Baader mystery eye piece

[25585]

I won & bought an advertised & photographed Baader Eudiascopic 25mm ep on ebay. 

But I have been sent, as in photos below, a Baader 25mm Symmetrical/Diascope Edition. 

Is this a re-labelled Eudiascopic? It is 31.7mm fit, has decent eye relief and Made in Japan on its winged eye cup. 

Looks similar to the Baader 25mm ADPS Symmetrical Projection Plossl. 

[michael.h.f.wilkinson]

There are older "achromatic symmetric" EPs out there. I had a 9mm 0.965" fit version years back. Maybe it is a similar design. These are usually two identical doublets with the convex sides facing each other. Like Plossls, they have an eye relief roughly 75-80% of focal length, or some 18-20mm for a 25mm. Should be comfortable. Bottom line: I don't care about the optical design, as long as the image is good

[25585]

TV Plossls according to some CN posters are symmetrical. Plossl sounds better for sales I guess. 

Microglobe.com has both the S/D & ADPS models, latter "original Siberian symmetrical from Russian production". So confusing..

I wanted an Eudiascopic for parfocality with my 30 & 35 Eudies. Annoyed with the ebay seller for sending me this, fine optically though it may be.  

Eye relief on the 25 is as you say, about 20mm, akin to Vixen LV, perhaps a little better. 

Researching deeper, this is the budget equivalent of Zeiss' own ep for their Diascope spotters. Might be great for astro, possibly better than an Eudiascopic as made for Zeiss scopes. Bino viewing size & eye comfort. Hopefully field curvature will be small or absent. 

[BillP]

1 hour ago, 25585 said:

TV Plossls according to some CN posters are symmetrical. Plossl sounds better for sales I guess.

The TV Patent shows it as a symmetrical and refers to it as "Plossl-like".  I've taken many apart over the years and indeed they are simple symmetricals with two identical doublets with convex surfaces facing each other.  The very first smooth sided ones were the more typical symmetrical prescription with plano outward facing surfaces, after those the next runs of the smoothies had the patent prescription with the concave outward facing surfaces.

In the photo, the first run smoothies on the left had the plano instead of concave surfaces.  These had a characteristic very pronounced bevel on the housing.  I call them the Big-Bevels.  The subsequent runs which had the infamous circle-NJ optical mark, were the patent prescription with the concave lens surfaces to better control astigmatism in the off-axis (at the cost of shortening the ER some I think).

 

[25585]

Thanks BillP. I do not have a TV 26mm to compare with my Baader, but do have a 32 as nearest FL. Not much eye relief difference between both

The Baader Symmetrical would not be a Eudiascopic design then, as they were "pseudo"-Masuyama? It does have a big flat-ish eye lens compared to my Celestron/Vixen silvertop & even TV 32 Plossls. 

[Louis D]

2 hours ago, 25585 said:

Annoyed with the ebay seller for sending me this, fine optically though it may be.

File a complaint with ebay under the category of "item not as described".  It should be easy enough to provide photos of what was delivered not matching either the description or auction photos.  ebay will generally favor the buyer.  Don't be conned into paying shipping either direction on an obvious bait and switch.  Escalate with your credit card company if ebay doesn't provide satisfaction.

[25585]

I have left suitable feedback & messaged the seller in case he made a mistake. Waiting...

[Louis D]

1 hour ago, 25585 said:

I have left suitable feedback & messaged the seller in case he made a mistake. Waiting...

Generally, you need to file a complaint before leaving feedback either way.  Feedback won't generally elicit any reaction from a seller because it can't be reversed once given.

[John]

Take the rubber eyecup and the sticker off and you have an eyepiece that looks rather like the original TAL 25mm plossl:

Nice eyepieces but not a Baader Eudiascopic.

Edit: Alternatively (but maybe still the same optics as above as well) one of these with the diascope adapter missing / removed:

http://www.microglobe.co.uk/baader-25mm-symmetric-wide-angle-diascope-eyepiece-p-14295.html

 

[25585]

2 hours ago, John said:

Take the rubber eyecup and the sticker off and you have an eyepiece that looks rather like the original TAL 25mm plossl:

Nice eyepieces but not a Baader Eudiascopic.

Edit: Alternatively (but maybe still the same optics as above as well) one of these with the diascope adapter missing / removed:

http://www.microglobe.co.uk/baader-25mm-symmetric-wide-angle-diascope-eyepiece-p-14295.html

 

This 'Baader' looks same as the TAL http://www.microglobe.co.uk/baader-25mm-adps-symmetrical-projection-eyepiece-p-15259.html

The ADPS Projection Eyepiece is the original Siberia Symmetrical Eyepiece with 25mm focal length from Russian production
This eyepiece has excellent projection properties with well-suited image field.

Zeiss like them http://www.baader-planetarium.de/zeiss_diascope/E_Diascope-Eyepieces.pdf

So, would this ep actually be superior to an Eudiascopic?

[BillP]

On 4/17/2018 at 14:34, John said:

Take the rubber eyecup and the sticker off and you have an eyepiece that looks rather like the original TAL 25mm plossl:

I used to have that eyepiece.  I liked it.

[25585]

Full test soon hopefully. It has slightly better effective eye relief than my 30mm Eudiascopic. Eye lens is closer to the barrel top. 

Found official details

E_Diascope-Eyepieces.pdf

I would be interested to know if apart from TAL & Baader, the optics have been used in any other ep. 

[John]

Andy Howie took one of the TAL 25mm Gen II plossls's apart. It's a symetrical design as far as I can see but these are often labelled as plossls. I have one (of the TALs) but the barrel is just a touch too fat to fit into most of my 1.25" adaptors so it does not get much use. They were supplied as stock eyepieces with TAL scopes. A nice eyepiece to use I seem to recall.

I note that the Bresser details mention a shortened barrel - I wonder if the field stop position has been changed to enable spotting scope use ?

Here is Andy's dissection photo:

 

[25585]

8 hours ago, BillP said:

I used to have that eyepiece.  I liked it.

Thanks BillP. I read your excellent review on the CN for TAL Plossls & Super Plossls. 

 

[25585]

8 minutes ago, John said:

Andy Howie took one of the TAL 25mm Gen II plossls's apart. It's a symetrical design as far as I can see but these are often labelled as plossls. I have one (of the TALs) but the barrel is just a touch too fat to fit into most of my 1.25" adaptors so it does not get much use. They were supplied as stock eyepieces with TAL scopes. A nice eyepiece to use I seem to recall.

I note that the Bresser details mention a shortened barrel - I wonder if the field stop position has been changed to enable spotting scope use ?

Here is Andy's dissection photo:

 

That's interesting John. The stem on my ep has no lenses in it, and is male to female (lens barrel) screwed in. All optics are half way up the lens barrel. 

The fact Baader made/had made for them, an adapter for Zeiss Diascope spotting scopes, might have affected the effective focal length of the spotter I guess. That also to me suggests that it was not designed exclusively for Diascopes. 

 

[John]

There are no lenses in the chrome/silver coloured barrel with the one that Andy has taken apart or in mine either. The 4 element, 2 group optical system is entirely contained within the black upper barrel.

While good symetrical / plossl eyepieces, it is not the 5 element Eudiascopic that you thought you were buying. I don't know how much you paid but the Tal 25mm plossls can be picked up for around £25 on the used market.

 

[25585]

Paid more than £25, but less than £100! 

Mine is Baader stickered & was title as Eudiascopic. Had it been a TAL, I would have bypassed it for the starting bid price.