Stub Mandrel

Can you post some example images?

I put a layer of ceramic thermal wadding under my bed and it heats up nearly twice as fast. Just lying a sheet of A4 on top speeds it up even more, but make sure you don't leave it in place... in the long term I might make a full enclosure.

I'm printing the first prototype mirror holder for a mirror cell, using Monoprice PLA+ which is printing beautifully, no change to settings.

To print the other parts of the cell I need to extend my Y travel 35mm to use the whole of my bed, so I've ordered a couple of 8mm rods and some M10 studding.

Just realised I need a longer toothed belt 😞

On 20/04/2020 at 12:56, Ships and Stars said:

My first photo of Messier 101 taken with a 20" SW Stargate 500p dobsonian and Nikon D810 with ES coma corrector under fairly bright town 20.2 SQM skies.

Excuse the terrible vignetting on the edges! Working on that. 👀

220 x 8 second subs at ISO 2500 for a tick over 29 minutes total integration. 

No darks/flats or bias shots.  The images were stacked in DSS using recommended settings, then edited in Lightroom 5.

Will learn how to stretch photos and add darks at some point 👍

 

 

Wow, that truly proves aperture is king!

Forgot to post the final version of this one. Please with the detail.

1 hour ago, mikeDnight said:

Yet another book arrived this morning from Book Deposatory,  via carrier pigeon. They informed me it was "winging its way to me" on April 3rd. 

I haven't read any of it yet, just looked at the pictures, but I must say it looks a promising read. Lots of nice refractors - which Neil E has the Hot's for deep in his heart. One day he might write a best seller entitled "Takahashi"! 

If I owned that table, I'd have to paint the underside greeny-grey-blue and mount a waterline model of a ship on top!

2 hours ago, knobby said:

Hi all, excellent thread ... Just wondering if the EQ6R will handle a C8 EDGE / ASI 1600mm / filter wheel etc, £1200 is a lot of money if it still can't guide my gear ? imaging scale is 0.56 so a big ask 🙂

 

Last night I was imaging with a 150PL (which is similar weight to the C8 because of the long tube), ASI1600, filter wheel plus a DSLR on a ball mount with a double battery pack on the counterweight bar. Focal length is 'only' 1200mm  but my imaging scale is 0.64" so I think yours might be a bit smaller than 0.56"?

Anyroad up... that's on an HEQ5 and my guiding tops out at 0.59" when the seeing is good and the wind isn't gusty, but to be honest I get tight, round stars and lots of detail. The EQ6 achieves similar accuracy, but it can take a greater payload so my thought is either HEQ5 or EQ6R will handle the C8. The EQ6 has teh potential to take much bigger scopes but will be better in a wind as well I suspect.

I think you would have to go to an EQ8 or similar to do better.

On 18/04/2020 at 20:44, glafnazur said:

Hi, this is my first attempt - M81 & M82 taken on 16/04/20. I used a Nikon D750, SW Esprit 100ED. It was unguided and something like 150 x 10 second at ISO 1000.

I see stop signs, not pictures...

Who needs the postman when you can collect everything you need yourself?

I threatened to go back and get more data. This is about 1 3/4 hours of L and almost as much one each of RG & B. Was a pig to get the colour balance right as there was a lot of blue in the background sky and od pattern noise in the L background that only appeared when I stacked both night's data .

Gradient Exterminator is well worth getting, but if you have Pixinsight, I'm pretty sure 'dynamic background extraction' does the same thing.

19 hours ago, MarkAR said:

A slight variation would be to taper the outside so that its slightly oversized the flange end.

That way the weight will create its own "Lock", to move it just lift the weight and slide the bush.

A possibility, but there may be too much variation in the bore of the weights as tehy are uaually pretty crude castings, plus I'm wary of relying on the bush alone to secure larger weights.

7 hours ago, Fieldsy said:

What to do if a spider takes up residence in your tube over night ?

New flats 🙂

19 minutes ago, geeklee said:

Agreed, that was worth the zoom.  Thanks for the info on the method of capture too (using Ha).

I've only got a slight twitch at it being upside down... honest 😅

I could post the right-way-up version but I don't want to waste storage SGL space!

