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Help me determine if and how BTs fit into my observing

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#1 Steve D.

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Posted 19 June 2019 - 07:17 AM

I’ve been getting more specific in using the “best” tool for the specific objects I intend to observe in a given session and with that in mind, I’m trying to figure out if a binocular telescope provides an additional capability that I don’t currently have.

 

I most often observe from a semi dark site (around NELM 4) that is about 35 to 40 minutes from my home.  A darker but less used site is about an hour and 45 minutes away.

Due to home storage and transportation requirements, I don’t have any intent at this point to go bigger than my current 8 inch dob.   I’m pretty set with all of my current telescopes.  Here’s how I use my current equipment.   My usage choices below are just my opinion but are pretty set based on my experiences, preferences and observing routine.

 

When viewing planets or the moon, I use the Mewlon 180 with binoviewers if time allows or the 102mm refractor with or without binoviewers for shorter sessions.   It’s unlikely I would ever choose the BTs specifically for a planet viewing session.

 

For double stars, I prefer either of the refractors or the Mewlon.   I enjoy single eyed viewing best for this class of object and it’s unlikely I would choose BTs for double stars.

 

For galaxies, I prefer my dob but occasionally use the refractors for brighter galaxies.  I’ve just recently really got into this class of object since I started using the darker observing site.

 

For getting the most from globular clusters, I prefer the dob for the increased resolution.   Based on comparisons with the 102mm refractor, it’s unlikely I would choose BTs for this class of object.

 

For planetary nebula, I prefer the dob due to the small size of many of these objects.   It’s unlikely I would choose BTs for this class of object.

 

That leaves open clusters and large nebula.   Depending on the object, the dob and refractors do a good job but maybe the BTs would add something here due to the wide FOV and two eyed observing but would the extra wide field of 10X50 binoculars I already have be even better?

 

So considering my current equipment and usage does a BT add anything to my current capabilities and if so, which size would be the most complementary?  ( I wouldn’t want to go larger than 100mm.)   What might I be missing that I’m not considering due to the fact that I haven’t used larger binocular telescopes before?   Is just the different “experience” (with perhaps a decrease in absolute performance vs my current equipment on some object types) enough to add BTs to my equipment?

 

Thanks for reading and any thoughts you have.


Edited by Steve D., 19 June 2019 - 07:22 AM.

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#2 edwincjones

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Posted 19 June 2019 - 08:39 AM

Brighter galaxy groups and clusters

 

I was going through the AL's Herschel 400s with my Fujinon 25x150

in Leo or maybe Leo Minor in dark New Mexico skies

I had 5 galaxies in the FOV, then moved a few degrees to the right

and saw 5 more galaxies.

My thought  "I am seeing the finger prints of God"

 

a moving experience - in spite of not being that religious

 

edj

 

also bright comets with tails


Edited by edwincjones, 19 June 2019 - 08:41 AM.


#3 Steve D.

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Posted 19 June 2019 - 08:52 AM

Brighter galaxy groups and clusters

 

I was going through the AL's Herschel 400s with my Fujinon 25x150

in Leo or maybe Leo Minor in dark New Mexico skies

I had 5 galaxies in the FOV, then moved a few degrees to the right

and saw 5 more galaxies.

My thought  "I am seeing the finger prints of God"

 

a moving experience - in spite of not being that religious

 

edj

 

also bright comets with tails

Good point on comets.   That's one I hadn't thought about.

 

I had a similar Leo galaxy experience with the dob recently.  It seemed like everywhere I look were galaxies.



#4 Beg

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Posted 19 June 2019 - 09:25 AM

Never underestimate a 100mm BT. I cannot stress how fun they are. I have seen things in my dark mountain skies that my C9.25 and Denk Binoviewer just can't provide. My BT surprises me all the time with it's perspective view on clusters and light and dark nebula. It's all about the perspective and BT's do that really well in an over performing way. 


