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Update on Mflenses adapter for Praktica PB-mount on EOS
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PostPosted: Thu Feb 26, 2009 4:27 pm    Post subject: Update on Mflenses adapter for Praktica PB-mount on EOS Reply with quote

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Price for the Praktica/PB to EOS/EF adapter:
USD40 each
Shipping: USD3
+ 3% paypal charges

This price seems a bit higher than most common adapters, but this is since the adapter is fully CNC'd to achieve the highest precision.

Note ... this adapter can achieve infinite focus.


Go out and buy the lower priced PB lenses Twisted Evil

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Some of you alreay know that i have been working on a PB to EOS adapter.

In the meantime i also found out that occasionally there are appearing some other PB-to- EOS adapters on Ebay.

I bought one of these adapters and compared this one with the one mflenses will be suplying soon.

Note that the Mflenses version is made on highly accurate CNC machines!


This is the camera body side, there is not much to see.


Note that the mflenses version is showing its brass material.
We considered to plate the internals, but since plating will add a certain thickness to the material, we decided not to do it.

The adapter has to be very very thin in order to achieve infitnite focus.

Thickness comparison
(inside of the flange)
Ebay Vendor A vs MFLenses
1.28mm 0.90mm

Difference is 0.38mm!!!!

Infinite focus
(tested using the PEntacon 135/2.Cool
Ebay Vendor A vs MFLenses
No Yes


Last edited by hk300 on Wed Mar 04, 2009 10:17 am; edited 3 times in total


PostPosted: Thu Feb 26, 2009 4:32 pm    Post subject: sample pics Reply with quote

Samples made with Pentacon 135/2.8
Subject about 200 ~ 300m

Ebay Vendor A adapter ... max distance, conclusion, cannot do infinite focus



Mflenses adapter ... can do infinite focus




sorry for the crappy pics Laughing


PostPosted: Thu Feb 26, 2009 4:49 pm    Post subject: Reply with quote

Thank you Alex! This is vital information!


PostPosted: Thu Feb 26, 2009 4:50 pm    Post subject: Reply with quote

congratulations, you did really a great work!


PostPosted: Thu Feb 26, 2009 5:11 pm    Post subject: Reply with quote

Very Happy


PostPosted: Thu Feb 26, 2009 5:13 pm    Post subject: Reply with quote

It looks good, Alex. How do you stop the lens in the position?


PostPosted: Thu Feb 26, 2009 5:17 pm    Post subject: Reply with quote

koji wrote:
It looks good, Alex. How do you stop the lens in the position?


stop ... as in how to lock the lens?
There is a hole in the adapter, in which one of the 3 PB electronic contact points will get locked. ... if you understand what i mean ... Laughing

I will try to make a pic tomorrow.


PostPosted: Thu Feb 26, 2009 5:28 pm    Post subject: Reply with quote

Ok, I got it. Something similar happens when the CZJ "electric" lens is
mounted to one of EF adapters. Very Happy


PostPosted: Thu Feb 26, 2009 6:03 pm    Post subject: Reply with quote

Great work.

When will it be possible to order?


PostPosted: Thu Feb 26, 2009 7:02 pm    Post subject: Reply with quote

Fantastic Alex


patrickh


PostPosted: Thu Feb 26, 2009 7:07 pm    Post subject: Reply with quote

Guess it would make sense to start buying some B mount lenses, Very Happy before these adapters will be know to the "common people"


PostPosted: Thu Feb 26, 2009 8:27 pm    Post subject: Reply with quote

Very good work, I have just now one with AF-chip bought.
Does the AF-chip pass the aperture stick, while lens will be mounted?

Surprised But which I am to do with the old adapters, that I purchased directly in Poland? - see www.praktica-b.org Wink


PostPosted: Thu Feb 26, 2009 9:10 pm    Post subject: Reply with quote

Torsten wrote:
Very good work, I have just now one with AF-chip bought.
Does the AF-chip pass the aperture stick, while lens will be mounted?

Surprised But which I am to do with the old adapters, that I purchased directly in Poland? - see www.praktica-b.org Wink


Welcome Torsten!


PostPosted: Fri Feb 27, 2009 2:09 am    Post subject: Reply with quote

Torsten wrote:


Surprised But which I am to do with the old adapters, that I purchased directly in Poland? - see www.praktica-b.org Wink


Try to sell it asap! Smile

BTW ... your Polish adapter ... can it do infinite focus?


PostPosted: Fri Feb 27, 2009 7:31 am    Post subject: Reply with quote

koji wrote:
It looks good, Alex. How do you stop the lens in the position?




do you see the locking pin?


PostPosted: Fri Feb 27, 2009 7:33 am    Post subject: Reply with quote

koji wrote:
Ok, I got it. Something similar happens when the CZJ "electric" lens is
mounted to one of EF adapters. Very Happy


Yes ... i had that problem when using the CZJ 20 /2.8 ... it has 3 ... THREE ... pins ... and the M42 adapter had holes exactly at those positions ...

It took me a lot of effort to remove the adapter Embarassed


PostPosted: Fri Feb 27, 2009 10:43 am    Post subject: Polish Adapter to thick Reply with quote

> BTW ... your Polish adapter ... can it do infinite focus

No, my polish adapter could not do that at open aperture and for that it is to expensive. Its thickness was between 0.6 and 0.65 mm.

Lens 1.4/50 and 1,8/80 could do focus up to 6...8 m.

Lens 2.8/20 was usable starting with aperture 4.

I had to use the same procedure, as Koji, in order to reach 0.45 mm. We called him but the supplier has obviously different conceptions over quality than its customers. Sad

We wrote an article about it in www.praktica-b.org - at moment in German only.


PostPosted: Fri Feb 27, 2009 3:04 pm    Post subject: Reply with quote

hk300 wrote:
...CZJ 20 /2.8 ...

So it has arrived Smile
Alex, I want the first adapter and as I will use it on the same lens as your CZJ I'm very comfortable about its performance Wink


PostPosted: Wed Mar 04, 2009 3:34 pm    Post subject: Reply with quote

Yes ... i will receive the first batch this weekend.

Prices are in the following thread.

http://forum.mflenses.com/finally-for-sale-pb-praktica-to-eos-ef-adapters-t15053.html


PostPosted: Tue Mar 10, 2009 6:52 pm    Post subject: Reply with quote

I just used one adapter with the Praktica 28/2.8 and EOS 50 (film) and I couldn't use it even at the closest focus because the rear of the lens did hit the mirror. I'm curious if you tested the adapter with that kind of lens as I suppose it's a lens problem with protuding back than no adapter could solve... but I hope in miracles Very Happy


PostPosted: Tue Mar 10, 2009 9:53 pm    Post subject: full format mirror Reply with quote

The minimum distance of mirror from the bayonet is about 16 mm at bottom and 9 mm at top in the original Praktica BX cameras.

At the back end of lens is a ring from plastic, that is mounted with two screws. The distance is 8 mm (9 mm near aperture stick) from bayonet inside the camera.

I heard that one must remove this ring and aperture stick from the lens with FF EOS cameras. The aperture stick ist mounted with two screws. Mark the position of stick on the aperture mechanism before you remove it, if you want to fit it later.