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Post by colray on Mar 10, 2012 17:25:26 GMT -5
The lens for my new camera project.  INDUSTAR 51 210mm Image view 13x18cm Made by KOMZ 1973 |
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Post by colray on Mar 10, 2012 17:28:24 GMT -5
William Henry Fox Talbot had the "Mousetrap" camera.. mine is the "Shoebox' (test only) Taken on paper negative then digitally converted into a positive image. Ilford grade 2 enlarging paper pre-flashed 20 seconds f8 + yellow filter.   |
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Post by colray on Mar 10, 2012 17:30:05 GMT -5
I have been running test at different focal points, and for the life of me I just can't work out why this lens will not focus beyond 4 mts, I realise it was made for use in a studio camera and would never been focused on long distances i.e infinity . Has me baffled . But the good news it it looks like it should take some cracking close-ups. Very rough test image.  Paper negative 6mins f8 pre-flashed |
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mickeyobe
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Post by mickeyobe on Mar 10, 2012 18:27:32 GMT -5
I have been running test at different focal points, and for the life of me I just can't work out why this lens will not focus beyond 4 mts, I realise it was made for use in a studio camera and would never been focused on long distances i.e infinity . Has me baffled . But the good news it it looks like it should take some cracking close-ups. Very rough test image. Paper negative 6mins f8 pre-flashed Perhaps if you positioned the lens closer to the film plane. Maybe baby shoes. Anyway, you have made a unique camera that works. Congrats. Mickey |
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Post by nikonbob on Mar 10, 2012 18:32:50 GMT -5
Colin
Looks interesting and I think Mickey is on to something. I wasn't sure so I checked on the net and am pretty sure the bellows extension needed for infinity focus with a 210mm lens is 210mm. Maybe try setting your paper to lens distance at 210mm.
Bob
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daveh
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Post by daveh on Mar 10, 2012 18:33:54 GMT -5
Unfortunately, I'm not seeing any of the photos yet. The problem at our end persists. It should be good when I can see them: I wouldn't expect anything less from Colray!
Photos coming up now. Just bought grandson a pair of shoes today: didn't get a box with them, though.
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Post by colray on Mar 10, 2012 20:12:15 GMT -5
Yes at infinity focus should be 210mm at the film and you extend the bellows the image will focus closer. With this lens it will not focus on infinity. The results I'm getting are as if the lens has been reversed mounted.
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Post by nikonbob on Mar 10, 2012 20:30:59 GMT -5
Sorry, I guess I misunderstood what you were saying.
Bob
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mickeyobe
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Post by mickeyobe on Mar 10, 2012 22:24:45 GMT -5
I wonder from what point of the lens the 210mm is to be measured.
Front element? Rear element? Somewhere in between?
What if you pointed the lens at the sun and moved it back and forth until you got a sharp image on a piece of paper. That should give you the actual focal length regardless of what is marked on the lens which might have been tampered with.
Or reverse the lens and see what happens.
Mickey (Always grasping at straws.)
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Post by nikonbob on Mar 10, 2012 23:31:08 GMT -5
Does the lens look like someone may have had it apart? I know I have taken a lens apart and reassembled it with one of the elements backwards. It would not focus properly till I flipped the element right way around. The Industar appears to be a relatively simple lens with no focusing helicoil to miff up.
Bob
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Post by colray on Mar 10, 2012 23:58:09 GMT -5
Re check: this is so strange set at 210mm it is in focus at just over 4 mts .. anything in the distance is way out of focus .. move the lens back towards the film .. this should increase the focus distance ..but very little change?
Go the other way: set at 250mm the focal point is now closer that's correct.
Try flipping the lens: this should give a macro .. NO JOY...correct way or in reverse the results are both the same.
The question is pull it apart.. or make a box camera that will focus at only short distances....That is the question
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daveh
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Post by daveh on Mar 11, 2012 3:55:30 GMT -5
The question is pull it apart.. or make a box camera that will focus at only short distances....That is the question ...or try with another lens? With the exception of using a lens rather than a piece of foil with a pin-hole in it, this is the camera we used to make when young. I have ((again) somewhere) a Patterson postcard enlarger which was basically a long cardboard box with a simple lens in the middle. Dave. |
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Post by nikonbob on Mar 16, 2012 20:06:49 GMT -5
Any more news on what is causing the miss focus at infinity?
Bob
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mickeyobe
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Post by mickeyobe on Mar 16, 2012 23:51:19 GMT -5
Could this be a process lens designed for close up graphics work and not designed for distance?
Is there an infinity ∞ mark on the focusing scale?
Is there a focusing scale?
Mickey
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daveh
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Post by daveh on Mar 17, 2012 5:23:51 GMT -5
Mickey, I've been thinking about you question: "I wonder from what point of the lens the 210mm is to be measured.
Front element? Rear element? Somewhere in between?"
Older lenses seemed to have more correlation between their focal length and their actual length. Then someone started putting in moveable rear elements and the correlation was lost. Does that make sense?
I'm not sure its an answer, other than to say the more simple the lens the easier it is to find the point of measurement.
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