Vixen BT81-S Binocular Telescope Unboxing/Review

[Stu]

If there's a problem with them Chris, I'm sure FLO will sort them for you.

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[NGC 1502]

Hi again Chris.  Really sorry to hear about the probs.  I've drooled over these binos at Astrofest, there were some set up on the Astronomia stand last Feb.

As said, FLO will sort them, they are a top dealer.

One question if I may  -  the eyepieces are angled at 45 degrees, so when viewing overhead, they will be pointing towards the ground.  With the friction fit EP holders, and with the looser fit on the left side, could the EPs fall out ?   I'd have thought a basic set screw would be better. Thanks in advance for your input on that.

Hope all the family are well, especially the brand new ones   Ed.

[Chris]

If there's a problem with them Chris, I'm sure FLO will sort them for you.

Sent from my iPhone using Tapatalk

Good point phew! thank goodness I got them from FLO and not off the second hand market like most my kit!

[FLO]

Don't worry Chris, we're here for you

The binocular's alignment was tested and tweaked by Vixen-UK prior to dispatch and the BT81 holds alignment well. But it is still possible it was knocked out of alignment enroute to you (it was a demo model so we didn't have the original box but we used lots of packing material).

I have a feeling the binocular is okay so would you mind if we send you two 15mm Vixen SLV eyepieces to try? We will then know for sure if the binocular needs attention.

We have already ordered new original box/packaging for you. It is enroute from Japan and we will send it to you as soon as it arrives so if we do need to collect the binocular it can travel in style. 

HTH, 

Steve

[Chris]

Hi again Chris.  Really sorry to hear about the probs.  I've drooled over these binos at Astrofest, there were some set up on the Astronomia stand last Feb.

As said, FLO will sort them, they are a top dealer.

One question if I may  -  the eyepieces are angled at 45 degrees, so when viewing overhead, they will be pointing towards the ground.  With the friction fit EP holders, and with the looser fit on the left side, could the EPs fall out ?   I'd have thought a basic set screw would be better. Thanks in advance for your input on that.

Hope all the family are well, especially the brand new ones   Ed.

Hi Ed, They are very drool worthy arn't they

As for the EP's falling out I doubt it, I think the left side is looser than it should be but the right side is such a snug fit that you could quite happily hang an eyepiece upside down from them if you wanted to. I was really hoping to give these a glowing review as I'm such a fan of both Vixen and using two eyes but I'm struggling with them if I'm honest, I think it must be such a difficult job to engineer these with the moving turrets for the IPD, plus the interchangable EP's. I'm starting to think these are quite delicate things that need tuning like a fast f/4 newt.

[Chris]

Don't worry Chris, we're here for you

The binocular's alignment was tested and tweaked by Vixen-UK prior to dispatch and the BT81 holds alignment well. But it is still possible it was knocked out of alignment enroute to you (it was a demo model so we didn't have the original box but we used lots of packing material).

I have a feeling the binocular is okay so would you mind if we send you two 15mm Vixen SLV eyepieces to try? We will then know for sure if the binocular that needs attention.

We have already ordered new original box/packaging for you. It is enroute from Japan and we will send it to you as soon as it arrives so if we do need to collect the binocular it can travel in style. 

HTH, 

Steve

Excellent Steve! My gut feeling is that something isn't right with them but I will certainly take you up on your offer on the Vixen SLV's! I'll go one step further even, if the Vixen EP's correct the issue I will 100% buy the eyepieces from you as I was thinking of getting these if I was happy with the binos anyway

I really hope it works Steve but I'm not sure why the collimation would drift so much by simply adjusting the IPD turrets if it was the non Vixen EP's I'm currently using? I really hope I'm wrong because if they were in fine fettle they would kick bottom with the 15mm SLV's!

Many Thanks Steve, 100% great service!!

Chris

[FLO]

Thank-you 

I know you know this, Chris, but for anyone else who has found this thread and is new to observation binoculars: The Vixen BT81 is a well corrected achromat, it is not an apochromat, so there will be some minor CA when observing bright stars. Particularly at the edge of field. It also uses friction-fit eyepiece holders (normal for this style of binocular) so you might need to fine-tune alignment by gripping the eyepieces and moving them into best position (nothing major, just very slight adjustment). All binoculars perform at their best when the eyepieces are centred correctly on our eyes but this is especially so with higher magnification optics.