Many of teh best targets for astrophotography are quite big. There are great things you can image with any lens, so a star adventurer on a decent tripod is a great way to start.

My experience is that although Ha needs longer exposures, the lack of dispersion and reduced seeing effects mean it amkes sense for lunar imaging.

This is a 4-pane mosaic using the ASI1600MM, each quadrant being 80%  of 89-100 frames, preprocessed in PIPP and stacked in AS3. Processing was minimal, just a very light deconvolution in Astra Image before combination, using feathered masks for the joins in photoshop. Then another, equally light, deconvolution and a touch of curves to raise the darkest parts of the moon while pinning the sky background under 10%.

It is worth zooming in and exploring, even though a near-full moon doesn't show a huge amount of relief. Yes I know it's 'upside down' but I think that makes it less familiar and more interesting.

Lots of people use weightlifting weights to add extra mass to their mount counterbalance, but the 1" diameter holes mean they are a sloppy fit, even when sandwiched between two 'normal weights'. This creates the opportunity for them to slip, jarring the mount and possibly spoiling a sub.

Here's a solution - 3D printed bushes.The bushes fit neatly in standard weights and fit standard 18mmm or 20mm shafts.

You can download the STL files from http://www.stubmandrel.co.uk/lifting-weight-adaptors-for-telescope-mounts

On 14/04/2020 at 20:16, CraigT82 said:

Ade have you figured out a way to fine align (polar) in the az direction using the mount adjusters? Without loosening the central mount bolt (which I cant seem to get at!).

If it's like my mount extension there should be a thrust bearing that allows you to tighten the holding screw without rendering the mount immobile. Not actually that good in practice.

21 hours ago, lnlarxg said:

Markarian’s Chain, taken early March when a few clear nights presented themselves 

SW130pds, modded canon 550d with SW aplanatic CC, astronmik CLS filter, 2.5hrs worth of 5min subs, DSS stacked and PI processed with final touches in Lightroom.  I recently started to use dithering and now I know what “dither or die” means

Hope you don't mind but I took a screen grab of your image, made a selection around the galaxies, inverted it and ran Gradient Exterminator on coarse/strong. There's a similar tool in pxinsight, if you run it on the full image the end result should be pretty impressive!

7 hours ago, CaptainShiznit said:

Really? Is that where the majority of the internal reflection problems lie then? Very useful info!

I think the mirror rings could be the secret to eliminating 'star bloom'

2 hours ago, CaptainShiznit said:

Just as a side note, did you find a dew shield to fit the 130 PDS? I was after something to reduce internal reflections from a street light without flocking and asked FLO about the Astrozap ones who replied that none were suitable.

I made one from an old camp mat, lined with flock. It's lasted years and been ace.

As for flocking the tube, a square opposite teh focus tube gives much of the benefit for little effort.

1 hour ago, pietervdv said:

Very nice, I really like b/w images like this. 

Pieter 

Thanks, I will be adding colour, but I think B&W images show textures better.

3 hours ago, johninderby said:

Helical fine focuser for the Omegon 127 Mak.

I use one of these for the guider on my 130P-DS, it's a lovely piece of kit for the modest price.

Two hour's data from last night, using the 150PL and ASI1600MM:

20 hours ago, tonyowens_uk said:

With proper sealing, updated clutches, steel shafts, precision bearings and an antibacklash Declination gear, an EQ8 controlled using Green Swamp server, (a modern alternative to EQMOD) will point and autoguide a 35 kg imaging payload for years, with excellent reliability. 

What is this 'green swamp' of which you speak?

Is it ASCOM compliant and more importantly is it more stable than EQMOD on W10 machines?

8 hours ago, gorann said:

By coincidence I just saw this video advertizing the more recent EQ8-R, and at the end of the video the seller proudly announces that it is capable if guiding at 0.6"/pixel, and that was with OAG on a 1000mm FL telescope. As long as seeing cooperates I regularly get 0.4"/pixel with my old EQ8 (recent curve attached) even if it is carrying 40 kg of SCT and 40 kg of counterweights

I think they deliberately quote conservative figures. My HEQ5 was guiding at 0.79" last time I was out, with a 1200mm scope on it. I'm not surprised an EQ8 can halve that, and I bet the EQ8R can as well.