Eyepiece WA advice.

[tico]

Hello,

I was looking for some advice on a good wide angle eyepiece, about 30mm, although I am not very clear if it is better to 82º or 72º ... I would like it to give about 5º of field .., one day I looked at a 31mm Nagler and I did not like it very much. feeling of having to move my head to see the end of the field, that is, at a glance I could not see the entire field ...
My telescope is a 4 "/ 460 FL refractor.
Thanks.
Tico.

 

[Ruud]

An Explore Scientific 34mm 68° would fit the bill, just like a second hand 34mm 68°series 5K Meade SWA, or if you're in Europe a second hand Maxvision 34mm 68°.

I have the Maxvision and I like it. It's every bit the same as the Meade, except for the brand name. Optically, the Maxvision and the Meade are probably not just identical to each other but also to the ES: they're all from the same manufacturer.

The Meade/ES/Maxvision have high image quality and plenty of eye relief. Ergonomics are just fine. They handle f/5 with ease.

TeleVue Panoptic  35mm 68° is more expensive and possibly a tad  better (not much though, there isn't much room for that).

More economic options also exist. I can't say much about them. No experience.

---

A lunar eclipse in a 5° true field  is quite fantastic and the Milky Way becomes a sea of densely packed stars. Large open clusters are magic too is a wide view.

[Don Pensack]

Try a 30mm APM Ultra Flat Field eyepiece.  It's a measured 72°, and has a long enough eye relief for glasses.

Even better, it has excellent sharpness and contrast.  It's a 2" eyepiece.

[Louis D]

What refractor are you using that's a 100mm f4.6?  Either it's an exotic ED/APO (Borg/Pentax?) or it's an achromat that has loads of color fringing.

The problem at f4.6 is trying to keep the exit pupil below 7mm.  A 7*4.6=~32mm would be your max usable eyepiece focal length to possibly make full use of your available aperture.  Another problem is finding an eyepiece that can handle the steep light cone.  I agree that the 30mm APM UFF would probably be a good bet for you.  However, you're only going to get about 4.7 degrees TFOV, a bit shy of the 5 degrees you desire.

[John]

9 minutes ago, Louis D said:

What refractor are you using that's a 100mm f4.6?  Either it's an exotic ED/APO (Borg/Pentax?) or it's an achromat that has loads of color fringing....

 

One of these perhaps ?:

https://www.bresser.de/en/Astronomy/BRESSER-Messier-AR-102xs-460-Hexafoc-Optical-Tube.html

 

[Louis D]

47 minutes ago, John said:

One of these perhaps ?:

https://www.bresser.de/en/Astronomy/BRESSER-Messier-AR-102xs-460-Hexafoc-Optical-Tube.html

 

Rather confusingly it claims "Richfield telescope with ED glass lens" and is also an "Achromatic Refractor".  If it has a 4" ED lens for that price, I'd be very impressed.

I wonder at low powers how much violet fringing would be visible.  I also wonder how well spherical aberration is corrected.  I'm just trying to figure out if it might work well enough with a 35mm Aero ED if there's all sorts of other aberrations to deal with.  The outer 25% of the field would be a bit fuzzy with it, but if there's a bunch of other stuff going on out there, it might not seem so bad.  It would definitely come close to maxing out the TFOV possible.

[johninderby]

Good review here.

https://www.cloudynights.com/articles/cat/user-reviews/bresser-4-inch-f-45-ar-102xs-refractor-visual-observers’-review-r3121

Found this quote.

In a thread on astro-foren.de http://www.astrotref...TOPIC_ID=209314 a Lunt Europe employee confirms, that the 102/460 has ED glass, but that Bresser decided to label it as an achromat, because it would have too much false color, due to its short focal ratio, to be called an ED, because to most people an ED is synonymous with a nearly color free lens. 

Edited September 7, 2020 by johninderby

[tico]

Yes, is the Bresser 102/460 with  ¿ED? lens ? Is one fantaastic wide field for low magnifications, 4.7º in the field can be great ...

Thanks for all comments!!

