39 replies to this topic

[TG]

Rather than add to the gigantic thread about this topic, I felt this deserved its own. In the thread I had complained about feeling eye stress from miscollimation but upon inspecting the divergence of a laser beam shot through the binoviewer, I found it to be less than 2 arcmin which didn't explain what I felt. @daslolo then suggested that the misalignment might be vertical rather than simple divergence and I set out to see if this was true.

 

First, I used the previous method of screwing in an eyepiece projection tube into the BV coupling ring and inserted a Howie Glatter alignment laser into it.

 

 

 

The BV was placed on a kitchen counter (these tend to be very level) and I checked the level with both an iPhone and a bubble level. The BV is shown above with eyepieces inserted but first I tested with them out and here is what saw about 4-5 yards:

 

 

Vertical misalignment! Inserting 35mm Ultrascopic eyepieces showed it was even worse with the expanded diffraction rings almost on top of each other. So could it be fixed? The Maxbright II does not have accessible alignment screws for the prisms but it does have adjustments for the eyepiece holders. To access them, first I had to loosen these set-screws completely:

 

 

There are three of them to hold the upper assembly to the bottom ring so I backed them out till they were sticking out but did not remove them completely as they're so tiny. It takes a tiny 1.3mm metric hex key to loosen them. After taking the upper assembly (diopter adjustment + eyepiece holder) off, you can see the bottom cell:

 

 

When the three screws are loosened with a 2mm metric hex key, the bottom cell/ring can slide laterally. I loosened them just a tad equally, put the upper assembly in along with eyepieces and moved it by hand till the diffraction patterns formed by the split laser beam were level:

 

 

Finally everything was tightened back. I won't have a chance to use the BV in a scope till probably tomorrow but looking into the eyepieces the field stops seem better aligned. Also notice the slight coma in the laser diffraction, seen also with shorter 12.5mm f.l. Ultrascopics. In a perfectly aligned BV this would not be present but with my earlier examination of star tests with the BV I don't think this is going to be a problem.

 

Tanveer.

 

 

 

[daslolo]

wow these are easy to collimate!

good job!

the coma doesnt show in your first photo, why is that?

no coma on your mkV?

[StarAlert]

Very interesting, Tanveer. I don’t know how much faith I’d put into your kitchen counter or an iPhone level to collimate the MB2. I just did a test of how sensitive the iPhone level is. It shows my counters are level in the first pic...

 

But it’s also level when I place 14 sheets of paper under one side. That’s a significant error. 
 

 

And it’s level with 18 sheets on the other side. 

 

So I’m guessing my counter is maybe off by 4 sheets at this specific place. I know granite is not perfectly level because it’s cut and polished. 
 

I look forward to hear if your adjustment has made any improvement. 

Edited by StarAlert, 31 May 2020 - 03:41 PM.

[TG]

wow these are easy to collimate!
good job!
the coma doesnt show in your first photo, why is that?
no coma on your mkV?

The coma comes from the slightly off center eyepieces I think. The first photo had the eyepieces out.

[TG]

Very interesting, Tanveer. I don’t know how much faith I’d put into your kitchen counter or an iPhone level to collimate the MB2. I just did a test of how sensitive the iPhone level is. It shows my counters are level in the first pic...


But it’s also level when I place 14 sheets of paper under one side. That’s a significant error.



And it’s level with 18 sheets on the other side.



So I’m guessing my counter is maybe off by 4 sheets at this specific place. I know granite is not perfectly level because it’s cut and polished.

I look forward to hear if your adjustment has made any improvement.

I cross checked the iPhone with a bubble level at the time and both agreed very well. I also used the iPhone without a case and made sure that the camera lens wasn't in contact. It's also the new SE model which has a glass back which is very flat and seems to have very accurate sensors.

[TG]

wow these are easy to collimate!
good job!
the coma doesnt show in your first photo, why is that?
no coma on your mkV?

My Mark V never gave me trouble so I never measured them except for collecting color histograms of the two sides (turned out to be identical). I've sent them off for repair so I can't find out currently.

