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12” F/5 Dob Eyepieces

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#1 kapps

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Posted 16 January 2021 - 06:39 PM

Sorry for another “what eyepieces should I buy” thread. I am patiently waiting on an Apertura AD12 and would like some guidance on eyepieces for my Bortle 4 skies.  I’ve heard the 30mm that comes with the scope is half decent but the 9mm super plossl is pretty bad. For starters, I’m looking at 2 eyepieces that fall into the best bang for your buck category in the mid price range. APM seems to be the current brand that meets this criteria. I am mostly interested in DSO viewing but it will be nice to look at planets or the moon if they are in the sky as well.  I’m leaning towards a 13mm XWA 100 degree that I can use with a 2x Barlow for planetary viewing. Then I’m also looking at either a 30mm UFF or a 20mm XWA.
 

A couple questions...

1. At f/5, I will be dealing with some coma on the 100 degree FOV eyepieces. Is this dependent on eyepiece focal length (ie. the 20mm would show more coma than the 13mm)?  Would it be better to consider eyepieces with less FOV?

2. The 30mm UFF and 20mm XWA have nearly identical FOV. Would you actually consider them replacements or would they still compliment each other once I start expanding the eyepiece collection more?

 

Any other comments would be appreciated. Thanks!



#2 chrysalis

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Posted 16 January 2021 - 07:18 PM

The 100° EPs I have - Explore Scientific - work excellently in my 12" f/4.9. I have the 5.5, 9, 14, and 20 mm versions; and the 14 mm is my most used eyepiece. You really can't beat the wide immersive views. I evolved up the ladder from Plossls to 66°, 68°, 82°, and finally 100° EPs. I use the 100° and to a lesser extent the 82° EPs nearly exclusively now.


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#3 Jethro7

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Posted 16 January 2021 - 08:24 PM

Hello Kapps,

You are going to love the Dob, unfortunately Eyepieces are in the eye of the beholder what works for me you may not work for you. All I can do is list what works for me. It is a short list. Of all the eyepieces I have owned, I pretty much only use four. I do not have much issues with coma with these eyepieces  using a Orion Skyline 12 F/5  but if you do, get a Coma corrector. That's all.

1- TV 10mm Ethos, 100° 

2- ES 20mm, 100° 

3- TV 31mm Nagler type 5, 82° 

4- Baader 8 X 24  Hyperion Mark IV Zoom plus the 2.5 X Barlow.

 

Just like Chrysallis posted. Mark, likes his 14mm eyepiece and is his most used. For me its the TV 31mm NT5 eyepiece that is my most used. The views are very different between the 14mm and the 31mm eyepieces.  Eyepiece focal length and the fields of view choices are something you will need to work out your self. But just get a good spread between the focal lengths, this will save a good bit of money. I do like to start out with my Baader Zoom to see just what magnifications are working for me that night depending on my sky conditions and the object being viewed. Heck sometimes I will just keep the Zoom in the focuser for the whole session rather than swapping it out for another eyepiece.

 

                                                   "Just for a heads up"

If you go for the monster 100° eyepiece you will need a couple two pound magnets and a one pound magnet to balance the Dob, because these eyepieces are very heavy. You can get these magnets from Home Depot or Amazon. Wrap them up in Duct Tape so you wont scratch up the scope body.

FWIW, I am a Florida Resident also and I have found the need to use a Dob secondary mirror dew heater.  At least were I live dew is a year round issue. Dew on the secondary mirror will end a viewing session cold. One more thing, get your self an astronomy observers chair, this will be one of the best accessories you will ever own for Astronomy.  There always seems to be one more piece of gear that you seem to need for this hobby, some of it is for Creature comforts or convenience, some are nessessary. I guess that this is part of the fun.

 

ENJOY THAT SCOPE AND KEEP LOOKING UP Jethro


Edited by Jethro7, 17 January 2021 - 04:46 PM.

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#4 sanbai

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Posted 16 January 2021 - 09:09 PM

Those two recent threads are related to the topic:

https://www.cloudyni...or-a-newtonian/

https://www.cloudyni...a-12-dobsonian/

#5 SeattleScott

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Posted 16 January 2021 - 10:08 PM

Assuming you have a manual, not computerized Dob, and need the wide field to find stuff.

70 AFOV will be less affected by coma than 100 AFOV.

100 AFOV is difficult to get perfect eye placement to see the entire FOV at once (if it is even possible). Then you have to maintain perfect eye placement as you move the scope around. The 30mm 70 is much easier to take in the whole view at once.

