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Doug Kerr
11-May-2007, 09:29
We sometimes encounter cameras shutters that allow us to set the camera exposure in terms of exposure value (Ev), a quantity that reflects the joint effect on exposure of shutter speed and aperture. An example is the Prontor SVS shutter often found on Graflex Century Graphic cameras with the Graflar 101 mm lens.

I have just posted to my technical information site, the Pumpkin, a new tutorial article, "Setting Camera Exposure in Terms of Ev", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#SettingEv

This brief (!) article explains what Ev means (and doesn't) and the significance and use of the Ev scale on camera shutters.

Ev is a part of an overall system called APEX, The Additive System of Photographic Exposure. An extensive discussion of this entire system is given in my companion article, "APEX - The Additive System of Photographic Exposure", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#APEX

Diane Maher
11-May-2007, 10:47
Thanks for letting us know about the articles.

RDKirk
11-May-2007, 11:18
Doug, old man, glad you're still writing.

Dave_B
11-May-2007, 19:11
Doug:
As always, good work. I learned a lot. As a fellow nerd, your web site is a joy to read. On another subject, you wrote in an earlier article about Graflok backs. You talk about them being a standard. However, I have two versions of Graflok backs that are different. One is from new Toyo 45CF. The distance between the arms that catch the pins on the body of the camera is ~146mm. The distance between the same arms on a Graflok back from a Crown Graphic camera from the early fifties is ~129mm. Are there various versions of Graflok backs or have I missed something? Thank you in advance for your help.
Dave B.

RDKirk
12-May-2007, 07:00
Dave,

There is a lot of presumed commonality between back accessories for Toyo and Horseman. Can you tell if that difference would affect how film plane devices and outer accessories attach to the Toyo versus conventional devices?

al olson
12-May-2007, 11:03
Doug, some additional history on the EVS.

Initially EVS was called LVS (Light Value System) when Kodak introduced it on the Retina IIIc 35mm cameras. It was later called EVS, but the exposure settings are identical.

My Retina was purchased in 1955, but I believe the camera was introduced perhaps a year earlier. The camera was made in Germany. The lens is a Schneider Xenon and the shutter is a Syncnro Compur. Kodak later improved on the light meter and called it the Retina IIIC (big 'C').

My camera has a built-in light meter with a needle-match that results in a reading of the LVS value. The LVS values were engraved on the shutter speed ring (opposite the engraved shutter speeds) where the coupling lever is set into the knurled notch. The notches allow the setting the coupler to be set to the nearest half LV.

As in your example, this couples the shutter speed dial with the aperture dial so the desired combination can be obtained by setting them opposite an index mark.

I loved the convenience of this design. The camera is compact -- The lens retracts into the camera, but very heavy for carrying in the pocket. The Schneider Xenon is an excellent lens, the between-the-lens shutter is quiet, and the meter is accurate. I still use this camera today.

I agree with your observation that it was innovative for its time but technology eventually made it obsolete. However, my Sekonic light meter still provides exposures in EVS. Certainly, the 'EV' term is more precise when discussing exposure compensation, rather than using 'stop' which refers to aperture rather than shutter speed.

Doug Kerr
12-May-2007, 15:15
Hi, Dave,


Doug:
As always, good work. I learned a lot. As a fellow nerd, your web site is a joy to read. On another subject, you wrote in an earlier article about Graflok backs. You talk about them being a standard. However, I have two versions of Graflok backs that are different.

I think I didn't make this sufficiently clear, but what is standard among the "international standard" backs is (a) the interface between the focusing plate and the "back foundation" (my term) for a standard film holder and (b) the interface by which an "accessory" (such as a roll film holder) goes onto the back foundation once the focusing plate has been removed.

The way the focusing plate is held on varies considerably between manufacturers, and that is considered a proprietary interface. (Thus, focusing plates are not necessarily interchangeable.)

My apology for lack of clarity in that regard (a matter that I only came to understand recently myself!).

Best regards,

Doug

Doug Kerr
12-May-2007, 15:21
Hi, Al,

Thanks so much for the additional info. Finding out just how this all came about has been very difficult.

I already have a second edition in the works whose current draft introduces Light Value as practiced in the early Polaroid Land cameras (95, 95A, 80). I'll incorporate the scoop you just sent me as well.

I also include a picture of my new Prontor SVS with EV coupling.

It should be released within a couple of days.

Thanks again so much for helping with this project.

Best regards,

Doug

Doug Kerr
12-May-2007, 16:17
Hi, Al,

In the Polaroid system of setting exposure in terms of Light Value, LV=Ev-9. That is, LV 2 corresponds to Ev 11.

Is that consistent with what Kodak used on your cammie?

(Recall than 1 sec and f/1.0 gives Ev 0, and the Ev goes up by one unit for each "stop" of decrease in exposure.)

Thanks.

Best regards,

Doug

Dave_B
12-May-2007, 17:19
Doug:
Thank you for the information. It now makes perfect sense (thanks to your explanation).
Best wishes,
Dave B.

al olson
12-May-2007, 21:00
Hi Doug,

I am not at all familiar with the LVS that was used by Polaroid. The scale used by my Retina IIIc goes from light value 2 to 18. An LV of 2 gives an exposure of 1 second at f/2. An LV of 18 sets the exposure to f/22 at 1/500 sec.

