Jump to content


Photo

DSO observing

  • Please log in to reply
15 replies to this topic

#1 Allan Wade

Allan Wade

    Messenger

  • -----
  • Posts: 453
  • Joined: 27 Jan 2013
  • Loc: Newcastle, Australia

Posted 21 August 2013 - 09:09 PM

I spend most of my time observing DSO, and I am set up with TV eyepieces to enjoy this in mono mode. I'm keen to give bino viewing a try, seems most people who try it never look back.

My main motivation for giving it a go are to experience the lunar and planetary views everyone raves about. But I was wondering if they are used for serious deep sky observing, or do you just switch back to mono mode.

I was also wondering if something like the BINOTRON 27 will perform well on DSO due to the larger prisms.

So I am considering the BINOTRON 27 with D21 eyepieces. Is there a better combination I should consider, or am I on the right road?

Thanks everyone.

#2 Sorny

Sorny

    Viking 1

  • -----
  • Posts: 776
  • Joined: 15 Mar 2012
  • Loc: Southern MN

Posted 22 August 2013 - 04:01 AM

I'm all about using the binoviewer on anything that fits into the FOV I can get with it. Really faint nebulae get the big ol' 2" eyepieces and appropriate filtration, but everything else gets the binotron/D21 combo.

You haven't seen M13 until you've seen it in binoviewers.

I think you're on the right road with the Binotron supersystem.

#3 roadi

roadi

    Apollo

  • *****
  • Posts: 1211
  • Joined: 18 Aug 2007
  • Loc: Great Grey Spot "Denmark"

Posted 22 August 2013 - 05:18 AM

I'm a fan of binoviewing and will never go back to mono when observing planets, on these objects binoviewing ROCK's!! :cool:

Deepsky on the other hand is a little mixed bag, every time I binoviewed Globs or galaxies they stood out very nice, 3D "like", but then switching to mono mode, the view wasn't as relaxed but then a little more crisp!
My binoviewer isn't a premium unit, this could be a reason why. ymmv

#4 crazyqban

crazyqban

    Vanguard

  • *****
  • Posts: 2112
  • Joined: 16 Dec 2008
  • Loc: Miami, Florida

Posted 22 August 2013 - 05:54 AM

I really like observing planetaries at high magnification with my binos. Especially the Eskimo.

#5 Qwickdraw

Qwickdraw

    Surveyor 1

  • *****
  • Posts: 1725
  • Joined: 03 Mar 2012
  • Loc: Ann Arbor, MI

Posted 22 August 2013 - 05:59 AM

I recently purchased the Denk, Binotron. After years of on again-off again observing I finally had the resources to make a substantial investment in quality equipment. I can say that the relaxed two-eyed viewing is a much improved way to observe planets, moon globs and even some bright DSO. If you are looking to view the faint fuzzies, I would not recommend it. The other day I saw the best views of the moon I have ever seen.

#6 REC

REC

    Fly Me to the Moon

  • *****
  • Posts: 5144
  • Joined: 20 Oct 2010
  • Loc: NC

Posted 22 August 2013 - 07:35 AM

Just to add, make sure you will be able to achieve focus in your Dob....I'm not doing real well with mine yet and keep looking for a solution.

Have fun, the view of the Moon will blow you away!

Bob

#7 Messyone

Messyone

    Viking 1

  • -----
  • Posts: 557
  • Joined: 02 May 2012
  • Loc: Down Under

Posted 22 August 2013 - 08:05 AM

Your on the road to viewing nirvana. Binotron and Denk21's first up...wow. May as well add the Denk 14's too. Then point your scope at Tuc 47 and if it's still around Omega Centauri and Centaurus A.
Enjoy.
Matt

#8 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 22 August 2013 - 08:17 AM

I think for a Newt, the Binotron 27 system is the way to go.

The size of the prisms don't make the view any brighter though. It only determines the field size that you can get, and this is one of the two weak points of binoviewing (not a Binotron issue, but a generic binoview issue).

The Binotron will give you a low power view with the 21s of about 90x in your scope (The focal lenght of the eyepeices is advertized as 21mm, but according to Russ, they measure about 21.6mm, but he feels that he can't advertise them as 22mm because people would feel cheated).

Now 90x is not bad. A lot of deep sky will fit into the field of this combination.

I used the Binotron (on loan) in my own 12" and it was great. My only concern was that to use the high power arm, it was necessary to slip the binoviewer out from the focuser a quarter of an inch.

The problem with this was that the Orion focuser tube only supports the OC at the top and if you slip it out, it can kind of flop around.

The solution would be a new focuser of course.

The other issue is that the standard (base) OCS will not well illuminate the field of your scope. The field won't appeear vignetted, but it will appear brighter in the center than the outside.

The solution is the OCS 45 (I think this is the part number) but this is another expensive option.

