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Olivon 22mm 70 deg eyepiece

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#76 Sarkikos

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Posted 21 May 2014 - 05:47 AM

If the iris is pressed inside the 1.25" barrel until it is touching the retaining ring with the bright interior, it will probably reduce the brightness in that ring still further since the light would have to be even farther off axis to hit the retaining ring at all.
That's what TeleVue did.
I bet you could find a suitable rubber or plastic washer at a hardware store to do just that.


Or just cut a disk of black foam core - painted flat black or covered in ProtoStar - to fit snuggly inside the 1.25" barrel. A disk cut from a plastic milk bottle would also work.

Mike

#77 Sarkikos

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Posted 21 May 2014 - 05:51 AM

I use this hole punch set, it pretty well covers the range of center holes needed, at least for 1.25" eyepieces:

http://www.harborfre...h-set-3838.html


Good idea.

But how do you use these? Hit the end with a hammer or rubber mallet? I have zero experience in leather working or whatever you would use these for.

:grin:
Mike

#78 Sarkikos

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Posted 21 May 2014 - 05:59 AM

Some vendors sell empty filter retaining rings that could be utilized to make baffle rings. A few days ago I bought 10 2" filter rings from Surplus Shed for about $40 shipped. I also have a supply of 1.25" rings.

Mike

#79 precaud

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Posted 21 May 2014 - 07:15 AM

I use this hole punch set, it pretty well covers the range of center holes needed, at least for 1.25" eyepieces:

http://www.harborfre...h-set-3838.html


Good idea.

But how do you use these? Hit the end with a hammer or rubber mallet?


Yep. I use a piece of scrap wood to back it for a clean cut.

Crafts shops sell fancy paper hole punches in various sizes, but they don't work with anything thicker than paper, unfortunately. One of them costs more than the entire set of punches.

#80 Scanning4Comets

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Posted 21 May 2014 - 11:46 AM

While this IS a great idea, you shouldn't have to do this in the first place !!!!
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#81 Sarkikos

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Posted 21 May 2014 - 12:00 PM

Exactly!

Mike
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#82 russell23

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Posted 21 May 2014 - 12:12 PM

While this IS a great idea, you shouldn't have to do this in the first place !!!!


Yup!
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#83 Starman1

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Posted 21 May 2014 - 02:17 PM

I just went through my black rubber plumbing washers I had on hand (a large assortment I've collected through many years), and I had one that fit in the 1.25" bottom that had an opening just a trace smaller than the bottom lens, but a small enough opening to cover the bottom retaining ring and a bit of the lens.
OMG!
It seemed to nearly completely eliminate any bright rings in the eyepiece whatsoever when looking through the eyepiece toward a bright sky.
My eye, I'm sure, won't see as much light as a camera would, but it does seem to me the difference was profound.
Small black rubber washers are available with innumerable O.D.s and I.D.s, so some experimentation is called for, but this seems to be a really promising result.
I think having it right next to the lens may be key.

#84 Scanning4Comets

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Posted 21 May 2014 - 02:38 PM

What did you do Don?

Could yo u provide a pic please?

#85 Phillip Creed

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Posted 21 May 2014 - 05:03 PM

I wonder how many eyepiece lines simple fixes like this would have salvaged. The Celestron Luminos series comes to mind.

Clear Skies,
Phil

#86 Starman1

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Posted 21 May 2014 - 05:49 PM

Go to a local plumbing supply store.

Buy a bag filled with assorted rubber washers, gaskets, bushings, and the like. Most are black, but some are red-orange (these can be made black with a magic marker).

Pick the ones that are about the same O.D. as the I.D. of the eyepiece (28-28.5mm, or 1-1/8") .
Look for one with a hole just slightly smaller than the bottom lens.
Press it into the eyepiece until it stops. If the washer is a bit too small, put two very small drops of Elmer's glue on the washer and press it in place (very little glue so you don't get any on the lens). Let the glue dry before using eyepiece. If you don't like what the washer does, pop it out--Elmer's won't hold it very strongly.

Examples:
http://www.homedepot...Parts-Repair...
or, the "Mother Lode":
http://www.metrogask...hers/index.html

My "press-in" one was 1-1/8" O.D. and had a 5/8" hole. If the lens were larger, a hose washer would work. If the lens were smaller, it might be easier to find a washer.

