Thinking about a binoviewer for my spotting scope

[flyer]

I tend to do things a little differently for a spotter, I use a couple cheap 500mm focal length Maksutov Cassegrain telescopes for spotters (one is my spare).

They have a 90mm objective so the resolution is high compared to smaller scopes.

A binoviewer does not make a set of binoculars, it just uses prisms to give you two eyepieces with one scope. Some people say it dims the image, some people say it enhances the view of dim objects because you are using both of your eyes. But that's for astronomy when you're looking at very dim objects.

The biggest thing it seems to do is reduce eye fatigue and let your brain do more image processing.

Any way, I'm going to try to delve in to the telescope binoviewer realm and figure out what I need for a binoviewer with long eye relief eyepieces, a wide field of view and about 40x magnification.

It seems like that might be around a $400 upgrade but if it does what I hope, it should turn a good spotting scope in to an exceptional one. With the downside being a bit of bulk and weight.

If anyone has used a binoviewer spotting scope, I would love to hear what you thought of the view.

It seems like the optical path length and getting to focus are the biggest issues. Maks seem to have focus mechanisms that work but they can pull the mirror out of the optimum position. People fix that by using a Barlow lens of some sort. I'll want a 45° erecting prism in there too so it will be a bunch of stuff working together, hopefully not vignetting.

 

[TripleBull]

It would be fun to set up your two telescopes as a binocular rig...

 

[flyer]

I've seen people try that. It's not fun, collimating binoculars is a pain in the ass.

 

[DetroitRearView]

Not the same, but similar...the Swarovski BTX 95mm is a real gamechanger for me.

 

[flyer]

Yes, my 90mm probably can't hang with a $3,000 Swarovski but maybe my 127mm can?

I'm trying to figure out the best way to put together the binoviewer with an erecting prism and probably some type of Barlow for focus and then choosing the eyepieces to get the magnification I want and as much FOV as possible. It's not a simple as OTA focal length ÷ eyepiece focal length * Barlow magnification and out of several possible configurations, only a few will come to focus, some better than others.

 

[flyer]

I made the leap today. I have a Lacerda hybrid 2"/T2 erecting prism 45° diagonal coming from Europe and an Arcturus binoviewer coming from China by way of New Jersey I think.

The diagonal can attach directly to the T2 threads on my Orion 90mm Maksutov Cassegrain spotting scope and the binoviewer should be able to slide in to the 1.25" eyepiece holder on the diagonal for a pretty short optical path (a long optical path can make focus impossible).

One nice thing about buying an expensive diagonal is that it has a 34mm optical path, a lot bigger than the cheap 1.25" diagonals that come with a cheap scope. That might not help with my 90mm scope but maybe my 127mm and if I get the new Bader binoviewer that is coming out at some point, extra optical path will mean wider FOV and maybe a brighter image.

It was also the cheapest 45° erecting prism with T2 threads.

A couple weeks ago I picked up a Manfrotto camera backpack. It should make a nice padded home for my spotter, binoviewer, range finder and Kestrel.

A little consolidation will make a trip to the 1,000 yard range a bit smoother.

 

[flyer]

I got out my scope and new backpack to arrange the internal pockets. That went well enough but when I tried to install the tripod carrying straps, the slots in the buckles are not wide enough to slide in the free end of the nylon strap.

I tried Manfrotto customer service. They have a form with a captcha. Fill it all out including the captcha (correctly), hit submit and it flushes all that down the toilet and tells you try again.

I found an email address for Manfrotto, typed in my complaint again, plus a new complaint about their customer service form, hit send: sorry this email has been deactivated.

Now I just forward that with a copy of the first email I sent to their holding company which seems to have a working email address.

Manfrotto seems to be great if you buy used off Craigslist but new is a pain in the ass.

 

[flyer]

I got my binoviewer today. No time to test it fully but at least I can say it reaches near focus around 12' and far focus at least 100' (limited by my line of sight).

