73 replies to this topic

[Jon Isaacs]

My 21 ethos replaced my 30/70 and my 20 degree EP, since like someone said above it does the job of both, having the same TFOV as a 30/70 but with the magnification of a 20. I know Jon will beg to differ because he likes large exit pupils when he needs them.

It is not that I "like" larger exit pupils, it's that larger exit pupils are brighter and sometimes the brighter image will show things not seen in dimmer images. 

 

At F/5, the 21 mm Ethos provides a 4.2 mm exit pupil, the 30 mm UFF, a 6.0 mm exit pupil. The image provided by the 30 mm UFF is slightly more than twice as bright.

 

That's why I have eyepieces that provide larger exit pupils. there's more to observing than just magnification and field of view.

 

Jon

Edited by Jon Isaacs, 27 May 2023 - 09:24 AM.

[turtle86]

 

The other alternative which is making me consider getting a 21E is the new Y axis balancer that Rowan is making for the AZ100, this would take all the weight considerations out of which EP to get.

 

 

Sounds like a good solution to me for the OP.

[f18dad]

Is there any reason to order the APM 20 100 XWA rather than the AT 20 100 XW?

 

Mike

 

No undercuts.

 

I didn't even notice that the AT 20 100 XW has an undercut.  I had to look at it now to verify.  So, the APM version doesn't have an undercut?  If undercuts are a big deal to someone, then I'd say order from APM.  But personally, for myself, I'm not going to order from outside the US, and pay shipping, to avoid undercuts.

 

Undercuts are way, way down the list of important features of an eyepiece for me.  I'd rather an eyepiece didn't have them.  But they make little or no difference to me in practice in the field.  They just don't.  I can't remember the last time an eyepiece with an undercut was any hassle at all to me when inserting or removing an eyepiece from a focuser.  I just do not notice it.  Is it the kind of focusers in my scopes?  Or the way I insert/remove eyepieces?  Who knows?   Not a problem.

 

I think the last time undercuts hung up eyepieces for me was when I was binoviewing, when the binoviewer had collets.  But I'm not going to binoview 2" eyepieces. 

 

Mike

 

I was just answering your question. For some it makes a difference...YMMV

[Jon Isaacs]

I didn't even notice that the AT 20 100 XW has an undercut.  I had to look at it now to verify.  So, the APM version doesn't have an undercut?  If undercuts are a big deal to someone, then I'd say order from APM.  But personally, for myself, I'm not going to order from outside the US, and pay shipping, to avoid undercuts.

 

Undercuts are way, way down the list of important features of an eyepiece for me.  I'd rather an eyepiece didn't have them.  But they make little or no difference to me in practice in the field.  They just don't.  I can't remember the last time an eyepiece with an undercut was any hassle at all to me when inserting or removing an eyepiece from a focuser.  I just do not notice it.  Is it the kind of focusers in my scopes?  Or the way I insert/remove eyepieces?  Who knows?   Not a problem.

 

I think the last time undercuts hung up eyepieces for me was when I was binoviewing, when the binoviewer had collets.  But I'm not going to binoview 2" eyepieces. 

 

Mike

 

Mike:

 

I'm with you when it comes to undercuts.  I'd rather an eyepiece didn't have an undercut but they rarely cause me a problem. And I swap eyepieces a lot.. multiple times per object.. 

 

Jon

[f18dad]

It’s good to know you both would prefer not to have undercuts, even though not adamantly.

I’m in the camp along with some others who would be willing to pay slightly more to lose them.

[Starman1]

4 of my 13 eyepieces have undercuts, and those all have copper tape filling in the undercuts.

The undercuts are no longer a problem in most ways.

A bevel on the lower edge of the undercut does help in removal before the tape is added, but I do find that even if the brass split ring is removed, the eyepiece tends to hit the lower lip of the brass split ring's groove

when being inserted into the scope, as does the upper lip of the groove on the eyepiece tend to hit the lip of the focuser/accessory as the eyepiece is inserted.  Tape helps the latter, but not the former.

A lack of undercuts on the eyepiece helps, but so would having a smooth bore in what the eyepiece is inserted in.

