Imaging with the 130pds

[Uranium235]

Time to see if the 130 and Star71 can play nicely together on the Beehive.... Got the 130 doing lum and the 71 filling in the colour with the DSLR at ISO400:

Been a bit naughty... absolutely no flats or other calibration frames

 

[Adam J]

Funny thing I was looking at M44 too, this is my attempt.  5x600s, 1000D, Flats and Bias, Astronomic CLS Clip.

[Owmuchonomy]

First light via the 130 PDS with the new ASI 174MM this morning gathering a few small blemishes on our star's surface.  Deepest joy, as I did all the capture with my MAC for the first time too.  How easy is that!  I compared a stack with and without a Wratten 56 filter.  It was definitely better with, so here it is.  The larger spot including penumbra is about 3 times the size that Mercury will appear against the Sun's disk on the 9th May during its transit. 

 

 

Edited April 28, 2016 by Owmuchonomy
Extra info.

[StamosP]

Today i tried flocking the tube with dc-fix black velour. I actually flocked half of it when i though that it's a good idea to see the differences before flocking the other half.

So i pointed a flashlight inside the tube and the result dissapointed me, when the angle of incidence to the surface was small the flocked surface looked shiny, more black but certainly shinier than the unflocked one.

I don't think this should happen so i gave up flocking until i gather more info...

[Galactic Wanderer]

I've got the sky watcher 150PDS. Would the results be better or worse. 

[Adam J]

7 hours ago, Galatic Wanderer said:

I've got the sky watcher 150PDS. Would the results be better or worse. 

As the F-Ratio is the same (F5) in both scopes it will not make too much difference, the actual focal is 650mm for the 130PDS and 750mm for the 150PDS, it will be ever so slightly harder to guide as it weighs a little more but this is probably offset by the fact that you sometimes have to add weights to the 130PDS to balance the tube anyway. So in the end it just depends on what it is you are taking pictures of, it will be better for some smaller targets but you may struggle to fit larger targets into the frame.

 

[Adam J]

M81 and M82 form Saturday evening, my first attempt at Galaxies, I found the processing to be much more difficult to get a pleasing result than I have with with clusters or Nebula.  Needed more data but my DSLR battery failed me at about 3am lol. 1000D (modified): Astronomic CLS clip filter, MPCC Mk3, 14 x 400s @ 1600ISO, 30 x Flats but no dark frames (because of the battery), I had to spend an hour manually removing the hot pixels lol.

Edited May 2, 2016 by Adam J

[Galactic Wanderer]

1 hour ago, Adam J said:

As the F-Ratio is the same (F5) in both scopes it will not make too much difference, the actual focal is 650mm for the 130PDS and 750mm for the 150PDS, it will be ever so slightly harder to guide as it weighs a little more but this is probably offset by the fact that you sometimes have to add weights to the 130PDS to balance the tube anyway. So in the end it just depends on what it is you are taking pictures of, it will be better for some smaller targets but you may struggle to fit larger targets into the frame.

 

I guess if the focal length is different by 100mm it wouldn't make that much difference.  Btw nice pics of M81 an M82. What camera and scope did u use?

SEB

[Adam J]

5 minutes ago, Galatic Wanderer said:

I guess if the focal length is different by 100mm it wouldn't make that much difference.  Btw nice pics of M81 an M82. What camera and scope did u use?

SEB

I actually said above in short hand, its a Canon 1000D DSLR, with the IR filter removed (astro-modifed) with the a 130PDS and a coma corrector, the image is slightly cropped. I see that you are in London, what is the light pollution like near to you? I imagine that you may be forced down the road of narrow band imaging...

Edited May 2, 2016 by Adam J

[Galactic Wanderer]

Ha! sorry I'm half asleep.

[Galactic Wanderer]

 

Hey Adam,

Awful. I have 10 streetlight right behind me but luckily my house blocks it so that lessens the effect a bit. I'm a bit of a newbie when it comes to astronomy and have not really tried any imaging yet. I am sorting out my power supply and then I hope to come to imaging soon. We've bought a house down in cornwall so I hope to try some there. The scope's a sky sky watcher explorer 150pds eq3pro and canon eos 60d

SEB

see post

 

[StamosP]

Today i removed the secondary mirror from my 200pds. Here is a side by side comparison between the two mirrors...

To my surprise there is a lot of mirror coating leakage to the edges, maybe a potential source of glare-reflections?

Anyway, i will not leave it like this, blackening the edges (black permanent marker is easier but i was thinking of black flat paint) is the next step before putting the mirrors back (the 58mm mirror is going to be installed to the 130 and run a couple of tests...)

[Adam J]

I removed my secondary a few weeks back only to find that the person who had installed it had left me with a dirty great thumb print on it.

[Uranium235]

On 03/05/2016 at 19:33, StamosP said:

Today i removed the secondary mirror from my 200pds. Here is a side by side comparison between the two mirrors...