#87 Sarkikos

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Posted 22 May 2014 - 07:23 AM

Is there a possibility that a washer could vignette the FOV? Maybe there is an optimal hole size for each eyepiece that would prevent EOFB but not vignette.

Mike

#88 russell23

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Posted 22 May 2014 - 08:32 AM

Is there a possibility that a washer could vignette the FOV? Maybe there is an optimal hole size for each eyepiece that would prevent EOFB but not vignette.

Mike


As long as the iris/aperture(?) of the baffle is larger than the field stop it should be ok. I measured the field lense diameter of the 13mm Olivon at ~18-19mm and settled on 16mm for the iris of my baffle. On page 3 Don provided the field stops for each Olivon FL. It turns out the 13mm has a 15.3mm field stop and I saw an unvignetted view of the field stop. So for the 22mm Olivon I could probably baffle it to 27mm (26mm Field stop) and there would be no vignetting.

Dave

#89 Sarkikos

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Posted 22 May 2014 - 09:21 AM

Yes, the field stop and the field lens should be the limiting factors for eyepieces which have a field stop above the field lens, in other words, between lenses of the eyepiece. In this case, the width of the light path at the field lens will be somewhat larger than the width at the field stop. So to avoid vignetting and still eliminate EOFB, the aperture of the baffle should be less than the clear aperture of the field lens but greater than the width the field stop.

Maybe a good rule of thumb would be to have the baffle a millimeter or two wider than the field stop?

For eyepieces with a field stop below the field lens, maybe a smaller baffle should be placed directly below the field stop. Of course, this would decrease the AFOV.

Mike

#90 russell23

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Posted 23 May 2014 - 12:54 PM

Today I measured the field lense on the 22mm Olivon to be about 27mm. The field stop is 25.9mm according to Don's numbers so there is not much to be gained with a baffle. Not surprising that this FL has very little EOFB.

Dave
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#91 russell23

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Posted 24 May 2014 - 11:54 PM

Tonight I had a chance to really test out the EOFB in the 22mm and 13mm Olivon. I compared views with the 13mm both with and without my crude baffle. The baffle makes a noticeable difference. Without the baffle I would say only the inner 40% of the field is free from EOFB. Basically M13 looked like an island surrounded by fog. With the baffle the inner 70% is free from EOFB and the remaining EOFB is not as intrusive but still a little annoying.

Without the baffle I can see the eyepiece could be excellent but simply cannot enjoy it. Stars are really sharp and right to the edge too - but it literally is like looking at those sharp stars through a fog.

With the baffle I started to get excited about the quality of the 13mm Olivon. The magnification is 61x with my refractor and that is great for both framing and resolving a lot of DSO. The exit pupil us perfect at 61x.

So I will continue my project tomorrow (today actually). I'm going to remove the retaining ring and spray it with some flat black paint. I also want to see how easily I can get at the rest of the internal structure.

Dave

#92 precaud

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Posted 25 May 2014 - 07:44 AM

Good results, Dave. FYI, Ace Hardware stocks a good selection of rubber gaskets just under 2" in diameter for less than a buck each. I was there yesterday and picked up one 1-27/32" OD x 1-9/32" ID (#02-2016P). It works, but a full 1-7/8" OD would be a more snug fit. I generally notice a bit worse EOFB and contrast with a coma corrector in place, whose field lens diameter is much larger than the size of the light cone at that point. So its a natural place to try this.

#93 Phillip Creed

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Posted 25 May 2014 - 04:53 PM

Dave,

What were your further impressions on the 22mm?

Clear Skies,
Phil

#94 russell23

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Posted 25 May 2014 - 05:19 PM

This afternoon I completely took apart the 13mm Olivon. The good news is the field lense is in a cell that threads into the 1.25" barrel. Then the upper housing can be separated from the 1.25" barrel and those lenses are also well secured. So there are no loose lenses when the eyepiece is taken apart.

I put flat black paint on the spacer that holds in the field lense and all inner surfaces of the 1.25" barrel portion. I also put flat black paint on the surfaces of the upper housing including the edge of the field stop. The annodizing on the Olivon is a flatter black than some I've seen, but it is still too reflective.

My hope is that the flat black paint will remove the remaining EOFB that the baffle did not remove. Will let you know if I get clear skies tonight.