 

For example, inserting and removing an eyepiece in a twist lock collet-style adapter is easy, whether the eyepiece has an undercut or not.  Inserting the same eyepiece in an adapter with

a brass split ring, whether the ring is removed or not, is a lot more problematic.  Not difficult, just not as easy as an adapter with a smooth bore.

 

Since I have eyepieces with and without undercut barrels, I can compare them all the time.

I have to say that sometimes merely aligning the barrel of the eyepiece with the adapter or Paracorr to even start inserting the eyepiece proves to be the bigger challenge.

Once the undercuts are filled in, sliding eyepieces in and out is not really difficult at all.

[Sarkikos]

Mike:

 

I'm with you when it comes to undercuts.  I'd rather an eyepiece didn't have an undercut but they rarely cause me a problem. And I swap eyepieces a lot.. multiple times per object.. 

 

Jon

Yes, I am with you.  I couldn't tell you off the top of my head which of my eyepieces have undercuts and which don't.  It pretty much flies under my radar.

 

Mike

[Sarkikos]

Eyepiece attributes which irk me much more than undercuts:

 

- zoom eyepieces which are not parfocal within their range of focal lengths

- astigmatism, especially when it is across the entire field

- field curvature

- heavy weight

 

Mike

[f18dad]

None of the current production of APM XWA's have undercuts and they are available domestically, except for the 20mm.

[sabir]

I have no idea what that is. Would you post pics, a link and/or explain?

Mike

Hi Mike,

I was referring to strainwave gear/harmonic drive mounts from the likes of ioptron, zwo, rainbowastro etc.

I had my TSA-120 on a DM4 + UNI28 combo and was perfectly happy with it except that I wanted tracking as the TSA-120 really soaks up magnification.

With regards to balancing, I had the DM4 balanced for a 13E and the scope remained put while swapping eyepieces which ranged from a tiny 4mm ZAOII to the 13E... no problems except when using the 21E, the scope would slowly dive at the focuser end which basically meant I never landed up using the 21E

I recently replaced the DM4 with a HAZ31 mount from iOptron as I wanted to have a tracking mount but at the same time did not want to loose out on the portability the DM4 provided.

The HAZ31 is a mount with a form factor just slightly larger than the DM4, weighs 8lbs and has a load capacity of 31lbs, has zero backlash, is impervious to unbalanced loads, requires no counterweights and has fully automated goto and tracking. All you need to do is plonk it down, level the tripod and switch it on... the mount takes over from there

More details can be found in the mounts forum and especially on this thread here:
https://www.cloudyni...c/850903-haz31/

Hope this helps

Sabir

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Edited by sabir, 27 May 2023 - 02:15 PM.

[RAKing]

Yes, I am with you.  I couldn't tell you off the top of my head which of my eyepieces have undercuts and which don't.  It pretty much flies under my radar.

 

Mike

 

The last time I worried about undercuts was........  I guess never.     I have never worried about undercuts, but I don't try to yank my eyepieces out of the diagonal, either.

 

Ron

[JeremySh]

Thanks everyone for your advice - I can see the thread is now moving on to undercuts.

It looks like the logical step is to stick to the E17 and N26. So logic will prevail unless OCD kicks in majorly, which would cost me £898.

 

Thanks for the various other suggestions. I really do want to avoid buying EPs made in Rep of China if I can. Taiwan is fine.

[Lizardman]

Thanks everyone for your advice - I can see the thread is now moving on to undercuts.
It looks like the logical step is to stick to the E17 and N26. So logic will prevail unless OCD kicks in majorly, which would cost me £898.

Thanks for the various other suggestions. I really do want to avoid buying EPs made in Rep of China if I can. Taiwan is fine.

You are for sure not a cheap date when it comes to eyepieces 😀. As far as China I am with you ; problem is I’d bet some parts of almost all things astronomy are made in China or outsourced from China . Sad but true.

[Deadlake]

Thanks everyone for your advice - I can see the thread is now moving on to undercuts.

It looks like the logical step is to stick to the E17 and N26. So logic will prevail unless OCD kicks in majorly, which would cost me £898.

 

Thanks for the various other suggestions. I really do want to avoid buying EPs made in Rep of China if I can. Taiwan is fine.

As you know £570 on SGL last sold for, tempted as well to get one.

[Starman1]

Thanks everyone for your advice - I can see the thread is now moving on to undercuts.