I'm glad I have a T2 thread 45° erecting prism diagonal on order, the thumb screw secured 1 1/4" cheapo diagonal in it wants to flop over from the weight of the binoviewer because it just doesn't clamp securely with reasonable thumb tightening.

More extensive testing will have to wait for the weekend. Because I've got some other stuff to test.

Here is a pic for now:

 

[flatland1]

Interested in hearing how this contraption works out for you.

 

[flyer]

My Lacerda 45° erecting prism diagonal came in today.

I had a chance to screw it in to the T2 thread piece and it solidifies the whole setup a lot. It will not flop over any more and the eyepiece side of the diagonal holds the binoviewer very firm.

I have another thread on here about using a photographic tripod gimbal head to tripod mount a rifle rather than a ball head.

In a more conventional use of the tripod head, I mounted up my spotting scope and it makes a very nice Alt/Azimuth mount.

Tomorrow I'll try to determine if the scope comes to focus at infinity.

I could try with a star or the moon but while there was seemingly no moon tonight there is light pollution which makes a star test less than ideal.

 

[flyer]

I was playing around with my scope in the daylight and I tried one of the included Barlow lenses (1.85x) and the focus point changed a lot.

In a Maksutov Cassegrain scope, generally there is a lot of focus travel in the scope but only one spot that gets ideal alignment between the corrector lens and the mirror. The long optical path of the binoviewer usually takes you out of that spot. The Barlow lens moves you back in to that alignment and magnifies also.

I'll probably be able to reach focus at infinity. If not there is also a 3x Barlow I can try.

Hopefully the optical quality is ok. I am going to have to do some binoviewer vs single eyepiece comparisons to see if I can find any weak links to upgrade.

 

[flyer]

I got a chance to test the scope with the binoviewer. Mercury was bright in the evening sky last night.

I was able to achieve focus so now I know that I will not have a problem at 1,000 yards or 50 miles for that matter.

After working on the diopter, I got the images to merge nicely. Mercury was a round ball of light with some faint diffraction spikes. There was no color fringing from what I could see. I wasn't blown away by the image but it wasn't bad.

I'm not set up to measure magnification and I'm not sure what the Barlow is doing to it but I estimate it's around 40x with the 30mm eyepieces.

After I can get a look at a 1,000 yard target for scale, I'll be able to figure out what the optimal focal length is, then I'll buy some nicer wide angle flat field eyepieces with long eye relief.

As it is I can already tell that it causes far less eye strain than closing one eye to look and hopefully the brain's 3D image processing will help me spot bullet trace and impacts.

It was a bit hard to align the scope on Mercury with no reference points on the blue (dusk) sky. I think I want to add a cheapo red dot to help with aiming.

 

[flatland1]

Sounds like you're getting along well with it. Neat project!

 

[flyer]

Yes, it seems to be a worthwhile addition even though it's tripled the cost of my spotter.

And that's with some really cheap eyepieces and a Barlow that is pretty questionable too.

I'm looking at better eyepieces now, it sounds like it might get a lot better.

They big plan is to eventually get a custom reticle etched for it to call out wind holds.

I'll still probably wind up under 20% of the Swarovski.

 

[flyer]

I found an upgrade for the Barlow lens.

Barlow's have a poor reputation because most people are familiar with the cheap toy telescopes with poor eyepieces and wildly optimistic magnification claims due to stacking a Barlow with an eyepiece whose focal length is already too short.

Today there are fairly well regarded Barlow's coming out of China with 3 element designs. I think that is what came with the binoviewer. It is certainly at least two elements and I haven't seen any glaringly obvious optical defects yet.

So I'm not sure it needs an upgrade but if it does, Brandon makes a Barlow called a Dackin that seems to be exactly the same form factor. It should screw straight in to my binoviewer.

Of course my Arcturus Chinese Barlow might be a pretty direct copy of the Brandon.

The Brandon is expensive too.

I'm narrowing down my eyepiece choices. I need to figure out my magnification and field of view. It would be easy if I could take it to the 1,000 yard range. I just don't have good sight lines to known size objects at known distances around here, too (sub)urban.

Chinese seems ok for eyepieces in the $40+ range. And $40 in a GSO or house brand Chinese eyepiece probably costs $60 with some cosmetics and a Celestron/Meade/Orion brand name.

There are a lot better than the middle tier Chinese eyepieces but with daylight use and not needing extreme wide angle views, I'm just hoping for flat fields and decent resolution without breaking the bank.

 

[Chris@InterstateGuns]

Not the same, but similar...the Swarovski BTX 95mm is a real gamechanger for me.

That BTX eyepiece is amazeballs.

 

[flyer]

It should be!

 

[DetroitRearView]

BTX 95MM 14 miles out @ 9K’ elevation with mag extender (60X) 3 bulls came out of the timber late afternoon shade
(IPhone image not nearly as clear as they were to my to me my fault didn’t focus it well)

The snow in the center will be a wallow this Fall.

 

[flyer]

I was just visiting a group of old friends and decided to bring along my scope to look at the Moon in a place with less light polution (the gathering was up in the hills).

Instead of the moon, there was a nesting ground of Herron to look at.

I got to set up on a hillside and look directly in to their nests at about 100 yards.

One of my friends there is a hunter with some rich hunter friends and he has looked through a BTX scope more than most people have. We didn't have them side by side but he was impressed by the images he saw in my scope.

From that I'll take a few things: the view is nice and does not have any flaws obvious to people who have looked through the best, if the BTX does anything a lot better than mine, it can only be light gathering near dusk.

One thing we did have to compare with was a nice pair of Swarovski binoculars, probably 8x42s or something and people were putting down the Swarovski's to look through my scope.

That could be just the higher magnification and no shake due to the tripod but it still says these optics are doing a pretty good job.

I am definitely going to add a red dot to act as a finder and get better eyepieces for more magnification and wider apparent field of view.

 

[HDWRENCH]

Late to the party but years back I has to big sky spotting scopes in a CNC bracket to make a high power bino set. Think 2001 so it was pretty high tech and it worked well but I never thought it was perfect not lined up well. I do not recall the company But today one would think it’s gotten better. ??? We CNC items to such Tolarances with engine parts Programs better. I have not looked so I may be just talking about nothing ha ha

 

[HDWRENCH]

I got mine from a guy off LRH they where kind like this but its not 100% the same . As i said it never allowed me to get it just right


IMG_0103 by GMR Performance, on Flickr

IMG_0102 by GMR Performance, on Flickr

 

[flyer]

I am working on a little upgrade.

Last time I had my scope mounted with a small Arca Swiss style rail bolted to the 1/4-20 hole in the scope mounting clamp. This kind of worked but the screw loosened up quickly. It didn't fall off but it's not a situation I want to deal with.

I needed a way to fix that and create a mounting point for a red dot finder scope to make this high magnification spotter easier to aim.

So Scope Rings:

These are from Explore Scientific for a 102mm refractor but the tube size is the same and it should fit perfectly.

I plan to bolt an 11 slot Magpul MOE accessory rail to the handle. This should allow me to attach an AR style red dot scope to the handle so it's a finder as well as a backup optic for an AR. The point of a finder is just to get your target in to the field of view of the scope so I can probably zero the red dot on an AR and still aim close enough to work as a finder for the spotter without any adjustment.

I went with a MOE rail because I think a plastic rail will be less likely to shred hands when grabbing the handle.

I think I'm going to replace the bottom rail with a piece of Arca Swiss to maintain some commonality between my tripod attachments for a somewhat modular setup.

 

[flyer]

I got my scope rings a few days ago.

My spotter did not drop in to them and the MOE rail wouldn't bolt up but today I got a chance to work on it.

The simple fix was the MOE rail, it just needed slightly longer 10-24 button head screws. I got 3/4" shank but 1/2" probably would have worked. Now it bolts up perfectly, the retainer nut plates fit right in the slot on the bottom side of the handle so they can't rotate and the bolts do not hang down past the slot so carrying it with or without the rail should feel exactly the same.

