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looking for lens info


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#1 Shane Kelly

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Posted 19 January 2007 - 05:13 PM

Maybe Oleg can help me. I'm looking for info on an Ekran 25-80mm t3 russian zoom. Anyone have one or resolution specs on one?
Thanks,
Shane.
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#2 Shane Kelly

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Posted 19 January 2007 - 05:41 PM

meant to say maybe Olexandr can help me.
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#3 Olex Kalynychenko

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Posted 20 January 2007 - 10:06 AM

Maybe Oleg can help me. I'm looking for info on an Ekran 25-80mm t3 russian zoom. Anyone have one or resolution specs on one?
Thanks,
Shane.


Need full name of lens.


But, i think, you mean of
35 OPF-29-1 25-80 mm F3.0
This is compact zoom lens from last series of design of russian lenses, have very good optical quality, small size and weight.

The technical charatceristics:

25-80 mm F3.0 / T3.3
angles - 47'23"-10'57"
size of image 16x 21.95 mm
rear optical distance - 50 mm ( from laste gless up to film )
Phtographic resolution on film ( KN-2 ) at centre 70 lines per mm, on corners ( 12.5 mm from centre ) 25 lines per mm.
The macimum diameter of body 74 mm,
The length of lens 154 mm.
The length of optical block 143 mm
Weight 0.85 kg.


This is lens had special version with rear externder 1.4x.
The zoom lens with 1.4 x extender had zoom 35-112 mm F4.2/T4.5
The photographic resolution on film ( KN-2 ) 70-55 lines per mm at centre and 15 lines per mm on corners

The lens had special version with rear anamoprhic adapter ( 35 OPF-29-1A ).
The zoom lens with anamoprhic adapter had zoom 50-160 mm F4.2/T4.6
The photographic resolution on film ( KN-2) 60 lines per mm at centre, 25 lines per mm on conrers ( 11 mm from centre ).

If you need view of lens, diagrams of optical blocks or other, send me request on e-mail olex@a-teleport.com
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#4 Shane Kelly

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Posted 20 January 2007 - 10:23 AM

Olex,
you are correct it's the 35OPF29-1/3. 25-80 T-stop - f/3.5. It looks to have pretty good resolution in the center but it falls off a lot compared to the ecran primes. I assume this is common to all zooms? Thanks for the information.
Shane.
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#5 Olex Kalynychenko

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Posted 20 January 2007 - 12:28 PM

Olex,
you are correct it's the 35OPF29-1/3. 25-80 T-stop - f/3.5. It looks to have pretty good resolution in the center but it falls off a lot compared to the ecran primes. I assume this is common to all zooms? Thanks for the information.
Shane.


I have other idea.
The designer will need create of modern alternative of Foton zoom lens ( 37-140 mm ).
Will need small size and compact lens, That's why, tyhe OPF-29 have not too high speed and a some lost resolution on corners.
Any case, OPF-29 have very high optical characteristics for small size 3x zoom lenses.

From other side, the all zoom lenses lost resolution from contral point up to corners with a some high volume from prime lenses.

If you not limited of size and weight of lens you can check information about more big size of lenses :

6 x 35 OPF-18-1 20-120 mm F2.5/T3.5 resolution :centre 75-50, corners 20-30
10x 35 OPF-15-1 25-250 mm F3.2/T4.2 resolution: centre 55-35, corners 20-15


4x 35 OPF 9-1 25-100 mm F3.2
4x 35 OPF-16- 1 25-100 mm F3.2/T4.2 resolution: centre 70-50

And other.
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