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Please help me decide -- APM 120 SD-Apo or APM 100 ED-Apo?

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#1 SupraVision

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Posted 07 February 2018 - 08:46 AM

Hello, I am about to purchase my first real binocular telescope. Currently I own a 25x100 Celestron but I am not very satisfied with (the only advantage was it was quite cheap).

 

I narrowed my options down to those two:

1) APM 100 mm 45° ED-Apo
2) APM 120 mm 45° SD-Apo

 

I would like to ask any people who have first hand experience with both telescopes, to help me decide.

 

What I need to observe?

Mainly low-light terrestrial objects (evening) but sometimes also galaxies and planets.

 

What is the main thing I am looking for?
First and foremost: sharpness and fidelity.

 

What magnification will I usually use?
Anything in the 50x-65x range.

 

Let me point out that I do know that the 120 mm BT is going to be a lot brighter than 100 mm.

 

My main question now is: Is there any noticeable difference in sharpness and fidelity between the two BTs when the magnification is in the 50x-65x range?

 

If not, one should probably go for the 120 mm to get a brighter image, which is always good to have. Am I right?

 

Weight or mobility is not a problem. It is going to stay in the same place.

 

I read that ED APO is higher quality (sharper?) than SD APO. If that is true, it might make the 100mm a better choice, mightn't it?

 

Also, do you know any better binocular telescopes than those that allow for 65x magnification and cost about the same?

 

Thank you.


Edited by SupraVision, 07 February 2018 - 10:43 AM.


#2 Neptune

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Posted 07 February 2018 - 10:02 AM

As with most things in life, BIGGER is usually better.



#3 GamesForOne

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Posted 07 February 2018 - 10:03 AM

Bigger is better but you have to consider the extra weight, bulk, and expense of a good mount.

 

With the 100's you can either use the APM center mount or opt for a relatively inexpensive tripod and fluid head. I love the center mount with my 100's, but it is a bit shaky compared to a beefier fluid head.

 

For the 120's you are probably going to need the APM fork mount, or something similar, or a really heavy duty tripod with a very large fluid head ($$$). Either way it will be expensive and bulkier.

 

If the setup is going to remain fixed at one location most of the time, go for the larger aperture. The 120 likely has better grade objective glass in FPL-53.

 

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Edited by GamesForOne, 07 February 2018 - 12:25 PM.


#4 SupraVision

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Posted 07 February 2018 - 10:45 AM

So it doesn't matter that the 120mm is an SD-APO while the 100mm is an ED-APO?

 

Doesn't ED-APO yield sharper image than SD-APO?

 

Also, have you guys personally compared the image quality of those telescopes at the 50x-65x magnification to be able to claim that bigger is always better?

 

I mean who needs brighter image if it gets less sharp, for example? That's why I'm asking for first-hand experiences with those two.

 

Thanks.


Edited by SupraVision, 07 February 2018 - 10:47 AM.


#5 GamesForOne

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Posted 07 February 2018 - 12:00 PM

I can't speak to a direct comparison between the 100 and 120. There are others on this group that can and have already posted remarks about the gains they experienced with the 120 as well as good performance with the FPL-53 glass. Both use low-dispersion glass in the doublet objectives, however I don't know of any affordable glass that can yield true APO performance with f/5.5 doublets.

 

Why is the 100 denoted "ED" (FK61) while the 120 is "SD" (FPL-53)? I don't know.

 

In my experience with the 100's, the performance is obviously better than any achromatic binocular I've ever used (especially when pushed to 50-65x), but not as good as my TMB 105mm f/6.2 APO triplet.

 

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#6 Mr. Bill

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Posted 07 February 2018 - 12:11 PM

Bigger is not always better IF you are going for the largest fov.....

 

I find the 100 APO BT hits the "sweet spot" for Milky Way sweeping.

 

YMMV


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#7 Mike Harvey

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Posted 07 February 2018 - 12:34 PM

I "moved up" from the 100 APO to the 120 APO

The FPL53 glass in the larger model is simply exquisite.