Many people don't mind slipping the OCS out for high power, and if you don't mind this, you can pass on the new focuser (mayby you already have a moonlight though and can just adjust with the tube and shims) but if it bothers you (and it did me) count on buying a new focuser.

And the OCS as mentioned would add to the price.

I do not know if there is an "Adjusted" price if you order the binoviwer withoutht standard OCS and just get the larger OCS, but otherwise you are lookingat almost $2000 for the Bintron, 45mm OCS, and D21s.

The D21s are the right eyepecie though. They have been designed to give the best possible result in the Denkmeier Supersystem, and in your scope, I think the perfect range of magnificaitions.

I actually bought my own 12" specifically because I thought it would be the best possible match for a Bintron 27!!!!

The low power is low enough and the high power is just right for planets on most nights where seeing won't permit much more.

So to me, you have the ideal scope for binoviewing with the Binotron.

As for the brightness. For deep sky, the issue is not the loss of light from the binoviewer, but rather the higher than normal powers.

For most targets, the binoviewrs will be fine.

For the dimmest objects though, remamebr that what makes objects bright is exit pupil

What dimming you get form the binoviewers can be easily overcome by simply using a slightly lower magnification.

For the dimmest objects, don't be afraid to swap in a pair of 25mm Plossls. The slighly bigger exit pupil will do a lot to offset the slight dimming caused by splitting the light in half for each eye, and the use of two eyes seems to make objects appear larger and easier to resolve.

This was one of the big lessons I learned about binoviewing. For the dimmest objects, your friend is exit pupil. Just by going to a lower power, you get that brightness back.

The tradeoff will be apparent field, but don't let this bother you.

I have a pair of 40mm Plossls that I use in my binoviewers all the time when I want to view the faintest objects.

I did not try them with the Bintrons, but they worked great with the Maxbrights and with the Mark Vs for when I wanted to look at faint targets.

We get hung up on apparent field these days, but a slightly bigger exit pupil in binoviewers can be your friend. You really won't notice the drop in image scale!!!

I had to put my Binotron 27 purchase on hold because I did not factor int he price of the 45mm OCS, and I needed to get the focuser sorted out, but I think the power switch is superb.

And agian, I personally believe that the 12" dob is the ideal scope for a powerswitch system. You can get an almost ideal range of magnifications, havin to change eyepecies only for the dimmest objects or for nights of good seeing for planets, but on most targets and on most nights, the Binotrons and the D21s may be the only thing you need.

#9 REC

REC

    Fly Me to the Moon

  • *****
  • Posts: 5144
  • Joined: 20 Oct 2010
  • Loc: NC

Posted 22 August 2013 - 08:54 AM

Ed, enjoyed reading your comments and suggestions for the Dob and as you know, I am trying to configure my Denks for me new 10" Dob. I plan on using my 20mm SWA as the main EP pair, but I like your suggestions for a pair of Plossls for DSO's. I have a pair of Meade 26mm SP that should work well...if I can ever get it to come into focus!

Thanks,

Bob

#10 Allan Wade

Allan Wade

    Messenger

  • -----
  • Posts: 453
  • Joined: 27 Jan 2013
  • Loc: Newcastle, Australia

Posted 22 August 2013 - 09:34 AM

Thanks guys, your replies are really helpful.

Eddgie, I am going for the OCS 45 because it is a small extra cost to upgrade at initial purchase. I have a Feathertouch focuser on my Dob which has been a nice improvement over the stock focuser. I shouldn't have the problems you did in your XX12g.

I was tossing up over the D21 or Pan 24 or 19. But I've not heard a bad comment at all on the D21 so that's what I have settled on.

I want to determine if the nosepiece is going to protrude into my tube. Can someone with a B27 for newtonians with the OCS kindly measure the length of the nosepiece from where it seats in the focuser. Cheers

#11 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 22 August 2013 - 10:29 AM

Two things. The D21s are indeed the right choice. The field stop is exactly matched to the binoivewer, so you get the maximum true field in the low power arm and getting wide fields it he big issues with binoveiwers because it kind of locks you into a longer focal length.

The second thing is do not worry at all about the OCS protruding into the light path. It is not at all important.

See, when you use the low power arm, you are going to rack in fully, but for low power observing, the increase in obstruction really does not matter at all. You can dismiss it fully and completely.

When you back out the low power arm, you will have to rack out the focuser almost an inch, and when you do, most (or perhaps all) of the protrusion will be removed. Even here though, it isn't important because for deep sky objects, even if there is bit still in the light path, it is not going to be enough for even the very very best observer to detect on deep sky or even planets.

And when you go to the high power arm, you have to rack out all the way (if you are lucky you won't have to slip the OCS out).

Anyway, this means that when you need all of your clear aperture for planets (about the only place it really matters) you will without doubt have the OCS completely removed from the light path.

