Newtonian hacks/improvements. Worth the effort?

[ONIKKINEN]

Cloudy october has rolled in and i thought why not tinker with equipment in the meanwhile? I noticed 2 potential issues with my VX8, the blackness of the inner surface of my OTA across the focuser (or anywhere else, if it matters) and the rough secondary mirror edge (the marked bit).

How much of an effect do these have for imaging/visual, but mostly imaging. While the paint is very matte and doesn't look all that reflective, it is also very much not quite what i would call black. The secondary mirror edge while not coated, will probably reflect at least some unwanted light somewhere towards the camera, potentially creating extra noise.

 

I am thinking of just painting these black with something like TS-black or another very low reflection paint. Although im not quite sure how to paint the mirror edge without ruining the mirror itself. Maybe using a marker or a very small brush?

[johninderby]

This will help.

https://www.firstlightoptics.com/misc/black-velour-telescope-flocking-material.html

Krylon camo ultra matt black works really well. Comes in a spray can but just spray some into the lid and brush it on.

 

Edited October 9, 2021 by johninderby

[ONIKKINEN]

4 minutes ago, johninderby said:

This will help.

https://www.firstlightoptics.com/misc/black-velour-telescope-flocking-material.html

Krylon camo ultra matt black works really well. Comes in a spray can but just spray some into the lid and brush it on.

I was looking at these velour rolls, but i wonder how well these handle extreme temperature ranges in terms of frosting and the adhesive? When winter rolls in properly i will have an up to 45 degree difference between inside and outside every time i take the scope out.

[johninderby]

The flocking FLO sells is made for the job of flocking a scope so it sticks really well. Not to be confused with the stuff you find in a DIY or craft store. Never had any problem with it coming loose in winter.

When I flock a whole dob I get some clear acetate shett which I cut to fit inside then apply the flocking with the acetate sheet flat on the table then inser it into the dob. More work involved but you get a better result.

Acetate liner made for the tube. Now to pull it out and apply the FLO flocking material and slide it back in place.

Edited October 9, 2021 by johninderby

[Louis D]

You could skip a step and order pre-cut ProtoStar FlockBoard in the size closest to your Newtonian's tube.  It just snaps into place, no adhesive required.

Edited October 9, 2021 by Louis D

[Zermelo]

1 hour ago, johninderby said:

This will help.

https://www.firstlightoptics.com/misc/black-velour-telescope-flocking-material.html

I did mine with this and it is very black now.
I got mine from Amazon as it was cheaper for the same size, but I think FLO must have reduced their price since then.
The 1m roll was enough to do the inside of a 150mm reflector, 750mm focal length, with a little left over to flock inside the focuser and a dew shield. I did my entire tube, which was a bit of a challenge as my primary can't be removed, so I was doing it all from one end. But I think you can get most of the benefit if you do just the wall opposite the focuser and the bottom of the tube around the mirror.
 

1 hour ago, ONIKKINEN said:

i wonder how well these handle extreme temperature ranges

It's been through a winter and a summer and shows no signs of coming away. Not a Finnish winter, of course 🙂, but it felt very "fixed" when I put it on.

 

[johninderby]

10 minutes ago, Louis D said:

You could skip a step and order pre-cut ProtoStar FlockBoard in the size closest to your Newtonian's tube.  It just snaps into place, no adhesive required.

Cost is the problem. It would cost over £100.00 to get the flockboard with shipping from the US. They charge a fortune for the shipping so just priced out of the European market now.

Edited October 9, 2021 by johninderby

[ONIKKINEN]

Lots of praise for the FLO flocking material, ill give that a go and see how it turns out. The "ridge" from the crimped part of the aluminum tube sticks out quite a bit and could cause problems, but if the adhesive is as strong as it seems then no problems, or ill just align the seams to the steepest part of the crimp.

