Imaging with the 130pds

[starwatcher_ch]

On 16/05/2022 at 09:12, Pitch Black Skies said:

How much of your focuser tube is protruding into the OTA?

My focuser tube is protruding into the OTA around 16mm (measured from the black outer tube) while MPCC/DSLR is in focus position. Maybe with a TSGPU it would be much better, since I read it extends the focus point about 10mm... I don't know...

Maybe someone here with a 130PDS/DSLR/TSGPU combo still in its original condition (tube not shortened)? What this combo looks like would be very interesting...

Edited May 17, 2022 by starwatcher_ch

[Pitch Black Skies]

Well I know @Jamgood uses the GPU with the original focuser tube, but I think he uses a 294 with it. Not sure if that makes a difference.

Edited May 17, 2022 by Pitch Black Skies

[Pitch Black Skies]

1 hour ago, starwatcher_ch said:

Maybe with a TSGPU it would be much better

It pushes the focus position up by 7mm when sat in the compression ring.

If you can screw it on to the focuser tube with an M54-M58 adapter it pushes the focus position up by 19mm.

Where these lines are flush with the white housing is where the focus position is.

I haven't included a line for when the cc is screwed into the focuser.

Edited May 17, 2022 by Pitch Black Skies

[Pitch Black Skies]

On 16/05/2022 at 03:34, braybarr said:

Can anyone tell me the size of the mirror stalk for secondary mirror? 

Hi,

I measured it in place so it's not exact but should be good enough for your purpose.

CS

[sagramore]

On 15/05/2022 at 20:34, starwatcher_ch said:

@Pitch Black Skies The past 3 days were intense 😉 But I read the whole thread! I see everybody struggles with more or less the same issues, but about one thing I didn't find enough information...

On my M13 and M57 images there are some reflections: faint on M13 (top mid right - vertical direction) but bright on M57 (bottom right - horizontal direction). 

What causes these reflections? Are they caused by bright stars outside of the FOV? I double checked the field of view in Stellarium and for M57 it's obviously caused by the star Sulafat. But is it possible that the 3 faint stars (almost in a row) outside of the FOV are responsible for the faint reflections (top mid right) in my image?

What would help to prevent such reflections? Flocking the scope/spider?

 

*IMAGES REMOVED*

 

 

Just a thought but is there any chance these could be caused by local stray light? Either getting in under the primary or even doing something weird... like reflecting off the secondary spider vanes?

[sagramore]

Accidental double post! Oops.

Edited May 18, 2022 by sagramore

[edarter]

Does anyone have details on what longer collimation screws and springs I would need to buy in order to push the primary mirror up the OTA a bit?

Edited May 18, 2022 by edarter

[starwatcher_ch]

16 hours ago, sagramore said:

Just a thought but is there any chance these could be caused by local stray light? Either getting in under the primary or even doing something weird... like reflecting off the secondary spider vanes?

I don't think so. Yesterday I did some M13 abd M57 exposures in a row, with the dew shield in place. Also I use a "swimming hat" for the primary mirror area to block stray light.

This was my initial "problem" image:

On 15/05/2022 at 21:34, starwatcher_ch said:

 

Yesterday I had the same reflection on M57 again... exactly the same position like before. But not on M13. It seems to be related to the selected field of view and most probably the CC. 

Each image is a stack of 12 sub exposures, no flats, no darks.

Edited May 18, 2022 by starwatcher_ch

[Bibabutzemann]

NGC 7000 , 3.2hours with the L extreme and EOS 1200Da cooled

I just did a quick processing, because i may add some data in the future. Just wanted to show the perfomance of this awesome filter under full moon conditions. 

No background extraction was necessary, which i still find mind-boggling. 

[Bibabutzemann]

5 minutes ago, starwatcher_ch said:

I don't think so. Yesterday I did some M13 abd M57 exposures in a row, with the dew shield in place. Also I use a "swimming hat" for the primary mirror area to block stray light.

This was my initial "problem" image:

Yesterday I had the same reflections on M57 again... exactly the same position like before. But not on M13. It seems to be related to the selected field of view and most probably the CC. 

Each image is a stack of 12 sub exposures, no flats, no darks.

maybe it would be helpful to rotate your camera and shoot the same target. Just to see how the reflection changes if at all.

Edited May 18, 2022 by Bibabutzemann

[starwatcher_ch]

24 minutes ago, Bibabutzemann said:

maybe it would be helpful to rotate your camera and shoot the same target. 

Thanks. Had the same idea. This is my plan for next CS 🙂 

At least I know now that the dew shield makes no difference.

Edited May 18, 2022 by starwatcher_ch

[braybarr]

22 hours ago, Pitch Black Skies said:

Hi,

I measured it in place so it's not exact but should be good enough for your purpose.

CS

Oh shoot! I’m new to this forum so I missed your reply. Thank you so much for taking the time to do this!

[braybarr]

Cropped view of my current project. About 5 hours of Ha data with a 1600mm-pro and ZWO narrowband filters. This newt is so dear to me. 

[Space Oddities]

3 hours ago, starwatcher_ch said:

Thanks. Had the same idea. This is my plan for next CS 🙂 

At least I know now that the dew shield makes no difference.

Could it be a scratch in the glass of the flattener perhaps?

[starwatcher_ch]

13 hours ago, Space Oddities said:

Could it be a scratch in the glass of the flattener perhaps?

I'll check if there are any scratches later. But I think if there would be a scratch, there would be reflections on every target... 