[StarAlert]

I cross checked the iPhone with a bubble level at the time and both agreed very well. I also used the iPhone without a case and made sure that the camera lens wasn't in contact. It's also the new SE model which has a glass back which is very flat and seems to have very accurate sensors.

I might be more effective to shoot your laser from the two spots the binoviewer EP holders are located, at the wall you’re using, before shooting it through the BVer. Mark those two spots as your reference points. Now it doesn’t matter how level the counter is. All that matters is the defraction rings match your reference points. 

[TG]

I might be more effective to shoot your laser from the two spots the binoviewer EP holders are located, at the wall you’re using, before shooting it through the BVer. Mark those two spots as your reference points. Now it doesn’t matter how level the counter is. All that matters is the defraction rings match your reference points.

Not sure I understand you. Perhaps you can draw a picture?

[StarAlert]

Not sure I understand you. Perhaps you can draw a picture?

The EP holders are 75mm apart on the MB2 when it’s lying flat. Set your alignment laser on these two spots (where the binoviewer will set) and point it at the target wall without going through the binoviewer. Mark the two points on your target wall. They will be exactly parallel with the counter. After you’ve got your reference points, you should align the diffraction rings to these two reference points. 

[TG]

The EP holders are 75mm apart on the MB2 when it’s lying flat. Set your alignment laser on these two spots (where the binoviewer will set) and point it at the target wall without going through the binoviewer. Mark the two points on your target wall. They will be exactly parallel with the counter. After you’ve got your reference points, you should align the diffraction rings to these two reference points. 

I think I see what you are suggesting but the laser has knurlings on it that prevents it from sitting absolutely flat on the counter. It's easier to use a bubble level to level the BV and match the laser spots against a known level surface (the wood fireplace trim in the picture, also checked with a bubble level). In any case, the proof of the pudding will be in its eating, hopefully tonight.

 

Tanveer.

[decep]

I quite literally just performed an alignment with my Williams Optics binoviewer.  I was planning on doing what you did, testing against the wall, but I quickly found there was a much easier way.

 

I have the GSO/Zhumell laser collimator that is like a Cheshire collimator.  I also have a non-laser generic Cheshire in the other eyepiece port.  Using the 45 degree part, I was able to just utilize the internal reflections of the prism to perform alignment.  Pre-collimating, I was having trouble with anything above 200x.  After collimating, I tested at 1000x with no trouble.

 

My alignment is a little bit off as the laser is not returning exactly to the center.

 

 

 

[StarAlert]

I quite literally just performed an alignment with my Williams Optics binoviewer.  I was planning on doing what you did, testing against the wall, but I quickly found there was a much easier way.

 

I have the GSO/Zhumell laser collimator that is like a Cheshire collimator.  I also have a non-laser generic Cheshire in the other eyepiece port.  Using the 45 degree part, I was able to just utilize the internal reflections of the prism to perform alignment.  Pre-collimating, I was having trouble with anything above 200x.  After collimating, I tested at 1000x with no trouble.

 

IMG_20200601_173329_s.jpg

My alignment is a little bit off as the laser is not returning exactly to the center.

What do you mean by “using the 45 degree part”
I’ve never had to collimate anything as I’ve only had refractors. 

Edited by StarAlert, 01 June 2020 - 05:14 PM.

[decep]

What do you mean by “using the 45 degree part”
I’ve never had to collimate anything as I’ve only had refractors. 

I could not come up with a proper name for the part.  Most Cheshire style collimators have a viewport on the side.  The viewport shows a surface tilted at 45 degrees so you can see the reflected light from the primary/secondary of a newtonian.  Sometimes the 45 degree surface has a grid/bulls eye on it.  Laser versions shine a laser through a hole of the 45 degree surface.  Non-laser versions, you can just shine a light down the pin size hole at the top.

[StarAlert]

I think this is going to be a useful thread for us bino owners. So I have a question for both of you. How do you know which eyepiece holder needs to be adjusted? Or do you just loosen one side and try to adjust it to the other? 

[StarAlert]

I could not come up with a proper name for the part.  Most Cheshire style collimators have a viewport on the side.  The viewport shows a surface tilted at 45 degrees so you can see the reflected light from the primary/secondary of a newtonian.  Sometimes the 45 degree surface has a grid/bulls eye on it.  Laser versions shine a laser through a hole of the 45 degree surface.  Non-laser versions, you can just shine a light down the pin size hole at the top.