Chris, if the BT81 alignment is okay and the SLV eyepieces are centred you will be seriously impressed. If you aren't then the binocular needs attention and we (ourselves and Vixen-UK  ) will be happy to do that. 

HTH, 

Steve

[FLO]

Also. while we are on the subject

When someone buys an observation binocular like the Vixen BT81, or a Chinese clone, they then understandably need additional eyepieces. But if the owner owns a budget eyepiece like, say, a Chinese Plossl, and then buys a second to make a pair, the second eyepiece might not match the first. Even if it is the same brand, model and focal length. The unspoken truth is the specification of budget eyepieces often vary batch-to-batch. The change is usually minor so often goes unnoticed but if you are trying to make a pair for use with a binocular or binoviewer, it can be a problem. I don't think this applies to Chris but I thought it worth mentioning nonetheless. 

HTH,

Steve 

[Chris]

Chris, if the BT81 alignment is okay and the SLV eyepieces are centred you will be seriously impressed. If you aren't then the binocular needs attention and we (ourselves and Vixen-UK  ) will be happy to do that. 

HTH, 

Steve

Thank you Steve thats very re-assuring

Just to add to what Steve has said, when viewing through one optic at a time the Vixen BT81's do seem to handle bright stars quite well for an achromat once perfect focus is achieved. This is using mid range William Optic eyepieces on axis so things will only get better with better eyepieces and the Vixen SLV's are a class act! I own a couple already and they perofrm like an Orthoscopic eyepiece but much more comfy to use. One thing that wont be helping with the WO eyepieces is that they have a taper half way up the barrel which is what I suspect Steve has in mind. I have rotated the eyepieces, swapped, and reseated the eyepieces a number of times without improvement so I'm 50/50 whther this is the cause but it could well be?

just to re-iterate my only issues with these binos are the aberration and double images which change when the interpupilary adjustment turret is adjusted, Also the left eyepiece holder is noticably looser than the right and the left focuser is stiffer than the right. These are all fixable things in the right hands of course and once fettled these binos will be superb as Steve has pointed out. These things can happen to any make of bino I'm sure, they weren't delivered in the usual packaging due to them being ex display so they could have been knocked in transit. Steve has very kindly arranged for the original packaging to be shipped from Japan which is outstanding service if you ask me!

I've got my fingers crossed that the completely smooth barrel of the SLV's and superior optics will help smooth out some of these issues but if they don't and they have been knocked in transit I have complete and utter faith in FLO to help resolve the issue

Chris

[Chris]

Very quick service as always the 2x 15mm Vixen SLV eyepieces are here!

I will use these to test the Bino the moment I see stars

[FLO]

I will use these to test the Bino the moment I see stars

No hurry Chris, please take your time. I am sure you will have your hands full with the new arrivals  

Steve 

[Chris]

Also. while we are on the subject

When someone buys an observation binocular like the Vixen BT81, or a Chinese clone, they then understandably need additional eyepieces. But if the owner owns a budget eyepiece like, say, a Chinese Plossl, and then buys a second to make a pair, the second eyepiece might not match the first. Even if it is the same brand, model and focal length. The unspoken truth is the specification of budget eyepieces often vary batch-to-batch. The change is usually minor so often goes unnoticed but if you are trying to make a pair for use with a binocular or binoviewer, it can be a problem. I don't think this applies to Chris but I thought it worth mentioning nonetheless. 

HTH,

Steve 

This is a good point which is why TV Plossls are so popular for binoviewing, they have excellent QC so the field stops match nicely I suspect the Vixen Plossls would work well also but I have no proof of this

[Chris]

No hurry Chris, please take your time. I am sure you will have your hands full with the new arrivals

Steve 

Thanks for not rushing me but strangely now might be the time? I'm on paternity then annual leave consecutively and the twins are still on special care so we go home late evening to put our 2 year old to bed and let the fantastic nurses take over for the night

If its clear in an hour I'll be out like a shot!

[Chris]

Success!!!