An internet search verifies that this camera was introduced in 1954 and produced until 1957 when it was superceded by the big 'C' version, produced until 1960. The following URL will give you a descriptive page from one of the manuals that is slightly more recent than mine:
http://intranet.beaufort.gloucs.sch.uk/~prv/Manuals/retina%203c/pages/kodak_retina_iiic_page5.html
This page from the manual provides instructions for setting the light value scale.

The following site refers to the Retina IIIC (big 'C' as opposed to the little 'c' version) as using the Exposure Value System:
http://elekm.net/pages/cameras/retinaiiic-big.htm
1957 may be when the terminology was changed from LVS to EVS. ???

[As an interesting sidelight, the Type 117 Retina, introduced in 1934, was the first camera to use the Type 135 film cassette. It was due to the popularity of the Retina that Kodak made Type 135 a standard.]

There are still thousands of these cameras around and if they are in good condition they will sell used for several hundred dollars. If you do a search on Kodak Retina or Kodak Retina IIIc and you will find a more complete history of the Retina series.

Until I read your paper I was unaware that this concept had been carried over to the Graflex lenses. I have never seen one with EVS. However, considering the close relationship between Kodak and Graflex it does not surprise me. Based on your paper, it appears that sometime between 1954 and 1958 the concept had become more formalized.

I hope this information is useful.

Doug Kerr
13-May-2007, 05:59
Hi, Al,

Some research last night on the Kodak Retina cameras indicates to me that the setting system used on various of the Retina models was in fact based on the bona fide Ev scale (which I should have guessed from your description of its onset in that camera.)

The research was largely motivated by the fact that a friend gave me last night (at the party celebrating his election to the Dallas City Council!) a lovely Kodak Retina I (Type 010). It is equipped with a Schneider-Kreuznach Retina-Xenar f/3.5 5 cm (50 mm) lens in a Compur-Rapid shutter (size 00). It is in exquisite condition, and comes in an original leather case in quite nice condition.

Of course the 010 (whose era is said to be 1945-1949) did not have Ev or LV exposure setting.

Best regards,

Doug

Doug Kerr
13-May-2007, 06:11
Hi, Al,

I sent my note this morning before seeing yours!

Thanks for the additional information and the links. It is very helpful.

The "LV" scale on your " III little c" is in fact the bona fide Ev scale.

Thanks again for all your help in this area (which of course takes on new signficance due to my new acquisition).

Best regards,

Doug

al olson
13-May-2007, 12:33
Doug,

I think there is a lot more history here than I first realized. Didn't Kodak make a lot of lenses for Graflex? Perhaps someone can help me out. Was the Graflar shown in Doug's paper made by Kodak? Perhaps that would explain the use of EVS on a large format lens.

An interesting question would be: Who holds the patent on this exposure system? AFIK, it does not occur on many other lenses. Polaroid shifted the scale. Was this to avoid patent issues? Or did they make some sort of deal?

Now days people who write reviews of the old Retinas scoff at this system for being awkward. However, it was strides better than anything else we had until the automatic exposure that came many years later. The nice feature is that it's very easy to select either the desired aperture or the shutter speed with the coupled aperture/shutter changing in parallel -- just like programed exposure on the automatics.

Doug Kerr
14-May-2007, 07:50
Al,

On your Retina IIIc, is the LV scale actually marked "LV"?

Thanks.

Best regards,

Doug

Doug Kerr
14-May-2007, 08:01
Hi, Al,


Until I read your paper I was unaware that this concept had been carried over to the Graflex lenses.

Here is the Prontor SVS size 3 on my new Century Graphic (c. 1964). It is annotated (it will appear in Issue 2 of the article on setting expsure by Ev) and the base picture is a bit low in resolution (it was extracted from the seller's picture on Not Sotheby's - I'll take one here today now that the camera is here).

http://images.dak.home.att.net/cameras/Prontor_SVS_01-2A1.jpg

Best regards,

Doug

al olson
14-May-2007, 10:01
Actually, Doug, the lens mount on your Graflar lens looks stunningly similar to the lens mount on my IIIc as can be noted in the image shown on the right at:
http://intranet.beaufort.gloucs.sch.uk/~prv/Manuals/retina%203c/pages/kodak_retina_iiic_page5.html
...except for the fact that the light value scale is engraved in reverse order as is the shutter scale.

This link to the same web site brings up a thumbnail index of all of the pages of the user manual.
http://intranet.beaufort.gloucs.sch.uk/~prv/Manuals/retina%203c/kodak_retina_iiic_index.html

To answer your question there is nothing engraved on the camera that denotes the scale as being LVS, only from the user manual is it referred to as "light values". However, in past searches for Retina information/history I have seen the IIIc cameras referenced as having the "Light Value System". Apparently this terminology changed to "Exposure Value System" in 1957 when the IIIC version was introduced with the larger viewfinder and a different exposure meter.