To my surprise there is a lot of mirror coating leakage to the edges, maybe a potential source of glare-reflections?

Anyway, i will not leave it like this, blackening the edges (black permanent marker is easier but i was thinking of black flat paint) is the next step before putting the mirrors back (the 58mm mirror is going to be installed to the 130 and run a couple of tests...)

I'd be interested to see how you get on with this. It is possible to flock the sides of a secondary, but you would have to be super-careful not to get any adhesive on the mirror surface.

[StamosP]

22 hours ago, Uranium235 said:

I'd be interested to see how you get on with this. It is possible to flock the sides of a secondary, but you would have to be super-careful not to get any adhesive on the mirror surface.

It was simple, at first i rubbed the edges with 120grit sand paper and removed most of the leaked coating, then using a small painting brush i painted it flat black. The result was shinier than i wanted so i used a small piece of green scotchbrite to make it matte by rubbing the paint job lightly.

I also used a piece of dc fix velour to the back of the mirror...

The problem is that i cannot center the 58mm secondary under the focuser using my sight tube, the holder should be approximately 5mm shorter (or the offset smaller). Even if i screw it all way in it is obviously closer to the primary than it should be...

Any thoughts?

Edited May 7, 2016 by StamosP

[Uranium235]

The only way I can think of is to move your spider vanes forward a little, but I cant imagine there being much room to do that.

[StamosP]

3 hours ago, Uranium235 said:

The only way I can think of is to move your spider vanes forward a little, but I cant imagine there being much room to do that.

Or maybe shortening the holder by 5mm... The problem is i don't want to deattach the mirror from its holder...

 

Edit:

The tests...

before at 0 degrees

 

at 90 degrees

 

after at 0 degrees

 

at 90 degrees

 

Note that after the replacement i didn't pay too much attention to collimation plus it was strange to do it without properly centered secondary...

Comments?

Edited May 7, 2016 by StamosP

[Uranium235]

In that case it would be easier to move the vanes forward.

Its difficult to tell if its been a success until you get it out under the stars to see what effect it has had.

[sagramore]

My first image of the sun! Taken on May 8th as a 4-panel mosaic. Full posting with image details can be seen here: 

Flickr for higher resolution here: 

 

 

 

     

 

[Adam J]

On 07/05/2016 at 15:45, StamosP said:

It was simple, at first i rubbed the edges with 120grit sand paper and removed most of the leaked coating, then using a small painting brush i painted it flat black. The result was shinier than i wanted so i used a small piece of green scotchbrite to make it matte by rubbing the paint job lightly.

I also used a piece of dc fix velour to the back of the mirror...

The problem is that i cannot center the 58mm secondary under the focuser using my sight tube, the holder should be approximately 5mm shorter (or the offset smaller). Even if i screw it all way in it is obviously closer to the primary than it should be...

Any thoughts?

Is it possible that the secondary from the 150pds would be a better compromise or is that the same one as the 130 or something?

[Uranium235]

The 150 secondary is midway between the two, so youre correct in your thinking. I think the main issue would be the amount of obstruction involved and whether it has an impact on the image quality. An alternative is to keep the existing secondary and lower the height of the focuser, but that also involves either moving the primary back and/or moving the spider foward so the focus point is shifted inwards.

[StamosP]

What's the minor axis diameter of the 150pds mirror?

If there are not any diffraction problems-artifacts due to the larger obstruction i think there will be a significant improvement when using a dslr for imaging dsos, my tests showed a 50-55% vignetting at the corners with the 47mm mirror...

The smaller overall amount of photons hitting the primary could be overcome by slightly longer exposure times (correct me if i'm wrong). Of course with smaller chip cameras maybe it is better to leave the stock mirror in place.

The tak e130d for example has a 64mm secondary mirror (ok thats comparing apples to oranges considering the quality differences).

 

 

[Owmuchonomy]

I used the 130 PDS for the Mercury transit in tandem Alt Az mode with my Lunt 60 thus:

..and about 2 1/2 hours in I used it with my ASI 174MM to capture some 15 minute interval shots compiled below:

Took we a while to de-rotate the individual layers to defeat the effects of field rotation!

Full thread is here:

 

[dyfiastro]

Well last night I got my first light.

[CosmicOrangutan]

Hey Everyone  

Can anyone offer any advice on cleaning the 130 PDS mirrors? What cleaning solution to use or brushes etc. I have some small speckles appearing on the secondary mirror and would like to get rid of them without damaging the mirror and the primary is gathering some larger chunks of dust somehow. I'm going to put my 130 into hibernation for the summer nights and want to give her a bit of a tune up. 

I'm also wondering whether to get the hacksaw out and chop out the section of the drawtube that protrudes into main tube. Is this a worthwhile endeavor (I use this scope only for imaging and an 8" SCT for obs/imaging)? if so can you roll the drawtube right out of the focuser to make the cut and then roll it back in?  

any other tweaks people would recommend im all ears.

Thanks in advance,

George