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Prakticar 2.4/50 + EXTENSION TUBES
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PostPosted: Tue Mar 09, 2010 4:18 pm    Post subject: Prakticar 2.4/50 + EXTENSION TUBES Reply with quote

It was a great moment when one parcel arrived today - the extension tubes for Praktica B have come over here!

Very nice seller from Germany and must say BIG THANKS to him.

f-stops mostly f/4 or f/2.4 - I really don't remember .. Smile











tf


PostPosted: Tue Mar 09, 2010 4:35 pm    Post subject: Reply with quote

I cannot believe my eyes that Pr50/2.4 does perform this well.
Wow, well done. TF


PostPosted: Tue Mar 09, 2010 5:19 pm    Post subject: Reply with quote

Thanks for these images! Prakticar 50/2.4 is quite rare, so it's not easy to find an example of its performance. These are really great!

I failed to find its optical diagram, but it's very uncommon design for a 50mm lens. Front optical group has 3 separated elements and rear consists of single element. 111-1 ... could be simple ernostar, but who knows Smile


PostPosted: Tue Mar 09, 2010 5:34 pm    Post subject: Reply with quote

Hi no-x -

I think it's the Tessar-like formula ...

but I am not sure Smile

tf


PostPosted: Tue Mar 09, 2010 5:35 pm    Post subject: Reply with quote

According to some, this one is 4 element lens. But I do not know its optical
design, only made for Practicar B mount cameras I guess.


PostPosted: Tue Mar 09, 2010 6:51 pm    Post subject: Reply with quote

unusable for macro, too much distracting aberrations


PostPosted: Tue Mar 09, 2010 6:59 pm    Post subject: Reply with quote

Nice series again! Congrats!


PostPosted: Tue Mar 09, 2010 7:50 pm    Post subject: Reply with quote

Nice pictures again.

There are two cameras with this Practicar 50/2.4 to be had over German Ebay. Both go for 69 for camera and lense

Click here to see on Ebay.de

Click here to see on Ebay.de

And there are also three of them without camera to be had over Ebay GB

Thomas


PostPosted: Tue Mar 09, 2010 9:05 pm    Post subject: Reply with quote



here's some info..

tf


PostPosted: Tue Mar 09, 2010 9:55 pm    Post subject: Reply with quote

Yeah, 5 element and 4 group design looks much more realistic to me.


PostPosted: Tue Mar 09, 2010 10:00 pm    Post subject: Reply with quote

I can't prove it, but I think the info isn't correct. At least my version (metal focusing ring) seems to be 4/4, not 5/4. I can't find anything what would look like cemented doublet. Flashlight test shows six colored reflection in front group (= 3 separated elemens) and two colored reflections in rear group (= 1 element). Cemented surface would show 1 white reflection, but I can't see any...

Tessar formula should be the 50/2.8 prakticar.


PostPosted: Wed Mar 10, 2010 1:01 am    Post subject: Reply with quote

Found another vote for 4/4: http://www.praktica-collector.de/Pentacon_Prakticar_2.4_50.htm. So no Tessar-design.


PostPosted: Mon Apr 26, 2010 1:27 pm    Post subject: Reply with quote

no-X wrote:
I can't prove it, but I think the info isn't correct. At least my version (metal focusing ring) seems to be 4/4, not 5/4. I can't find anything what would look like cemented doublet. Flashlight test shows six colored reflection in front group (= 3 separated elemens) and two colored reflections in rear group (= 1 element). Cemented surface would show 1 white reflection, but I can't see any...

Tessar formula should be the 50/2.8 prakticar.


I ever suggest in some forums to use this metod to know how much elements have the lenses, but sometimes when there are cemented elements, the reflection correspond to them is very small and can't see easily.

Rino.


PostPosted: Sun Jun 13, 2010 3:32 pm    Post subject: Reply with quote

no-x is RIGHT...

I have taken the lens in a bits today and there are definitely 4 elements:

See the picture:

3 GLASSES are on the left side and 1 elements (REAR) remains in the barrel -- it wasn't necessary to take it out of the barrel:



PostPosted: Sun Jun 13, 2010 3:42 pm    Post subject: Reply with quote

Thanks Smile

Could you describe shapes of the elements (convex/concave)? Is it like this?




PostPosted: Sun Jun 13, 2010 4:57 pm    Post subject: Reply with quote

I had to take the lens in bits again, but never mind -- it's easy job

so it;s ALMOST identical except the REAR element -- the curvature on the Prakticar rear glass is in red colour..

so PRakticar 2.4/50 = definitely 4 elements



tf


PostPosted: Sun Jun 13, 2010 5:15 pm    Post subject: Reply with quote

Great! Many thanks!

So Prakticar 50/2.4 = simple Ernostar Smile


PostPosted: Thu Jun 17, 2010 9:11 pm    Post subject: Reply with quote

Great find!!!

And it is nice to know some one uses an Ernostar (type) lens today.

Thank you Trifox.


PostPosted: Thu Jun 17, 2010 11:03 pm    Post subject: Reply with quote

no problem Smile

I am facing to big problems over disassembly of Prakticar 5.6/500 (Pentacon)

all aperture blades collapsed Smile and this 'monster' really needs to be taken in bits in particular way Smile

tf


PostPosted: Fri Jun 18, 2010 12:07 am    Post subject: Reply with quote

trifox wrote:
no problem Smile

I am facing to big problems over disassembly of Prakticar 5.6/500 (Pentacon)

all aperture blades collapsed Smile and this 'monster' really needs to be taken in bits in particular way Smile

tf


That would be a big undertaking! Shocked


PostPosted: Fri Jun 18, 2010 2:54 am    Post subject: Reply with quote

SUPER results !


PostPosted: Thu Oct 07, 2010 7:56 pm    Post subject: Reply with quote

trifox wrote:
I am facing to big problems over disassembly of Prakticar 5.6/500 (Pentacon)
all aperture blades collapsed Smile and this 'monster' really needs to be taken in bits in particular way Smile


Did you succeed? I remember doing Pentacon M42 500mm and standard tools were to small so i had to find some extra parts just to open the top.

Superb results there with Prakticar!


PostPosted: Wed Mar 16, 2011 6:31 pm    Post subject: Reply with quote

trifox wrote:
I had to take the lens in bits again, but never mind -- it's easy job
...
so PRakticar 2.4/50 = definitely 4 elements


I know this is an old thread, but please -- how did you disassemble the PB 50/2.4? I ask because the focusing ring on mine is dented, and it looks as if I must remove the ring in order to pound it back into shape. But I see no points to attack! No screws, nothing that comes apart with my hand-pressure. How do I start disassembling this? Thanks!


PostPosted: Fri Mar 18, 2011 3:24 pm    Post subject: Reply with quote

great lens ! and very nice results.

Cheers
Tobias


PostPosted: Fri Mar 18, 2011 4:03 pm    Post subject: Reply with quote

Gorgeous results Shocked ....