For ASTRONOMICAL PURPOSES, that, and the extra aperture, enable the 120's to perform at a higher level than you'd expect from just 20mm more.

 

However, deep sky observing doesn''t seem to be a priority for you. And youve stated that portability is not an issue. That complicates the decision!  :)

 

MY only "issue" with the 120's is that portability IS a concern. If I had a permanent mount such as yours, I would unhesitatingly  recommend the 120's (and be anxiously awaiting the 150's!).

IF, on he other hand, there might be times when you want to travel with the binos...I would recommend the 100's. They are much more "user-friendly" in this respect.

 

BOTH binoculars are simply excellent. Optically, you can't go wrong with either choice.


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#8 lulz

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Posted 07 February 2018 - 01:06 PM

Has anyone compared the Semi-APO 100s vs the APO 100s?



#9 Mad Matt

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Posted 07 February 2018 - 01:28 PM

Since low light evening observations seem to be the priority I would recommend the 100 ED APO of the two. Having said that, I think you will find the 82mm version of the same series will possibly perform better then the 25x100 you currently have and be generally easier to handle.

#10 Mr. Bill

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Posted 07 February 2018 - 03:30 PM

Has anyone compared the Semi-APO 100s vs the APO 100s?

Owned both....REAL APM APOs are light years better in all respects except off axis ghosting; there the semi APOs fare better.

 

I question whether the "semi APOs" have any special glass....IMO a marketing ploy....the words have no legal status


Edited by Mr. Bill, 07 February 2018 - 04:14 PM.


#11 edwincjones

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Posted 07 February 2018 - 04:24 PM

you already have 100mms, seems like a 100 and a 120 makes more sense that two 100s

 

edj


Edited by edwincjones, 07 February 2018 - 04:24 PM.


#12 Mr. Bill

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Posted 07 February 2018 - 04:33 PM

you already have 100mms, seems like a 100 and a 120 makes more sense that two 100s

 

edj

Owned both....."donated" semi APO to a friend as it was superficially damaged and couldn't be sold.

 

Still on fence about purchasing  a 120mm....6 inch f/5 refractor seems to fill this nitche nicely.



#13 Mark9473

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Posted 07 February 2018 - 04:52 PM

Mr. Bill, I believe you are talking about the previous generation semi-apo's, not the current one, right?



#14 GamesForOne

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Posted 07 February 2018 - 04:54 PM

Depends on which semi-APOs are being referenced... The new semis have the same body style (and prism design?) as the APO version.

 

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#15 Allan Wade

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Posted 07 February 2018 - 04:55 PM

Image brightness has nothing to do with aperture, it is dependant on eyepiece exit pupil size. The 100’s at 50x and 120’s at 60x both have a 2mm exit pupil, and the object brightness will appear identical. The advantage of the larger aperture is a larger image scale at the same brightness/exit pupil, which may help see more detail.

 

Comparing the ED/FK61 glass in the 100’s to the SD/FPL53 glass in the 120’s is like comparing apples and oranges. There are a lot of other variables like bino focal ratio and mating glass that affects things. All else being equal though, an APM 100 made with FPL53 will have better colour correction and possibly sharpness than an APM 100 made with FK61 glass. Though the FPL53 bino will be more expensive.

 

As your main use will be for terrestrial objects, I don’t see the advantage of going to the 120’s. They are quite a deal larger and more expensive than the 100’s, and require more substantial mounting. I think the 100’s would be more suited to what you’re looking for.



#16 Mr. Bill

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Posted 07 February 2018 - 05:09 PM

Mr. Bill, I believe you are talking about the previous generation semi-apo's, not the current one, right?

Yes.....I believe that's what was being referenced in post # 11

 

You are right, my comments are about the older semi APO which is still being sold by APM

 

http://www.apm-teles...-binocular.html



#17 Mark9473

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Posted 07 February 2018 - 05:37 PM

You initially replied to post #8 and there, from a potential buyer who hasn't said he's looking on the used market, I would have assumed he meant the current model.

