74 replies to this topic

[Princess Leah]

In terms of on-axis sharpness of this zoom (or indeed any eyepiece), would focal ratio effect this?

Could it work better in a F11 achromat for instance?

[PKDfan]

In terms of on-axis sharpness of this zoom (or indeed any eyepiece), would focal ratio effect this?
Could it work better in a F11 achromat for instance?

Hi Leah !!

IDK if the on-axis will be improved but certainly the slower the feed the better the edges are.


I wonder if others will have data suggesting an improvement also for on-axis?

I will check next time i use BHZ with 5X PM and will do a more investigative examination on-axis but i suspect little change.



CS

[Princess Leah]

Thanks CS that's what I would think.

[SeattleScott]

The on axis views should improve some with slower F ratio. But contrast isn’t just about spot sizes. It is also about baffling, polish, coatings. These won’t be aided by a slow scope.

[Jon Isaacs]

Thanks CS that's what I would think.

 

Nonetheless, the Baader zoom still was quite good at F/4.4 + Paracorr =F/5.06 and F/5 + Paracorr = F/5.75, that was the 10 inch. The planetary views were clean and crisp at 180x.

 

I used it mostly between 8 mm and 16 mm but tests on Polaris showed it was reasonably well corrected corrected at 24 mm, the companion was a tight disk at the edge of the field. 10 inch 60x.

 

Jon

[PKDfan]

Hi again Leah !!

My names Lance. CS = Clear Skies.


I'll not only check the BHZ with the 5X PM but also investigate the field with my 2X 3element ED Barlow which i recently cleaned and its performance now closer to the TV telecentric'ish PM and can with ext. tubes reach 4X.


I think its almost impossible to see if a point at 5arcminutes is improved to 4arcminutes is really detectable. I think thats the level of improvement to expect but so difficult to see so why the edge improvement much easier to see and quantify.

If instead that point @10arcminutes improves to 5arcminutes that would be seen much easier.

I'm trying to figure out an ideal target which would shed 'light' upon this experiment?

A point or an extended line ?

The double double or rilles ?



CS

[SeattleScott]

Hi again Leah !!

My names Lance. CS = Clear Skies.


I'll not only check the BHZ with the 5X PM but also investigate the field with my 2X 3element ED Barlow which i recently cleaned and its performance now closer to the TV telecentric'ish PM and can with ext. tubes reach 4X.


I think its almost impossible to see if a point at 5arcminutes is improved to 4arcminutes is really detectable. I think thats the level of improvement to expect but so difficult to see so why the edge improvement much easier to see and quantify.

If instead that point @10arcminutes improves to 5arcminutes that would be seen much easier.

I'm trying to figure out an ideal target which would shed 'light' upon this experiment?

A point or an extended line ?

The double double or rilles ?



CS

A bright star will really show any abberations. Kind of a worse case scenario.

[PKDfan]

A bright star will really show any abberations. Kind of a worse case scenario.

I've been thinking about this since responding to Leah Scott & HI !!

I agree that a star is perhaps easiest as we're interested in how big/small a point can get and Vega and DD ideally placed for me. Can quickly then zip down to the ring nebula.

I've never actually split the DD in either of my apos but did in the 60mm B&L and NOT pretty.

I'll use my 62mm and BHZ alone + 2X & 5X amplifiers.

I'd be interested in minimum power to split them and Airy disc development as i increase powers.

Perhaps use Albireo too for any contrast changes to their beautiful colours.


Clear Skies

[SeattleScott]

I feel like 100x is about the minimum to split Double Double, and even then arguably they look oblong as opposed to a clean split. 200x gives a clean split. In 4" refractor or larger scope. Can't speak to 62mm.

 

Basically to split you will need to barlow, which changes the correction attributes of the eyepiece alone. So for evaluating edge correction, you could use Vega near the edge. Splitting DD would be more evaluating the contrast and resolution of the scope (and perhaps to a latter extent the eyepiece).

 

Now it could be informative to look at how the barlow cleans up Vega at the edges. 

Edited by SeattleScott, 15 June 2024 - 03:19 PM.

[PKDfan]

I feel like 100x is about the minimum to split Double Double, and even then arguably they look oblong as opposed to a clean split. 200x gives a clean split. In 4" refractor or larger scope. Can't speak to 62mm.

Basically to split you will need to barlow, which changes the correction attributes of the eyepiece alone. So for evaluating edge correction, you could use Vega near the edge. Splitting DD would be more evaluating the contrast and resolution of the scope (and perhaps to a latter extent the eyepiece).

Now it could be informative to look at how the barlow cleans up Vega at the edges.

Since i have no double star experience Scott i have no preconceptions. The whole gamut of possibities is open wide, so what it takes for me and my fine eyesight to a
achieve in double star'ing finally be figured out.
I can rank myself !

That particular facet i've never once appreciated so of the how much it requires in actually doing the splitting and all the possible ways or combinations to make the same power and then examining mr. Airy in detail while exploring this is kinda exciting !