[braybarr]

20 hours ago, starwatcher_ch said:

I don't think so. Yesterday I did some M13 abd M57 exposures in a row, with the dew shield in place. Also I use a "swimming hat" for the primary mirror area to block stray light.

This was my initial "problem" image:

Yesterday I had the same reflection on M57 again... exactly the same position like before. But not on M13. It seems to be related to the selected field of view and most probably the CC. 

Each image is a stack of 12 sub exposures, no flats, no darks.

Hey, what dew shield is this and how well does it work for you? 

[starwatcher_ch]

11 minutes ago, braybarr said:

Hey, what dew shield is this and how well does it work for you? 

It's exactly this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p8075

I've only used it once so far... so the only thing I can say about it: its stiff enough to attach the Bahtinov mask to it for focusing. 

My hope was the dew shield will eliminate reflections I'm struggling with, especially on M57 Ring Nebula wide field. But also with the dew shield there are reflections...

[braybarr]

Just now, starwatcher_ch said:

It's exactly this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p8075

I've only used it once so far... so the only thing I can say about it: its stiff enough to attach the Bahtinov mask to it for focusing. 

My hope was the dew shield will eliminate reflections I'm struggling with, especially on M57 Ring Nebula wide field. But also with the dew shield there are reflections...

Sweet, thank you. I’ve read a bit about your reflections and I hope you can sort it soon. My backyard isn’t very dark but thankfully I’ve never had any issues other than my secondary getting dewed over. I’m hoping this dew shield is effective but it gets very humid where I am. Might be the best move to just get a heater + controller to be sure.

[Pitch Black Skies]

2 hours ago, braybarr said:

I’m hoping this dew shield is effective

FWIW I've been using said dew shield for ~6 months. It has completely stopped the secondary from fogging up.

I'm assuming you are from Bray, Co. Wicklow?

I'm in Waterford on the coast so probably pretty similar humidity.

[braybarr]

43 minutes ago, Pitch Black Skies said:

FWIW I've been using said dew shield for ~6 months. It has completely stopped the secondary from fogging up.

I'm assuming you are from Bray, Co. Wicklow?

I'm in Waterford on the coast so probably pretty similar humidity.

I’m from a small city in Ontario, Canada. I live next to a Great Lake so humidity is always very high. It’s rare to be more than 2° above the dew point. I’ll definitely give it a shot, though. 

[Space Oddities]

8 hours ago, starwatcher_ch said:

I'll check if there are any scratches later. But I think if there would be a scratch, there would be reflections on every target... 

Hmm true. And I also just noticed the flare seems exactly parallel to the spikes. Could the spider be involved in this reflection, somehow?

 

I had an interesting read regarding modifications to the bigger brother, the 150P-DS. I already upgraded the dovetail to a Losmandy one, which is very convenient to put the scope on the table, for instance when collimating it. The green dovetail has 2 protruding screws that prevent you from doing that... The Bob's knobs I picked up will definitely help as well, it's so much easier now.

I ordered some flocking material, as suggested in this blog post. I realized the inside of the tube is more like a dark gray than a black... And the sides of the secondary mirror aren't painted, so I'm wondering if adding some paint there and on other parts could improve the contrast a bit? Can't be worse, I guess!

Finally I need to find something to cover the bottom of the telescope, there is definitely light coming through... Too bad the 3D printed cover shown in the blog post doesn't exist for our 130PDS, it looks great! 

 

Edited May 19, 2022 by Space Oddities

[Space Oddities]

I just spent a couple hours flocking the inside of the tube. It wasn't easy to align all the pieces properly, but I managed to get it done! I'm happy with the result, the inside of the tube is so much darker now. Perhaps this will improve the contrast.

The flocking material is good quality, it's very black and the adhesive doesn't look too bad, but just in case I added some glue. Hopefully it will stay in place, it wasn't an easy task!

I tried to make a before/after picture, but with the complex lighting situation, it's not a very scientific comparison. But I think the 2nd picture speaks for itself! The scope was facing the window 🙂

[starwatcher_ch]

37 minutes ago, Space Oddities said:

I just spent a couple hours flocking the inside of the tube. It wasn't easy to align all the pieces properly, but I managed to get it done! I'm happy with the result, the inside of the tube is so much darker now. Perhaps this will improve the contrast.

The flocking material is good quality, it's very black and the adhesive doesn't look too bad, but just in case I added some glue. Hopefully it will stay in place, it wasn't an easy task!

I tried to make a before/after picture, but with the complex lighting situation, it's not a very scientific comparison. But I think the 2nd picture speaks for itself! The scope was facing the window 🙂

Looks great! Well done.

[Pitch Black Skies]

5 minutes ago, starwatcher_ch said:

Looks great! Well done.

Agreed, really tidy job 👏

[starwatcher_ch]

Yesterday I took M 57 test shots again (12 exposures, each 60sec, no flats, no darks). With the camera rotated by 90°. This time it doesn't seem to suffer from reflections... but only at first glance.

There is also a faint reflection in the lower left area. When I check the field of view in Stellarium, the reason for these reflections has to be bright stars outside of the field of view on the oppisite side... Sulfat on my first M 57 and Sheliak on yesterdays image. They are the brightest stars in the outer filed of view at around Mag. 3.5.

After the M57 test shots I switched to NGC 6946 Fireworks Galaxy. There is also a very very faint reflection in the stacked image that must be caused by HIP 102011.

So far I've no other explanation...