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How far have you “pushed” your APM 100 BT?

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#1 ERHAD

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Posted 12 October 2019 - 05:01 AM

I have come to love lunar observation with my APM 100 ED BT. I normally observe with a 5mm ED Starguider eyepiece set. These are by no means premium eyepieces but I have been extremely satisfied with the views so far. While I understand 110x is not considered very high-detail observation, there is enough to be seen in Luna at this power to keep you busy.

 

However, last night sky was great and felt I could “squeeze” some more out of it. The 5mm are my shortest eyepieces so I decided to try some barlowing. I have two Orion “shorty” barlows that allow unthreading the lens cell from the Barlow body, which can in turn be threaded directly to the eyepiece giving you an estimated 1.5x mag. So if I’m not mistaken I must have been somewhere in the 150-165x neighborhood. Wow! Two things struck me: first that the binos held collimation at all. Collimation was just perfect. I did have to fiddle with the eyepiece a bit rotating it in order to merge images, but they merged perfectly. Secondly, how much detail is still preserved at this magnification. Resolution obviously suffers a bit, and floaters start to be a real nuisance for sure at this exit pupil, but if you relax and learn to look “through” them, the image was still very sharp and made for a very pleasant session. A lot of detail!
 

There was a little bit of color on the limb, but really not a lot. The Barlow lens configuration is, I presume, not perfect and I’m sure quality and ghosting would be greatly improved by using a dedicated eyepiece. Even though I rarely go over 40x for DSO and star sweeping, this has opened a door and I’m considering getting a shorter eyepiece just for lunar observation.

Would love to hear your experiences, how far have you pushed your BT. Any issues with collimation and where is your “comfort limit”? Any shorter eyepieces you use that work well with the BT100  and that you would recommend, again, just for the purpose of lunar (and I might have to give it a try for planeatary) observation?

 

Thanks.

 

Erik.


Edited by ERHAD, 12 October 2019 - 05:03 AM.

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#2 markb

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Posted 12 October 2019 - 08:10 AM

My first 100's were the blue tube semi-apos (more CA than the grey tube semis), bought used as a dealers demo scope. Collimation was perfect, and my 4.8 Naglers were very comfortable. I have always assumed they were cherry picked for collimation as demos as APM recommends power be limited to 50x normally. The blue tube 100s were so enjoyable I decided to upgrade immediately to an ED apo to lose the color (actually tolerable for an f5 or 5.5), and to get a wider purpose scope for retirement. I know a single scope can't readily do DS and planetary, but I wanted to come close. Hey, ultimately it is just a very high quality ED APO telescope, times 2!

 

My ED APOs are probably a less informative example to go by, as, in consultation with Markus, I sprung to have them tuned, which involved restructuring the cells and recollimating for 125x plus and improved resolution, IIRC.

 

I ran some daytime trials with barlows and short Naglers as well as UO Widescans to see which combos reached focus, without abberations. I don't think the matched barlowed Mark IV Baaders zooms did, darn. But they did, as claimed, without the barlows. The Mk IIIs did not. I believe the 2.8 UO Klee barlows did well. The Baader BCO-set barlow, surprisingly, did not work well with some eps.

 

The UFFs were phenomenal in the 100s, but are not available in short enough fls.

 

My notes on the barlow pairings have been misplaced, I can edit this when they pop up.

 

I have not used the 100s much since the purchase, as my time has gone to clearing 30 years of accumulation for a crosscountry move, and prepping (and finally getting the push to upgrade and 'perfect') several scopes for sale, only 2 to go! (Jaegers 6" f8, and either a etx125 or 6339 Sears Royal Astro 76mm).

 

The ED APOs easily handle the Nagler 4.8s. They were quite sharp with very little or no observable CA, pending star tests,, very noticably sharper than the blue tubes (which were very good on their own), but I have not done any really critical testing yet since the first outings were so positive. Two were daytime tests, which are slightly less collimation critical, but way more color and possibly sharpness critical in brief testing, in my experience.

 

I have yet to bring them out for the current Jupiter and Saturn fest, spending my few decent nights testing scopes post-improvement or to verify performance pre-sale. Jaegers refractors are amazing, for 50 year old achromats!

 

I don't do lunar, way too bright for me in the APMs and any large f5 until I get Baader neutral density filters.

 

I will try the 4.8s, and 7mm Naglers, in the APMS when weather clears, possibly tomorrow. And combine them with the 2.8 Klees, or the screw in Barlow elements you mentioned, I have 2 or 3.

 

My Wellenform test certificate indicated they tested it with a Nagler 3-6 zoom! This would be a great match for your intended purpose, just pricey. I have never read how well they do barlowed, a possible use in the short fl APMs. There are several high grade barlows to try.

 

My alt az mount, with sliding CW and green laser, has not presented a tracking issue when using very high powers, even with the 6" Jaegers, but this will also be a good time to try fitting the APMs to my Vixen dovetail converted GPS11 Nexstar mount for powered tracking.

 

I, also, will be interested to hear of the experiences of others.


