Binoviewing to kick off Planet Season - First Light

[Dave882 (David)]

Well I managed to track down a second hand pair of Denkmeier 1 Binoviewers from the CN forums a couple months ago and finally got round to piecing it together with a pair of Baader Mk3 zooms and my deforked 10" LX50 on the trusty CGEM mount. Plenty of incentive this last week with Saturn & Jupiter nice and high and a Sydney lockdown!

So after spending a bit of time tweaking the collimation, trying to work out the best backspacing, and about 30min learning how to position my eyes and adjust the focus etc it was time to see if all that effort and anticipation was worth it.

One word...WOW!

I was expecting a bit of an improvement from a mono eyepiece, but this was really something else. I started on Jupiter and at 200x had a great view of the red spot, and even some detail within the red spot, equatorial and temperate belts, as well as some of the other minor storms (need to read up more about all the different features). The moons were clear and i reckon i almost could have seen some detail if the seeing allowed.

Next over to Saturn - and clear view of the Cassini division, and good colour in the surface bands. Clear view of the major moons too.

Was really outstanding, and although the seeing wasn't good enough to push higher magnifications, the longer I looked, it seemed the more my eyes adjusted I could glean even more detail. Because both eyes are in use, I didn't need to take a break so this became quite rewarding. Even when the seeing deteriorated, the detail was still better compared to a single eye.

Looked at my phone and it was 2am... not quite sure where 5hrs just went (with no eye fatigue at all). Just totally engrossed with the views, honestly almost like seeing it all for the first time. And yes was out the next 4 nights straight too.

Honorable mention to the CGEM that just chugged along with all that extra weight hanging so far off the back and just does everything i ask of it without complaining.

I did try a few globs and open clusters as well and was a bit disappointed with how dim they came up. Not sure whether that was my inexperience or choice of eyepiece or perhaps this is better for one eye.

A couple of quick question for any experienced bino folk out there:
1) Do you have a particular method for focusing? I found myself doing rough focus with the telescope and adjusting both eyepiece holders individually for fine focus but seemed to be chasing perfect focus almost all night.
2) Collimation with or without the binos?
3) Any DSOs you can get good views and what eyepieces do you prefer?

Well- time to get some sleep. ProjectPluto has the GRS back in view on Tuesday night so you know where I'll be...

Dave

[DeWynter (ILYA)]

Congrats with binos, David! After I tried planets with binos I stopped mono for planets completely and don't want to go back.

1) I simply adjusted focus for one eyepiece, locked it and never touched it again. Now I only need to focus on the telescope. Not sure why you need to touch both EPs for focusing as adjusting focus on the telescope should be enough for at least one eye. The idea is the same as adjusting focus for binoculars - majority of them have EP focus adjustment on one side only.

2) Collimation for the scope I guess? Cannot comment as I've got a refractor. But if weight of the binos adds something to the collimation then I guess it's better with binos as they are heavy and their weight could bend the entire system.

3) Use the longest focal length EPs and lowest GPC/barlow. I've got a pair of 32mm plossls and 1.7x GPC for that purpose. I've got 2.3mm exit pupil which is good for DSOs. So here are the good targets for binos: compact open clusters like Jewel Box, NGC6231 and Trumpler 24 in Sco, M6, M7; bright globulars like Omega Centauri, M2, 47 Tucanae etc. Bright galaxies like Sculptor Galaxy look good as well. Omega Centauri and 47 Tucanaelook look absolutely mind-blowing in binos.

[Dave882 (David)]

Thanks for that list of dso targets Ilya! The only double eyepiece I have is the 8-24x baader zoom so I might need to invest in something else down the track as the 24mm setting has very small fov.

The denkmeier binos have helical focus adjustments in both eyepiece holders. I found that i needed to tweak the left side for fine focus (the sct stock focus knob is terrible) and right side to combine the images. And then back and forth a bit to get it right whenever I changed magnification. I think I may have been chasing shadows a bit cause the seeing was all over the place.

Not sure if you noticed with the refractor but I found that I had to keep backspace to a minimum. So the 2inch diagonal was much dimmer image to the 1.25”.

[DeWynter (ILYA)]

Yes, indeed 24mm at 8-24x Baader zoom has 48deg FOV, but that's not too much difference from a standard plossl (~50-52deg). But I've found that a pair of cheap Celestron Omni plossis 32mm work excellent for DSOs.