A whole new part of the visual spectrum to explore !

To my scopes ability all i can say the trapezium is more often than not six stars so as far as quality goes i know my figure intimately well and what a potent tool it is despite to some its anemic light gathering power.

Its a full on direct into the eye experience vrs a bounced off world and they ain't the same thing.

Kind regards
Lance

CS
Edit typos and grammar

Edited by PKDfan, 15 June 2024 - 03:48 PM.

[Jon Isaacs]

I feel like 100x is about the minimum to split Double Double, and even then arguably they look oblong as opposed to a clean split. 200x gives a clean split. In 4" refractor or larger scope. Can't speak to 62mm.

 

Basically to split you will need to barlow, which changes the correction attributes of the eyepiece alone. So for evaluating edge correction, you could use Vega near the edge. Splitting DD would be more evaluating the contrast and resolution of the scope (and perhaps to a latter extent the eyepiece).

 

Now it could be informative to look at how the barlow cleans up Vega at the edges. 

 

I made a clean split of the double-double last night in my NP-101 with the 7mm Type 5 Nagler, 77 x. Both pairs were unambiguous.

 

When I was younger, I could routinely make the split at 66x. I didn't try last night, the seeing was somewhat unstable.

 

Jon

[Princess Leah]

The on axis views should improve some with slower F ratio. But contrast isn’t just about spot sizes. It is also about baffling, polish, coatings. These won’t be aided by a slow scope.

Completely agree.

But would on-axis improve with a 80mm F11 achromat, compared to a F6 80mm APO?

[Princess Leah]

Nonetheless, the Baader zoom still was quite good at F/4.4 + Paracorr =F/5.06 and F/5 + Paracorr = F/5.75, that was the 10 inch. The planetary views were clean and crisp at 180x.

 

I used it mostly between 8 mm and 16 mm but tests on Polaris showed it was reasonably well corrected corrected at 24 mm, the companion was a tight disk at the edge of the field. 10 inch 60x.

 

Jon

Did you ever try it without the Paracorr?

[Princess Leah]

For me there is no need to split double stars! I can see clearly the image is softer in the Baader zoom, even at modest magnifications.

Was comparing with moon last night. Will write more later.

[Princess Leah]

Hi again Leah !!

My names Lance. CS = Clear Skies.


I'll not only check the BHZ with the 5X PM but also investigate the field with my 2X 3element ED Barlow which i recently cleaned and its performance now closer to the TV telecentric'ish PM and can with ext. tubes reach 4X.


I think its almost impossible to see if a point at 5arcminutes is improved to 4arcminutes is really detectable. I think thats the level of improvement to expect but so difficult to see so why the edge improvement much easier to see and quantify.

If instead that point @10arcminutes improves to 5arcminutes that would be seen much easier.

I'm trying to figure out an ideal target which would shed 'light' upon this experiment?

A point or an extended line ?

The double double or rilles ?



CS

CS Lewis!

 

Sorry Lance, can't believe I thought your name was CS!

[PKDfan]

CS Lewis!

Sorry Lance, can't believe I thought your name was CS!

Lol. No worries Princess !

Its not really polite is it to offer advice or experiences always as a nameless anonymous source and expect the same priviledges as another whom gives their full name.

I'll try and share it more often so Thanks for helping me out !


Kind regards & CS

Lance

[Jon Isaacs]

Did you ever try it without the Paracorr?

 

Yes, I tried it without the Paracorr, I tried in my refractors up to F/7.

 

One sign of a reasonably well corrected eyepiece is that one can see coma.  In a poorly corrected eyepiece, the off-axis astigmatism overwhelms the coma.  The Baader zoom is corrected well enough that the coma is quite apparent.  

 

Realize, I was using it to bridge the gap between the 13mm Ethos and the 8mm Ethos.. These are two eyepieces that are just about as sharp as it gets in a fast scope. People use them at F/3.  The Baader zoom was not quite as sharp but it wasn't disappointing either.  

 

The difficulty was the AFoV/TFoV, it's hard for a zoom to compete with 100 degree eyepieces..  The TFoV with the Baader zoom at 24mm was about the same as the 10 mm Ethos which I eventually acquired and only about 25% narrower than the 8 mm Ethos..  Imagine you are observing faint galaxies at 280x (10mm eyepiece).  Using the Baader, if I needed a wide field of view to locate the galaxy, reducing the magnification down to the 24mm, (120x), the faint galaxy would no longer be visible.  With the 10mm Ethos, I did not have to reduce the magnification, it provided the same TFoV at 280x as the Baader zoom did at 120x.. 

 

For my eyes, in my scopes, I find it to be a quality eyepiece.. It's not as sharp as a type 6 Nagler but few eyepieces are.

 

Jon

[quilty]

I made a clean split of the double-double last night in my NP-101 with the 7mm Type 5 Nagler, 77 x. Both pairs were unambiguous.
 
When I was younger, I could routinely make the split at 66x. I didn't try last night, the seeing was somewhat unstable.
 
