Program shift steps on EOS bodies

greenspun.com : LUSENET : Canon EOS FAQ forum : One Thread

I have just become aware that many EOS bodies only offer program shift in one-stop increments. Why is this?

It surprised me when I discovered it using an EOS 3, because I expected it to shift in 1/3rd stop incremements, because the metering is reported to the user in 1/3rd stops.

The reason I was surprised is that I have an EOS 5, and that reports metering in half-stop increments, and allows program shift in half-stop increments. So, why have Canon massively reduced the usefulness of program shift on the EOS 3 and also on several other bodies (EOS 1 and EOS 1V act in the same way as the 3)? Anyone know?

-- Isaac Sibson (isibson@hotmail.com), September 28, 2001

Answers

Don't know direct answer to question but will contribute this: The elan 7/7E (30/33) also supports program shift in half stop increments. At times I resort to adjusting ISO to get 1/3 stop shift.

I don't have first-hand experience with this, but I notice that custom function 6 on the EOS 3 appears to pertain to this. Evidently the default for Tv and Av is for 1 stop shifting (1/3 in other modes?).

http://www.photozone.de/EOScf.htm#3

***

-- Rod (rod.nygaard@boeing.com), September 28, 2001.


I do believe my 1V and 1N will shift the program by the f-stop increment (1/3rd, 1/2 or 1 stop) that I've programmed according to CF#6.

-- kurt heintzelman (heintzelman.1@osu.edu), September 29, 2001.

No. The CF-6 affects the settings made in Tv and Av modes, and exposure compensation. It does not affect the Program shift.

What I am talking about: In Program AE mode (P), the camera will set a metering level (ie a shutter speed and aperture combo). You can then shift this, to make shutter speed faster or slower, aperture larger or smaller. This is done by moving the main dial once the camera has decided on it's exposure level.

Now, let's say (for example), that the camera has chosen 1/60th at F4.0. On my EOS 5, if I turn the dial one click one way, it will go to 1/45th at F4.5. If I was to turn it the other way, it would go to 1/90th at F3.5. If I was to do the same thing on an EOS 3 or an EOS 1V, it would go to 1/30th at F5.6 or 1/125th at F2.8, either of which would be reached on the EOS 5 by clicking the dial in that direction a second time.

Now let us say that the lens we were using was a 50mm, and we wanted to quickly maximise DOF for available light, but not get camera- shake. Most people can hand-hold a 50mm for 1/45th without camera- shake, but 1/30th is pushing it. So, the EOS 3 or 1V user can't quickly select the "ideal" 1/45th combo, but only 1/60th and 1/30th. Of course, many people would use Tv or Av mode in such a situation. However, I use program shift a lot when I'm shooting a lot of different things, and don't wish to keep switching modes. My question is, why have Canon needlessly removed some of the functionality of program shift in their best cameras? Seems utterly stupid to me.

-- Isaac Sibson (isibson@hotmail.com), September 29, 2001.


From pg. 102 of the EOS 1V manual, regarding CF#6: "You can change the increments for the exposure setting (shutter speed and aperture) and exposure compensation (AE, AEB, flash exposure). CF-6-0: 1/3-stop exposure setting/ 1/3-stop exposure compensation; CF-6-1: 1-stop exposure setting/ 1/3-stop exposure comp.; CF-6-2: 1/2-stop exposure setting; 1/2-stop exposure comp."

-- kurt heintzelman (heintzelman.1@osu.edu), September 29, 2001.

Addendum: "Shifting the Program" can be done in Av, Tv, or P ("AE Programmed") automatic shooting modes with either the 1N or 1V, and the increment of this will be determined by the CF #6 setting, to the best of my knowledge.

-- kurt heintzelman (heintzelman.1@osu.edu), September 29, 2001.


Shifting the program is the entire point of Tv and Av modes. However, if you were actually to TEST what you're saying, you'll find that CF- 6 does not affect program shift in P mode.

Test it like I described in P mode. You will find that CF-6 makes no difference. CF 6 affects, as described in the manual, the exposure settings (ie in Tv, Av and M modes), and exposure compensation. It does NOT affect Program shift.

Kurt- Please actually TRY doing this. You will see that regardless of CF 6, program shift happens in 1 stop increments on the EOS 1 series and EOS 3.

-- Isaac Sibson (isibson@hotmail.com), September 30, 2001.


Isaac, I just checked my 1V's P mode with the 28-70/2.8, and you're indeed correct, it shifts the program in 1-stop increments in P mode. Please accept my apology. [For some time now, I have rarely used P mode, as you've probably guessed! (Except I do like P mode when spontaneously and casually shooting indoors with FLASH, in which case the program can't be shifted at all)].

Of course, P mode is the most automated and microprocessor-driven shooting mode, and I do think it has its merits, even on professional level cameras. Needless to say, P mode can be extremely effective when a photographer is suddenly faced with the unexpected, and he/she simply doesn't have time to think much beyond just pointing and shooting-- photojournalism being but one example. How many times have we seen news footage or news photos in which hoards of press photographers are holding their cameras high above their heads, shooting blindly down into a crowd, hoping to get decent shots of some prominent figure or event?