With 100 AFOV the eye can’t actually focus on the entire FOV at once. So even if you manage to find perfect eye placement and hold it, the outer portion of the view will be out of focus. That won’t matter much if your target is Andromeda, Orion Nebula or Double Cluster. But small, faint targets could slip by undetected in the outer portion of the view that is out of focus.

So especially without a coma corrector or GoTo, the answer is pretty obviously the 30mm APM. Unless you have really bad light pollution.

Scott
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#6 kapps

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Posted 17 January 2021 - 11:55 AM

Thanks for the info. It sounds like I’m on the right track with regards to focal lengths. That’s a good point about smaller FOV being easier to use but I can also see that everyone has their own feelings on the subject.  The UFF is probably best for me since I am a newbie and in a dark enough area that the larger exit pupil will help rather than hurt. 



#7 SeattleScott

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Posted 17 January 2021 - 12:11 PM

For viewing a target, 100 AFOV is nice. For sweeping and finding targets it isn’t as advantageous. Plus you have coma to factor in.

Scott

#8 cimar

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Posted 17 January 2021 - 12:16 PM

Hi,

with a similar scope I am happy with 72 degree field of view eyepieces with the following focal lengths:

31mm, 17.3mm, 10mm, 6mm, 3.5mm


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#9 Echolight

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Posted 17 January 2021 - 12:24 PM

The Meade 28 PWA is a pretty decent 82 degree eyepiece that's relatively easy to see a sharp field stop in.

And is in the vein of a Nagler 31T5 at a fraction of the price, as well as a half a pound lighter. Though likely lagging behind a bit in edge sharpness. I'm impressed by it but have only used it in f7.5 and f8 refractors. The contrast, color correction, and overall presentation are very nice. Probably the favorite out of all my eyepieces. And the least expensive of the ones that I use.

 

I imagine it has a good deal larger true field of view than the 30 UFF without giving excess exit pupil.



#10 Spile

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Posted 17 January 2021 - 12:50 PM

After doing a lot of reading and wanting to replace the two default oculars that came with my 200P Dobsonian, I opted for a Zoom lens. 

I am happy with the choice as it hits the sweet spot in terms of optic quality, convenience and cost. As there is a Barlow deal on offer I included that as well.

The only other purchase was a 42mm wide angle and my plan is to stick with these...

IMG_20201230_135507.jpg.fb359e19e7e405bb


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#11 25585

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Posted 17 January 2021 - 02:05 PM

Good choices listed above. With 60 to 76° AFOV, I don't find coma too bothersome & in general prefer that range anyway. But depends what you look at, and how you look/follow a view, I keep centered mainly if possible while viewing, others watch drift from side to side.

 

A big True FOV is better for a main scope finder eyepiece though.



#12 JIMZ7

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Posted 17 January 2021 - 02:06 PM

When I owned the Discovery 12.5" f/5

Split-Tube Dobsonian it came with a full case of ES82 eyepieces. Of course 82 degrees fov is so much better to navigate the heavens with a Dobsonian reflector. The views you will see is stunning for a 12" or actually any size scope.

Jim


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#13 chrysalis

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Posted 17 January 2021 - 02:20 PM

After doing a lot of reading and wanting to replace the two default oculars that came with my 200P Dobsonian, I opted for a Zoom lens. 

I am happy with the choice as it hits the sweet spot in terms of optic quality, convenience and cost. As there is a Barlow deal on offer I included that as well.

The only other purchase was a 42mm wide angle and my plan is to stick with these...

IMG_20201230_135507.jpg.fb359e19e7e405bb

As others said, it is a matter of personal choice. I purchased the same EP for my set up for the same reason, but I think after years of being spoiled by 100° views, I was turned off by the 48° AFOV at 24 mm, and not a lot happier about the 68° AFOV at 8 mm. I ended up returning it.

 

See page 3:

 

https://www.baader-p...oom_mark_iv.pdf


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#14 aeajr

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Posted 17 January 2021 - 02:34 PM

You have lots of good advice here.

 

I have the same scope, the Apertura AD12.  I like it very much.   I added an azimuth scale to the mount and use an angle gauge to use AltAz coordinates to find my targets.   I don't do a lot of star hopping. 

 

If you are an active star hopper, I would suggest adding a Telrad. Those circles can be very helpful with star hopping. 

 

All I can say is that there are lots of good choices for eyepieces.   I have standardized on the Explore Scientific and Meade 82 degree eyepieces with no plans to go wider.

 

After my two 2" wide view eyepieces, my Baader Hyperion Zoom is my most used eyepiece.   Based on my Bortle 5-8 observing locations, seeing and transparency conditions, the bolded ones on the list are my most used in this scope with the Baader zoom being my single most used eyepiece. 

