Should cooling fans and Dobsonians and Newtonians suck or blow? As I see it: In use, these telescopes are typically used pointing generally upwards. In damp conditions this is less important, but in drier and dustier conditions this will become increasingly important. Air close to the ground will likely contain more dust per unit volume of air, than air higher-up from the ground. A warm mirror will naturally warm air that will convect upwards past the mirror, into the tube carrying with it any dust in that air. A fan pushing air upwards will likely exacerbate this process. A fan that sucks air down through the tube will draw cleaner air through the telescope. Because of the dust, I suspect the latter arrangement is more desirable. It is true that the fan that sucks will have to work slightly harder, but a speed controller and choosing a higher quality, low-noise cooling fan will keep vibration levels down.
It wouldn't destroy the mirror, I got a 10" from a friend who had changed to longer bolts to move the mirror forward, and when I was adjusting it one went through and i heard a huge crunch. A big chip was made in the back of the mirror. Maybe I got lucky, but the views were not affected at all
@reflactor I could see that happening with your 14 conical, but not much chance on a full thickness mirror. But there is a chance that a chip could induce astigmatism if the shape of the mirror is affected, but that would have to be a big chip. I just took off the cap and looked down the tube of my 10 for the first time in over 3 years, yeah that thing needs a recoatong badly, not very bright, and (as it was when I got it for $60), many spots where thr coating is completely gone. It is a very old scope, when I got my GSO 10" in 2005 it had a crayford, and when I started at OPT in 2006, starhoppers were being made by synta not.GSO. I don't know when the change happened, probably 2004 when synta bought celestron. Mine has to be at minimum 20 years old , probably a few years older, and the original owner treated it like crap, and my friend got it for about $50 with a broken ground board which wouldn't slew. He had an extra base from a 12 which he gave me, and a groundboard swap fixed it, and also gave it wheels which came in handy when I used it from home, since I am in close quarters, maybe 8 feet of space between buildings, and no horizons, so the scope needs to be moved alot to be able to see over the roofs.. and because my van was stolen by the city of fountain Valley, home use is likely the only use that dob will continue to see. When m13 passes overhead it still gives a decent view, and I am probably bortle 9. Who knows, maybe I will get motivated enough to set up my 10" meade out front this summer, though I am probably more likely to setup the c8. Or just the 6" dob. The 4" refractor makes the most sense but all the counterweights except the 4# were in the van. I was really enjoying the 127mak I had re acquired (not the same exact one, but my 2nd scope 20 years ago was an orion 127mak), on the astroview with wooden vixen tripod out front, before losing the tube in the van. I still have some decent stuff, just no way to get it anywhere
I cant stand having only a right angle finder, it is so hard to aim the scope when you arent looking in the same direction you are aiming. I have really nice right angle polar finders on my vintage SCTs, that I wouldnt replace with cheaper modern straight finders, so the addition of a telrad really helps aim the scope. In fact, I generally didnt use optical finders that often anyway, before my storage was broken into, I used gem mounted C11 and only used a telrad, and an 8"ARC(acf) that i just used a basic red dot with. On my televue 101 I used a starbeam, and a basic red dot on my pronto via a vixen dovetail base on the clamshell. I miss those scopes. I didn't get a dime from insurance so I had to start over with the least expensive scopes possible and through a trade for the losmandy tripod, counterweights and hardware the theives didnt know to steal, i got an old 10" meade, and through another friend i got an old c8 for a steal of a price.
I know the feeling. I had my storage building burglarized many years ago. Fortunately, it started raining really hard while they were there so they only got "half" of the good stuff. Still very upsetting.
I just got my first telescope (I was planning on getting a dob, but got a great deal on a used starsense explorer dx 130az) and I'm hoping to employ some ove the upgrades ive learned about from your channel. I want to get a digital inclinometer, replace my collimating screws with some from Bob's Knobs, and possibly figure out a way to adapt a setting circle to a tripod. Thanks for giving me the courage to buy a used telescope! I never would have had the confidence without watching your channel.