Sorry guys it must have been the combination of eyepieces with a tapered undercut and the friction fitting that was causing the problem. Thats all I can think it could have been because wow these binos were good with both the Vixen 15mm SLV's and the 25mm skywatcher super plossls I also received yesterday.

This time out I could adjust the IPD turret without the collimation drifting at all! And as for the views, well this may be an achro but its a very good one! stars looked simply beautiful in these, with no exagoration the best view of the double cluster I can recall, it was simply stunning! if you add the pin [removed word] stars with lovely star colour and the shear immersion and comfort these binos make literally any part of the sky enjoyable, you don't even need to be looking at any particular object, star fields are so pretty in these! I did however also bag M81/82, M27, M52, M31 which where good considering the conditions (neighbours outside light on all the time). 

The slightly loose left eyepiece holder is still an issue as the left eyepiece loses focus a touch periodically, but I'm sure I can figure something out to tighten this up. I don't think the combo of this and the tapered eyepiece undercut of the WO eyepieces helped previously. 

The Vixen SLV eyepieces are a lovely match for these binos, yes they are expensive but they really are the cherry on the cake! having said this the 2x 25mm super plossls worked amazingly well also, these also have perfectly smooth barrels and these are what I used to view the double cluster which blew my socks off! also amazingly they were par focal with the SLV's!

My advice to anyone buying these Vixen binos is (you guessed it) to buy straight barrel eyepieces, they really will give you a false impression if you have large or tapered undercuts which don't seem to sit true in the friction fit eyepeice holder. however, if you do get decent eyepieces with straight barrels then you will be richly rewarded with lovely views. Aberration on bright stars consists of just a touch of red flaring rather than a purple halo, infact I couldn't see much in the way of purple fringing but the real test for this will be the Moon.

Setting up and packing away is very easy due to the carry handle and they are quite light also.

Many thanks for everyones help especially Steve at FLO I need to head over to special care now but I will pay for the eyepieces later on and leave a note to remind that they have already been sent

One last question though, do you think these binos would work better on an Horizon tripod? the handle and the tripod legs somewhat limits my declination on the AZ4 so I can't point them far enough up to see objects like M13, M57 etc

Many Thanks all

Chris

[FLO]

Excellent. We like happy endings 

[Chris]

Un-expected package from FLO arrived today. Couldn't believe it when we opened it to find two packs of sleepsuits and muslin clothes for the twins plus a card! Both me and my wife are blown away and wish to thank everyone at FLO, we really are touched by this gesture!

A big thank you to FLO from Chris, Bella, Alex, Freya and Seren.          

[NGC 1502]

Hi again Chris.  Pleased for you that things have worked out well, and what great service from FLO.

The point FLO made about truly matching eyepieces is so worth bearing in mind, and useful also I presume for those that use a binoviewer on a regular scope.

I was also disappointed initially with what you found, because those bins were on my wish list, then they were off, but now firmly back on 

Regards, Ed.

[Chris]

Hi Ed, Glad they are back on the list and I'm glad I was initially wrong about them! I probably should have waited for my second 25mm SP to turn up so I could try a second pair of EP's before passing my initial judgement on them, I guess I panicked!

Weirdly the cheap Chinese super Plossls work fantistically with these binos, well the 25mm ones do. I suspect though that as focal length gets shorter the need for quality EP's becomes more apparent. Talking of which I'm now the proud owner of 2x 15mm Vixen SLV's which really are stunning when combined with these binos! Next time out I'll be attaching my pair of Baader UHC's to these to see what effect that has.

Anyway the number one thing I now believe when it comes to eyepieces and friction fit binos is to get smooth barrels! my WO 66 degree EP's with there tapered under cut were very very good at convincing me that the binos were out of collimation, they felt like they were seated true but they clearly couldn't have been! 

Looking at your sig Ed I can see a pair of these would fit nicely with your existing kit

Chris

[NGC 1502]

Looking at your sig Ed I can see a pair of these would fit nicely with your existing kit

They would deffo fit my sig but they need to fit my wallet too 

Have fun with yours, and best wishes to your now extended family, Ed.

[FLO]

... we opened it to find two packs of sleepsuits and muslin clothes for the twins plus a card!

We felt they were a little young for a mug and baseball cap 

My two sons are now 7 and 10 but I remember their first year well. Hard work but wonderful! 

Steve