Alan Sheehan (sheeny) has kindly written an DIY article on how to build dew shields for the 20x80 triplet binoculars. You can read the article on the IceInSpace Projects & Articles page, or directly by clicking on the link below:
Hi, I followed Alan's specifications to the letter and created my own set of dew shields, for my Andrews 20x80 Triplets. The project came out exactly as desired and I would like to thank Alan for such an expertly worded project.
I have attached my not too clear photograph below, despite the poor photographic quality, you can still clearly see that the dew shields are awesome. Thank you to IIS and Alan Sheehan.
That looks great Ron. If not too late add some baffles, sounds crazy but I recon form what I have seen thru mine it is a must. Look at the Hubble they have baffels way past the secondary. Light reflects off the blackest of surfaces, if unconvinced roll up some black cardboard and look at a candle in a dark room about 30 degree out of the field of view.. You will notice a lot of light in that tube. My contention is the light we as humans dont think is there is in fact very much there and baffles reduce it to bring contrast and hence better views.. How do I know this well sitting up in the hills with out company one learns things that others would not bother with..if in a dark site you will notice contrast varies as you remove or replace the dew shields..You can keep the dew at bay but having a structure to place baffles you are so close to perfection why not go for it.
I have a 2.5 foot dew baffled unit for my 150ar and it changes it to a very good scope..I would even say it reduces the CA but being colour blind I am not confident as to that being the case but contrast it heaps better with baffles.
This view is not supported by most folk so they dont try it so they never know but that does not mean that it is not correct..even two close to the end will make a huge difference more so in a dark site..do the rolled up cardboard and think about what I suggest...this is of course in my humble opinion.
alex
If not too late add some baffles, sounds crazy but I recon form what I have seen thru mine it is a must. alex
Thank you for your contribution Alex and now I must show my ignorance, can you tell or point me to a comprehensive overview of how to add baffles. I did a Google without much success, plus I looked through our own (IIS) projects section. I understand baffles to stop light from reflecting down a barrel. Of course you know that I spray painted the inside of the dew shields with matt black paint, three actual coatings, it is as black and flat as you can get.
Any more instructional tips on how I actually construct the baffles, I am more than willing to try, but how?
... I spray painted the inside of the dew shields with matt black paint, three actual coatings, it is as black and flat as you can get.
Ahem! Not quite. I've used OPTICAL flat black paint many moons ago and it's much blacker than ordinary flat black. Also, put either of these paint finishes beside good quality velvet, and that looks even blacker!
Someone recently noted you can get self-adhesive felt (not velvet?) from Spotlight (the fabric store) so that may or may not be better.
Don't really know where to get optical flat black nowadays, and not sure if the felt would be any better than ordinary paint.
Thanks Mike, I am going to Westfield's to purchase one of those camera air blowers, that you squeeze to blow dust away, so at the same time I'll drop into Spotlight and ask about the self adhesive felt. I can understand what both you and Alex are saying about the quality of the black. It seems as if the felt sort of absorbs the light or to the highest degree does not reflect it.
Thanks Dennis, this is exactly what is required, I will try to find an Australian manufacturer/supplier, it seems strange to have to order this direct from the USA. The image below, borrowed from that site, really illustrates the difference between flocking and just having flat black paint.
I hope I haven’t sent you down the wrong path Ron. I provided the link for general info only, regarding issues such as loose fibres. The Protostar flocking material is mainly used for flocking the inside of telescope tubes and is probably overkill, and too expensive, for lining the inside of dew shields for bino’s.
That’s not to say don’t do this, as this hobby is great for exploring different techniques and applications of materials to squeeze the last photon out of the objective!
Cheers
Dennis
PS - There is no Australian supplier as far as I know, when I contacted Protostar late in 2006
Thanks again Dennis. It seems this topic was covered a few times in IIS already and most people found felt or velour a good option, and this is available from Spotlight and sometimes Bunnings.
I appreciate both of your posts in this thread, thanks
I built dew shields for my 20x80s from this DIY project description back in December. But I'm slack, just cleaned the surface up a bit and slapped on some matt black paint (el-cheapo spray can from Bunnings). Well, I don't know any better and I'm happy so far. Ignorance is bliss!
Bahhhhhhhhh I just walked for 2 hours around a dozen shops, the closest I got was at Lindcraft, they had self adhesive felt but every colour except black. There was no Spotlight in Parramatta, but I will go to one in Blacktown tomorrow. I cannot rest until I have the material in my possession, no matter how long it takes or what extraordinary lengths I have to go to, I will prevail and I will create my baffles, no matter how much it baffles me
