Siberia 50mm erfle

[markse68]

Spotted this beast on eBay from ENS the other day and couldn’t resist- another addition to my growing  “interesting eyepieces” collection 😉 I found an old thread about it on here but no opinions other than it being tricky to focus- the focal plane seems to be about 10-12mm above the barrel/nose junction so you’d need plenty of in-travel on your focuser. Anyway I’ve nothing to put it in till I sort out the 2” focuser on my dob but will update then- hoping for a nice widish view low power “finder” ep 🤞

PS it’s new old stock and they had a few if you like unusual eps

[Ruud]

It does look interesting!

Is that the field stop I can see in the bottom up view?

[markse68]

5 minutes ago, Ruud said:

It does look interesting!

Is that the field stop I can see in the bottom up view?

No it doesn’t seem to have a field stop as such Ruud so the edge of field isn’t super sharp. I just measured and the focal plane is about 15mm above the barrel/nose junction so that is really quite a lot of focuser in-travel 😳 I think I have to rethink my focuser plans...

[Stardust]

I found this eyepiece and thought it looked interesting too. The only search I could find was someone on here that couldn't get it to focus in any of his scopes, I guess for the reason you have mentioned. I would love to know how it performs and what it can successfully be used in. Does the silver barrel unscrew? My thought is to remove it and shorten, then machine down 15mm of the the knurled part to the same diameter. 

Edited September 27, 2019 by Stardust

[Kev M]

I have one of these somewhere, will dig it out and try it again...

[Stardust]

1 hour ago, Kev M said:

I have one of these somewhere, will dig it out and try it again...

please do and see what you think. Tal made some good eyepieces and wonder if this is one of them

 

[markse68]

2 hours ago, Stardust said:

My thought is to remove it and shorten, then machine down 15mm of the the knurled part to the same diameter. 

😳

I don’t think I could bring myself to do something like that but I guess if there were no other option... yes it does unscrew.

I'm still in the planning stages of my upgrade to a 2” focuser and the plans have just changed once again since I picked up a replacement focuser tube giving me over an inch extra travel so I plan to redesign the adapter mount allowing enough infocus to handle this bad boy- hope it proves to be worth it 😉

It’s really light btw- ~300g

seems to have a bit of a yellowish caste though unfortunately but might try the old Russian camera lens trick of leaving it in sunlight to see if the uv clears it

Edited September 27, 2019 by markse68

[Kev M]

Well mine comes to focus with the ED80 & diagonal with only about 20mm of inward travel left.

Unable to see quality as its dark and there are no stars ( ok can see them through cloud enough to focus on them ).

Will try and give a go again over the weekend.

 

 

[Stardust]

That sounds a good start. If you get chance to get a look at some stars I'd  be very interested in what you think and how sharp across the field it is.

[Stardust]

16 hours ago, Kev M said:

Well mine comes to focus with the ED80 & diagonal with only about 20mm of inward travel left.

Unable to see quality as its dark and there are no stars ( ok can see them through cloud enough to focus on them ).

Will try and give a go again over the weekend.

 

 

Could  you try it during the day to assess the image quality please. I think edge of field problems would show up at least.

[DaveL59]

saw that one too and was tempted for a brief moment, tho for the Tal100RS I'd need to buy a diagonal too. Given funds are tight at the mo and that likely the tal 40mm 1-1/2 EP I have would be more than enough somehow sanity took over for a change and I passed  

[Stardust]

A friend has looked at one at Kelling today but with the weather there isn't anything much set up he could look through. My TAL100RS won't accept a 2" diagonal and eyepiece.,not enough infocus. Another friend had the rear of the tube cut down which I might yet do.

 

[F15Rules]

Anyone got any further info on this ep, such as field of view, or night time testing? 

Btw, judging by the performance of Russian binoculars I have/have owned, some of which had a yellowish cast, it wasn't really an issue on the night sky, hardly noticeable..what was noticeable was the pin sharpness on axis and high contrast images, so I would hope this big Erfle would be similar..

Dave

[markse68]

Fov iirc is not huge- maybe a little more than a plossl- will check again when I get home. Am hoping for good sharpness too but need a focuser first....

[Stardust]

A reply from ens said they used one in a mak newt at jellingcand is was a good eyepiece. Not very conclusive and couldn't  find anyone else that had looked through one. Still interested to know.

[markse68]

8 hours ago, F15Rules said:

 

Anyone got any further info on this ep, such as field of view, or night time testing? 

 

Just did a comparison and the afov is about the same a a standard plossl. In pic below it’s about the same as the 32mm plossl. It’s a bit smaller than the Tal 25mm- my example of which seems to have an enlarged field stop (and consequent soft focus edges) which matches the Pentax XF ( 60deg afov) but it is a fair bit  bigger than the silly 1.25” 40mm plossl which is more like an ortho afov 🤦‍♂️ So probably the same as a 2” 55mm plossl but shorter more practical eye relief 

Mark

[Stardust]

looks good, just itching to know how it performs, if it's good they might start selling a few.

Edited October 8, 2019 by Stardust
Spelling

[Stardust]

Any views under the stars yet?

[markse68]

Not from me yet but parts for my 2” conversion being printed this week so maybe soon...ish

[Stardust]

Any progress on this eyepiece  in use yet?  I see one sold on Ebay. Be handy if it was a member here.....

[dannybgoode]

I’d be very interested to hear how this performs. Would like a nice low powered 2”-er in the box. Would be very useful. 

[markse68]

@Stardust @dannybgoode I made a new post comparing this ep to some others- 

Mark