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NexStar 6SE eyepieces FOV

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#1 audio_mad

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Posted 15 April 2019 - 05:28 PM

Hi,

I apologize in advance if the question has been discussed before:

I am getting a new 6SE and from what I read in the forum, one of the issues of SCTs is their narrow field of view.

As I am getting ready for the most necessary equipment to compliment the scope, I've decided the essentials would be (that's based on reading a lot in this forum):

 

Dew Shield,

Telrad Reflex sight,

Baader Hyperion 8-24 zoom eyepiece,

Explore Scientific 24mm 68 degrees eyepiece,

Celestron Luminos 7mm 82 degrees eyepiece,

Celestron 7-Amp Powertank

I already have Stellarvue dielectric diaginal

 

Since you probably notice an overlap in the ranges of eyepieces, I wonder if it's a proper thing or not. My thinking behind this range was: to get a great low magnification piece in ES 24mm, a convenient zoom (I found this zoom very useful on my small refractor) and high magnification 7mm with a very wide angle.

I am not sure if this makes sense though. Baader will cover pretty much the whole range I need but do I have enough field of view at 68 degrees? Will it be enough to observe comfortably and do I really need the ES 24mm at 68 deg. and 7mm 82 degrees (I thought at 7mm I really need the wide angle otherwise I will see a super small area at 68 deg. of the Baader)

Hope I managed to describe my conundrum clearly enough and also hope experienced users of 6SE could help with advise,

Thanks in advance guys!


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#2 Sam M

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Posted 15 April 2019 - 06:01 PM

That's what I've got, except I have a 6.7-82 instead of a 7.  I'd say the 24 is more important than the 7, since the AFOV on the Baader is much better at high mag.  Also, since you have tracking, a wide AFOV is less important at high magnification.  The other thing you could do is get a 2x barlow and unscrew the cell so that you can screw it onto the Baader effectively giving it about 1.5x.  Hope this helps.

 

Also, you might not need the Telrad with the go to.  And you might do better with a cheap lithium ion battery rather than the Celestron one.  The other accessory people frequently like is a 6.3 focal reducer, for a wider true field of view.

 

Clear Skies


Edited by Sam M, 15 April 2019 - 06:09 PM.

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#3 AJK 547

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Posted 15 April 2019 - 07:05 PM

I got my 6SE back in Aug. last year and I'm really impressed with the quality views when 'seeing' is especially good. The EP's I gravitate to mostly are my T/V 32 P, BHZ 8-24, 6.7 Meade UWA, and the Baader Hyperion Zoom Barlow (2.25X).

The T/V 32 P is an easy to use EP for me for general 'targeting'. The BHZ, as you know, is a fine zoom for the price and sits in the diagonal most of the time. For planetary views, If seeing is good, I will immediately drop in the Meade 6.7 UWA, which gives me ~224X. Now... if 'seeing' is REALLY GOOD, I screw the Baader Barlow onto the BHZ and it gives me a full range from ~10.5mm to about 3.5mm. The 'sweetspot' for the BHZ/Barlow combo ranges from 10.5 to ~ 6mm for the 6SE. Any more 'push' in power and view quality drops off quickly.

What I enjoy experimenting with now are various filters (Contrast Booster, UHC, OIII, etc.). The Baader Contrast Booster has flushed out details on Jupiter and Mars, while the UHC and OIII has given nicely enhanced views of various Nebula in my main 8.5 Bortle viewing spot.

Also, as Sam mentions above, an inexpensive Lithium Ion brick (Talentcell, etc.), was a nice accessory to eliminate any possibility of cord wrap.

Edited by AJK 547, 15 April 2019 - 09:31 PM.

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#4 Taosmath

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Posted 15 April 2019 - 07:43 PM

I agree with both prior posters.  I used a zoom (celestron or baader - I have both)  and a wider field 24mm ( I have Panoptic, but I'm told ES is almost as good).  I didn't need a Telrad on my 6SE- I found the standard red dot finder good enough to align the goto.  I also agree on the lithium battery - 30$ from Amazon & you don't worry anymore about cord wrap.