Jon

splitting DD is no challenge to any aperture above 3" but certainly is to the visual acuity. If you see it as a rod or two points at 100x depends on your eyes.
For the image is the very same when powered up to 200x or 300x

[3C286]

Has anyone compared the transmission of the Baader Hyperion Zoom to the cheaper zooms?

I recall noticing in the past that I could see some faint targets with the Baader Hyperions (the fixed focal length EPs; not the zoom) but not with my Celestron 8-24 zoom. Presumably due to Baader's better coating.

 

I found a scribble in my observation log for M81/82 that the Celestron 8-24mm "didn't seem to have great transmission" and the Baader Hyperion Zoom (this time the zoom) was "good". It was just a note and not a full comparison. I'd be interested in hearing if anyone's done a proper comparison.

 

 

Tak

[Princess Leah]

Yes, I tried it without the Paracorr, I tried in my refractors up to F/7.

 

One sign of a reasonably well corrected eyepiece is that one can see coma.  In a poorly corrected eyepiece, the off-axis astigmatism overwhelms the coma.  The Baader zoom is corrected well enough that the coma is quite apparent.  

 

Realize, I was using it to bridge the gap between the 13mm Ethos and the 8mm Ethos.. These are two eyepieces that are just about as sharp as it gets in a fast scope. People use them at F/3.  The Baader zoom was not quite as sharp but it wasn't disappointing either.  

 

The difficulty was the AFoV/TFoV, it's hard for a zoom to compete with 100 degree eyepieces..  The TFoV with the Baader zoom at 24mm was about the same as the 10 mm Ethos which I eventually acquired and only about 25% narrower than the 8 mm Ethos..  Imagine you are observing faint galaxies at 280x (10mm eyepiece).  Using the Baader, if I needed a wide field of view to locate the galaxy, reducing the magnification down to the 24mm, (120x), the faint galaxy would no longer be visible.  With the 10mm Ethos, I did not have to reduce the magnification, it provided the same TFoV at 280x as the Baader zoom did at 120x.. 

 

For my eyes, in my scopes, I find it to be a quality eyepiece.. It's not as sharp as a type 6 Nagler but few eyepieces are.

 

Jon

Is coma not off-axis? I'm not criticizing the off axis performance. Thanks Leah.

[quilty]

Tak,
Make the coatings that difference? The C 8-24 was advertised as "APO" super Plössl with just 4 elements.
It should have a good transmission. I have the omegon branded version and did not notice an improper light loss yet
(Quite in fact I can't believe in those just 4 elements for the zoom)

https://www.astrosho...po-1-25-/p,3919

and the SW

https://www.astrosho...m-1-25-/p,60719

Seem to be the very same as well as the SW 8-24 zoom

Q.

Edited by quilty, 16 June 2024 - 07:08 AM.

[Princess Leah]

Has anyone compared the transmission of the Baader Hyperion Zoom to the cheaper zooms?

I recall noticing in the past that I could see some faint targets with the Baader Hyperions (the fixed focal length EPs; not the zoom) but not with my Celestron 8-24 zoom. Presumably due to Baader's better coating.

 

I found a scribble in my observation log for M81/82 that the Celestron 8-24mm "didn't seem to have great transmission" and the Baader Hyperion Zoom (this time the zoom) was "good". It was just a note and not a full comparison. I'd be interested in hearing if anyone's done a proper comparison.

 

 

Tak

I have five zooms and the Baader is the best I have used. Although still disappointed!

If you like zooms then I imagine the Baader is a good choice.

I feel the zooms I use birdwatching (including the Baader) are OK as I'm usually observing below 40X

[Princess Leah]

Hi again Leah !!

My names Lance. CS = Clear Skies.


I'll not only check the BHZ with the 5X PM but also investigate the field with my 2X 3element ED Barlow which i recently cleaned and its performance now closer to the TV telecentric'ish PM and can with ext. tubes reach 4X.


I think its almost impossible to see if a point at 5arcminutes is improved to 4arcminutes is really detectable. I think thats the level of improvement to expect but so difficult to see so why the edge improvement much easier to see and quantify.

If instead that point @10arcminutes improves to 5arcminutes that would be seen much easier.

I'm trying to figure out an ideal target which would shed 'light' upon this experiment?

A point or an extended line ?

The double double or rilles ?



CS

Just look at the moon at around 90X with a plossl and then the Baader zoom. The plossl will be much sharper on-axis. That's providing my badder zoom isn't defective!

[Jon Isaacs]

Is coma not off-axis? I'm not criticizing the off axis performance. Thanks Leah.

 

You asked about the performance without a coma corrector.  The coma corrector does not significantly affect on-axis performance, I hope you knew that..  So why did you ask?

 

Jon

[SeattleScott]

Completely agree.
But would on-axis improve with a 80mm F11 achromat, compared to a F6 80mm APO?

I would expect F11 to improve on axis performance somewhat, but I only evaluated the BHZ once using one scope.