Tico

[Louis D]

After reading the review's mention of field curvature, I'd have to recommend budgeting for a TSFLAT2 to flatten the field if you're going to use it for widest field scanning of the skies.  I use one with my 432mm FL 72ED to good effect.  Screwing it onto the front of the rather long 2" diagonal insertion tube of my 2" GSO 99% dielectric diagonal resulted in slight overcorrection, causing field curvature of the opposite sign.  Since that diagonal has SCT threads, I replaced the nosepiece with a 15mm SCT to M48 adapter tube and thread the TSFLAT onto the end of it.  The resultant field is just about perfectly flattened.

[Louis D]

12 hours ago, John said:

One of these perhaps ?:

https://www.bresser.de/en/Astronomy/BRESSER-Messier-AR-102xs-460-Hexafoc-Optical-Tube.html

 

Yes, not sold in the US, so not familiar with it at all.  I think I'll stick with my AT72ED for widest field scanning of the skies.  I don't think I'd want to trade off excellent color correction, two speed focuser, and all metal construction for an additional 30mm of aperture, though.  It would be intriguing if they went with an FPL-53 triplet to bring down the false color to at least ED levels.  Of course, the price would be at least $1000 higher.

[johninderby]

The focuser on the Bresser is a very nice CNC 2.5” R&P one and a lot better than the one on the 72ED.  However the 72ED is a proper APO and a very nice little scope.

With the optional dual speed knob.

Edited September 7, 2020 by johninderby

[Louis D]

23 hours ago, johninderby said:

The focuser on the Bresser is a very nice CNC 2.5” R&P one and a lot better than the one on the 72ED.  However the 72ED is a proper APO and a very nice little scope.

With the optional dual speed knob.

Getting off-topic (sorry OP and mods)

Indeed, yours looks similar to the one on my TS-Optics FPL-53 triplet 90mm APO minus the camera angle adjuster.  However, the one in the Bresser description and the CN review describe it as single speed with plastic wheels:

Did you mod those features with aftermarket parts?

You're right, though, that 2.5" focuser is nicer than the 2" AT72ED focuser in that it doesn't slip because it is a R&P focuser:

Otherwise, they're very similar in smoothness and resistance to tilt.

[johninderby]

Bresser had two lines of refractors. The ones with a basic focuser with plastic wheels and the better line with the all metal CNC R&P focusers. My focuser is totaly stock with the dual speed option.

 

Edited September 8, 2020 by johninderby

[Louis D]

26 minutes ago, johninderby said:

Bresser had two lines of refractors. The ones with a basic focuser with plastic wheels and the better line with the all metal CNC R&P focusers. My focuser is totaly stock with the dual speed option.

 

Excellent.  Unfortunately, neither made it to this side of the pond. 🙄

[johninderby]

Had a look and could only find the low end Bresser scopes in the US.

[Pixies]

25 minutes ago, johninderby said:

Had a look and could only find the low end Bresser scopes in the US.

I suppose they are competing with the stable-mate Explore Scientific scopes. ES imports Bresser into the US, don't they? Both are owned by the same company - JOC.

[johninderby]

No JOC is only a part owner. Bresser is jointly owned by Mr. Rolf Bresser,  Jinghua Optical + Electronics Co. Ltd. and Helmut Ebbert.

Shares:

Mr Rolf Bresser - 40%

Jinghua Optical + Electronics  - 40%

Helmut Ebbert. - 20%

 

Edited September 8, 2020 by johninderby

[Louis D]

Probably would make for an interesting discussion in the lounge as to why Bresser and TS-Optics don't market their wares more in the US.

[johninderby]

Think Bresser’s arrangements with Meade and Explore Scientific doesn’t let them compete in the US market and TS is a German telescope dealer so would need to set up a US distrubution centre to compete in the US narket so might not be worth it to them? 🤔

[Ricochet]

Some of the Bresser Messier line is sold in the US as Explore Scientific First Light. Unfortunately, there are only a few OTA-only options and looking at the images, it appears that which focuser you get depends on which mount you buy the telescope with. In fact, in the 102mm Refractor listing, even the telescope changes from the f10 to f6 version with one of the mounts.