Zoom eyepiece for h alpha

[Adam Barnsley]

Hi all.

I am looking for a zoom eyepiece to 60mm lunt. My first choices are Lunt zoom and Pantax smc xf zoom. Which will work better? Can you have any other offer? You could say something more about these eyepieces while observing h-alpha? 

[johninderby]

I found the Pentax xf zoom was slightly better but not a huge amount.

The TS version of the Lunt zoom is on special right now at Telescope Express and a great buy. 

https://www.teleskop-express.de/shop/product_info.php/info/p4651_TS-Optics-Premium-Zoom-Eyepiece--7-2-mm-to-21-5-mm---1-25-.html

[John]

51 minutes ago, johninderby said:

..The TS version of the Lunt zoom is on special right now at Telescope Express and a great buy. 

https://www.teleskop-express.de/shop/product_info.php/info/p4651_TS-Optics-Premium-Zoom-Eyepiece--7-2-mm-to-21-5-mm---1-25-.html

I have one of these which was a very good H-Alpha scope and pretty good at night as well. It certainly looks the same as the TS one:

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_330

I think the TS spec for the max field of view is more accurate than the Opticstar one though.

[Buzzard75]

My Lunt 80mm came with the Lunt zoom eyepiece. I asked the same question before I got it. The Lunt is actually quite good and I've been happy with it.

[John]

24 minutes ago, Buzzard75 said:

My Lunt 80mm came with the Lunt zoom eyepiece. I asked the same question before I got it. The Lunt is actually quite good and I've been happy with it.

I have the feeling that the Lunt zoom is the same eyepiece that have been linked to above under different brandings. I have compared mine to a Lunt zoom and, apart from the branding, it looked and performed the same.

Lots of choice in this design, Skywatcher do one as well:

https://www.rothervalleyoptics.co.uk/ovl-hyperflex-7e1-72mm-215mm-high-performance-zoom-eyepiece-125.html

Look at the price on this one with Orion (USA) branding !:

https://www.astroshop.eu/eyepieces/orion-7-2mm-21-5mm-1-25-zoom-eyepiece/p,17113

 

[JeremyS]

+1 for the Opticstar XL 7.2mm-21.5mm http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_330

I use one in my Lunt 50.

[Buzzard75]

2 hours ago, John said:

I have the feeling that the Lunt zoom is the same eyepiece that have been linked to above under different brandings. I have compared mine to a Lunt zoom and, apart from the branding, it looked and performed the same.

Lots of choice in this design, Skywatcher do one as well:

https://www.rothervalleyoptics.co.uk/ovl-hyperflex-7e1-72mm-215mm-high-performance-zoom-eyepiece-125.html

Look at the price on this one with Orion (USA) branding !:

https://www.astroshop.eu/eyepieces/orion-7-2mm-21-5mm-1-25-zoom-eyepiece/p,17113

 

Agreed, they all look fairly identical in design and specs.

[Adam Barnsley]

Tanks gentlemen. Could you say something about the Pentax?

[johninderby]

The Pentax XF is by a little bit the best HA zoom eyepiece, very sharp and contrasty and very small amd lightweight. Would be my first chpice for an HA zoom if price didn’t come into it.

However the eyepiece is complete rubbish for regular night time observing. Just plain horrible. So much distorsion it just isn’t usable.

So as a dedicated HA zoom the Pentax XF is great but only as an HA eyepiece. The distortion that makes it useless at night has no noticeable effect with HA.

Edited July 24, 2019 by johninderby

[Adam Barnsley]

Only intended for h alpha. So Pentax zoom has an advantage over others.

[johninderby]

In that case it’s the one I would go for. Such a nice eyepiece to use and optically rivals a good ortho eyepiece in performance on HA.

 

Edited July 24, 2019 by johninderby

[Ricochet]

17 hours ago, johninderby said:

So much distorsion it just isn’t usable.

Out of interest, which distortions do you notice? 

