Baader Hyperion zoom and barlow fitting issues

[Prador]

This is quite possibly stupid questions and I may be missing the obvious here. I recently purchased a BH MkIV zoom with barlow and encountering a couple issues. With the barlow in place and using in a 1.25" adapter in my diagonal, the zoom sits 'proud' of the adapter leaving a 15mm gap to to body of the zoom. Am I being an idiot and this is as intended? I'm so used to bits sitting flush and neat with each other and looks odd to me.

Second problem is with the barlow in place and using the 2" attachment in my 2" diagonal the bottom of the barlow hits the mirror. Is it normal to require a smallish extension piece to alleviate this?

Many thanks in advance for any advice

[Franklin]

In the 1.25" format it does stick up like a stalk. But if you remove the 1.25" nosepiece fitting there is a secondary thread which attaches the barlow directly to the zoom field lens snout and then fit the 2" nosepiece. That way it will sit flush and shouldn't protrude so much to hit the mirror in the diagonal. In this configuration the barlow will rotate with the zoom field lens snout so cannot be used like this in 1.25" focusers.

[Prador]

Many thanks Franklin!

I've spent some time unscrewing various bits and screwing other bits on and all good. Barlow is close to the mirror but not touching.

[Spile]

I experimented with fitting the Barlow directly to the eyepiece but when you turn the zoom, it also turns the Barlow. I eventually came to the conclusion that the best aka most convenient way was to attach the 1.25” adapter and use the 2” sleeve. The Barlow attaches to the adapter so no rotation. Explained with diagrams here https://astro.catshill.com/the-zoom-eyepiece/

Edited November 19, 2022 by Spile

[Jakke]

Hi, 
I use this small Baader T2 eyepiece holder.
Attach the barlow lens to it with the provided T2 adapter and it will allow you to use the barlow as a normal one.
Much more convenient, no more screwing / unscrewing in the dark… 

https://www.firstlightoptics.com/adapters/baader-125-t2-eyepiece-holder.html

 

 

[F15Rules]

Something perhaps indirectly related to this?..

Like many others I suspect, I only use my zoom barlow with non Baader 1.25" eyepieces.. but when I bought my zoom barlow kit, I basically ignored the connecting top (widest) part of the kit which threads into the zoom itself, and just used the bottom 2 sections containing the optics (threaded together), inserted into whichever eyepiece I want to use..

But the other day, when fiddling about with my bits box, I remembered that my Baader clicklock 2" to 1.25" adapter has a T2 thread underneath it. So I put the whole 3 section Barlow together, so it makes a nice single Barlow unit, and then threaded that into my Clicklock. This makes the whole assembly very stable. Moreover, the Barlow/Clicklock assembly can then be a permanent assembly if you wish, and the required 1.25" eyepiece you want to barlow can then pop straight in and out of the clicklock/barlow, with no need to screw and unscrew the eyepiece into the barlow body each time.

I'm sure others do this routinely, but it might be of help to some who don't..?🤔😊

Dave

 

Edited November 21, 2022 by F15Rules

[Franklin]

3 hours ago, F15Rules said:

I'm sure others do this routinely,

And if you use the Baader fine focusing T2-1.25" adaptor instead of the clicklock you end up with a "Variable barlow" by using the focusing mechanism the mag factor of the barlow can be altered as it brings the field lens of the zoom closer or further from the barlow. No idea by what factor though.

[F15Rules]

19 minutes ago, Franklin said:

And if you use the Baader fine focusing T2-1.25" adaptor instead of the clicklock you end up with a "Variable barlow" by using the focusing mechanism the mag factor of the barlow can be altered as it brings the field lens of the zoom closer or further from the barlow. No idea by what factor though.

That's interesting, Tim. The same could apply also to my proposed setup above, as we would be increasing the distance between the Barlow optics and the eyepiece by the depth of the clicklock body?

Perhaps Louis (who is very good with calculations like this👍) could chip in with his thoughts on the likely effect on the magnification with both permutations?

Over to you, Maestro!😂

Dave

[Prador]

This is what I like about this community. I ask a really dumb question and some really helpful knowledge falls out.

Many thanks for the very useful replies 😁

[F15Rules]

1 hour ago, Prador said:

This is what I like about this community. I ask a really dumb question and some really helpful knowledge falls out.

Many thanks for the very useful replies 😁

There is only One "really dumb question" on this forum, and that is..

"Is it likely to be clear tonight?"🤦😂😂

Dave

[Louis D]

3 hours ago, F15Rules said:

Perhaps Louis (who is very good with calculations like this👍) could chip in with his thoughts on the likely effect on the magnification with both permutations?

@vlaiv is the mathematical wizard on here.  He's posted on other threads how to calculate the magnification factor of Barlows as a function of separation distance.  However, it usually requires knowledge of the Barlow's focal length which is never published.

[PeterC65]

I once found an article reviewing the Hyperion Zoom and Barlow that mentioned this calculation. Unfortunately I can no longer find it, but I do have some notes that I made:

The Baader x2.25 Barlow Lens will also screw directly into the Zoom eyepiece without the (A) Adapter attached which reduces the optical path length by 15mm putting it closer to the eyepiece optics and reducing the magnification to x2.0 (x2.25 – 15mm / 59.4mm, where 59.4mm is the focal length of the Barlow Lens).

The arrangements above will increase the distance between the Barlow Lens and the eyepiece optics and therefore increase the magnification factor of the Barlow beyond x2.25.

By the way @F15Rules, you should be able to screw the (B) adapter directly onto the Barlow body without the (A) adapter, and then onto the Baader Clicklock 2" to 1.25" adapter. This will make the whole assembly 15mm shorter.

