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clarnibass2
Joined: 11 Jul 2018 Posts: 6
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Posted: Tue Nov 13, 2018 6:47 am Post subject: Red line on Zenzanon lens |
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clarnibass2 wrote:
Hi
I'm trying to find out what is the red line on this Zenzanon lens https://thumbs.worthpoint.com/zoom/images4/1/1215/16/bronica-zenzanon-ps-50mm-3-lens-sq-sq_1_bfe4f9fd22f2815edea87e20be0a6507.jpg
I mean the vertical line just slightly to the right of left f/8 line in the focus distance scale (not sure abotu the exact terms in English). I tried to find in some manual but couldn't find a lens that has that line and also a manual available online (that I could find at least).
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luisalegria
Joined: 07 Mar 2008 Posts: 6602 Location: San Francisco, USA
Expire: 2018-01-18
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Posted: Tue Nov 13, 2018 7:04 am Post subject: |
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luisalegria wrote:
Infrared infinity mark.
IR infinity varies from visible light infinity. _________________ I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work. |
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kypfer
Joined: 27 Sep 2017 Posts: 523 Location: Jersey C.I.
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Posted: Tue Nov 13, 2018 8:03 am Post subject: |
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kypfer wrote:
luisalegria wrote: |
Infrared infinity mark.
IR infinity varies from visible light infinity. |
Not quite ... it's the i/r focus reference point. Basically, you focus the lens "as normal", make a note of the focussed distance on the lens, then move the focus ring until this noted distance aligns with the red mark. Then fit your filter and make your exposure ... it's not an intuitively fast process |
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SkedAddled
Joined: 19 Oct 2008 Posts: 1437 Location: Michigan, USA
Expire: 2021-08-12
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Posted: Tue Nov 13, 2018 11:32 pm Post subject: |
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SkedAddled wrote:
kypfer wrote: |
luisalegria wrote: |
Infrared infinity mark.
IR infinity varies from visible light infinity. |
Not quite ... it's the i/r focus reference point. Basically, you focus the lens "as normal", make a note of the focussed distance on the lens, then move the focus ring until this noted distance aligns with the red mark. Then fit your filter and make your exposure ... it's not an intuitively fast process |
That's something I've never read or heard about, and fascinating to me.
Not intuitive, to be sure. _________________ Craig
Of course I'm all right! Why? What have you heard!?
Canon Digital EOS 5D Mk IV, EOS 50D, Powershot S3 iS
Vivitar 28 f/2.8 OM - Zuiko 50 f/1.8 OM - Tamron SP 28-80 f/3.5 AD2[Favorite!] - Hanimar 135 f/3.5 M42 - Soligor 135 f/2.8 T4 - Tamron SP 60-300 f/3.8 AD2 - Soligor 75-260 f/4.5 M42 - Soligor 400 f/6.3 T4 - Soligor 500 f/8 T2 Cat + Matched 2X TC - Addiction Growing!
This is us -- We drive these -- We're named these |
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clarnibass2
Joined: 11 Jul 2018 Posts: 6
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Posted: Mon Nov 19, 2018 5:00 am Post subject: |
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clarnibass2 wrote:
Thank you.
So here's a follow up question...
This was a "riddle" someone asked. I'm guessing out of everyone he asked, I'm most likely to ask on an online forum. Some of the others would probably only google "lens red line" and other similar things. This is what I did at first (a bit more than just that) and couldn't find anything.
Then I tried to come up with other ideas, like trying to find manuals for those lenses (he had 50mm and 80mm Zenanon lenses if I remember) and couldn't. I then tried to find a lens that has that red line and a manual available online, but couldn't. I did find some lenses with lines in different colours (e.g. some Nikon MF lenses), but being colourblind I couldn't really tell, since it was very different (not a single red line among the other lines).
So... if there wasn't an online forum like this, how would I be able to find out what it was?
Thanks again |
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kypfer
Joined: 27 Sep 2017 Posts: 523 Location: Jersey C.I.
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Posted: Mon Nov 19, 2018 7:56 am Post subject: |
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kypfer wrote:
clarnibass2 wrote: |
Thank you.
So... if there wasn't an online forum like this, how would I be able to find out what it was?
Thanks again |
RTFM ... details like this were usually documented in the user manuals of the day, else any publication on the use and application of infra-red film would have probably detailed it. It's something I've "always known", so it must have been written down somewhere relevant !
I do still have some "proper" books, possibly even the data sheet from one or more packs of infra-red film squirrelled away somewhere ... if I get enthusiastic I'll have a dig about one evening |
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