It looks like the logical step is to stick to the E17 and N26. So logic will prevail unless OCD kicks in majorly, which would cost me £898.

 

Thanks for the various other suggestions. I really do want to avoid buying EPs made in Rep of China if I can. Taiwan is fine.

Taiwan is ROC, Republic of China.

Mainland China is PRC, People's Republic of China.

[JeremySh]

Taiwan is ROC, Republic of China.

Mainland China is PRC, People's Republic of China.

Yes I know. Been to both. I want to avoid EPs from PRC.

[Sarkikos]

The last time I worried about undercuts was........  I guess never.     I have never worried about undercuts, but I don't try to yank my eyepieces out of the diagonal, either.

 

Ron

Yep.  I don't spend a lot of time on each object ... unless it really warrants it.  Most don't.     But I am slow, fully conscious, and deliberate when I interact with the astro gear.  I don't want any falls, cracks, bends or breaks.  

 

Mike 

[swsantos]

So, the y-axis balancing system raises/lowers the saddle to balance the scope laterally (y-axis), just as pushing a scope's dovetail back or forward in the saddle balances the scope longitudinally (x-axis). 

 

In effect, the y-axis balancing system is a way to rebalance when switching among eyepieces - or binoviewer, etc. - without adding, removing or moving around counterweights.

 

It seems you would still need tension locks on the axis to maintain the scope's position while removing a heavy eyepiece from the focuser, during the time when there is no eyepiece in the focuser.

Yes a tension lock is necessary to hold the telescope’s position while removing a heavy eyepiece.

 

The Y-axis balance adapter for the AZ-100 can either be used on the fly by pointing the telescope straight up then balancing by sliding the telescope slightly to rebalance with a new eyepiece. It is very easy, easier and quicker in fact than sliding the telescope back and forth on the dovetail to achieve X axis balance.

 

Or it can be used by setting the Y-axis adapter to balance your mid weight eyepiece which will then provide very good balance throughout your entire eyepiece weight range. The results are much less messing around with altitude friction while using different eyepieces than would otherwise be required without being balanced on the Y-axis.

 

Remember that the center of gravity of a telescope on the Y-axis with a diagonal in it is always above its midline even with nothing in it at all so it starts off out of balance from the get go, with a finder on top even more so. Add an eyepiece, especially a heavy one, and you are constantly fighting variable imbalance with altitude friction.

 

Setting Y-axis balance to mid eyepiece weight greatly mitigates all that and using it on the fly solves it. The Y-axis balancing adapter even fully balances the AZ-100 with my Maxbright II binoviewer with two Morpheus eyepieces on board.

Edited by swsantos, 27 May 2023 - 05:10 PM.

[25585]

Or moving the refractor back and forth on its dovetail.  But a long dovetail can sometimes get in the way of the focuser knobs or the focuser retaining screw or something else.  Ask me how I know ...

 

Mike

Make sure to buy a dovetail with lots of holes to give tube ring placing options. 

[25585]

https://www.astrobuy...php?view=200617

[GrassLakeRon]

Or the AT 20mm 100 XW. AFAIK, it is the same as the APM 20mm XWA, just a different branding. If anyone knows differently, let me know. At this time, they are about the same price. I bought an AT 20 100 XW from Astronomics with free shipping. It arrived in two days.

Mike

I did buy an AT from Astronomics. I keep calling that one an APM because all my others I bought from Don and are APM. Mike was great at Astronomics.

[Deep13]

Personally, I just upgraded from a 27 Panoptic to a 26 Nagler, so it's hard for me to see how a 21 Ethos would be worth it. If the 21 is heavier than the 26, then yeah, it's a real weight problem.

[Starman1]

Yes I know. Been to both. I want to avoid EPs from PRC.

I was that way until I tried a few of the newer eyepiece like the APM UFF 30, the Baader Morpheus line, and the 7mm and 9mm XWA.

The fact a few very nice eyepieces are made in the PRC doesn't mean they all are, but the truth is that 90% of all eyepieces are made there now, and it is a bit limiting

to confine your purchases to only Japan and Taiwan.

Life is short.

[desertlens]

To my eye, the 21mm Ethos is a special experience in the TV-85. A bit of ballast up front is helpful.