[vlaiv]

4 hours ago, F15Rules said:

That's interesting, Tim. The same could apply also to my proposed setup above, as we would be increasing the distance between the Barlow optics and the eyepiece by the depth of the clicklock body?

Perhaps Louis (who is very good with calculations like this👍) could chip in with his thoughts on the likely effect on the magnification with both permutations?

Over to you, Maestro!😂

Dave

Formula is simple one - but application of it often not - as there are so many factors that we don't really know.

Magnification of the barlow is given by its focal length and distance to focal plane:

Magnification = 1 +  distance / focal_length

(it is actually the same formula used for focal reducers except barlow is negative optical element and then it turns minus in above equation to a plus).

Problem is - we don't really know focal length of the barlow element, and we don't really know where do we need to start measuring (as optical elements are inside housing and it's not always clear where the nodal point is - or center of the lens).

It also not always clear where the focal plane will be located as that depends on eyepiece used. Eyepieces should place focal plane on "shoulder" level - but not all do. Otherwise all would be parfocal.

In any case - increase in distance - higher magnification factor, and decrease in distance - lower magnification factor.

If one finds approximate FL of barlow element and has approximate distance - then approximate calculation of increase in magnification is simple.

Say that we have barlow that is x2 normally and we judge that there is about 50mm between barlow element and eyepiece adapter top (where we judge focal plane will be for most eyepieces).

How much magnification would we gain by adding 20mm extension?

Mag = 1 + distance / focal_length => 2 = 1 + 50mm / focal_length => focal_length is about 50mm

If we increase distance by 20mm we will get

1 + 70 / 50 = 1 + 1.4 = x2.4

We go from x2 to x2.4 by adding 20mm extension (in this example case).

 

[Louis D]

So solving for the BHB's nominal separation distance from the FL (59.4mm) provided by @PeterC65 above:

     2.25 = 1+d/59.4

solving for d yields

     d=74.25mm

That's almost 3 inches, which seems a bit long for the nominal separation distance yielding 2.25x from the connectivity pictures I've seen online.

How long does the nominal 2.25x working distance seem with the BHB?  What series of adapters yields this magnification?

[Don Pensack]

Since focal plane positions in eyepieces vary a lot, there is a simple way to determine the magnification of any barlow for any eyepiece and automatically

take into account the focal plane position in the eyepiece:

Point scope at star near the celestial equator (it can be anywhere, but the process is faster near the equator).

Time the passage of any star from edge to edge in the eyepiece.

Insert eyepiece in Barlow and time the passage of the same star across the field.

Time 1 / Time 2 = Barlow magnification factor.

 

You can duplicate the process with any eyepiece.

 

Edited November 21, 2022 by Don Pensack

[Second Time Around]

Some of you will know I'm a great fan of Barlows, especially those where the optics can be separated from the complete Barlow.  This means that the Barlow can be used at different amplifications.  The Baader Hyperion is one of these of course.

I've almost finished measuring the amplications of the Hyperion Barlow and several others (both using complete  Barlows and with just the optics) in the new APM Superzoom.  The latter can be used as both a 1.25 and 2 inch eyepiece, and I'm testing both as the amplification is higher in the 1.25x configuration. 

These measurements also clearly show that the amplication factor with the APM Superzoom is higher than the nominal (published) values.  This is due to the position of the focal plane, as pointed out in a previous post.

I'm doing the observations with my 72mm refractor pointed at a tape measure on the window sill at the far end of our lounge.  The tape is secured with Blu-Tack.

I note how much of the tape measure I can see both with and without each Barlow.  Dividing the higher measurement by the lower gives the amplification factor.

I'll publish the results once the work is completed. 

Edited November 21, 2022 by Second Time Around

[vlaiv]

2 hours ago, Louis D said:

So solving for the BHB's nominal separation distance from the FL (59.4mm) provided by @PeterC65 above:

     2.25 = 1+d/59.4

solving for d yields

     d=74.25mm

That's almost 3 inches, which seems a bit long for the nominal separation distance yielding 2.25x from the connectivity pictures I've seen online.

How long does the nominal 2.25x working distance seem with the BHB?  What series of adapters yields this magnification?

If I'm not mistaken, this combination should give x2.25:

that is barlow element + "adapter A" - screwed into 1.25" filter thread.

I don't know how big things are in above image - but ~75mm does sound sensible as barlow and 1.25" nosepiece are about as tall as zoom body and from this image:

that seems about right +/- we don't know exact location of focal plane of the zoom EP.

[PeterC65]

I've come back to this post as I'm trying to work out the magnification of the Baader Hyperion Zoom Barlow when using it with a camera.

The Barlow has at least two lenses, one just inside the 1.25" barrel which appears to be slightly concave and one at the eyepiece end which is very convex. Assuming the Barlow element is the one just inside the barrel, then when the A Adapter is fitted this lens is about 32mm from the filter thread shoulder that screws in to the eyepiece barrel. So to get x2.25 and the required 74mm of separation the BHZ eyepiece's focal plane must be 42mm inside the end of its 1.25" barrel. That puts it 17mm inside the body of the BHZ as the nosepiece is 25mm long. Does that sound sensible? The moving lower lens of the BHZ sits within the 1.25" barrel so this puts the focal plane is well inside that.

If this all stacks up then the back focus required for the Baader Hyperion Zoom Barlow to give its specified x2.25 magnification is 42mm. Quite a bit more than most eyepieces will give if their focal plane is at or about the 1.25" barrel shoulder.