The other good news is that if you have the Moonlight, you can jiggle your shims. My guess is that for most people, with the focuser set to about 3" of height, and a 2.37" focuser tube, you sould be able to reach focus in all three modes without slipping the OCS tube in and out.

This will of course mean that when racked in for low power, there will be a lot of intrusion, but again, and low power, I promise that you will not be able to see the effect on the image.

And for medium power you most likele be mostly out of the light path, and at high power where it counts, completely clear.

You may not mind slipping the OCS for high power, but I did not like it at all.

When you have three magnifications and it is easy to change, you tend to change a lot because it is so easy. If you want to "zoom in" on a target, you can do it quickly.

But slipping the OCS ads two additional steps.. Slipping the OCS out when you go to High Power, and then slipping it back in when you drop down to low power, and if you are like me, you will do this a lot.

I would far prefer to have the light path slightly obstructed in low power where you really can't see the damage than having to fuss with the OCS. The whole point of the Supersystem to me is to make it quick and easy to change powers, and the simpler and easier you can make this, the more I think the system makes observing easier.

Just my thoughts on the subject, but don't worry about protrusion in low power. It is meaningless.

#12 Allan Wade

Allan Wade

    Messenger

  • -----
  • Posts: 453
  • Joined: 27 Jan 2013
  • Loc: Newcastle, Australia

Posted 22 August 2013 - 11:40 AM

Thanks Eddgie for the effort you put into posting.

I am feeling good about these D21's.

I want to add a filter slider that I can use in both mono and bino. I like the moonlight filter slider that I can fix on the inside of the tube. But if the nosepiece protrudes into the tube I am in trouble with that option. I have 3.5" from the top of the focuser to the tube, so if the nosepiece is shorter than that, I can go ahead and get the filter slider.

I emailed Denk, but no reply, so was hoping to get the answer here.

#13 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 22 August 2013 - 11:48 AM

I would hold off because I doubt that the OCS will fit completely into the tube of the focuser.

It is hard to say without trying it.

The problem is that you don't really know how far the OCS will stick out until you put it on the scope.

The reason is that the OCS lens cell is adjustable. To adjust it, you start with it fully screwed up against the tube and try to bring your scope to focus. If you don't have enough in travel, you have to then lengthen the OCS tube by threading out the OCS and locking it with a ring.

If you can't reach focus, the pull it out and lengthen it again, and you do this until you can reach focus.

This though determines how long the OCS tube really is, and it is very likely that it will extend past the end of the focuser.

I would recommend that you wait for your system and then get it adjusted before you make any other changes or decisions.

Getting the optimal configuration for binoviewers can be complicated and I recommend one step at a time.

#14 Qwickdraw

Qwickdraw

    Surveyor 1

  • *****
  • Posts: 1725
  • Joined: 03 Mar 2012
  • Loc: Ann Arbor, MI

Posted 22 August 2013 - 11:59 AM

Thanks Eddgie for the effort you put into posting.

I am feeling good about these D21's.

I want to add a filter slider that I can use in both mono and bino. I like the moonlight filter slider that I can fix on the inside of the tube. But if the nosepiece protrudes into the tube I am in trouble with that option. I have 3.5" from the top of the focuser to the tube, so if the nosepiece is shorter than that, I can go ahead and get the filter slider.

I emailed Denk, but no reply, so was hoping to get the answer here.


Allan,

I have both the D21's and the 14's. You will not be disappointed. The powerswitch basically gives you 3 sets of EP which can be very useful.

#15 Allan Wade

Allan Wade

    Messenger

  • -----
  • Posts: 453
  • Joined: 27 Jan 2013
  • Loc: Newcastle, Australia

Posted 22 August 2013 - 12:10 PM

Thanks Qwickdraw.

Eddgie, I just found the B27 instruction manual, which explains the OCS as you have done. So yes, I better wait until I get the system all set up and then go from there with the filter slider.

#16 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12675
  • Joined: 01 Feb 2006

Posted 22 August 2013 - 05:10 PM

Yes, as you can see, there are some unknowns.

And again, you may be able to re-shim the Moonlight focuser for an optimal height that allows you to reach focus in all three modes.

My bet though is that it will require the 2.37" travel focuser, and perhaps even the 2.5" travel tube.

Again, this is only a big deal if you want to avoid slipping the OCS in and out for high power. I would rather have a tube that sticks into the light path in low power mode when it does almost no harm than have to slip out the OCS every time I used high power, where you are likely to be observing planets.

That is me though, and that is my own plan. I am over-committed at the moment and have had to put the Binotron purchase on hold for now, but at least I have a focuser coming. In my own scope, I already know I can make it work with a 2" travel tube, but my scope is f/4.9. The slower the focal ratio the more tube travel you will need I think.

Only an issue though if you want to avoid slipping the OCS.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics