Rodenstock Ysarex on Polaroid 110b Conversion - Lens Question

Discussion in 'Rangefinder Forum' started by Fragomeni, Jun 2, 2011.

  1. Fragomeni

    Fragomeni Subscriber

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    Hi all. I have a Polaroid 110b 4x5 conversion that I've built but the lens is doing something that I can't figure out and I'm wondering if there is something I'm missing. I get that it is designed to set exposure based on EV values but the shutter has regular aperture and shutter speed marking which should be able to be combined like with any other lens, or so I thought. I've found that when I set an exposure combination with just the aperture selection and shutter speed ring, the exposure come out a stop over exposed. However, when I set the exposure based on the EV selections the exposure comes out correct. To clarify what I'm talking about, I am a zone system user so I meter a scene, say a portrait. I determine that I want to place a highlight which reads EV 7 2/3 in zone 6. An exposure for this would be f5.6 @ 1/60 if using 3000 iso Fuji FP-3000b. This should be the correct exposure but on the 100b it comes out 1 stop over exposed. When I compare the exposures to one made at that exposure combination using a different and known lens/camera combo (this serves as a known or control) I find that in order to match it I need to change the exposure combination on the Polaroid by 1 stop i.e. instead of setting it to f5.6 @ 1/60 I set it to f5.6 @ 1/125 and the exposures will match. However, if I set the 110b to expose at the EV level determined by an incident meter reading then the exposure matches the exposure made by the control lens/camera combo determined by spot metering and zone system placement as I described above. Maybe Im just really tired but I cannot for the life of me figure out what's going on. Also, the shutter speeds on the 110b sound accurate. I don't understand where the 1 stop difference is coming from when I set an exposure combination the same way I do on any other lens. Is there something about the 100b Ysarex I need to know?

    I just re-read that and it didn't seem very clear. Sorry, I am tired. Basically what I'm saying is that in order to match exposures, for some reason I need to meter and expose with the 110b as if I were using a film 1 stop/ iso higher then it actually is. I'm wondering if anyone else is experiencing this or if it is due to some obvious reason that I've just missed. In the end it doesn't really matter to me. I'll set the meter 1 stop higher iso if I have to because then the exposures match perfectly. Anyway, I digress. Any insight?
     
  2. Rick A

    Rick A Subscriber

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    The Ysarex does have EV setting, but can be switched off and back on as you prefer. The switch is located to the right(facing lens) of the flash socket. To disengaga, depress the lever and move it away from the flash socket. To reengage, depress and move lever toward the socket. What I do is disengage EV, meter and set desired speed and aperture, then reengage the EV. Now when I change either the speed the aperture changes setting automatically, or reset the aperture, and speed changes. When you have the setting you desire, cock the shutter and fire.
     
  3. Fragomeni

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    I thought it had something to do with the EV switch as well but that doesn't seem to be it. It's not a matter of the shutter and aperture being connected or moving each other. The issue is that any shutter speed and aperture combination makes an exposure 1 stop over exposed. If my film rating is 100 iso and I make an exposure at f5.6 @ 1/60 the exposure will expose the same as if I'd set any other shutter/lens to f5.6 @ 1/30. In order to get the proper exposure I have to set my meter to 200 iso and then the exposure will match what it should be for iso 100. On the other hand, i can set the meter to the proper iso, in this case iso 100, and have it read an overall EV setting which I plug in using the EV scale on the lens and the exposure works properly. I think there is something with how the EV scale relates to the shutter speeds and aperture that I'm missing. This is blowing my mind.
     
  4. Rick A

    Rick A Subscriber

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    Are you sure the shutter speeds aren't off on the lens?
     
  5. Fragomeni

    Fragomeni Subscriber

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    Shutter speeds sound right. I'd have to bring it somewhere to actually have them checked which I may do.
     
