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TeleGizmos Finder Covers
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Two new accessory covers from TeleGizmos: useful items or just "gadgets?"
I am sure every Red Dot Finder user sooner or later experiences this malady. You are star-hoppin' happily along when your RDF suddenly winks out. You think you just ran down your thirtieth battery. Instead you discover that the finder's window is totally covered in dew. Solutions to this problem were tossed about on a Yahoo Group when word fell upon the ears, (or eyes) of Bob Pitney, owner and founder of TeleGizmos. Bob makes high quality fitted covers that have saved many a telescope and mount from the ravages of Nature. He just recently introduced two new "downsized" covers to protect your finder scopes from dust and moisture. Do these two new covers really do the job? Or are they just "gadgets"?
The idea of a cover for an RDF makes sense; after all, you probably spend only a minute or two looking through your finder during an observing session that may last for hours. Why not cover the RDF to keep it clean and dry while you are not using it? Unlike other TeleGizmos covers, it is designed without a drawstring and to have a slightly loose fit so that you can take the cover on and off without disturbing the alignment of your RDF. Will it actually keep off the dew? I tested this little cover several times under observing conditions where the telescope dewed over either while outside, or when I carried it inside and it dew over from the warm moist indoor air. I determined that while it will not keep the dew off forever, it does indeed retard the formation of dew on the RDF's window.
"But wait," you might say. "Isn't it cheaper and easier just to make your own little dew shield?" I had actually made a dew shield several months ago to target my dewing problem. So, which was more effective? Well, here's the "head to head" (or "cover to cover.") Appearance: okay, so I'm no artist. For construction, fit and finish, the TeleGizmo wins hands down. Cost: it's definitely cheaper to make your own, out of stock model plastic (as I did) or card board, or perhaps even aluminum foil. The RDF cover, however, currently costs less than $5.00. So, in my opinion, cost is not much of an issue. Still, that point goes to the home-made unit. Performance: after using my home-made dew shield for two months and the TG cover for a few weeks, I determined that both performed more or less equally well. I still had dewing problems with both systems, but much less frequently, even when everything else had already dewed over.
The next product from the TeleGizmos laboratory is the cover that fits you optical finder scope. This cover, like its larger cousins, sports a drawstring so that it could be fitted to virtually any optical finder up to 9x50, with either straight or right angle eyepieces. (Yes, I could make my own cover, but I'm no tailor either!) Many optical finders do not come with end caps, so this cover can be useful for keeping out dust and dew. Actually, to fight dew in an optical finder, there is another simple, very low cost option: tissue paper stuffed down the front! I can think of two situations, however, where the TG optical finder cover might be considered a useful option. Astro-photographers might prefer keeping their finder scope completely covered while capturing those award-winning photos during an all-night session. Solar observing can be safe and fun. But if the proper precautions are not taken it can also be dangerous. For solar observing, I take all precautions and cut no corners. So I have two options with my optical finder: remove it to prevent the possibility of damage or personal injury (with magnified sunlight shining through the finder and out the eyepiece), or cover it with the TG cover. Many will prefer the first option. I ended up preferring the TG cover. By covering instead of removing the finder, I don't have to re-align the scope the next night out. The aluminized surface of the TG cover keeps the finder cool and safe, and I don't have to worry about an end cap heating up in the hot sun, popping off, and creating a hazard. Below is a photo of my 102mm doublet set up for solar observing. My RDF finder is mounted on the side, just below the 9x50 finder.
So here's the recap:
On the Plus Side:
Functional- performs the job basically as intended
Lightweight and durable
Useful (IMO) for solar observers
On the Minus Side:
Cheaper to make your own covers (or remove finders)
The RDF cover won't keep dew off forever. Those with severe
dew problems may still need to use heat tape or hair dryer
For you optical finder, caps or tissue paper may be just as effective
Okay, so is it worth it? Well, astronomy is a hobby, and like all other hobbies, we buy not what we need, but what we want. The TeleGizmos covers do perform a useful function. For about half the price of a cheap plossl eyepiece you can purchase one or both covers and actually find a use for them, rather than toss them in your "drawer of broken dreams" along with all of those unused eyepieces and filters.
Post script: You may want to check your RDF finder right now to make sure you turned it off, so you won't run down your thirty-first battery!