The tough part is that the rings are set too far apart and the rings are a hair too small for my scope. I have two ideas of how I can fix the ring spacing. Neither is great but I think one of them could be pretty elegant and the other is pretty rough but should work. The ring size is going to be a minor pain in the butt. I pretty much fixed it by tearing out the white padding applied inside the rings but now my rings are coated with adhesive residue and metal on metal contact isn't ideal. I'm playing around with my spare optical tube assembly (OTA), a white tube Celestron. It should be identical beside the paint and brand name engraving. To protect it from the rings and make it more "tactical", I wrapped it with Allen camo tape. The white portion of the tube was exactly 3x as wide as the tape roll so three strips of tape gave 100% coverage. Now I can clamp it anywhere without fear of damaging the tube.

I just need to remove the left over adhesive from the white padding I removed or else try to cover it up with tape like I did for the scope tube.

I need to order a piece of ARCA rail to finish the rings and I want to finalize my ARCA setup so I can buy mostly one brand to maximize compatibility and hopefully not spend RRS type of money.

Any way, it's getting close and once my rings are sorted, I just have to figure out my LRF mounting and Kestrel mounting. Using my gimbal mount I realized that I can mount everything on one tripod without causing interference between any of the pieces and my Kestrel mounting should stay level even as I pan and tilt my spotter/LRF.

 

[LRShooter101]

Very Interesting, thanks for sharing!

 

[waveslayer]

I am not sure what you have invested in this? I have the 85mm BTX from Swarovski, I couldn't be happier. The picture is clear, the quality is top notch, and you can get a magnifier with the same results. It is a bit pricey but worth every penny. The idea you have is cool, but having all the controls under one roof just makes life that much easier.

 

[flyer]

So far if you don't count the cost of my spare scope, I'm about $500 in.

The MRO was about $400 which is really expensive as a red dot finder for a scope but I don't really count it because I've wanted a good red dot scope for a while and it's going to be dual purpose.

If I add a pair of reticle eyepieces, that is probably about $130 more. A custom reticle is ?

I don't think I'll have to spend more than about $100 on ARCA rails and clamps because I'm not going to go super high end.

If I add it all up, I might have $3,000 in it at the end of the day but that's a spotter with binoviewer, SIG BDX binocular LRF, Trijicon MRO red dot finder, Kestrel 5700 weather meter/ballistic computer, a Bogen Manfrotto tripod and a gimbal mount that allows for a balanced mounting without counterweight.

I'm pretty sure the Swarovski BTX starts at a higher price than that, doesn't have a LRF, finder scope, weather meter/ballistic computer and no tripod either.

I'm not sure which controls aren't under the same roof? I've got a focus knob on the OTA and diopter focus at the eyepieces, those are the controls on the spotter and diopter is a set and forget adjustment.

The point of the rings and gimbal and ARCA rails is to bring together everything a spotter/scout needs to generate a ballistic solution with as much automation as possible, a red dot finder to get on target as quick as possible, a high power spotting scope that you can look through for hours if you have to and it should all fit in a smallish backpack beside the tripod.

That all fits in to a bigger plan of streamlining my load out for long range shooting to rifle case, range bag, spotter backpack, tripod and shooting mat.

 

[flyer]

Work in progress, I need to modify the handle portion and replace the Vixen rail with ARCA:

Once it's fixed up I'll transfer over the binoviewer to make sure the Celestron scope is up to task.

If it isn't, I'll tape up my Orion and swap the rings over to it.

If it is, I have two capable OTAs and might duplicate the complete setup at some point.

 

[flyer]

I added two more pieces to my load out, two tripod stools from GCI Outdoors.

One has two piece shock cord legs and packs up in to a case about 15" long. The other is like a fold up camp chair except much smaller, three legs and the seating position is very upright.

The smaller stool is for times when I want a stool for spotting but don't want to carry a lot of weight.