  6. Fragomeni

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    Ok, so on my lunch break I went home and got the camera and brought it back up to work (camera store). I pulled out the shutter speed testing machine and tested the shutter speeds to verify that they aren't off. The shutter speeds are right on the money. I'm going to play with the camera. Maybe I was just exhausted last night when I was testing it. There has to be something very clear that I'm missing here. I just don't understand why standard shutter speed and aperture combinations wouldn't work on this lens if everything is accurate. I'll play with it again when I get home.
     
  7. Rick A

    Rick A Subscriber

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    I'm having a hard time following what you are doing with EV. I set my shutter at 1/60and open my aperture to max, and I cannot get EV 7 2/3rds, I get EV 10 1/2. When I set my meter for iso3000, and read 1/60@5.6 I get EV 11(incident), which coresponds with my lens EV setting of 5.6@1/60. Setting my meter for iso100, 5.6@1/60 is still EV11. Now, my question to you is how did you get EV 7 2/3?
     
  8. Fragomeni

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    No, you misunderstood what I was explaining. I was illustrating what happens with the camera. In the example I metered the highlight portion of a scene which read EV 7 2/3. Using the zone system I can place that highlight in any zone I wish. I chose to place it in zone 6. After making that choice I know what shutter speed/ aperture combinations will make an exposure with the highlight exposed for zone 6. 7 2/3 is the meter's EV reading and served only to illustrate an example, it is not what I dial in on the camera. Hope that clarifies it. Anyway, I'm home now so I'll mess with it a bit.
     
  9. Fragomeni

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    Alright, I've fully tested everything I can think of. Indeed exactly what I described above is occurring and it was not my overly tired imagination. I tested the shutter today at work and all speeds are dead on. After testing, the only thing that I can think of is that somehow something is marked wrong on the lens which doesn't make sense to me. Oh well, I'm done worrying about this. All I know is that as long as I set my meter 1 stop/ 1 iso higher then the images will work as they are supposed to. This was rather frustrating. I'll probably end up swapping out the lens for another 127mm just so I don't have to be bothered by this anomaly (which will nag at me in the back of my head because I can't explain whats going on).
     
  10. Bill Burk

    Bill Burk Subscriber

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    Are you confusing the meter needle with EV?

    When I set my Pentax analog spotmeter "Linear Value" to 6 2/3 (to place the 7 2/3 reading on Zone VI) and ASA 3000, then f/5.6 @ 1/60 is indicated.

    But the combination f/5.6 @ 1/60 is EV 11
     
  11. Fragomeni

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    AHHHHHHHHH!!!! Thats it! I knew it was something so simple that was evading me! I've always understood that the numbers indicated by the needle by the Spot Meter V are LV (Light Value) numbers but I've always referred to them as EV (as a matter of fact they even use this terminology in the original manual). I'm primarily a LF photog and my spot meter is the only one I really use so I didn't even think to take into account the difference between the Linear Scale on the Spot Meter and actual EV numbers.

    So here is the explanation of the solution to this (wow I feel silly that this went over my head and caused all of this grief):

    Using 3000 iso film, I set my meter to 3000iso and read a highlight at LV 7 2/3 (notice LV not EV, this was what I was overlooking) that I decide to place at zone 6. The shutter speed combination for LV 6 2/3 (proper exposure to render highlight at zone 6 as decided) is indeed f5.6 @ 1/60. F5.6 @ 1/60 on the 110b's EV scale is EV 11 as Bill points out. LV 6 2/3 translated to EV is EV 11! They match! I just forgot to translate the LV reading to EV! For those unfamiliar with translating LV to EV, LV=EV at iso100. When you deviate from iso 100 add or subtract the number of stops difference in iso from the LV number to get the EV number i.e. to find the EV number for an LV reading of LV 7 at iso 3000, consider that iso 3000 is 5 stops higher then iso 100 so you take the LV reading of LV 7 and add 5 to it which becomes EV 12. Simple as that.

    Thanks for your help guys! This would have driven me insane. Its always the smallest things that fly under the radar! Much appreciated!