[Craig a]

I can vouch for FLO flocking material I did my skywatcher 10 inch f4 newt about 5 years ago and that lived permanently mounted outside under a cover for months at a time seeing hot and cold weather and the material never budged, it’s good stuff 👍

[bish789]

5 minutes ago, Craig a said:

I can vouch for FLO flocking material I did my skywatcher 10 inch f4 newt about 5 years ago and that lived permanently mounted outside under a cover for months at a time seeing hot and cold weather and the material never budged, it’s good stuff 👍

What kind of cover did you use?

I've just bought a big barbecue cover for my setup, and allegedly its windproof, waterproof, UV resistant etc.

Only thing showing is the last few inches of the tripod feet.

Air looks like it will circulate so that can't be bad.

Edited October 10, 2021 by bish789
Misspelling

[Craig a]

5 minutes ago, bish789 said:

What kind of cover did you use?

I've just bought a big barbecue cover for my setup, and allegedly its windproof, waterproof, UV resistant etc.

Only thing showing is the last few inches of the tripod feet.

Air looks like ut will circulate so that can't be bad.

I use a telegizmos 365 cover, it’s very good, I use rechargeable silica dehumidifiers under the cover as extra protection it’s cream coloured to reflect the suns heat so the mount doesn’t get too warm under there melting the grease, it’s also foil lined to reflect the suns radiation, I use the skywatcher pillar mount to the cover is tight around the central column when I’ve tied it hence the silica dehumidifiers in there 

Edited October 10, 2021 by Craig a

[bish789]

Only potential problem is if there's any electronics on the setup, then any moisture could wreck them.

Other advantage to the Telegizmo is the foil lining, which being a Yorkshireman would look to use an emergency foil blanket first before putting the cover on.

If only I was rich enough to have an observatory

[Craig a]

3 minutes ago, bish789 said:

Only potential problem is if there's any electronics on the setup, then any moisture could wreck them.

Other advantage to the Telegizmo is the foil lining, which being a Yorkshireman would look to use an emergency foil blanket first before putting the cover on.

If only I was rich enough to have an observatory

On a warm summers day under a dark cover it will get very warm very fast, that’s why I chose the telegizmos because it’s almost white 

[bish789]

Have to try and work out a fix for that, or bite the bullet and buy a Telegizmo

 

[Craig a]

3 minutes ago, bish789 said:

Have to try and work out a fix for that, or bite the bullet and buy a Telegizmo

 

Worth ever penny 

[bish789]

Suppose it would be a good Xmas present from the Mrs.

 

[philhilo]

Another vote for the flo flocking. The difference was dramatic. Alas I upgraded from a dslr to an astro cam at the same time so never saw the difference in images. 

Also Telegizmos covers, excellent. Yes the kit will suffer long term but it gets used 10x more. 15 minutes to get up and imaging as opposed to hour or more and lots of cable issues etc. Not much point in having it if it doesn't get used.

[Nyctimene]

On 09/10/2021 at 19:17, ONIKKINEN said:

I am thinking of just painting these black with something like TS-black or another very low reflection paint. Although im not quite sure how to paint the mirror edge without ruining the mirror itself. Maybe using a marker or a very small brush?

Painting the secondary edge with a black felt tip or paint will still leave some reflexivity, esp. when light hits the mirror under grazing angles. I preferred to flock the secondary's edge (only half of it's circumference can be seen from the focuser) with self-adhesive velour flocking material (D-C-Fix here in Germany). Working in small pieces, I started with making a trapezoidal paper template for the part of the secondary, that points directly at the sky ( - the region of the major axis' exit) and cut it with fine scissors to the correct size and shape. I then transferred the template's outlines with a fine pencil on the velour's paper side, and cut out the part. A small pincette was used to put it into place. The same somewhat fiddly procedure followed with four more pieces (but you have to measure and cut only two templates, that are used back-to-front). The result is shown here with my Skywatcher Heritage 130 P Flextube:

You don't have to work with extreme precision - the main point is just to get most of the stray light absorbed.

