Explore Scientific 82 24mm 2" EP won't focus
Posted 19 January 2013 - 02:39 AM
Based upon many favorable reviews I decided to purchase one of these for my Birthday and upon testing the device tonight I determined that I was unable to cleanly focus the EP in my Orion XT8 dob. While it was able to get Jupiter reasonably in focus, Jupiter's moons never completely resolved (to fine dots) like they look after I switch over to a Celestron Ultima 30mm.
So now I'm trying to figure out what the cause of the issue might be, collimation? My laser collimator is on order and will take another week before it ships, though if it was collimation (I currently use a collimation cap that came with the scope) I would think that I would see the same problem with the Celestron and my other EPs.
I thought I had read where someone had gotten an EP (it could have been a different brand) and needed to unscrew the lens. With this lens being N2 purged and waterproof I want to avoid messing with it.
Is it possible that this EP is just not going to work with my scope? I had to extend the focuser out as far as it would go but it seemed like it needed to go a little further before the moons would resolve. The EP has a recessed area where the screws make contact and seating the EP beyond that point seems like it's risky. Is there a solution for this that I haven't heard of yet?
Thanks everyone for listening, and yes this is my first time posting.
Posted 19 January 2013 - 02:46 AM
Posted 19 January 2013 - 03:23 AM
Using an extension may not work. I have a 35mm extension, which was the shortest that I could find, that only work on my 9mm since the barrel on the 9mm is shorter than the 14mm and 30mm. When I use the 9mm with the extension, the focuser is almost all of the way in. When I use the 14mm and 30mm with the extension, they stick out to far to achieve focus even with the focuser all the way in.
Posted 19 January 2013 - 10:11 AM
Posted 19 January 2013 - 10:36 AM
I think it's called PVC pipe. It was a very low cost, yet extremely simple and effective solution.
Posted 19 January 2013 - 10:56 AM
I now have it on the 34mm ES with a stiff, rubber parfocal ring.
That's your best bet IMO.
Posted 19 January 2013 - 10:57 AM
Another good thing about this is that the fine tuning ring is extremely flat black on the inside and also threaded for 2" filters.
Posted 19 January 2013 - 11:12 AM
Here's a pic:
Posted 19 January 2013 - 12:48 PM
I have the ES82 11mm and have no focus travel issues, except if I attach the lens module from bottom of my GSO 2.x barlow (approx 1.5x effect), which causes me to have to back the barrel out a bit, to achieve focus. This was a commonly reported condition, so it came as no surprise to me when doing this. Backing it out is not needed when used without barlow or with barlow fully assembled and attached.
Is this limited to the lower powered ES82's, perhaps? Just curious and it would be nice to know what to expect from the ES68. Although, more importantly, I'd like to know WHEN to expect the ES68. I fear I am at the back of a very long line of backorders that encircles the entire planet.
Posted 19 January 2013 - 01:46 PM
Posted 19 January 2013 - 02:19 PM
Why can't they make it with a longer barrel or are they optimized for a certain kind of scope?
Posted 19 January 2013 - 02:50 PM
Posted 19 January 2013 - 03:40 PM
Posted 19 January 2013 - 04:16 PM
Posted 19 January 2013 - 04:50 PM
Posted 19 January 2013 - 06:44 PM
Posted 20 January 2013 - 01:41 AM
According to my specs the XT8 is an F/6 so that would probably explain why I haven't seen any coma with any of my EPs.
It was nice to get more of the nebula in Orion into the field of view though at this point I have to wonder if I should have gotten a 30mm instead of the 24mm. I'm going to hunt down Andromeda while I still can and see what the view is like with my scope and this EP. So far I've only seen it with my bins.
Posted 20 January 2013 - 10:06 PM
Check the primary mirror collimation screws. If they have been tighten up it may be possible to move the primary forward 1/2" or so simply by loosening the collimation bolts that much. Of course you will have to recollimate when you do this.
Add a spacer bewtween the focuser and the tube. There are a number of easy to work materials you could use such as cork tile. Get a 1/4" here, and another 1/4" at the primary and you'll be all set.
Posted 21 January 2013 - 03:37 PM
Posted 21 January 2013 - 06:34 PM
Posted 22 January 2013 - 09:05 AM
Posted 22 January 2013 - 12:37 PM
Posted 22 January 2013 - 02:12 PM
I bought a 2" extender (like a Barlow, but no lens). I had to search to find one that was short enough so that I didn't run into a lack of in focus with it!
There was far more consistency in my other eyepieces than I expected. Almost parfocal, despite their wide differences in design, age, and manufacturer. It was really odd to me that ES would design their eyepiece to be different.