Dobsonian Light Shield

[John]

I have quite a lot of lateral lighting to contend with until around midnight and my neighbours go to bed and switch their lights off.

This light has a tendancy to find it's way into the top of the OTA of my Meade Lightbridge 12" dobsonian and causes a noticable drop in contrast when the scope is pointing at certain angles.

I'd like to get or make a light shield (similar to a dew shield) to put on the top end of the scope to reduce / remove this issue. I'm guessing that I will need one around 18" tall to be really effective in shielding the secondary - does that sound about the right height ?.

I'm also going to need something that goes right around the OTA (rather than the partial one that Astro Engineering make) because my unwanted light comes from a number of directions (including my own house when my family are still awake ).

Has anyone made anthing like this and, if so, could you share the details. I'd prefer something a light as possible because the Lightbridge is already rather "top heavy" especially with a 2" Nagler eyepiece in the drawtube !.

Would commercially available dew shields be appropriate ? - I saw one of these being used at the SGL4 Star Party but that was on a SW Flextube 12" and I wonder what it's (the dew shields) weight was.

All suggestions and further ideas welcomed

Thanks,

John

[Doc]

Not cheap at £55

Dew Prevention - Astrozap Flexible Dew Shield

[omneferuss]

cheapo campmat, very light, paint it matt black....

[M110]

Campmat works well for me - stapled to the correct size

Haven't got round to painting it yet although that would probably make a good deal of difference.

regards,

Alex

[Jarndyce]

Camp mats are available in black - saves painting them.

I wonder if this would be any good?

MultiMat Adventure Compact Mat from Nevisport.com

[JAO]

John

I have Kydex extention shields on both my 12" and 18" Dobsonians and even in dark site conditions they enhance contrast. In the circumstances you describe I am sure you will get some benefit. On my 12" the shield is 10" high and on the 18" the shiled is 12" high. In both cases the shields go around 50% of the tube circumference, centred on the point opposite the focusser.

I have found these people an excellent source of Kydex (and indeed other ATM materials, nice poeple too!)

Kydex Ebony Star Laminate Telescope Bearings

Hope this is of help

Regards

Adrian

[Doc]

Camp mats are available in black - saves painting them.

I wonder if this would be any good?

MultiMat Adventure Compact Mat from Nevisport.com

These look really good.

Add somme velcro and thats one awesome light shield.

[John]

These look really good.

Add somme velcro and thats one awesome light shield.

Thanks for all the suggestions folks

I think the adapted camping mat approach looks very promising - I must make sure that I don't get a self-inflating one by mistake though - could be rather awkward !.

John

[RobH2020]

On 03/05/2009 at 23:47, John said:

Thanks for all the suggestions folks

I think the adapted camping mat approach looks very promising - I must make sure that I don't get a self-inflating one by mistake though - could be rather awkward !.

John

John bumping a very old thread of yours here 😀 found it when Googling this topic...

Did you ever make that camping mat light shield? Do you have any photos I could use for inspiration if so? And did it help?

Cheers!

Rob

[John]

3 minutes ago, RobH2020 said:

John bumping a very old thread of yours here 😀 found it when Googling this topic...

Did you ever make that camping mat light shield? Do you have any photos I could use for inspiration if so? And did it help?

Cheers!

Rob

Where did those 11 years go !

I actually purchased one of the semi-circular ones instead from Astroboot and it has served me very well:

 

[Barry-W-Fenner]

On 09/08/2020 at 18:19, John said:

Where did those 11 years go !

I actually purchased one of the semi-circular ones instead from Astroboot and it has served me very well:

 

I would really like one of these for my 12" flex tube. Are they still available to purchase? Have you flocked your oo 12" John?

I have just purchased some flocking from FLO, I will be doing the bottom section of my tube to keep me occupied while the weather is so poor..