In my own amateur/hobbyist photography pursuits, I've probably resorted to P mode mostly while trying to shoot fast-moving freight or passenger trains that have evaded advanced detection by my radio scanner, and which then "sneak-up" on me while I'm trackside. This often happens while waiting for trains that are quietly descending a slope of track in hilly terrain; often right after I suppose that my chosen location is hopelessly non-productive for that day, and I've just stowed my my gear!! In these situations, when I suddenly find myself scrambling just to grab a camera and lens, the "intelligence" of P mode can really save the day. And yes, I often shift the P mode program in these nerve-racking situations, but Isaac, you've made me realize that I've never paid any real attention to the f-stop increment of the Program shift; rather, I'm usually most focused on seeing a shutter speed of at least 1/250sec. or FASTER... On the other hand, if I see that I have very high shutter speeds for one of these stealthy trains (as one example) while relying on P mode, I may elect to QUICKLY dial-in a greater chunk of depth-of-field.

Isaac, this thread of yours has led me to entirely re-consider the power and usefulness of P mode, and I thank you for this. Here's what I'm now pondering: In their envisioned applications and design of P mode and it's distinctive "Program Shift" with the higher-end EOS cameras, Canon may have reasoned that a more aggressive and definitive 1-stop increment in Program shift would be best suited and most appropriate with the situations in which professional and advanced photographers would be most likely to use P mode. This design strategy might be analogous to the "high-gain" vs. "low-gain" settings of an electronic amplifier or receiver, where-in each gain setting has their own advantages and disadvantages which must be matched with the task at-hand. Clearly, there are situations where the authority and aggressiveness of 1-stop Program shift increments will be very useful, and there are also many situations where this will not be so. At any rate, P mode is obviously but one of several automated shooting modes with higher-end EOS cameras, within a progression of automation that ranges from manual or M mode, to the intermediate levels of Av and Tv; next, to the "DEP" mode; and then on to the most automated, P mode. For the time being, these are the shooting-mode choices among the higher-end EOS cameras, and I for one don't find myself at all dissatisfied, but your opinions may vary from mine.

-- kurt heintzelman (heintzelman.1@osu.edu), September 30, 2001.


Yes, the EOS 3 P mode behavior is a strange design choice. I'm very surprised at the lack of a CF to give you 2 or 3 choices as to program shift. I rarely use P mode, so I hadn't noticed the full stop shift on the EOS 3!

All my other EOS cams--IX, A2, Elan & Elan 7E--have half stop P mode shift.

-- Puppy Face (doggieface@aol.com), September 30, 2001.


Ok...I didn't mean to seem so aggressive Kurt. My apologies for this. You have some good possible reasons there.

However, I agree that it should be on a custom function. All this would take would be a small change in the firmware of the cameras. There's obviously no reason that it is NOT possible, as the lower EOS models with half-stop metering show.

This has put me off the EOS 3 somewhat (a camera I was lent for a short while, and very much enjoyed using in almost all other respects), along with the lack of a controlled vertical grip that does not cost a fortune or weigh a ton (like the PB-E2). I am used to using P and it's shift function rather than Av or Tv mode on my EOS 5, and I'll explain why (just so you don't think I'm a brainless point and shoot user); with Program shift, I immediately get a metering value which will be usable, with the camera looking out for the reciprocal rule to some extent. I can then home in on an aperture OR a shutter speed for some particular purpose, without having to change mode in the meantime depending on which value it is I want to control. Not to say of course that there's no need for Tv and Av and M...I use them as well (well, I rarely use M), when I know I want to minimise DOF, or whatever.

-- Isaac Sibson (isibson@hotmail.com), September 30, 2001.


Isaac, you wrote, "...Ok...I didn't mean to seem so aggressive Kurt. My apologies for this..." Isaac, I don't think you've been aggressive or nasty in the least here, and as I said, I thank you for TEACHING ME! I just re-read my last post, and I don't think it was in any way hostile or haughty. You're a bright young man, Isaac, and I look forward to your continued participation at Photo.net!

-- kurt heintzelman (heintzelman.1@osu.edu), September 30, 2001.


Adendum: Isaac, I just realized that you may have taken some of my most recent comments and compliments as being sarcastic, when in fact I meant them in all sincerity.

-- kurt heintzelman (heintzelman.1@osu.edu), September 30, 2001.

Kurt-

Thanks. I wasn't taking your comments sarcastically....I've been a bit on edge lately, and been tending to jump on people a bit (lot) too much, and I felt I had done so to you.

Anyways, 'tis cool. :-).

-- Isaac Sibson (isibson@hotmail.com), October 01, 2001.


One more thought along this line occurred to me over the weekend: it may be a related fact that the P mode does not have persistent settings. As far as I know this is the case for all Canon EOS bodies.

This fits right in with the previous comments about P being a rapid shooting mode; Canon's approach seems to be that the main intended use of P is to capture a shooting opportunity quickly, finger never leaving the shutter release. This goes right along with the thought advanced earlier that the P mode would have a high gain for quick shutter speed / aperture adjustments.

It does sorta make sense. ***

-- Rod (rod.nygaard@boeing.com), October 09, 2001.


Moderation questions? read the FAQ