I’ve been doing a fair bit of reading about the reflections on my RH200 and what a lot of the discussions come back to is light reflecting off the intervals of the light shield. So to that end I’m contemplating flocking it. I had considered a paint like Black 3.0 but I do get dew on the inside of the light shield at times (I have a few strap wrapped around the middle of it to help mitigate this issue) so I’m thinking a felt or black velvet would likely be a better way to go.
Is there any product that would be suggested/recommended?
ScopeStuff have a adhesive backed black velvet which would allow both the internals and the front lip to be done easily.
Pro star have a flocking board that you cut to size and it holds itself in place without the need of any adhesive.
I believe it was Alex a year or so ago mentioned that his second hand SCT had the material disintegrating within the OTA so I’d rather avoid that (it’s external, in front of the lens).
I've used flocking from Scope Stuff. It was quite fine although try to get it to stick first go as if you peel, realign and attach the adhesive is less effective.
On the dew shields I've been making for my Maks I've been using the black velvet roll Bunnings sells. Once iin place I take to it with a vacuum cleaner with a brush fitting to suck up whatever loose fibers there might be (and there will be no matter what stuff you use).
Funny thing is the Mak of mine that had the degenerating stuff (i have no idea what this stuff was brand wise) did not benefit from that flocking as the internal baffles were just as good if not better! That stuff just made a mess like a black Labrador slept in it...
DO NOT use Black 3.0 on any surface that is liable to get wet!!!
It is not designed for use as an external/water resistant paint, particularly on a surface that is going to be man handled or manipulated in any way. Sure, use it on the inside of your SCT, frac or Mak - I have - but it isn't going to get damp or wet there.
It also isn't designed to be flexible, so don't use it in a situation where the paint is liable to be bent or folded. This goes for all paints.
Like Alex, I have used the black velvet adhesive rolls from Bunnings (crafts section, near the art supplies). I have used it on all sorts of scopes, it was applied to the inside tube face of my truss tube newt that i built, as carbon fibre tube is shiny as extruded. Also used it on my truss tube iStar TCR. Used it on the inside of the fixed dew shield of my old Bresser, etc.
This is very timely for me to see. I am trying to eliminate a reflection issue that appears to be caused by Antares out of field, which must be bouncing off the (Pretty well blackened) rear tube on my corrector. I can see a diffraction pattern of lines from the knurling on the end face of my UV-IR cut filter cell (Not quite parallel lines which all radiate from the position of Antares) and I am about to try an experiment of adding a 10mm M48 extension tube to the objective side of the filter cell as a baffle to see if it cuts that path off. I am probably going to flock it with the Bunnings material as the best thing I will be able to lay my hands on at short notice.
If it works OK I will have to buy a roll of the Scopestuff material to improve it further. Is there any Australian stockist of the Scopestuff material? Recent experience with shipping under COVID 19 says if I have to buy it from the US I will be lucky to see it my my birthday (July)
I have been waiting for over a month since the last tracking update (California) for a small adapter coming from Agena via Ebay, for the first time the shipping time is looking like hitting the silly side of the estimates they give. So I am pretty keen to buy local as much as possible now, even if it means a bespoke part where I might normally be able to buy an off the shelf one.
Just got back from Bunnings, it’s black but it’s not quite black enough :/ Or, I should say, it’s black but a little too shiny.
First, I am NOT promoting any material here, nor putting down any other. How I am presenting this post is with my DIY hat on
The two above posts need to have some context put into them, otherwise it will be giving confusing and even misleading information about the materials in question by the way each item has been presented.
Colin's test is not an accurate way of how the flocking material is used (I have PM'ed Colin about this). There is a bright torch used to create that photo, which is firstly not how an astro situation would present itself, and hence not how the velvet itself would be acting as a flocking/light attenuating tool. In an astro application, this material may well provide excellent light baffling properties.
The photo that Peter's link goes to, similarly is a little out of context. There is obviously a significant difference between the two velvet products, but again this photo does not present an astro situation. The only appropriate comparison is one where each material is put into a scope and both are then subjected to the same imaging and visual scrutiny/comparison.
By all this I mean if one product is available and the other ("better") product is not, in an astro application there may not necessarily be that much if any difference.
What concerns me most about any flocking material is just how stable it is over time, and then if I would want to put any of these products inside a scope of mine, . My experience is limited to one scope and I do not know what the product was that had shed fibres. So with the experience I do have I have limited the use of flocking materials ONLY to the inside of dewshields.