Congratulations! I've heard great things about the Starsense Explorer system. The thing I like about Bob's Knobs is that he often has the exact screws that you need for your model. On occasion, you can buy similar screws from Amazon, but you have to be careful about the head sizes (they can sometimes be wider than the central mirror). Quick note about the digital inclinometer - just using that can get you very close to your target. Manually point the telescope as close (azimuth compass-wise) to your target, then use the digital inclinometer to get the exact altitude angle. Sweep back and forth and you'll often find your target. Good luck!
@Reflactor Just because sometimes things don't work as intended, is not a reason to be dissuaded from making your valuable videos. The person who never made a mistake never made anything. It is also much easier to criticise others than to attempt something difficult and awkward, especially when videoing it and publishing what went wrong. I am immensely impressed by some of the things you've achieved and I am fairly confident that had I attempted the same, it is likely that I would not have been successful.
Nice restoration project, good job! Maybe those "green eyepieces" were the main reason for you to buy the 10" dobsonian in the first place? 😂great video, clear skies!
Thank you for the kind words. I honestly didn't know about the eyepieces when I bought it. They had to dig this out of their closet and I was busy packing the telescope when he handed me the "grocery sack" of eyepieces. For the price I paid, I expected old broken eyepieces.
I run the cooling fan with 3 18650 Lithium batteries. Amazon sells 3 cell series battery boxes which I Velcroed to the tube. The Zhumell 8 inch scope came with a fan installed, and was a plug and play, as the scope had a female jack and a switch built right in. I had a male plug, so a couple second quick solder job got everything connected. These 18650 cells are 4.3 volts, so 3 cells give you plenty of power, and they're rechargable. If I were to use AA cells like you did, I'd definitely use rechargeable batteries. A bit of expense up front, but you only have to buy them one time. I found your channel recently, I've watched all your videos, and enjoy them. Good work, and thanks!
My Zhumell also came with the cooling fan installed (unfortunately the seller had lost everything else, including the viewfinder, adapters, etc... and the mirror needed recoating, lol). Generally speaking, I've been very impressed with Zhumell equipment. Thank you for watching so many videos. I hope they were educational/helpful.
Ah the green font. There was an ebay sale for a telescope with four eyepieces with the green font in the photos (not mentioned in the description), two panoptics and two naglers, I was swimming.
For me, SVBony 6x30 RACI finder was a game changer. It shows so much more stars in light polluted area and unlike larger 50mm ones is gives very wide FOV of around 7.5° and is quite lightweight. It is especially useful for setting up go to system as it is very accurate and has wide FOV.
The one thing I probably wouldn't have bothered with is the fan. Unless it has benefits beyond just acclimating the mirror. I usually set up way beforehand so I can collimate the finder scope to the OTA on some distant landmark while I still have daylight. The inclinometer was a nice tip though. Bought one for the workshop, but I could see myself using it for aligning my equatorial mount perhaps.
I agree that the utility of a fan is site-dependent. In my case, I can't leave anything valuable outside unattended (not the safest neighborhood), so the shorter the cooling time the better.
@@reflactor I wouldn't address the fan for basically the same reason as the comment above. Also, if it were to blow outside air past the primary mirror into the OTA, it would carry a lot of ambient dust and debris with it. That's why I prefer to wait a while for the mirror to adjust to the ambient temperature. Otherwise, your videos are perfect and I always look forward to the next one. Clear skies.
Excellent point. If you live in a pretty dry area (Arizona, New Mexico, high-desert, etc.), I can see where dust would be a big issue with fans. That's not a problem here fortunately. Thanks for watching!
@@reflactor Well John, I live in Central Europe but due to the light pollution where I live I am forced to drive my 12" Dobson far out of town into the field. So I know what I'm talking about in terms of dust and pollen season. However, my reward is the dark sky Bortle 1-2.