 

 

Apertura AD12 12”/305 mm Dobsonian/Newtonian, 1520 mm FL F5 FR
Resolving power -   .4 arc seconds

AA SWA 38 mm/70                   40X and   1.75 degrees FOV   EP 7.6 mm  2”
Meade  20 mm/82                    76X and    1.07 degrees           EP 4.0         2”

 

ES          14 mm/82                     108X and    .75 degrees             EP 2.8
ES          8.8 mm/82                    172X and    .47 degrees             EP 1.7
ES          6.7 mm/82                   226X and    .36 degrees            EP 1.3
Meade   5.5 mm/82                  276X and     .29 degrees            EP 1.1
ES          4.7 mm/82                   323x and     .25 degrees            EP   .94

ES          6.7+2XB                        452X and     .18 degrees
Meade   5.5+2XB                        552X and    .15 degrees

 

Baader Hyperion 8-24  zoom    63X to 190X and .79 to .35 degrees
Baader Hyperion 8-24+1.5XB      94X to 285X
Badder Hyperion 8-24+2XB        126X to 378X
Baader Hyperion 8-24+2.5XB     157X to 472X

 

Photos:

 

I use a hand truck to move mine around.  Makes it very easy to manage.

 

I added an AZ scale to the mount and use an angle gauge to find Alt.  Stellarium on the phone provides my real time AltAz coordinates. 

Attached Thumbnails

  • Apertura fitted to red handtruck (480x640).jpg
  • IMAG0473 (640x480).jpg
  • Angle Gauges on XT8 OTA (240x202).jpg

Edited by aeajr, 17 January 2021 - 02:42 PM.

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#15 RLK1

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Posted 17 January 2021 - 02:45 PM

I use a lot of eyepieces in both my astrosystems 16" f4.5 dob and my 12" f5 dob including quite a few of those previously mentioned in this thread. But the contrast of a 10mm Ethos in either in a truly dark sky is something to behold...



#16 25585

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Posted 17 January 2021 - 02:57 PM

My 35mm Panoptic and both ES92s with a Paracorr 2 are the main 3 eyepieces I use with my 12" F5 S-W 300P DS, Dob-mounted. For shorter FL, Baader Morpheus 76° 9 & 6.5mm, the "Super 6 set".


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#17 Spile

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Posted 17 January 2021 - 04:36 PM

This is my frugal collection...

IMG_20210115_115256.jpg.89d61c7bb1085924


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#18 StarCurious

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Posted 17 January 2021 - 04:47 PM

 my 12" F5 S-W 300P DS, Dob-mounted. 

Excellent idea. How did you mount this shorter imaging OTA?  Was it a custom dob base?  Any picture please?



#19 Jethro7

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Posted 17 January 2021 - 04:54 PM

As others said, it is a matter of personal choice. I purchased the same EP for my set up for the same reason, but I think after years of being spoiled by 100° views, I was turned off by the 48° AFOV at 24 mm, and not a lot happier about the 68° AFOV at 8 mm. I ended up returning it.

 

See page 3:

 

https://www.baader-p...oom_mark_iv.pdf

Hello Mark,

Oh my yes, it is easy to get hooked on 100° eyepieces. And they work so well with just about every scope I own. Especially a Dob.

 

HAPPY SKIES AND KEEP LOOKING UP jethro.



#20 John Huntley

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Posted 17 January 2021 - 09:26 PM

I use the following set with my 12 inch F/5.3 dob:

 

31mm Nagler

21mm Ethos

17mm ES / 92

13mm Ethos

8mm Ethos

6mm Ethos

4.7mm Ethos

 

Occasionally I will use a 3.5mm Pentax XW as well, when really high magnifications are needed / usable. The 31mm Nagler does not see that much time in the scope so is more of a "nice to have". The 17mm focal length is often skipped over as well which is why I don't maintain an Ethos there now.

 

The APM 100's are very good and somewhat lower cost alternatives smile.gif

 

Personally I have been hooked on 100 degree eyepieces with this scope for some time now. Your mileage may vary though smile.gif


Edited by John Huntley, 17 January 2021 - 09:27 PM.


#21 StarCurious

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Posted 18 January 2021 - 01:31 AM

Just saw this on Astromart. I can't get it since I am not in ConUS.

 

Used APM 100° 9mm for $150

 

https://astromart.co...-hdc-100-degree

 

I have no idea whether this listing is still active, expired or sold.  I don't have an Astromart account.  I was googling for review of the eyepiece.

 

Do your own due diligence.


Edited by StarCurious, 18 January 2021 - 01:32 AM.


#22 25585

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Posted 18 January 2021 - 11:29 AM

Excellent idea. How did you mount this shorter imaging OTA?  Was it a custom dob base?  Any picture please?