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#5 markb

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Posted 19 June 2019 - 09:33 AM

I concur absolutely with Brian, and would add that they also excel in low stress, just for fun, low power touring in badly light polluted areas, my skies are Bortle 9 I believe. I look for globulars, always jaw droppingly beautiful.

 

Don't fret about light throughput due to the large amount of glass (Russian 120 are factory speced at something like 50% light loss). My 70 year old uncoated flaks will blow your socks off, still cannot believe it. And current 45 degree 100s, wow.  Avoid straight throughs, I could never use them comfortably.

 

In dark skies you can get lost for hours.


Edited by markb, 19 June 2019 - 09:37 AM.

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#6 Steve D.

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Posted 19 June 2019 - 09:57 AM

Brian and Mark, great information.   I've been intrigued by the thought of larger binos and may decide to finally jump sometime in the near future.



#7 garret

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Posted 19 June 2019 - 11:53 AM

 

Is just the different “experience” (with perhaps a decrease in absolute performance vs my current equipment on some object types) enough to add BTs to my equipment?

100mm BT:

Set-up and break-up time: minutes

Cool-down time: minutes

TFOV: 2.8 degree both eyes, 1.1/4" ep

Heaviest part: 6.6 kg/ 14.5 lbs (Oberwerk 2 lbs lighter)

Non reversed and upright view.

Both astronomical and terrestrial viewing. 

 

70, 80, 100, 120, and 150mm aperture to choose from.


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#8 Steve D.

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Posted 19 June 2019 - 01:25 PM

If I jump, I'm kind of leaning toward the ED 100s.   Do you think based on my current equipment that the 82s would be a better choice since they have a larger max FOV?   On the other hand, I have fun using just my 102 refractor from our semi-dark site so two 100s should be twice the fun.



#9 Mr. Bill

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Posted 19 June 2019 - 02:04 PM

My 70mm covers low mag/wide fov; my 100mm covers medium and higher mags......using the pair together at the same time covers the bases for my binocular needs.

 

OTOH, my 10 inch SCT with binoviewers gives great high mag views of objects such as GC and PNs.

 

Binocular viewing trumps one eyed viewing hands down, IMO.


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#10 Steve D.

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Posted 19 June 2019 - 04:35 PM

I have a wooden Oberwerk tripod.   Do you think it would be stable enough to handle the APM fork mount and a pair of 100 ED APOs?



#11 Nightfly

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Posted 19 June 2019 - 04:37 PM

I'm in agreement with Brian.   The BT-100 exceeded my expectations.   Under a good dark sky the night opens up and the tapestry of the Milky Way is revealed.  Perhaps it's important to have both good instruments and dark skies.  Seeing things not written about in the literature of astronomical observing.  Overwhelming in a good way.

 

Witnessing a 2.8° field of view down to 13th magnitude is routine.  Meandering the Great Rift for one night was worth the cost of these binoculars. One reaches for strong and lofty words.  The word revelation comes to mind.

 

Now, if I can just get some clear skies without the Moon, I may be able to wax poetic again about the observations.  


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#12 Vondragonnoggin

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Posted 19 June 2019 - 05:04 PM

I think most that get BT’s are already Binocular enthusiasts and enjoy Binocular views so much that the thought of going low to medium power with two eyes, interchangeable eyepiece options, are the first draw.

 

Better and better BT’s have become available to the point where ED glass is now available for apochromatic views which support higher powers than previous achromatic BT’s supported, so it makes for an appealing instrument to get satisfactory views on a variety of targets at <100x (SD’s and FCD100 probably at  <150x max comfortably) without the limitations a binoviewer has for low power.

 

Options in 45° or 90° oculars are available so longer sessions with less neck ache can be done easily so a plus over standard straight through binoculars - even the large astronomy specific marketed straight through binoculars.

 

You have to be enthusiastic about the ease and comfort of two-eyed viewing and see the benefit in detail seen over one-eyed views. If not an enthusiast of two-eyed viewing at as many powers as possible before having to resort to binoviewer use for very high power or single eyepiece use for very high power, then a person might not see a benefit to owning them.