I see. Thanks for the lesson.

[decep]

I think this is going to be a useful thread for us bino owners. So I have a question for both of you. How do you know which eyepiece holder needs to be adjusted? Or do you just loosen one side and try to adjust it to the other? 

Because the prisms have nice flat surfaces that are supposed to be perfectly perpendicular to the light path, each surface of the prism can reflect laser light.  The light even bounces back and forth between the prisms themselves.

When I first started with my WO binoviewers, I had something like 3-4 reflected spots from a single beam.  I had completely removed the prisms to clean them, so it was not entirely unexpected for collimation to be so far off.

I just started adjusting one prism until the reflected beams from it returned to the exact center of the cheshire.  Go the second prism.  Alternate back and forth between each prism until everything reflects back to the exact center.  I also swapped the laser and cheshire between the eye ports multiple times.

[StarAlert]

Oh. So this is different than what Tanveer is doing. The prisms in the MB2 can’t be adjusted. Only the eyepiece holders.  At least that’s my take. 

[StarAlert]

One more question, though. Is the binoviewer in your scope while you’re collimating it? Wouldn’t the laser be coming out of the nosepiece? Sorry for all the questions. 

[daslolo]

I quite literally just performed an alignment with my Williams Optics binoviewer.  I was planning on doing what you did, testing against the wall, but I quickly found there was a much easier way.
 
I have the GSO/Zhumell laser collimator that is like a Cheshire collimator.  I also have a non-laser generic Cheshire in the other eyepiece port.  Using the 45 degree part, I was able to just utilize the internal reflections of the prism to perform alignment.  Pre-collimating, I was having trouble with anything above 200x.  After collimating, I tested at 1000x with no trouble.
 
IMG_20200601_173329_s.jpg
My alignment is a little bit off as the laser is not returning exactly to the center.

Beats an optical bench!
If I get it: the prism merges both the laser and non laser and send it to each one.
Do you put a mirror in the front nose piece?

[decep]

Beats an optical bench!
If I get it: the prism merges both the laser and non laser and send it to each one.
Do you put a mirror in the front nose piece?

I did try a mirror at the nose piece, but it overpowered the internally reflected beams.  You can always try it both ways, it just did not help me.

[TG]

I think this is going to be a useful thread for us bino owners. So I have a question for both of you. How do you know which eyepiece holder needs to be adjusted? Or do you just loosen one side and try to adjust it to the other?

I just picked the side that seemed off level. I suppose you could adjust both sides so the adjustment is split into moderate amounts.

[StarAlert]

I did try a mirror at the nose piece, but it overpowered the internally reflected beams.  You can always try it both ways, it just did not help me.

I’m still confused. If you shoot a laser into one of the eyepiece holders, doesn’t it come out the nose piece? How did you get the laser to come back out the other eyepiece holder without it being reflected at the nose piece? 

[StarAlert]

Tanveer,

Any word on how your re-collimated BV works? 

[daslolo]

I’m still confused. If you shoot a laser into one of the eyepiece holders, doesn’t it come out the nose piece? How did you get the laser to come back out the other eyepiece holder without it being reflected at the nose piece? 

I think a prism splits light like a geometric line and not like a fluid where flow vector matters.

[TG]

Tanveer,

Any word on how your re-collimated BV works? 

I took it for a spin a couple nights back but the seeing was mediocre. I did however feel that there was reduced eyestrain with the eyepieces that gave me the most trouble (a 17mm Plossl pair) and I felt only a smidgen. With shorter wavelengths, 12.5mm and 10mm, I there was no eye-strain nor did I see any aberration that could possibly be attributed to the "coma" seen in the laser diffraction spots. So my assessment is that the optics are superb but alignment could be a tad better for the BV. Given that it's their cheaper BV, I suppose it'll be the luck of the draw for people.

 

One advantage with the new coupling ring is that it makes the BV's position w.r.t your eyes very easily and safely adjustable. With the MarkV, you had to loosen the dangerous set screw to do the same.

 

Tanveer.