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The other day we were bequeathed a number of astronomical items. One of them was a mint Skywatcher 90mm Mak. We already had the 102mm version so I was interested in a comparison. Terrestrially I was surprised to find considerable field glare which washed out the image unless the eye was placed perfectly on axis, this would no doubt also be obvious with lunar viewing. Close inspection revealed that the interior surface of the baffle tube, although black, was high gloss finish. The baffle tube itself is pretty small and would not easily be a candidate for flocking. As an experiment I lightly scored the surface in rifling fashion with a pointed needle file, the improvement, perhaps unsurprisingly, was dramatic. Anyone else noticed this issue with the 90mm?     ? 

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Yup, my C90 has the same shiny baffle tube.

I used some thin non-adhesive flock paper from Edmund Optics to fix this. Cut a piece to length, rolled it into a tube, and inserted inside the baffle. It doesn’t interfere with this view and, as Peter says, it’s much improved ?

James

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15 minutes ago, Alien 13 said:

This has me thinking about my C90 now, maybe I should get some of that blacker than black nano tube stuff but other thoughts welcome.

Alan

Your C90 is the same I think - I stumbled across a YouTube video of some guy that showed how to flock the tube of a c90 a while back. Reckoned it made a huge difference

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2 hours ago, jkwhinfrey said:

I used some thin non-adhesive flock paper from Edmund Optics to fix this. Cut a piece to length, rolled it into a tube, and inserted inside the baffle. It doesn’t interfere with this view and, as Peter says, it’s much improved ?

James

Hi, did you use the 0.01 or 0.02 paper they stock please?

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1 hour ago, happy-kat said:

Hi, did you use the 0.01 or 0.02 paper they stock please?

Hi happy-kat, it was the #40 non-adhesive flock paper that’s 0.01” thick. Once rolled into the baffle tube it doesn’t seem to move much.

James

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13 hours ago, Mr niall said:

Your C90 is the same I think - I stumbled across a YouTube video of some guy that showed how to flock the tube of a c90 a while back. Reckoned it made a huge difference

Thanks, was this the video as the difference with flocking is quite dramatic in the daytime.

Alan

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58 minutes ago, Alien 13 said:

Thanks, was this the video as the difference with flocking is quite dramatic in the daytime.

Alan

Yep that was it - sorry should have dug it out for you was stuck on a train at the time. Yes it's quite a big difference isnt it?

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The video is great but no advice on how to actually do the flocking!

My tube has a texture to it on the inside and doesn't seem as bad as the one in the video, I guess Celestron responded to criticism. I think I may try heat resistant paint but I will trial on a random bit of thin, long tube first!

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12 minutes ago, Stub Mandrel said:

The video is great but no advice on how to actually do the flocking!

My tube has a texture to it on the inside and doesn't seem as bad as the one in the video, I guess Celestron responded to criticism. I think I may try heat resistant paint but I will trial on a random bit of thin, long tube first!

I think my C90 is the same. the baffle tube internal seems to be a matt finish and has a texture. I will certainly try a piece of rolled up flocking (non sticky) to see if there is a difference though. I noticed from the link supplied by Happy-kat that the dimensions of the material required to flock the C90 was 53x190 mm.

Alan

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2 minutes ago, happy-kat said:

From re reading the post flocking the tube looks pretty but the real improvement comes from flocking the baffle, the inner thinner then a thin thing.

Thanks just corrected my previous post.

Alan

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It was surprisingly easy to put a bit of self adhesive flock inside the tube. 50mm by 130mm for the record, but about 2mm too long so slight overlap, about 5mm short at each end of the tube. I rolled it around a pencil and carefully worked it until it stuck to itself, once in the tube it stuck to the tube more than itself and I was able to 'wind' it off and into position.

Having see the vids and looking down the tube the difference is very big, more than enough to make up for 1-2% of lost light.

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