Of course, you're right and he could snatch up that last one of the older model that APM have on stock.

Just to clarify for the poster in #8.


Edited by Mark9473, 07 February 2018 - 05:40 PM.


#18 range88

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Posted 07 February 2018 - 08:07 PM

This is a very easy question, since weight is not a consideration, 120 is the clear choice, or if money is not, either, you can go 150sd.
100ed has 51 class ed objectives while 120sd has 53 class. In apm terminology, sd is always better than ed. Actually, 50-60x is at the limit for good quality image in 100ed while 120 can handle much higher.
They are simply no match.
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#19 range88

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Posted 07 February 2018 - 08:17 PM

P.S. If in your second thought, portability comes up very high in your list, my advice is waiting for 100ed upgrade to 100sd with 53 obj. Though this is not on schedule now but I think it will happen. Or 100ed will be stuck in an awkward situation between 2 sd models, 82 and 120.

Edited by range88, 07 February 2018 - 08:19 PM.

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#20 Mr. Bill

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Posted 07 February 2018 - 08:22 PM

Works for me...the most I use in my 100 APOs is 50x (11mm DeLite).....if I want more, 6 inch f/5 refractor with 13mm or 10mm Ethos works great.

 

For me, binoculars are for low mag, wide fov views.

 

Again, YMMV



#21 starzonesteve

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Posted 08 February 2018 - 08:31 AM

If money, weight, bulk and mount are all no issue, then I don’t see why you would not go for the 120s. I have owned both of these binos and think they would both admirably suit your needs. I had no problem using either in the magnification range you describe. That being said, if there is any advantage to saving money, weight, or mount bulk then I think the 100s make more sense with the kind of usage you are describing.



#22 SupraVision

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Posted 08 February 2018 - 10:09 AM

I "moved up" from the 100 APO to the 120 APO

The FPL53 glass in the larger model is simply exquisite.

For ASTRONOMICAL PURPOSES, that, and the extra aperture, enable the 120's to perform at a higher level than you'd expect from just 20mm more.

 

However, deep sky observing doesn''t seem to be a priority for you. And youve stated that portability is not an issue. That complicates the decision!  smile.gif

 

MY only "issue" with the 120's is that portability IS a concern. If I had a permanent mount such as yours, I would unhesitatingly  recommend the 120's (and be anxiously awaiting the 150's!).

IF, on he other hand, there might be times when you want to travel with the binos...I would recommend the 100's. They are much more "user-friendly" in this respect.

 

BOTH binoculars are simply excellent. Optically, you can't go wrong with either choice.

 

Thank you very much for the information. There is going to be an AMP 150mm APO? Any idea when?



#23 Mad Matt

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Posted 08 February 2018 - 10:17 AM

 

Thank you very much for the information. There is going to be an AMP 150mm APO? Any idea when?

 

 

Lots of info on the vendor forum: 

 

Here: https://www.cloudyni...s/?hl= apm 150

and here: https://www.cloudyni...s/?hl= apm 150

 

The price has not been officially stated yet but it looks like the 150SD will be a 10k+ investment: https://www.cloudyni...50#entry8289228


Edited by Mad Matt, 08 February 2018 - 10:17 AM.

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#24 SupraVision

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Posted 08 February 2018 - 10:29 AM

This is a very easy question, since weight is not a consideration, 120 is the clear choice, or if money is not, either, you can go 150sd.
100ed has 51 class ed objectives while 120sd has 53 class. In apm terminology, sd is always better than ed. Actually, 50-60x is at the limit for good quality image in 100ed while 120 can handle much higher.
They are simply no match.

Oh, thank you for that info -- I did not notice (the website didn't say) the the 100 ED is FPL-51. The website does say that the 120 SD is FPL-53. Then I agree with you that this is really easy -- 120 SD should be the best choice.

 

However, if there's going to be a 150 APO from APM soon, I'm thinking I might wait for that.



#25 lulz

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Posted 08 February 2018 - 01:40 PM

150s is supposed to be priced at around 10k though :|




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