Edited by markb, 12 October 2019 - 08:12 AM.

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#3 markb

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Posted 12 October 2019 - 11:25 AM

I forgot to add, smoothie (early) 4.8 and 7mm Naglers are, like C11 OTAs, one of the best bang for the buck bargains on the used market. UO Widescans and Klee barlows too. As great today as they were in the 80s.



#4 oldmanrick

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Posted 12 October 2019 - 11:52 AM

In my 100mm Lunt ED APO, I have used a Morpheus 9mm pair in ES 3X focal extenders, giving about 195X.  I was able to merge the images, and bright terrestrial and lunar views were surprisingly good, but there was too much contrast loss and fuzziness for satisfactory planetary use.

 

Rick


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#5 markb

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Posted 12 October 2019 - 01:07 PM

Hmm, 328x on the 4.8 Naglers with Klee Barlows, 220x on the 7 Naglers with Klee Barlows. It will be interesting to see if anything like that is usable at all, given decent conditions.

The C11 does 583 with just the bare 4.8, and 400 with the 7; very enjoyable image scales, and easily stopped down to 4 inches, unobstructed, which I have not yet tried. If the APMs can do even half of that it will be interesting indeed.

The curse of f5 or f5.5 scopes; beloved, transportable, but hard to get high powers. Lots of CA in acromats too; looking forward to my new Baader 495LP filter for the Jaegers. My big f5s are bright and sharp, but it is hard to get large image scales for planets and doubles. Which, of course, is not what they are made for.

#6 ERHAD

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Posted 13 October 2019 - 01:11 PM

Thanks for your input, really interesting. I am in no way looking to go 200-plus x with them, too many compromises. I am preparing to follow some lunar observation programs and I would benefit from a bit more mag. I am considering getting an eyepiece set in the 3.2-3.5 mm range. These would be exclusively for lunar observation, though I’d love to give the BT00 a try for planets at 150-170x...

 

I got my APM 100 ED from Markus himself. Mine was also,used .I ignore if it was a demo, it does have a few blemishes and scratches on the body though it has been flawless optically. It was too good an opportunity to pass. I also ignore if collimation is out of the ordinary in my unit, I didn’t get any certificate with my unit. It appears though that this binos are capable of higher magnifications than what they are advertised for.

 

Would love to hear any other opinions or experiences...

 

Erik


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#7 oldmanrick

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Posted 13 October 2019 - 09:49 PM

I have found the Morpheus 6.5mm at 85X, to be the most used, and best higher powered eyepiece I've used in my Lunt 100mm binocular.

 

Rick 


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#8 garret

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Posted 14 October 2019 - 01:07 PM

5mm Delite = 110x, that's is how far I can go.

If the seeing for viewing the moon is very good/ near perfect I wish I had more power, my APM 100-45 ED APO can handle it, but...  'eye-floaters' prevents me to use more power.

 

edit: translation fix


Edited by garret, 14 October 2019 - 03:13 PM.

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#9 ERHAD

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Posted 14 October 2019 - 01:44 PM

Hi Garret. I agree. While I comfortably observe with my 5mm eyepieces at 110x, I have to admit that from there floaters start to be a real nuisance, doable, but it takes some concentration. But on good nights for finer lunar detail it’s a trade off I’m willing to accept...

 

Erik.



#10 oldmanrick

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Posted 14 October 2019 - 02:16 PM

Hi Erik,

 

I've used ES 4.7mm pair in my 100 Lunt for 117X.  For the Moon, these are good, although they are a bit more critical for eye placement, and floaters start to become a problem.  The moon is so bright that even at this power, contrast and image quality are quite good, depending on seeing.  They are not as good as the Morpheus 6.5's for planets or DSO.  YMMV.

 

Rick



#11 garret

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Posted 14 October 2019 - 03:25 PM

 

They are not as good as the Morpheus 6.5's for planets or DSO.

The 6.5mm Morpheus ep is (are) on my wish list, they fit perfectly between my 9mm and the 5mm Delites.

Rick, how do you rate the 6.5mm?

 

My current eyepieces for the 100mm APM are:

22mm LVW Vixen (8/10)

17.5mm Morpheus (7/10)

12mm Delos (9.5/10)

9 and 5mm Delite (9/10)



#12 oldmanrick

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Posted 14 October 2019 - 04:59 PM

As far as other eyepiece pairs at or near the same power, I have the 7mm delites and 6.7mm ES 82*.  The Morpheus 6.5's get much more use than either of those other pairs.  For me, the 6.5's are just so much more comfortable, and to me optically slightly better.

 

I just can't find an eyecup position with the Delites that is comfortable for me.  Of course, the Delites have a significantly narrower FOV too.  The ES 6.7's don't seem to be quite as good optically as the Morpheus 6.5's, and I even like the ES 4.7's in my Lunt 100 better than the ES 6.7's.  Even though on paper the FOV is less, to me the Morpheus 6.5's seem to provide a more expansive appearing view.  YMMV.

 

Rick 




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