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flocking a newt


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Flocking the inside is generally reckoned to be a worthwhile action, it reduces the amount of light bouncing around and should improve contrast. How much improvement could depend on how sensitive you are to it.

Not sure about baffling the focuser. You would have to be sure that you don't cut into the optical path of the image. Which although close to a cone isn't quite.

Another thing to realise is that light coming down the tube will "hit" theflocking material at a shallow angle. Make sure that whatever you use is still matt at shallow angles. When you look at many materials they are quite reflective at a shallow angle.

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I have just ordered a metre of black felt from the Fabric factory(E Bay)-at £4.75 can't go too far wrong. I intend using PVA,which is easy to use and a better bet than self-adhesive items IMHO.I have been convinced by earlier threads that flocking is worthwhile,and since looking at the sky isn't an option very often in this bxxxxx country,I spend a lot of time looking at my telescope and taking it to pieces.very good at collimating and taking primary mirrors out and putting them back.....

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This S&T article will tell you everything you need to know about flocking and baffling:

http://www.urania.be/forum/download.php?f=1&file=baffling.pdf

I used the tips on my 12" flextube with good results.

http://stargazerslounge.com/equipment-discussion/99482-improving-flextube-contrast.html

A point to note is that you don't need to flock the entire inside of the tube, just whichever part is sending stray light to the eyepiece. I bought one sheet of Protostar and had plenty left over.

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I can only base the improvements I feel I have gained from flocking both my 8" & 10" scopes and whether there would be any significant improvements from flocking a smaller aperture scope is negligible.

I feel flocking my scopes has made enough improvement to justify both the cost and effort involved. I have used both Protostar Protostar Telescope Making & Upgrading and Edmund optics flock Light Absorbing Black-Out Material - Edmund Optics. Having used both I have no doubt Edmund's do the same flocking paper as Protostar which is regarded as the flock to use. Using Edmund's flock works out a tad cheaper (£10 based on a full 8" OTA flock) and as long as they have it in stock delivery will be next day.

Hope this helps.

SPACEBOY

Trying to do it on the cheap more than often ends up costing more (not always in the money sense) in the long run.

Edited by spaceboy
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I've just checked my Skymax 150, the central tube from the secondary to the eyepiece holder is awful!! shiny, shiny! gonna be a pig to do that, its about 1" inside dia. and 6-8 " long.

Barry

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As I see it needs depend on demand. In my case having a top of the range OO was never going to happen on my income so a Chinese reflector it was going to be. Anything mass produced has to have a level cheap about it but this doesn't mean it can't be improved upon. Flocking is just one of these improvements. Like buying accessories for your car that will improve it's performance. Sure the improvements may only subtle but any improvement is better than no improvement (with in reason) . My demands were to try and get more contrast from my scope and improve my chance of seeing faint and fuzzes under the light polluted skies. I believe that I have gained improvements and when I replaced my old 8" reflector with a new one I flocked that also. Had I felt there was no gain I wouldn't of wasted money on the buying more flock. If astronomy is your thing and you want to get the best you can out of it then you do what you can. If it is just a hobby between hobbies then the money would be better spent on an eyepiece as flocking a scope adds no real monetary value to the OTA.

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bazzaar just out of interest how is the 200p newt for its need of flocking? am buying one second hand tomoro :hello2: cnt wait

Not too bad, could be improved. The main tube seems good, what I could see causing a problem is the inside of the focuser, the bare glass sides of the secondary and the inside part of the main tube directly opposite to the focuser. So no need for yards of material.

Barry

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Not too bad, could be improved. The main tube seems good, what I could see causing a problem is the inside of the focuser, the bare glass sides of the secondary and the inside part of the main tube directly opposite to the focuser. So no need for yards of material.

Barry

This is an interesting point you make Barry. I have read a few threads on the net that mention only small patches are needed but a previous thread of mine may suggest there would be an advantage in flocking the length of the OTA due to off axis light entering the tube. http://stargazerslounge.com/beginners-help-advice/143039-warning-centeral-obstructions-focal-ratio-help-needed-2.html

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You may well be right, you have looked into this further than I have. I did a visual check down the empty focuser and the tube didnt light up the way the focuser did, but my main concern was on axis light, to cure a halo I get around Saturn.

Two things occur to me here, 1,does off axis light stay off axis all the way to the focuser? if it does curing it at either place is equally effective, but the focuser would be easier. 2, once the focuser and secondary are flocked will the tube reflection then become apparent? Due to our eye/brain latching on to the most apparent areas of brightness at the expense of others.

Has any body tried flocking a dew shield? if that works we could adopt the use of tube extensions/dew shields for multiple benefits, and they are easy to implement.

Barry

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1,does off axis light stay off axis all the way to the focuser? 2, once the focuser and secondary are flocked will the tube reflection then become apparent? Has any body tried flocking a dew shield?

I suggest you read the Gary Seronik article I linked to in my earlier post which explains things better than I can. But:

1. The way to find out what light is reaching the focuser is to draw a ray diagram or (far better) look through the drawtube. Whatever you can see through the drawtube is light that is reaching the focuser. All of it has to be reflected off the surfaces you can see: secondary and tube wall (or directly from the empty space beyond end of tube). If all of these surfaces become blackened (in the latter case, by means of a dewshield) then any light reaching the focuser is being reflected off these low reflectivity surfaces. So the aim is to make sure these surfaces are as unreflective as possible, then it doesn't matter where the light impinging on them is coming from, the point is that very little of it is ending up in the focuser.

2. Once flocking and baffling is done to the parts you can see through the focuser, what you see is light reflected off those blackened parts. And if they've been well blackened, you see very little light at all.

Flocking a dewshield: I considered it but found I could get good enough results using a black camping mat. Again, if flocking a dewshield, then you only need to flock the part that will be visible through the focuser drawtube.

Seronik's article points out a couple of other places that might need attention, notably the part of the tube immediately above the primary: if stray light can reach this then it may be visible in the reflection you see on the secondary, and that would need attention. In my 300P it wasn't an issue - I only flocked the part opposite the focuser. I blackened the visible upper edge of the secondary with a felt pen. I found that these simple steps improved planetary views noticeably.

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