[johninderby]

The Pentax XF zoom is designed for daytimr use in a spotting scope and so is optimised to give the best view in the centre of the field at the expense of field distorion. Not a problem when looking at the sun but for general astro use the distortions are much worse than would be acceptable in an astro eyepiece. 

It’s not a question of being a bad eyepiece but rather one optimised for daytime use. 

[RT65CB-SWL]

1 hour ago, johninderby said:

The Pentax XF zoom is designed for daytimr use in a spotting scope and so is optimised to give the best view in the centre of the field at the expense of field distorion. Not a problem when looking at the sun but for general astro use the distortions are much worse than would be acceptable in an astro eyepiece. 

It’s not a question of being a bad eyepiece but rather one optimised for daytime use. 

I have heard that too, [ref: Pentax XF zoom], from non-SGL'ers. 

[johninderby]

It’s simply that daytime and. astro eyepices have to correct for diiferent types of distortions. Naglers can look very distorted in a spotting scope as well.

Edited July 25, 2019 by johninderby

[Paul73]

I’ve happily used the Baader Zoom for Ha. Can’t remember seeing any distortion to speak of. I used to have a duel WL / Ha setup with a Baader zoom on each side.

Paul

[Highburymark]

Have given the same advice many times over the years - the XF zoom is a superb solar eyepiece, and as a package unbeatable in my view. Equalled optically only by Televue plossls in a solar scope, and noticeably sharper than the Lunt zoom, it's light, relatively affordable and offers a perfect range of powers for Ha solar. Don't buy from astronomy retailers unless you see a good deal - camera stores are usually more competitive for spotting scope eyepieces like this - try Wex etc.

[Paul73]

That sounds like a nail in the Lunt’s coffin. I use TV Plossls for my Ha viewing. They really aren’t that much sharper than the Baader Zoom. Which would put the Baader ahead of the Lunt. I haven’t tried the Pentax so can’t comment on that one. Although enough experienced observers seem to rate it highly.

I would always choose Zoom over fixed length eyepieces for solar work.

Paul

Edited July 25, 2019 by Paul73

[johninderby]

Microglobe has a very good price on the Pentax XF zoom although waiting on stock.

https://www.microglobe.co.uk/pentax-65-195mm-zoom-eyepiece-smc-xf-series-p-4507.html

Wex is more but in stock

https://www.wexphotovideo.com/pentax-xf-65-195mm-zoom-eyepiece-1529787/

 

[Adam Barnsley]

4 hours ago, Paul73 said:

I’ve happily used the Baader Zoom for Ha. Can’t remember seeing any distortion to speak of. I used to have a duel WL / Ha setup with a Baader zoom on each side.

Paul

What baader did you use?  Friend bought hyperion III and immediately dismissed it because of internal reflections.

[Paul73]

I’ve used the mk3 and 4 without issue.

Anyone else had issues with these?

Paul

[John]

2 hours ago, Paul73 said:

I’ve used the mk3 and 4 without issue.

Anyone else had issues with these?

Paul

I've owned Mk2 and a couple of Mk3's. While they were not perfect eyepieces, they fulfilled the Baader Zoom's reputation as excellent zoom eyepieces.

Personally I think the 7.2 - 21.5 that I now have is as good though. Not such a wide field across the focal lengths but optically pretty good.

 

[Adam Barnsley]

Thank you for your time and opinions.👌🤳I opted for Pentax Zoom

[johninderby]

You won’t be disapointed by the Pentax zoom. You may be surprised by how small and light it is. 

Edited July 26, 2019 by johninderby

[Highburymark]

If I remember accurately, the Pentax zoom was the first 'non-stock' eyepiece I ever bought. I went to the retailer (as we used to do in the olden days - physically walked there - complete madness!) in search of a Baader zoom for standard night viewing, about which I'd heard good things. Anyway, they were out of the Baader, but recommended the Pentax XF, claiming it was even better, and worth the extra few quid. When I tried it out I was disappointed - even on slow scopes it was a step down from the perfectly good plossls I'd been using for years. Then later I got to use it for solar white light and ha, and it's been a faithful companion ever since. Hope you enjoy it as much as I have Adam