I needed a new OTA for an old 12" F5 Dob I had, so the S-W specs fitted & I fix the tube in the rocker box with a ring each side. Quite handy as I can slide and rotate my OTA if needed. Got Bob's Knobs to make collimation easier.   

 

This Dob is like "Trigger's Broom" https://rhodestothep...triggers-broom/


Edited by 25585, 18 January 2021 - 04:52 PM.

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#23 Starman1

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Posted 18 January 2021 - 04:35 PM

Sorry for another “what eyepieces should I buy” thread. I am patiently waiting on an Apertura AD12 and would like some guidance on eyepieces for my Bortle 4 skies.  I’ve heard the 30mm that comes with the scope is half decent but the 9mm super plossl is pretty bad. For starters, I’m looking at 2 eyepieces that fall into the best bang for your buck category in the mid price range. APM seems to be the current brand that meets this criteria. I am mostly interested in DSO viewing but it will be nice to look at planets or the moon if they are in the sky as well.  I’m leaning towards a 13mm XWA 100 degree that I can use with a 2x Barlow for planetary viewing. Then I’m also looking at either a 30mm UFF or a 20mm XWA.
 

A couple questions...

1. At f/5, I will be dealing with some coma on the 100 degree FOV eyepieces. Is this dependent on eyepiece focal length (ie. the 20mm would show more coma than the 13mm)?  Would it be better to consider eyepieces with less FOV?

2. The 30mm UFF and 20mm XWA have nearly identical FOV. Would you actually consider them replacements or would they still complement each other once I start expanding the eyepiece collection more?

 

Any other comments would be appreciated. Thanks!

1) No, coma is dependent on apparent field.  It appears the same in all focal lengths of eyepieces with the same apparent fields.

It is half as wide in a 10mm 100° eyepiece in a linear sense than it is in a 20mm 100° eyepiece, but because the comatic star has a size, it is magnified 2x in the 10mm, and 2 x 1/2 = 1.

To to avoid coma, stick to narrow apparent fields.  In a sense, coma correctors made 100° eyepieces possible.

2) The 30mm UFF is a bit better corrected at the edge than the 20mm XWA, coma excepted.  However, the 2 might complement one another due to the 50% difference in magnification, but only in a long focal length scope.

I see no reason to use eyepieces closer together than 45-60x at low power in a 12", and one would yield 51x and the other 76x--too close together to be viable in that scope.

I think the next logical step from a 30mm is a 15mm +/- 2mm.  There are lots of users of similar scopes here on CN who flip from a 30mm to a 13mm as the next eyepiece.

Depending on your viewing preferences, you could jump 50x between eyepieces to 70x between eyepieces and have a very nice set.

 

One setup I am recently finding favor with is to have a favorite magnification, then have the magnifications on either side slowly increase in steps from there.

To illustrate:   a favorite magnification of 160x, with the first steps on either side to 120x and 200x, then 70x and 250x and then 330x, 430x, etc.

If you favor planet and lunar viewing, you might want higher magnifications close together to hold the magnification limit to what the seeing allows.

In that case, you might favor constant steps in magnification from the bottom up, which puts the % changes to get smaller as magnifications increase, e.g. 50/100/150/200/250/300x etc.

That will make the focal lengths appear to get closer together at high power as the % increase diminishes.

 

Were I buying eyepieces for a 12" to start with, I'd probably start at 22mm instead of 30mm, but I have no problem with the 30mm.

I might then move to 17.5mm, 10mm, 6mm and stop there until I knew where I wanted to go.

I'd fill in the gaps as I learned what kind of viewing I favored and figured out which gap needed filling.

Your preferences might change, too, leading to a different line of eyepieces.

It took me a long time to realize my favorite range of eyepieces was 8-11mm with my 12.5".


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#24 25585

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Posted 18 January 2021 - 05:18 PM

A near/widest TFOV is, whatever FL, one I regard as essential for any manual tracking scope. That eyepiece is the bridge between finder scope and main scope, it should show stepping stone stars, asterisms leading to your target.

 

Next after that should be revealing what the target is distinctly, large or small, but keeping as wide as possible TFOV. 

 

Third starts zoning in more precisely. There you can sacrifice some FoV for a higher magnification.

 

Fourth & onward is closing in on your target where target assessment, best exit pupil and other considerations such as filters become relevant. My 4th eyepiece is usually 1.25" fit, but 1st & 2nd are normally 2", 3rd being variable.

 

I have found the above is good for both DSOs and stars/bright planets. Differentiating Uranus & Neptune from background stars, is always hit & miss. 




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