 

I have the achromatic versions in 100mm and 70mm and switch over to BV’s for higher power than about 50x

 

I can go wider with a small fast refractor and low power single eyepiece by a wide margin, but I prefer two eyes to view and I prefer the same comfort my refractor with diagonal offers by using a BT over straight through viewing, so they make a lot of sense to me.

 

This also extends to Night Vision eyepieces I have and prefer using biocular Night Vision setups over monocular night vision setups. I vastly prefer using two eyes over one.

 

For me the BT’s are good for emission and reflection nebulae, open clusters, lower powered galaxy views at dark sites, but definitely best for:

 

General Milky Way sweeping looking for largest globulars, open clusters, nebulous star clouds, largest nebulae, etc.

 

If I had the ED apo or SD versions that would extend to planetary views <150x while I had the instrument out.

 

They are grab n go instruments as well. Fork mounts or fluid heads and adjustable center column tripods for the 100mm or less make for an easy and light setup that requires near zero cooldown times for acceptable views at low to medium powers and not very long at all to reach optimal cooldown for the highest power views the instrument supports.

 

Anyway, that’s my take on it and why someone might want to add a BT to their equipment list.



#13 Steve D.

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Posted 19 June 2019 - 05:15 PM

I think you all of sold me.   I've always enjoyed my 10x50's and even more so my prior 15X70's.   (I should have never sold them.)   I just need to decide between 82 or 100.  Some of you have both the 70s and the 100s.   I'm wondering if I should split the difference and go with the 82s but the 100's collect a good amount more light.



#14 Mr. Bill

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Posted 19 June 2019 - 06:24 PM

Certainly 82s split the difference, but if you can afford it, having both allows you to use two magnifications to compare views at the same time without having to change out eyepieces, a BIG deal.

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Edited by Mr. Bill, 19 June 2019 - 06:37 PM.

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#15 Steve D.

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Posted 19 June 2019 - 06:52 PM

I would probably only purchase one size.  With that in mind, is the potential increased FOV of the 82’s worth choosing over the increased light grasp and resolution of the 100’s?



#16 Allan Wade

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Posted 19 June 2019 - 06:55 PM

I tend to use my APM82’s for lower power observing. The small, light 24 Pans are great with that setup. That leaves my APM120’s setup next door with my 12.5 Docters for some higher power viewing. From the time I got hooked on binoscopes I always had the plan to get a big set and a smaller set to complement each other. For one Bino that does most things well, the 100’s are a pretty good option. 

 

I’ve never used an instrument that provides as much pleasure in observing dark nebula like my APM120’s do, and that includes my big dob. I spend hours panning up and down the Milky Way band exploring these fascinating dark patches. Clusters and Nebula look stunning in the binoscopes as well. Those are the objects I chase mostly in the binos.


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#17 Steve D.

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Posted 19 June 2019 - 06:59 PM

I think the 100’s are the way to go.  I can always set up my 10x50’s on my parallelogram mount for the really wide field view.



#18 Allan Wade

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Posted 19 June 2019 - 06:59 PM

I would probably only purchase one size.  With that in mind, is the potential increased FOV of the 82’s worth choosing over the increased light grasp and resolution of the 100’s?

If I could only own one binoscope, hands down it would be the 120’s. After my 32”, the APM120’s are my favourite piece of Astro gear. They are fantastic performers and the larger aperture is so revealing under good skies. Given your choice, I would go for the APM100’s.


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#19 markb

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Posted 19 June 2019 - 09:44 PM

On the mounting issue, I use my 10x80 flaks and APM100s on the same, simple, affordable and stable mount setup, which is a breeze to bring out for a quick peek:

Astro tripods with a old CG5/GP style head (60mm hole), or, much preferred, a $70-80 CST/Berger surveyors tripod, preferably the model with spread limiter, or add a simple homemade spreader. The standard hole is 63mm, just swap out the 11/16? bolt for a M10 bolt and knob.

Add a zero friction alt az like the old EzTouch, the AYO Swiss or economical Sergio Bonilla (vixen portas will not work, the sideload hangs them up and the load rating is flat wrong) with a vixen clamp on each side. Put the binos on a Orion $30 vixen dovetail L bracket or the pricer vixen L platform, and use the appropriate theaded knobbed bolt to clamp the bino on. Pad with foam if needed to protect the paint. APM 100s fit fine, and the weight is not an issue.

Shifting balance points are cured by using a cheap 12-18" dovetail extrusion with a chinese vixen compatible clamp, with a weight attached (look for camera balance weights to stay cheap). Slide as needed to balance, very natural and easy. Many folks already have the compatible astro tripod in a closet.

Sorry I don't have a photo handy, my tripods are in AZ and binos in NY. If I find an old one I'll post it.

Photo tripods are OUT for me; except for ones costing megabucks they are much less stable than even a $39 surveyors tripod.

#20 markb

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Posted 19 June 2019 - 09:59 PM

Having 10x80 flaks, 10x80 soviet border guards (multicoated and listed in the classifieds) and APM 100 apo eds, I'd go for the 100s if they are in your budget.

The 80s will not be a source of buyers remorse if that is what you can afford. Interchangable eyepieces are good, but you may double the cost of the BT.

Under no circumstances get straight throughs. I sold 3 pair I barely used due to the neck and positioning issues, including a fantastic UO pair I bought new.

Last point- 2.8 degrees? No, my flaks and border BTs are 7 degrees, 70 degree ep at 10x. Ad no noticable chromatism on the 70 year old flaks despite a fl around 280mm (IIRC). Forget the exit pupil 'waste', apparently the large exit pupil is one reason they are so amazingly comfortable for extended sessions. The APMs come with 18mm for about the 2.8 figure, but will take longer/wider eps., the 500 or 550 mm fl does restrict rft limits.
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#21 edwincjones

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Posted 20 June 2019 - 04:16 AM

Steve,

 

In the distant past there were standards

-for refractors the 100mm

-for SCTs 8"

-dobs 6-8"

then things started expanding

 

for binoculars I think levels

-10x50s for handheld

-then 70mms

-then 100mms

-now going to 150s (maybe)

others may disagree, but for me 100mms seems the best compromise in size

-70mms just do not see enough

-150s are just too big

 

been there, done that    

edj


Edited by edwincjones, 20 June 2019 - 04:20 AM.

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#22 Steve D.

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Posted 20 June 2019 - 06:35 AM

Decided:  100mm ED APO 90 degrees plus the APM fork mount.   Working with Markus now to place the order.

 

Thanks everyone for your help.   I've wanted these since they came out but I kept talking myself out of it.   As I've had the chance to get more experience observing from our semi-dark site, I've really had the opportunity to see what different scope types and sizes provide in terms of views, the magnification range I like to use, etc.   I think these big binos are going to get a lot of use.  With the 85mm and 102mm refractors, I will often use a single eyepiece for the entire night giving me 45X or 65x depending on which scope.  I think the 30X with the included eyepieces will be about perfect...at least until I get some experience.   Then I can start thinking about adding a lower and higher magnification set.   I already have some pairs for my binoviewers that will work until then.  (They are only 52 degree AFOV so will need wider at some point)

 

I'm really excited!!


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#23 Mr. Bill

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Posted 20 June 2019 - 08:27 AM

Good choice.....what tripod will you use?

 

I use the Manfrotto 161MK2B with the 100s and APM fork and find the combo rock solid.


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#24 Steve D.

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Posted 20 June 2019 - 08:30 AM

Good choice.....what tripod will you use?

 

I use the Manfrotto 161MK2B with the 100s and APM fork and find the combo rock solid.

I have an Oberwerk wooden tripod that I'm hoping will be stable enough.   I don't expect that I'll often go above 50X so it should be OK.



#25 Mr. Bill

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Posted 20 June 2019 - 10:11 AM

That should work fine.




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