the loop is around my neck so that if the screw driver slips, it doesn't hit the primary mirror, but remains hanging by the chord. Allen keys are a bit harder to "secure" like that.

My Allen key set consists of keys from 1.5 mm to 5 mm. With the focuser I have used all the other keys but 4 mm.

I tore the focuser into pieces originally, because the coarse focusing knob next to the fine focusing knob was rotating free. I decided to do an overhaul now that it was in pieces on my table. I greased it with lithium grease, and put it back together. I tightened the tightener nut such that the fine focus would turn the big knobs even if there was some resistance. After just some tries, the fine focuser became loose and had no effect. So I tore it apart again, tightened the nut, and put it back again. It felt good - for a while. Then it became loose again.

Any ideas why does it get loose? And should there be some kind of lock nut?

I'm a beginner myself, but...

At least it's good to check the temperature range of your mount. Also some zoom eyepieces tend to ger really rigid in -20C. The hint is to warm it in your pocket.

The dew, especially when frozen, is a problem, but there are tube warmers (I have heard). I don't remember hearing any other limitations by cold for the optics. I don't think the dew - even frozen - causes damage to your optics, unless there is plenty of it and it melts fast, when you come back in. Probably not much even then - just spots left from evaporated water.

I've also heard that you should dress for -20C as if it was -25C. Standing still a long time makes you feel cold compared to normal outdoors activities.

My 2 cents, and greetings from Nokia, Finland, where it's sometimes about -30C in winter.

On 13/08/2020 at 11:41, AstroMuni said:

Just drawing the rays on a piece of paper helps for me 🙂

Did that yesterday to figure out the secondary offset.

4 hours ago, popeye85 said:

Thanks for the comments. 

Noted about the m31/32 gaff!  (Although in my defence the guide will get you to m32 aswell!!)

I like the suggesting of @Vox45  about getting a mic to attach to my shirt and will certainly be a investment ! (Thanks for the video aswell!) 

I'm also working on sorting out the mirror imaging and hopefully that won't be a problem going forward.

Thanks for the comments and keep them coming! The only way for me to improve is identifying the faults!

Colin.

It's also important to hear about the good things , that you should not change.

12 minutes ago, John said:

There is a section in this piece by Howie Glatter titled "BARLOWED LASER PRIMARY ADJUSTMENT" which goes into the optical principles:

http://www.collimator.com/collimation

Loads of thanks! I have to ponder that for a while, but it's just the right language for me, and it seems to make sense to me. I actually think, what I'm looking for, is there. I just need to get that info organized in my head. I think I'm getting close...

I'd still be interested on how the barlowed laser method works - optically.

BTW, is it important that the laser output hole is in the very middle of the target? I assume that it doesn't have to be that precise.

10 hours ago, Ricochet said:

It basically turns the laser into a torch which illuminates a patch in the centre of the primary. So long as the secondary collimation is close enough that the doughnut is illuminated, you will see the shadow and be able to use it to collimate. I think because the beam is diverging, small changes in secondary collimation will not alter the angle of the rays hitting the centre of the primary and so the reflected image is the same. 

I understood that moving the secondary mirror or focuser a bit, moves the lit spot, but the doughnut reflection stays put around the laser output (as long as the spot covers the doughnut).

3 hours ago, AstroMuni said:

Over and above what Richochet has mentioned, it helps compensate for any wobble in the focusser. This figure taken from book Astronomy hacks may help explain it better...

Thanks.! It definitely did!

Still curious, though, about what makes it work such that alignment errors of secondary and focuser don't mess up the results.

I wonder if anybody could bend the method for me from iron wire?

I tried to figure out how it's done from Carlin's web page, but I still didn't quite get it.

And why pretty much only the primary mirror collimation affects the result?

Does anyone know where to find the S&T article?

2 hours ago, PeterCPC said:

Hello and welcome. You can change the Theme at the bottom of the page.

Peter

Found it, thanks. Much better now.