@Reflactor Great vid John. I made a 60mm right-angled finder scope from old binoculars with a 40mm Plossl eyepiece for around $70 including the adjustment rings. That's always a good upgrade to find your targets. Far brighter image than a 50mm finder scope. I also used Medican bottle tops on my ten-inch Newtonian on the collimation screws, as I found they were not that easy to turn, they fit snugly but used some glue as well. I love the fan upgrade you used I have a few spare PC fans, and will use one in my next project like yours! Another upgrade that I have seen on Astrobuscits channel, is to take off the metal pads that hold the main mirror in, as it can pinch it, and use Adhesive double-sided pads to hold the mirror in the cell. Thanks again for your knowledge. Folks give a like for John as it helps his channel!
Thanks! Wow, you are the master of making astronomy equipment. About those mirror retainer clips... Mine don't actually touch the mirror. They are there to keep the mirror from falling down the tube, lol. Even the lightest tightening would flex the mirror and that would be bad news.
You are correct. I use a rechargeable Talent cell pack to run my entire GoTo telescope and it works great. In this case, I chose batteries due to budget.
love your vids ! keep making them ! for future reference , if you run out of ideas , maybe you could find a way to put an eyepiece on a raci finder or a filter on it .
Thanks! For now I have a ton of videos planned out, but I will add that to the list. Unlike the "big guys", my production rate is a bit on the slow side, lol.
Replacing the setting circle and the inclinometer with some adhesive Velcro and an extra cheap case for whatever phone you use for astro hopper might offset costs a bit as well.
This may be the last time I add a setting circle. Since the advent of Astrohopper, I've been using them less and less. I do still use the digital inclinometer when trying to find objects at sunset or sunrise when the rest of the stars are nearly invisible.
Could never get used to using a right angle finder. I usually know what area of the sky I want to point at and looking directly in that direction is just second nature to getting me close. Half assed pointing it there and then looking down at your tube to look thru a right angle finder is a sure recipe to never finding what you want!
@@reflactor Yrs ago, when I was a teen, I made a 6" newt grinding and polishing the mirror (something every astronomy nut should do at least once in their life just to experience it... I went crazy and did a 12.5" after that! lol). Getting back to my point... That 6" never had a finder scope on it... I would point it like a gun by siting down the tube from the mirror end towards the area of the sky I wanted to look in and then go up to the eyepiece and start a methodical scan of the area with my lowest power eyepiece... if I was lucky the object I wanted to see could be found with a few swipes of my scope back and forth. But many times I had to go back and site down the tube again. Last yr I finally bought a Svbony finder for it with the white stalk. I was going to paint it black but after being out on a moonless night I noticed that leaving it white made it easier to see where the finder was against the scope so I have left it white.
@@reflactor yeah from my balcony i can see Leos triplet no problem, well its just a little village here but still have some annoying Street Lights. Even dimm Stuff like Dumbell Nebula or M57 is possible without even going to Dark Regions
Normally yes, that is true. Most of the mount stalks have that little clip at the bottom. For some reason, the dual Y-adapter doesn't have the tip. I hope they start putting those back on.
I was getting strange circles in the Celestron C6 I just bought. I called Celestron and sent them some photos and they told me that the "baffle" tube had not been flocked. I ordered some flocking material which arrived today. Am hoping for the best. I have 9x50 and 6x30 right angle finder scopes due to my bad back. Since most things I am looking for cannot be seen with a finder scope, I have found that my go to mount will get me close and SharpCaps plate solving feature can get my there. A 10-30 camera exposure will usually show me something. Could have done without the fan. Good work on your 10" reflector. Thumbs up!
Chasing nebulas, eh? Same here. Under my sky, the only viable targets are the Orion nebula and the Pleiades. Don't have a goto, all manual here, so I'm gonna have to learn to find the rest by star hopping or whatever.
