Re: Lens question please_Gundlach, Turner-Reich series II No. 1

"____" <internetphobic@[EMAIL PROTECTED]
> wrote in message 
news:internetphobic-4F68B9.19084014022008@[EMAIL PROTECTED]
> In article <13r8viujmvit6e0@[EMAIL PROTECTED]
>, <jjs> 
> wrote:
>
>> "AAvK" <notforspam@[EMAIL PROTECTED]
> wrote in message
>> news:L1djj.926$Ca7.438@[EMAIL PROTECTED]
>>
>> > What about for mono films?  I think because of this 
>> > problem I
>> > would never use this lens for color films!
>>
>> I took it that Richard was addressing B&W. If aberation 
>> occurs in a
>> particular color for which the film is sensitive, a 
>> correcting filter will
>> help.
>>
>> Black & White film is sensitive to color (obviously) and 
>> not equally
>> sensitive to all colors. Filters are im****tant.
>
> In my early day of LF photography
>
> I once bought an ARTAR that was supposed to be a good lens 
> and covered
> 8x10, it sucked royally for B&W all kinds of ghosting on 
> b&w even when
> pointed 180 degrees away from the sun on a cloudy day. The 
> bastard I
> bought from extracted a 50 dollar restock fee out the 350 
> dollar check I
> bought with even after I had to pester him for about 3 
> months to refund
> my money.
>
> I can think of only one nice thing to say about him: 
> Cocks---er,  may he
> rest in pieces.
>
> -- 
    The Apo Artar is a four element air spaced lens with 
eight glass-air surfaces. It does have some flare but should 
not have bad ghost images. I have two, one a very old 
uncoated lens from the 1920's. Its very sharp and has good 
contrast. The other is from the 1960's and is coated so it 
has little flare.
    Note that while both flare and ghost images come from 
internal reflections and are helped by coating they are not 
quite the same. Most flare is in the form of an overall 
diffuse field of light all over the image while ghost images 
are fairly sharp, or at least recognizable, images in the 
image field of bright objects either in the image or just 
outside of it. Ghosting is usuallyu due to the design of the 
lens rather than just having glass-air surfaces. Both flare 
and ghosting can also be cause by reflections from the 
inside of the lens barrel or cells or from the inside of the 
shutter. I would say your experience with the Artar is 
unusual.
     The Apo Artar was designed for use on process cameras. 
These were used for making printing plates, or rather, 
negatives used to expose the photo-resists that were used to 
control the etching of the plates. Process lenses are 
designed to work best at magnifications near unity. The 
Artar is designed for three-color work where the color 
separation negatives must all be in focus and be of exactly 
the same size. Although the lens is optimized for equal 
object and image distance (unity magnification) it performs 
very well even at infinity focus if stopped down a bit.
     One cause of flare in lenses is haze but this won't 
cause ghost images. Haze seems to form on many lenses with 
time. I am not sure of the cause but the haze is easily 
removed with any lens cleaner. The problem is getting to the 
inside surfaces. Most Artars have back caps on the cells so 
that cleaning the insides is not difficult.


-- 
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@[EMAIL PROTECTED]