I had to switch to 1.25" Baader prism diagonal (with a 2" nosepiece) to save some backfocus as with a 2" mirror diagonal I had only about a few millimeters of backfocus and it was way too heavy. It worked, but with 1.25" prism it's much better.

Here is my setup (from right to left):

SWBD100ED - 2" ClickLock (#2956256) - 2"/T2 Nosepiece (#16/#2408150) - T2 Prism Diagonal (#1C/#2456005) - GPC 2.6x (#4C/#2456317) - T2 Changer System (#06 & #07 #2456321) - Binoviewer.

http://www.genkin.org/lj/astro/Verno...-Review-14.jpg

However, I'm planning to add ADC in the future so I'll have to move GPC to the front of the diagonal to save optical path even more and to eliminate any possible spherical aberrations in prisms.

[gaseous (Patrick)]

Originally Posted by Dave882

A couple of quick question for any experienced bino folk out there:
1) Do you have a particular method for focusing? I found myself doing rough focus with the telescope and adjusting both eyepiece holders individually for fine focus but seemed to be chasing perfect focus almost all night.
2) Collimation with or without the binos?
3) Any DSOs you can get good views and what eyepieces do you prefer?

Well- time to get some sleep. ProjectPluto has the GRS back in view on Tuesday night so you know where I'll be...

Dave

I certainly wouldn't consider myself an experienced binoviewer user, but yes, focusing can be an issue at first. I use a pair of Denkmeier Binotrons, and they are awesome. I normally get the left eye focused with the scope, then just adjust the right eye accordingly, then don't really need to mess with the eyepiece focus for the rest of the night. Hard to get it exactly correct, but I'm telling myself that having two eyes working instead of one will help a bit. I always collimate my dobs before viewing, and while the binos themselves can be collimated, I've never seen the need to. Under dark skies, you can get great views of any of the brighter nebulae (lagoon, eagle, omega, triffid, eta carina, orion) providing you've got low power eyepieces. Even some of the brighter planetary nebulae are awesome, as are brighter open and globular clusters. In summary, everything looks great! I've got matching 32mm and 21mm denkmeier eyepieces, plus the 3D denkmeier eyepieces, which I find amazing on open and globular clusters. I normally use the 32mm ep's, as the binotron has some inbuilt magnification, plus there's a slider which provides two additional levels of magnification.

[Dave882 (David)]

Thanks for those tips guys. I know it’ll only get better with practice and some dark sky (which is a pretty exciting prospect). I think a pair of 24mm eyepieces may be next on the shopping list as I don’t have the inbuilt slider like the denk2 and Binotron version do (def on my wish list tho!)

Patrick- I can only imagine the views you must get through the 20” dob with these things!!!

Ilya- interesting you mention the adc cause I just picked one up and was wondering about adding this to the bino mix. Would love to hear how you go with this and if the views improve significantly.

Cheers
Dave

[gaseous (Patrick)]

Yes, with the 3D eyepiece in the 20" dob, Omega Centauri is mind-boggling.

[Finbar (Barry)]

Also not yet experienced binoviewer: I bought new WO binoviewer, used with Baader mark IV zooms - Omega Centauri was beautiful in the 11" SCT, not great in the 5" refractor. Loved the experience on the Moon so much that I wanted more. Timely, as a Denkmeier Binotron 27 system then came up for sale here on IIS. Due to its significant weight, and its power switch, I've not tried the Baader zooms, only Denk 21mm and Kson 16.8mm sets (and want to add 12mm for planetary in the refractor and 32mm for DSO's in the SCT).

1) I am not sure exactly how our two Denks compare, but as others have indicated, focusing at the eyepiece is better understood as a dioptre: Denkmeier advise to set both in the middle of the range, focus the scope using one eye (I use left, non-dominant, as for for my birding binoculars with only right dioptre), then using the other eye (right) adjust that dioptre until the object is in focus. Check with both eyes and fine tune if needed, then leave them alone. They should not need adjustment on changing eyepieces; refocus the scope as needed. It only gets awkward if other viewers need different dioptre settings.

2) I haven't tried to collimate the SCT with the Binotron, yet, and should do so, but we've had such poor seeing this cloudy winter that I settled on using only the refractor for limited opportunities on the Moon, Jupiter and Saturn - - definitely the best views I've ever had.

[Googaliser (Marc)]

I recently invested in Binos too and the views are the best I have ever seen when the clouds co-operate. It feels almost as if I am viewing again for the first time. The detail in Jupiter is beyond what I thought I would ever see with the naked eye