 

So my recommendations: Don't buy a Telrad or a Celestron battery.  Do buy a lithium (talent cell or equivalent).   Use the money you save to also buy a 0.63 focal reducer - without the FR, the TFOV with the Panoptic was 0.96 degrees (and the same with a 40mm plossl) .  With the FR the TFOV was 1.45 degrees for both the 24mm panoptic & the 40mm plossl.


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#5 audio_mad

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Posted 15 April 2019 - 09:43 PM

Thanks a lot Guys! Real valuable information here, much appreciated. Seems like FR 0.63 is the way to go.

As for a lithium battery, I don't see much around.

Talentcell Rechargeable 6000mAh Li-Ion Battery Pack isn't available on Amazon anymore for some reason, the ones that are available either cheap untrustworthy brands, or the ones that are more expensive than Celestron powertank. If there are some brands you had a good experience with, please recommend.

 

A question around Barlow that Sam and AKJ mentioned, I heard Barlow wouldn't work well with 6SE. Any comments? Does it really work or you lose clarity when pushing magnification to the limit with Barlow?

 

Thanks again!



#6 AJK 547

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Posted 15 April 2019 - 09:58 PM

A question around Barlow that Sam and AKJ mentioned, I heard Barlow wouldn't work well with 6SE. Any comments? Does it really work or you lose clarity when pushing magnification to the limit with Barlow?
 
Thanks again!


Audio_mad, I spent quite a bit of time (actually days) testing my EP's using the ISO 12233 lens chart. With the BHZ MkIV 8-24 and Baader Hyperion Barlow (2.25X) the 'pairing' of the two was extremely good IMHO. The only time I noticed any minor 'softening' of the FOV, using the BHZ and Barlow combo, was when I pushed the combo to the extreme of the zoom range. This effect occurs even on EXTREMELY good photographic zooms...

What I noticed is that I could get a reasonable 35X per inch of aperture under good 'seeing' and could approach 40X per inch when 'seeing' was excellent with my 6SE. No more. FWIW, my 6SE is also in excellent collimation.

Like I mentioned, for planetary viewing I will start out with the BHZ to give me an idea of conditions, and if very good, then pop in the Meade 6.7 UWA. However, now I'm experimenting with the Barlow to very good effect! Like I mentioned, the BHZ and Barlow combo is a surprisingly good 'combo'... YMMV...

Ps. I just checked Amazon and they seem to have the Talentcell 6000 mAh and 8300 mAh 12V batteries is stock as of a few minutes ago. Another inexpensive item I bought was a 1ft. cable to go from the Talentcell to the 6SE mount.

Attached Thumbnails

  • Talentcell 6000.jpg
  • Talentcell cable.jpg

Edited by AJK 547, 15 April 2019 - 10:13 PM.

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#7 Sam M

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Posted 15 April 2019 - 10:36 PM

By all accounts I've read the Baader Hyperion barlow 2.25X (which is designed to work with the BHZ) performs beautifully.  That is what AJK is using.

 

I chose to go a different route and take a garden variety 1.25" 2x barlow and unscrew the lens cell from the bottom and screw it into the filter threads on the bottom of the BHZ.  I chose this for a couple reasons.  First, it's the cheapest option.  Second, it brings the BHZ to about 1.5X, so that means it's shortest focal length, and widest AFOV is at about 6mm, instead of 8mm.  Opinions vary about how much magnification a C6 can take, but I don't need to push mine past 6mm (250x without a focal reducer).  I can say that my ES 4.7 always feels like a bridge too far.

 

It's probably not as sharp as the Baader barlow, and the the scope can use more magnification, if you have a focal reducer attached. So, there you have it.


Edited by Sam M, 15 April 2019 - 11:01 PM.

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#8 AJK 547

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Posted 16 April 2019 - 07:05 AM

Sam_M, I reviewed the specs on the Baader Barlow and read where this Barlow has an 'anastigmatic field flattener' lens system built into it. WOW, never knew that.

Looks like some more field testing is in store for me!

Edited by AJK 547, 16 April 2019 - 07:08 AM.

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#9 audio_mad

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Posted 16 April 2019 - 08:39 AM

Thanks again for this info AJK and Sam! I did need to check the US Amazon site, Talentcell isn't available at Amazon in Canada anymore for some reason. Will definitely get this from Amazon.com.

 

 A question about focal reducer though. There's a whole discussion on their use for visual only at this forum and it seems the consensus is: unless you're into astrophotography, don't bother with FR on 6CE. They say it's useful for visual and doesn't flatten the image on 8CE but doesn't do much except dimming the view on 6SE. In a nutshell, they say "must have" for photos and "don't buy" for visual only. So,I am confused here...

 

But nothing is like hearing from the 6SE users who have experience with FR. You guys think it makes sense to get one for visual only.

 

Please share your thoughts on this,

 

Thanks again!



#10 Taosmath

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Posted 16 April 2019 - 08:53 AM

I suspect that the FR helps photographically, but doesn't make much of a difference visually on the field flatness and since it adds optical surfaces to the image train, it will inevitably reduce image brightness a little.  I didn't notice that.  

 

However my recommendation for purchasing it is purely to increase the field of view (about 50% compared to the 1.25" diagonal alone).  You can get almost exactly the same maximum total field of view (about 1.45 degrees) without the focal reducer by using a 2" diagonal BUT

  • It's more expensive to buy a 2" diagonal plus 2" eyepieces than a FR  (unless you already have a 2" set up)
  • It's very clunky on a 6SE and may protrude so far back from the rear of the OTA that you may not be able to reach zenith
  • May be difficult to balance the OTA.

 

Hence if you want more TFOV than the native 1 degree, my suggested route is to get an FR.  

 

Of course if , because you don't look at larger objects (there aren't that many bigger than 1 degree) , or you don't want to see your target in a wider context, then you may be satisfied with a 1 degree field and hence a 1.25" diagonal  is all you need.



#11 AJ

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Posted 16 April 2019 - 09:08 AM

Seems like FR 0.63 is the way to go.

 

A f/6.3 reducer/corrector works great in the 6SE, as does the ES 24mm 68 deg eyepiece.  I use that combo often In my 6SE.  It nicely frames M81 & M82 together, well inside the field of view; same for many other large DSOs.



#12 AJK 547

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Posted 16 April 2019 - 10:08 AM

Quick update on the 2.25X BHZ Barlow with 'anastigmatic field flattener'.

I got out my ISO 12233 Lens chart and in indoor daylight conditions I can definite see where this BHZ Barlow DOES extend the apparent field resolution across the ENTIRE BHZ FL range. I'm impressed!

The 'sweetspot' for overall FOV resolution was 16mm (as suspected), but when I inserted the BHZ Barlow the sweetspot extended to ~75% of the FOV. This quick qualitative test was repeatable across the zoom range.

Note: there was mild field 'darkening' and a 'hint' of softening with the BHZ Barlow in the chain, but results showed to me the excellent 'combo' synergy. Comparison would be like Zone 10 on-axis (w/o Barlow) vs. Zone 9.5 on-axis (with Barlow).

Sorry for hijacking this thread a bit, but the results helped qualitatively answer the OP's question on potential Barlow impact on general field resolution. Results with other Barlow combinations can vary as you can imagine...

Edited by AJK 547, 16 April 2019 - 10:17 AM.


#13 audio_mad

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Posted 17 April 2019 - 10:31 AM

Great info! Thanks a lot for sharing everyone! That was really helpful. I know what I need now.


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