200pds- enhancements?

[Flame Nebula]

Hi

Just wondering if any of owners of this scope  have modified it since purchasing, to improve imaging and/or visual observation? 

Example, I've heard replacing the spider can give razor sharp spikes and flocking can make a big difference, with imaging, to avoid light reflections. 

Did you replace the part that grips the dslr? 

Finally, did you need to get an extension tube to do visual observation? 

Thanks 

Mark 

 

[Aramcheck]

I've made several modifications to my 200 pds:-

• Sub-aperture mask fitted over the primary mirror clips, to reduce the flaring of bright stars
• Replacing the primary mirror springs
• Repositioning the primary mirror centre spot (mine was 3mm out of position)
• Flocking OTA + painting the edges/rear of the mirrors with black paint
• Astro-Essentials Compression Ring Adapter on focus tube / followed later by replacing the focus tube with a Baader Diamond Steeltrack
• Replacing the spider with one of the Backyard Universe type. This makes the diffraction spikes sharper, but increased the amount of light that is diffracted, so fainter magnitude stars also appear with spikes...
• Not forgetting the black shower cap fitted over the bottom of the scope to reduce light leakage through the gaps around the primary
• Light pollution / Dew shield made from a black foam camping mat.

I've also switched from using the suppied Finderscope as a guider, to an OAG.

The only modification I've undone was using silicone sealant to hold the primary, as I ended up with the mirror being pinched & horrible stars... Took ages to figure that was the problem too!

The scope came with a couple of extension tubes for visual, but only use the 200pds for imaging & have a second hand 200 dobsonian for visual (that was free)!

Recent image of NGC2805 below...

Cheers

Ivor

[Flame Nebula]

3 hours ago, Aramcheck said:

I've made several modifications to my 200 pds:-

• Sub-aperture mask fitted over the primary mirror clips, to reduce the flaring of bright stars
• Replacing the primary mirror springs
• Repositioning the primary mirror centre spot (mine was 3mm out of position)
• Flocking OTA + painting the edges/rear of the mirrors with black paint
• Astro-Essentials Compression Ring Adapter on focus tube / followed later by replacing the focus tube with a Baader Diamond Steeltrack
• Replacing the spider with one of the Backyard Universe type. This makes the diffraction spikes sharper, but increased the amount of light that is diffracted, so fainter magnitude stars also appear with spikes...
• Not forgetting the black shower cap fitted over the bottom of the scope to reduce light leakage through the gaps around the primary
• Light pollution / Dew shield made from a black foam camping mat.

I've also switched from using the suppied Finderscope as a guider, to an OAG.

The only modification I've undone was using silicone sealant to hold the primary, as I ended up with the mirror being pinched & horrible stars... Took ages to figure that was the problem too!

The scope came with a couple of extension tubes for visual, but only use the 200pds for imaging & have a second hand 200 dobsonian for visual (that was free)!

Recent image of NGC2805 below...

Cheers

Ivor

Thanks Ivor

So, I guess the burning question is, which of the modifications you made do you think gives the biggest return on effort, with respect to visual and imaging? 

Mark

[PeterC65]

I've replaced the focuser clamp with the Astro Essentials compression ring adapter and have considered changing the whole focuser, but the only sensible upgrade is to the Baader SteelTrack and that's almost as expensive as the OTA and requires the drilling of new holes.

I have a dew shield which stops the secondary from dewing up and helps reduce spurious light, and use a dew heater for the primary.

I've just bought a black shower cap (double layer, from Amazon) as I've noticed light entering from the primary end.

Other than that, I'm disinclined to make changes that require the OTA to be dismantled such as flocking and changes to the primary mirror, but I'm doing EAA not AP so I'm noy looking for perfection.

 

[Flame Nebula]

1 hour ago, PeterC65 said:

I've replaced the focuser clamp with the Astro Essentials compression ring adapter and have considered changing the whole focuser, but the only sensible upgrade is to the Baader SteelTrack and that's almost as expensive as the OTA and requires the drilling of new holes.

I have a dew shield which stops the secondary from dewing up and helps reduce spurious light, and use a dew heater for the primary.

I've just bought a black shower cap (double layer, from Amazon) as I've noticed light entering from the primary end.

Other than that, I'm disinclined to make changes that require the OTA to be dismantled such as flocking and changes to the primary mirror, but I'm doing EAA not AP so I'm noy looking for perfection.

 

I'm planning on doing AP, but I'm not looking for perfection either. 🤣

What is the difference between EAA and AP? 

[bottletopburly]

I’d mirror others comments, to start off do the simple tweaks that cost minimal outlay , Flocking ota , blacken inside of draw tube, blacken edge of secondary, check centre spot on primary, mine was out 6mm , apeture mask to primary to stop reflections, upgraded springs to primary, shower cap to end of ota , 6mm bar across ota rings on to stiffen tube , then if the bug bites cnc spider off Aliexpress (£60), Steeltrack focuser , 

 

[PeterC65]

1 hour ago, Flame Nebula said:

What is the difference between EAA and AP? 

With EAA you're observing on the night at close to real time, so live stacking the frames and stretching / making minor enhancements on the fly, usually using SharpCap. I capture snapshots of what I've seen as a record of the session, and sometimes I will enhance these later using Affinity Photo (just stretching and colour tweaks since the stacking was done on the night).

I don't do AP but it seems to me that it is a data collection exercise on the night and then later a task of stacking and enhancing the collected data to build an optimal image (which requires significant skill).

AP images are generally much better than what you get with EAA so people doing AP are generally more concerned about getting the last bit of performance from their kit.