Stephan

[ONIKKINEN]

1 hour ago, Nyctimene said:

Painting the secondary edge with a black felt tip or paint will still leave some reflexivity, esp. when light hits the mirror under grazing angles. I preferred to flock the secondary's edge (only half of it's circumference can be seen from the focuser) with self-adhesive velour flocking material (D-C-Fix here in Germany). Working in small pieces, I started with making a trapezoidal paper template for the part of the secondary, that points directly at the sky ( - the region of the major axis' exit) and cut it with fine scissors to the correct size and shape. I then transferred the template's outlines with a fine pencil on the velour's paper side, and cut out the part. A small pincette was used to put it into place. The same somewhat fiddly procedure followed with four more pieces (but you have to measure and cut only two templates, that are used back-to-front). The result is shown here with my Skywatcher Heritage 130 P Flextube:

You don't have to work with extreme precision - the main point is just to get most of the stray light absorbed.

Stephan

This looks pretty nice too. I do wonder whether the fibers would attract dew/frost and just bring it closer to the mirror. The backside of my secondary is sometimes wet/frozen, but so far the mirror side has been mostly dry.

 

I have 2 rolls of flocking and some paint coming soon so plenty of extra material to test and play with.

[Nyctimene]

14 minutes ago, ONIKKINEN said:

I do wonder whether the fibers would attract dew/frost and just bring it closer to the mirror

Never observed this with my two dobs, that have the secondary flocked (8" f/4 and 5.1" f/5). They rarely dew up, and definitely not starting at the secondary's edges.

Stephan

 

[Tiny Clanger]

26 minutes ago, ONIKKINEN said:

This looks pretty nice too. I do wonder whether the fibers would attract dew/frost and just bring it closer to the mirror. The backside of my secondary is sometimes wet/frozen, but so far the mirror side has been mostly dry.

 

I have 2 rolls of flocking and some paint coming soon so plenty of extra material to test and play with.

As condensation occurs when moist air comes into contact with a surface that is good at conducting heat (like glass or steel) , I'd guess that flocking would act as an insulating layer, and actually decrease the chances of the sides of the secondary dewing up . As the back of the secondary is facing space, and losing heat , it is going to be colder, and more prone to dew than the front of the secondary.

Heather

[ONIKKINEN]

1 hour ago, Tiny Clanger said:

As condensation occurs when moist air comes into contact with a surface that is good at conducting heat (like glass or steel) , I'd guess that flocking would act as an insulating layer, and actually decrease the chances of the sides of the secondary dewing up . As the back of the secondary is facing space, and losing heat , it is going to be colder, and more prone to dew than the front of the secondary.

Heather

Didnt think about that at all. The flocking material is the exact opposite of a reflective glass mirror, so will probably be dryer than any metal/glass parts. Radiation of heat will probably have a lesser effect too when the insides are completely flocked all the way to the top of a dew shield.

Edited October 14, 2021 by ONIKKINEN

[Sky_LO]

I used scope stuff adhesive backed flocking.

Just reached inside the top and placed inside in pieces.  I figure seams or tiny gaps don't matter that much as the goal is to minimize reflectivity, and not beauty.  (function over form) 

 

[ONIKKINEN]

Couple hours of Saturday arts and crafts and its flocked very nicely. I ended up painting the secondary edge with Black 2.0 as i found it difficult for the flocking mat to stick to the glass and to cut it to the correct curved shape. 3 coats of paint and it is very matte and black. The tube itself is lined inside with the flocking mat from FLO. Looks noticeably darker than what it was before. The flocking material does seem to attract dust and especially lint but i don't think that matters all that much. Ill just clean it up before finishing up and more shouldn't magically find its way in there with the dust caps off. Probably should have vacuumed before doing this though.

[ONIKKINEN]

Just saw very frosty conditions at -5c and 95% humidity. Every outside surface was covered in a thick frost layer, but the inside was perfect. Nothing on the flock or anywhere inside the tube, so nothing to worry about.