Of the folding Retinas, the LVS/EVS was only used on the unmetered IIc and the metered IIIc/IIIC series. The II series had a f/2.8 lens and the III had a f/2. The II and III had rangefinders. On the following web site, the author mentions LVS and EVS in the "Shutter Assembly" section about the IIc.
http://www.dantestella.com/technical/retina.html

But Kodak apparently used the LVS terminology for the nonfolding s-series rangefinder cameras (1959-1960), at least according to this web site:
http://www.cameraquest.com/ret3s.htm
[Also note the comment that the author finds using LVS to be a pain. You can tell that he is not from the pre-AE generation.]

When Kodak introduced the Retina Reflex line (ca. 1958), replacing the rangefinder line, they apparently dropped the use of EVS on the reflexes. By the early 70s, German reflex production could not compete with the Japanese and Kodak gave up production.

As I recall from the reviews in Popular Photography, Modern Photography, et al, back in 1954-1955, this system was being touted as the future way to go in photography. This was one of the selling points when I purchased my camera, as well as having the light meter in the camera (I had never been able to justify the cost of a light meter before) and the f/2 lens.

It is curious as to why it never caught on with most of the other manufacturers. This is why I believe that patents were involved and they were not willing to pay the royalties. It is a shame that this system was not more widely accepted.

I have been learning a lot from this discussion.

Vaughn
14-May-2007, 10:39
Am I correct in assuming this is the same system my first TLR Rolleiflex had? (f3.5, ser no 1712201).

The back of the camera has a chart with pictures (of dofferent types of scenes) with corresponding EV numbers, with corrections for time-of-day and cloud conditions. One's chosen EV could then be set on the wheel on the front and locked in.

I prefer working with the "EV" values on my Luna pro and the numbers on my Pentax Didital Spot. The last thing I do is determining the actual F/stop and shutter speed.

al olson
14-May-2007, 19:58
Vaughn,

I am not aware of anything about EVS on the TLR Rolleiflex, but it sounds like the same system. My Sekonic also reads in EVS and these values are the same as the LVS for setting exposure on my Retina.

Do you have any idea when your Rolleiflex was manufactured? I would guess that it was between 1954 and 1960. Some of the press photographers I worked with in the 1959-1961 time period were using Rolleiflexes, but I don't recall that they had EVS. Convincing the editors that they were just as good as a Speed or Crown Graphic was a very hard sell, but they succeeded and the TLRs became more popular for press photography.

Doug Kerr
14-May-2007, 21:36
Hi, Al,

Thanks so much for the wealth of information.

Actually, it looks from pictures I have seen as if the LV/Ev systems were also used on the Retina Ib/IB (IB was metered but with no rangefinder!).

This is an early Retina 1b (type 018):

http://www.wctatel.net/web/crye/ret018.jpg

This is a Retina 1B (type 019):

http://www.wctatel.net/web/crye/ret019.jpg

[The later Ib (type 010/0) also has a meter and looked like that.]

I assume the stuff at the bottom of the shutter is the LV/Ev indicator/setting lever.

Here is another picture of that area on a IB (019):

http://captjack.exaktaphile.com/Retina/RetinaIBbig-4.jpg

Great stuff! I didn't know anything about the Retina line until just before midnight this past Saturday!

Thanks again so much.

Best regards,

Doug

Helen Bach
15-May-2007, 05:14
"1957 may be when the terminology was changed from LVS to EVS. ???"

A 1957 article in US Camera about the Aires, Olympus, Ricoh and Konica cameras that used the Seikosha shutter with EV markings refers to 'light value system also known as the exposure value system'.

Best,
Helen

al olson
15-May-2007, 06:30
"1957 may be when the terminology was changed from LVS to EVS. ???"

A 1957 article in US Camera about the Aires, Olympus, Ricoh and Konica cameras that used the Seikosha shutter with EV markings refers to 'light value system also known as the exposure value system'.

Best,
Helen

Helen, it looks like there were more manufacturers using the LVS/EVS than I was aware of. Vaughn's Rolleiflex adds to the list as well.

It would be interesting to know how many different brands of LF lenses were also using LVS/EVS.

Doug, I didn't realize that the I-series was still in production after the III-series came out. The body of the IB is almost identical to my IIIc, except for the different light meter and the positioning of the range finder (if, indeed, the two windows very close to gether are for the rangefinder--non of the prior I-series had rangefinders).

In 1954 the lens door on the Retinas was changed from a squarish design to a rounded door, the film advance lever was put on the bottom of the camera, apparently the LV scale was added to the shutter ring on all models at this time as well (I haven't noted any images of post-1954 models without it).

Did a little more internet research and I found that apparently, the Ia-series had the f/2.8 or f/3.5 non-interchangable lens; the I(b/B)-series had the f/2.8 non-interchangable lens; the II(c/C)-series had the f/2.8 interchangable lens but no light meter; and the III-series had the f/2 interchangeable lens. The IIa was f/2 non-interchangable.

This site gives a lot more information on a long list of various models including some production numbers:
http://www.wctatel.net/web/crye/retina.htm