Stub Mandrel

Thanks Julian.

16 hours ago, mAnKiNd said:

I would still think that you'd get Pacman stars with the drawtube protruding into the light path, because just like the spider vanes render diffraction spikes, so would the drawtube in taking a chunk out of that side - but I might just test that to see. I'd need to reorganize my imaging train so that the coma corrector is not sunk further down.

Well I've already done the 'unkindest cut', but the clip ring does seem a good idea. Here's a comparison of a 150PL star (left) and 130P-DS star. I think teh slight assymetry of teh 150PL star is because it was near the side of the frame and using a 1.25" nosepiece does cause vignetting:

Two nights ago, just before the so-called 'Pink Supermoon', I ran runs of ~480 frames using my 150PL and ASI1600 through each on L, R, G, B, Ha Sii and Oiii. These are the results:

L only:

L RGB:

S, Ha, O:

On 07/04/2020 at 14:12, Chaz2b said:

Pushing this thread along, has any Linux user have a preference of distro for astronomy?

chaz

Microsoft 🤣

Sorry!

5 hours ago, Dr_Ju_ju said:

And here is the proof of that type on a Prusa printer...   The Black & Red is for some LED's instead of the Ikea lights....

Ah, I like the cover for the wiring, could you upload an STL for it?

On 02/04/2020 at 16:41, mAnKiNd said:

For anyone interested in fixing their star shapes (subject is Vega) from this to this:

I designed a 3D print on tinkercad (.sti file attached)Skywatcher 130PDS Newtonian Primary Mirror Aperture Mask.stl, found a local 3D print shop to make it for me and applied to the mirror clips as such:

 

Minos 

That makes me wonder if the drawtube shortening is really curing anything. Very tempted to do this when my printer is back in action.

1 hour ago, Dr_Ju_ju said:

If your budget will stretch to it I'd recommend getting a Meanwell version of one of these https://www.ebay.co.uk/itm/AC-DC-12V-15A-180W-Transformer-Power-Supply-Driver-Switch-for-LED-Strip-Light-UK/264540526259

but then I use that type anyway, with no issues....

I use a 150W version of those for my astro, but because of the construction and access to the terminals I fitted it inside an outer case with a cooling fan.

Is 180W enough for a Prusa-type rpinter?

Help folks!

Yesterday I printed my 20th mask headband and 18th chin piece then without a pop my printer fell suddenly silent.

This morning I found the culprit, a length of wire and somehow got into the fan and stopped it, it looks like it's blown a thermal fuse.

Although the 500W ATX PSU worked fine, I am very happy with the 150W 12V PSU I use for astro, and I see people often have similar ones mounted to the frames of their printers.

This could be a good time to fit one (and the remote switching PCB for my hot bed).

Can anyone recommend a model they have found safe and reliable without breaking the bank?

(Although I'm beginning to think another ATX supply might be safer as it is fully cased...)

Thanks

It's soo unfair. Venus has spent almost all of this apparition either behind or rapidly approaching the Evil Tree(TM).

On 02/04/2020 at 21:39, CraigT82 said:

Excellent thread. We are privileged to have vlaiv as a member of the forum: he is a great resource! 

I just wish he'd put his face mask on properly...

On @Vlaiv's second point it's a bit like this:

TESTING TESTING ONE TWO THREE

The text is only marginally brighter than the background and appears almost invisible, but if you backed the black point downwards it would be become visible and could be stretched to be normal black and white.

2 hours ago, JeremyS said:

I'll be listening to Handel's Messiah whilst installing it.

Hallelujah!

20 hours ago, JamesF said:

This from the BBC News website:

Apple has purchased the weather predicting app Dark Sky and plans to shut down the Android and Wear OS versions.
...
The app's creator Adam Grossman said the partnership would allow Dark Sky to reach "far more people".

James

Ah, but iAstronomers are a better class of astronomer so they count twice.

On 30/03/2020 at 16:18, RolandKol said:

I am in the list of people who were not able to get a correct spacing with SW CC+ASI1600MM on 130PDS...
Standard ZWO rings were very close, but coma was present... With delrin spacers managed to reduce it, but not completely...

I guess, it also depends how primary is colimated... Full in or Full out and etc... Not yet figured out...

Hmm. Shouldn't depend on where the primary is.

Took me a  while to find this but I posted this back in December:

I've just taken some 'real world' measurements.

It looks to me that ZWO have supplied a pretty much optimal set of adaptors, assuming a standard 55mm back focus for the typical field flattener or coma corrector.