The larger stool will be much more comfortable for long spotting sessions and it even has a cup holder. While it is pretty small and handy compared to the four legged style folding camp chairs, it is still kind of bulky but pretty light weight.

I'm not sure exactly what my tipping point will be, I've got to finalize my load out and optimize it with everything I need, nothing I don't and a good way to carry and organize it all.

I'm beginning to look at my range bag because it is a disorganized mess like a woman's purse (some women any way). I see a lot of room for improvement there.

I've been working on my tripod and mount too. Some improvement, some weight reduction.

I'm hoping to get my full range load out down under 40lbs and packed to carry everything in one trip from the car. That's rifle in soft case (right hand), spotter, mount, LRF and Kestrel in a backpack, tripod, shooting mat and compact stool strapped to the backpack, a range bag in my left hand and possibly the larger stool over my left shoulder.

It will be a while before I can get the stools out to the range to test them out but they seem pretty nice. Their prices are pretty reasonable, the best deal was to order direct from GCI Outdoors, one retailer had a lower price but the shipping killed it. GCI Outdoors had free shipping and I got a 10% off coupon by subscribing to their email list which made the total price $40.50 for both stools which is entirely reasonable considering the alternatives. Oh, both stools are rated for 250lbs, I'm fairly close to that and did not feel like I was stressing them beyond their ability.

I don't think I'm ever going to be looking at the stools as something I need to replace to improve my load out.

 

[flyer]

I've been combing through online catalogs, eBay listings and photography forums to try and figure out how I'm going to hook everything together and get things aligned.

I want to do it light weight, cheap, quick to assemble/disassemble, rigid to avoid shakes and ergonomic so the spotter isn't moving around too much or dodging the Kestrel vane.

All of these factors are working against each other and most of the off the shelf parts are defficient in two or more areas.

I thought I had a solution almost worked out yesterday but I scrapped most of it (for the third or fourth time) and went down a couple more rabbit holes until I found a combo I like.

I'm going to use parts from smallrig, 80/20, KDG and Trijicon plus some generic stuff I still have to price out but it should hit all the marks.

I think my gating item will be waiting for Sig to start shipping the BDX LRF binoculars, I should have most everything beside a custom reticle by the time they deliver.

 

[flyer]

I got a few items today.

The first is a $42 Zomei Z888C carbon fiber tripod. For the money it seems nice. There was a cheaper and more compact model with 5 section legs but I want to use it seated so I figured longer leg sections would allow me to use it without extending the legs at all for maximum stiffness. It also comes with a short column which I will be using. It seems like a good choice so far, not rock solid and won't hold my weight but it should hold up my spotter setup.

The second is a Manfrotto 138 Claw Ball adapter. It's kind of an inverted version of a ball leveling head with a 72.91mm ball which attaches to the tripod column and a claw portion which attaches to my mount. It should be pretty equivalent to a 75mm bowl tripod in clamping force and the claw opens up so the mount can separate from the tripod quickly and easily.

The third and most expensive part is the mount but it is missing a crucial piece so that is going to be a hassle.

Any way, the mount is almost complete, once I get that missing part, I just need to make my adapter which will hang all of my gear on the mount. That will involve some drilling, tapping and countersinking with possibly a little cutting. Easy stuff.

 

[flyer]

I got to do some 1,000 yard testing on Sunday.

The 30mm eyepieces were less magnification than ideal but the reason I couldn't see bullet holes was mirage. There was lots of mirage.

Other than that, the binoviewer and scope performed as expected.

I think the cheapo 30mm eyepieces that came with the binoviewer are 50° apparent FOV and now I'm looking at a set of 20mm eyepieces with 70° apparent FOV which should give me nearly the same FOV but blown up. They have an Erfle optical design which is known for good color correction and a flat field (important because I think your brain can merge two images better if there isn't a lot of edge distortion). It's also interesting because they seem to be the same optical design but one has a reticle. So now I have to figure out where the focal plane is in an Erfle design and see if I can change the reticle for one with a scale, possibly custom etched.