Dave

#95 russell23

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Posted 25 May 2014 - 05:25 PM

Dave,

What were your further impressions on the 22mm?

Clear Skies,
Phil


It is very good. I didn't test it very much last night because I was really studying the effect of the baffling on the EOFB of the 13mm, but I like the 22mm Olivon a lot. Both eyepieces are very sharp and really their only flaw for me is whatever EOFB they do exhibit - significant in the 13mm and mild in the 22mm. If the flat black paint takes care of the EOFB in the 13mm I will take apart the 22mm and see if I can eliminate the mild EOFB in that one too.

Both eyepieces are sharper to the edge than the ES68's. The 13mm is sharp to the last 5% in my Vixen 140 refractor. It is quite impressive and left me asking why they haven't properly baffled and blackened it.

I'll try to pay more attention to the 22mm next time I go out to observe.

Dave

#96 russell23

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Posted 27 May 2014 - 08:44 AM

I had some really good skies last night - an excellent chance to test both the 13mm and 22mm Olivon. My efforts to eliminate the EOFB in the 13mm have so far been unsuccessful. The EOFB was reduced by the baffle. The internal blackening seemed not to make any additional difference and even with the baffle there is still too much EOFB for my tastes.

The only other thing I can try at this point is making my own internal baffle. I may try this but I won't have much time this week for it.

The 22mm Olivon is very nice. It provides sharp views and the mild EOFB is really not a problem. I had some really nice widefield views of the Milky Way with it. I have a 22mm LVW on standby to be loaned to me when I am ready. So I will make a comparison between those two when I have a chance - probably in July.

Dave

#97 precaud

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Posted 27 May 2014 - 11:38 AM

Don't want to hijack your thread, but along the same lines I had great results with the baffle I mentioned above with the GSO coma corrector... major reduction in EOFB, and much improved contrast across the FOV. Stars that were on the border of visibility became easy to see. Will be interesting to try the baffle with the P1.

#98 russell23

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Posted 31 May 2014 - 06:38 PM

Last night I had excellent skies and while I was observing and testing my 32mm Plossls, I also took an opportunity to see how the 22mm and 13mm Olivon perform.

As I've reported I've tried to eliminate EOFB from the 13mm Olivon by creating a baffle and blackening the internal surfaces with flat black paint. Last night I confirmed that the baffle helps, but does not eliminate the EOFB. In fact the 13mm Olivon still has too much EOFB to really enjoy - at least for deep sky.

So I decided that since the external baffle helped and the internal blackening made very little additional difference it was time to make another baffle for the inside of the barrel. There is a shelf near the top of the lower housing that perfectly supports a baffle. I cut the baffle so that its iris is just large enough to avoid cutting into the field stop. My hope is that this baffle will fix the EOFB, because absent the EOFB this eyepiece is just outstanding with my Vixen 140NA.

The 22mm Olivon is very comfortable and presents a nice natural view of the sky. Today, thanks to a generous CN member I received a 22mm Vixen LVW on loan to compare with the 22mm Olivon. I will make that comparison tonight and report on it tomorrow.

Dave

#99 russell23

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Posted 01 June 2014 - 01:24 AM

Well, the baffle brought the EOFB in the 13mm Olivon down to a small enough level that it can be enjoyed for DSO. Will say more tomorrow.

Ok, let me talk about the 22mm Olivon. I don't know what has been wrong with me but after tonight and comparing it with the 22mm LVW I have to say that I have seriously understated the performance of this eyepiece. I've mentioned some very mild EOFB - saw zero EOFB with it tonight. I was cruising around a lot of objects with it tonight. Wow, wow, wow. That is what I have to say. This eyepiece was just kicking it tonight. I've mentioned how natural the view is with it and tonight man that is what I was seeing. Very clean, natural quality to the light. Seriously - like looking through a Brandon in that respect but sharp almost to the edge.

Gotta get to sleep, but I will comment more on the comparison with the LVW tomorrow. If you have been on the fence about buying this eyepiece it is time to get off the fence and get one. It is simply stunning and I'll share why I did not immediately realize that tomorrow as well.

Dave

#100 Phillip Creed

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Posted 01 June 2014 - 09:21 AM

David,

How did the TFOV / drift times compare between the 22LVW and the 22OL-70?

Clear Skies,
Phil


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