Without the EFW:

ASI1600 --->  21mm T2 adaptor** ---> female/female adaptor** ---> T2-48mm adaptor**

6.5mm + 21mm + 11mm + 16.5mm =   55mm

**supplied with ASI

With EFW:

ASI1600 --->  EFW --->  T2-T2 male/male adaptor* ---> female/female adaptor** ---> T2-48mm adaptor**

6.5mm + 19.97mm + 1.96 mm + 11mm + 16.5mm =   55.93mm

*supplied with EFW

**supplied with ASI

Allowing for ~0.7mm shortening of the light path by the filter, this is pretty close again at 55.2mm.

3 minutes ago, JamesAstro2002 said:

Did you require any extra spacers to get the right backfocus?

Some people have criticism of the SW CC, but it needs no spacers to work with a T-adaptor and DSLR, and if used with the ASI1600 there are two spacers supplied that give the correct spacing; unlike other types it seems to be relatively insensitive to spacing anyway. Some people get reflections of bright stars, but I've found that only Sadr and Alnitak are bright enough to cause a visible 'ghost' image and was easily able to correct it.

And here are a couple of works (some in progress) from last night:

Well done, I wish my view would let me get 17 hours on a target!

I managed about 30 minutes each for LRGB last night, need more to reduce the noise in the extended disk.

1 hour ago, JamesAstro2002 said:

Hi all,

I've been thinking about cracking my 130pds out again for imaging with my asi 1600mm. Any other users of the 1600mm and this scope?

And would an adapter like this be okay for connecting the cam? I want to test the scope out before purchasing a CC again.

https://www.firstlightoptics.com/adapters/astro-essentials-2-inch-t-mount-camera-nosepiece-adapter.html

Lots of us! It's a match made in heaven 🤣

I think you will want a CC, the Skywatcher one works well when used with the two spacers that come with the camera.

This is one from Friday night. I was chuffed to get the faint outer spiral.

@Whistlin Bob this is indeed a fine target, can't believe I haven't found this gem before!

I've added some Ha:

I'm beginning to get the hang of processing LRGB. This is M51 from last night, with my 150PL, which at 120mm is ideal for galaxies.

I lost the guide star a few times during the first half of the night so lost a lot of my L subs (nearly an hour salvaged out of two hours effort), but all the RGB ones (about 30 minutes each) were spot on.

Last night felt more like a 'getting to know you again' session than anything else. Guidescope focus was a bit off so stars aren't perfect, especially in the first image. Iffy transparency meant almost all frames suffered from LP gradients.

Some stuff near the cone nebula in Ha (it's actually just poking into the top of the frame...) Gradients are a bit off as it was auto-flat corrected by sharpcap using the wrong flat...

The snowman nebula, which is far to faint to image last night as it barely showed above the LP, so very, very noisy. I need a night of almost perfect transparency for this one or lots and lots and lots of data.

And my first proper L-RGB DSO image, the Leo Triplet, still showing a bit of gradient.

Originally intended for 'show us your setup at night'... I've stretched this image 🙂 and it shows what I'm hanging off the 130PDS stock focuser.

On 12/03/2020 at 13:51, mos6522 said:

I double checked my collimation, and sure enough, it needed some help. I am using a Skywatcher EVOSTAR 80ED that I thought was in good order. However, using my laser collimator from my reflector and my cheshire, I could tell it was not.

The telescope wasn't that far out, but to resolve it, I had to take the focus/back tube assembly off, elongate one of the holes that it mounted too (with a file) and then re-assembled using the slack to make up for the bad collimation. 

Finally, I noticed that the 2"->T-Ring was looser than I wanted from the focus rack to the camera train, so I replaced it.

I did do a star test, and the point in the out of focus is in the middle, but I still see slight banana'ing. This was all without a flattener, just Objective->Filter->Camera. The interesting thing, after I collimated, the bananas lined up better, like the ends were in perfect lines, prior to collimation, they were kind of all over the place.

The thing I am chasing is just what I feel are blurry pics. I will try and get a good sample distoration. 

What I am trying to fix is what I feel should be "more stars". The following is a Whale Galaxy shot done through a 7nm Ha filter using 5min exposures. It seems there are some "fuzzy" blobs that should be stars, but don't come out at all. Am I at the end of what I can do with this camera and scope?

 

That's not bad actually, that area isn't very starry the shapes in the galaxy are not points. Ha isn't ideal for galaxies, and for comparison here's a shot of mine and you can see my stars are nowhere near as nice as yours...

2 hours ago, Adam J said:

When using a heavy camera and with the additional weight of the auto focuser you are forced to place the rings as far forward as possible, the 130PDS already suffers from being nose heavy. 

It's still possible OK as I just attach the dovetail to the mount near the front ring (best position for me is with about 1" between the stop screws and the cl;amp on the mount) . A small amount of nose-heaviness helps limit dec backlash.

11 hours ago, Adam J said:

Won't work gets in the way of the tube rings. 

Not on my scope.

Depends where you have the tube rings!