 

[Flame Nebula]

49 minutes ago, PeterC65 said:

With EAA you're observing on the night at close to real time, so live stacking the frames and stretching / making minor enhancements on the fly, usually using SharpCap. I capture snapshots of what I've seen as a record of the session, and sometimes I will enhance these later using Affinity Photo (just stretching and colour tweaks since the stacking was done on the night).

I don't do AP but it seems to me that it is a data collection exercise on the night and then later a task of stacking and enhancing the collected data to build an optimal image (which requires significant skill).

AP images are generally much better than what you get with EAA so people doing AP are generally more concerned about getting the last bit of performance from their kit.

 

Thanks Peter. 👍

[Aramcheck]

On 07/04/2024 at 20:15, Flame Nebula said:

So, I guess the burning question is, which of the modifications you made do you think gives the biggest return on effort, with respect to visual and imaging?

Apologies for the delay in replying Mark - we were in (dark-ish) Wales last week & I had no access to my SGL log-in.

I can only speak about imaging... for me the most annoying thing was the flaring around bright stars, so I'd say the primary mirror aperture ring would be my biggest return on effort. You can buy a ring, get one 3D printed, or make one from a sheet of plastic (provided you're not going to be using the scope for Solar). It's worth using a piece of tape to mark the position of the primary mirror cell on the outside of the OTA, so that when you re-insert the cell back into the OTA you can get it in the same position. You will still need to recollimate, but it shouldn't be too far out.

I found it useful when collimating to have the location of the 3 mirror clips marked on the aperture ring with a small bit of white electrical tape, as you'll no longer be able to see the clips once the aparture mask is fitted.

When fitting the ring, the screws holding the primary mirror should only be tight enough to hold it in place, but you should still be able to just about rotate the mirror in the cell with your fingers. (Search on the SGL for this & any mods you decide to do!)

If you're also worried about hanging a camera (or eyepiece) by the two bolts found on the Skywatcher focus tube, the Astro-essentials compression ring will buy piece of mind & also centre the camera more accurately. (It also won't scratch your eyepieces) The first one I got didn't fit properly due to slack manufacturing tolerances, but FLO's customer service was brilliant (as usual) & they soon got me a replacement.

One other piece of advice is to only do one modification at a time, that way if something goes pear-shaped, it'll be easier to diagnose & fix!

Cheers
Ivor

[Flame Nebula]

5 hours ago, Aramcheck said:

Apologies for the delay in replying Mark - we were in (dark-ish) Wales last week & I had no access to my SGL log-in.

I can only speak about imaging... for me the most annoying thing was the flaring around bright stars, so I'd say the primary mirror aperture ring would be my biggest return on effort. You can buy a ring, get one 3D printed, or make one from a sheet of plastic (provided you're not going to be using the scope for Solar). It's worth using a piece of tape to mark the position of the primary mirror cell on the outside of the OTA, so that when you re-insert the cell back into the OTA you can get it in the same position. You will still need to recollimate, but it shouldn't be too far out.

I found it useful when collimating to have the location of the 3 mirror clips marked on the aperture ring with a small bit of white electrical tape, as you'll no longer be able to see the clips once the aparture mask is fitted.

When fitting the ring, the screws holding the primary mirror should only be tight enough to hold it in place, but you should still be able to just about rotate the mirror in the cell with your fingers. (Search on the SGL for this & any mods you decide to do!)

If you're also worried about hanging a camera (or eyepiece) by the two bolts found on the Skywatcher focus tube, the Astro-essentials compression ring will buy piece of mind & also centre the camera more accurately. (It also won't scratch your eyepieces) The first one I got didn't fit properly due to slack manufacturing tolerances, but FLO's customer service was brilliant (as usual) & they soon got me a replacement.

One other piece of advice is to only do one modification at a time, that way if something goes pear-shaped, it'll be easier to diagnose & fix!

Cheers
Ivor

Thanks Ivor

Very helpful reply. It sounds like the aperture ring will be useful. I think probably the first thing to do, when I get the scope, is test it in its native form for visual observation, then try planetary imaging, which is one of the main reasons I'm planning to get it. After this initial testing, I can proceed from there, although, I am tempted to get the compression ring at the same time as the scope, as I have one of those got my 80ed,and there are very good. 

Mark 

[PeterC65]

Inspired by this thread I've decided to make some further enhancements to my 200PDS and 150PDS over the summer while they are not being used.

The biggest issue I have is dew build up on the secondary mirror. My EAA sessions tend to be quite long and after a couple of hours I start to see lots of noise in the background sky due to dew on the secondary. I've solved the problem of dew on the primary by using a dew heater band at that end of the scope, but even with a dew shield I still get dew on the secondary. So my plan is to install Backyard Universe secondary mirror covers and to fit fans to the primary to blow some of the warmed air up the tube towards the secondary. I've bought Noctua Redux fans and some cut to size plastic discs to which I will fit them. The plan is to use phono cables to supply power to the fans from the same supply that I use for the dew heaters.

I also find that I need to adjust the collimation of the secondary on the 200PDS most times I use it so I'm replacing the spiders with CNC versions (from CYCK), changing the adjustment screws to cap head hex bolts with a dedicated T-handle Allen key, and adding a washer between the adjustment bolts and the secondary stork. I've decided not to go with Bob's Knobs as I've read reports that they are too small to allow for accurate adjustment and to get the required torque.

I have also considered adding primary mirror masks but I don't currently have an issue with star shapes so I'm not going to do that at the moment.