There are other ways of controlling stray light that does not involve flocking materials. Sand lining the tube and then painting it over with a suitable black paint works very well. This process is much more labour intensive. But with a sealed OTA, such as an SCT or Mak or refractor, Black 3.0 could be used to enhance things even more. One scope Brand that I know of does this internal sand layer and the result is quite striking.
I've also experimented with my own dewshield making, where I used both sand and extra baffle rings on the inside of a rigid dewsheild (see pic below). If you do look at using extra baffle rings, these MUST be carefully made, circular and smooth or it will introduce unwanted diffraction patterns from those uneven areas. The dewshield pictured below I made for an 8" Newt, and it actually works to improve contrast with the Moon.
First, [I][U][B]The two above posts need to have some context put into them, otherwise it will be giving confusing and even misleading information about the materials in question by the way each item has been presented.
The photo that Peter's link goes to, similarly is a little out of context. There is obviously a significant difference between the two velvet products, but again this photo does not present an astro situation. The only appropriate comparison is one where each material is put into a scope and both are then subjected to the same imaging and visual scrutiny/comparison.
I think you are taking the post out of context Alex. I'm merely showing that one material is significantly blacker and less reflective that the other. It is also a lot less hairy.
Sorry if you feel I have taken your post out of context. I did not want to do that. If you reread my post, I am talking about in an actual in-scope application any difference may be very little or insignificant. I actually remarked at the immediate difference between the two. I have not disagreed with your statement
It is also important also note that the photo is a comparison between two specific products, one of which is particularly preferred for an astro application. The other less black item should not be thought of as indicative of other off the shelf velvet materials. Even the stuff sourced by Spotlight does vary from batch to batch as they source from different places and manufacturers - Spotlight does not manufacture anything, but sources products from many different places.
Alex.
Last edited by mental4astro; 13-05-2020 at 02:06 PM.
I didn't think there was anything confusing or misleading in terms of which material was more black, less reflective and less hairy. I'm sharing some actual data showing a side by side comparison of the above qualities - not just an opinion.
I've used both of these materials on the inside of Newtonian and Schmidt Newt OTAs and based on that experience, I'd buy the Scopestuff one if I wanted something that is black, low reflectivity, doesn't shed hairs and has excellent adhesive performance over a long period of time, but that's just my opinion.
You mention "in an actual in-scope application any difference may be very little or insignificant"...or it may be significant - only some specific data will help us decide.
I had actually considered mixing sand and glue and then painting the inside, I think it was TeleVue that did this at one point? They’ve also used a flocking felt as well. I have an older Zeiss 135mm F/2 that has felt on the inside of the light shield.
Looks like ScopeStuff is the way to go, it’ll certainly be easier to deal with than the Bunnings stuff as it’s quick thick and as you mention Alex, no way of knowing if it’ll leave a mess in the long term. It does look quite a lot blacker when seen front on but it gets shinier with incident light which is what is seen more so in astro applications.
Hmm. I might make my test just a matter of putting the M48 tube in there as is and see how it goes.
Tomorrow night looks promising weather wise for a test, but I won't get a lot of time on my target before moonrise, and Friday, Saturday and Sunday nights look reasonably promising for a good couple of hours on target if the extension tube actually works as a baffle.
I've used the Bunnings stuff on the inside walls of the obs (the shaded side) as they were quite shiny powder coated zinc. The adhesive is not very good and a lot of it is peeling off.
In the same environment, the Scopestuff material is still firmly attached to the inside of the OTA five years later.
I've used the Bunnings stuff on the inside walls of the obs (the shaded side) as they were quite shiny powder coated zinc. The adhesive is not very good and a lot of it is peeling off.
In the same environment, the Scopestuff material is still firmly attached to the inside of the OTA five years later.
last word?
That shine is what I experienced visually but thanks for the durability comment... or lack there of
That shine is what I experienced visually but thanks for the durability comment... or lack there of
I've still got some offcuts of the Scopestuff material and a wall full of the Bunnings one so can do a side by side comparison with side-on lighting if you are interested.
That stuff just made a mess like a black Labrador slept in it...
. My experience is limited to one scope and I do not know what the product was that had shed fibres. So with the experience I do have I have limited the use of flocking materials ONLY to the inside of dewshields.
