'honeycomb extinction filter'?

[Astronomist]

spotted this lurking on eBay today, I was wondering if such a stray light blocker could work. the one advertised looks quite shiny inside, so is probably useless, but is the concept workable? I get the idea behind it but i imagine i would have seen one before if they were at all useful?

https://www.ebay.co.uk/itm/203868931199?hash=item2f7789047f:g:4h4AAOSwwndiL5NL

thanks

Astronomist

[Mr H in Yorkshire]

The diffraction effects would be to die for.

[vlaiv]

Just use long dew shield - it will block any stray light and won't block light or cause diffraction issues.

[Louis D]

Might look similar to my apodizing mask:

[Astronomist]

Thanks everyone , that's kind of as i expected with the diffraction effects. Out of interest @Louis D, how effective is your apodising mask for high magnification? Does it really help with poor seeing very much?

[Louis D]

4 hours ago, Astronomist said:

Thanks everyone , that's kind of as i expected with the diffraction effects. Out of interest @Louis D, how effective is your apodising mask for high magnification? Does it really help with poor seeing very much?

I've only tried it during good seeing.  It seems like it might increase the contrast of low contrast details on Jupiter and Mars, but using a binoviewer is far more effective.  During the last Mars opposition, I tried it with binoviewing, and it seemed to increase contrast a tiny bit more.  However, the psychedelic effects are pretty hard to ignore immediately surrounding the object.  Overall, I wouldn't recommend taking the time and effort to make one.  It's not particularly hard or expensive to make, but it seems like a waste of time and storage space.

Here's the mask itself made from two sheets of crafting foam board, three offset layers of black window screen spray painted flat black, and some short screws (not visible) around the perimeter holding the layers together and in place:

The taped nubs are the heads of two long bolts threaded through the board that the mask hangs off of while on the front end of the telescope tube.