CANON EOS FAQ Version 2.4
Date: November 1993

All original material is Copyright © 1992, 1993, 1994, 1995 Alvin Chia-Hua Shih and Robert M. Atkins.

9. Miscellany:

  1. Can I get warranty service, even if I didn't buy it in this country?
  2. It is the policy of Canon USA and Canon Canada to honor the warranty of any Canon product regardless of how it is purchased. However, this may be subject to parts availability. That is, parts may not be available for items that are not normally available in the USA or Canada (for example, the EOS 10 QD). Call Canon to confirm warranty service on esoteric items. (see section 9.21)


  3. How do I leave the film leader out?
  4. Some EOS bodies have a custom function which leaves the film leader out after rewinding. For those of you without access to such a custom function, find a film-leader retrieval tool [see section 9.3].


    If you are quick, and feeling lucky, you can try to pop open the camera back just after the frame counter has gone past "1" during the rewind process, but before the film has been wound fully into the film cassette. This requires good judgement. At best you will get what you want. If you are a little slow the leader will have already wound back into the cassette, or worse if you are a little too quick you will fog the first frame or so. The technique is actually quite easy, but practice on a roll of old film first just to get the feel of the timing required. On an Elan you should wait for about 1 second after the frame counter has reached "1". Note that there is the possibility of the film leader coming to rest in the region of the shutter. It's just possible this might cause a problem since the shutter is very fragile. If you get the timing right, this won't happen!


  5. Where do I get a film leader retrieval tool?
  6. You'll probably be more likely to find one at a store which also handles darkroom equipment, since some people like to wind their film out of the cassette onto the developing reel (rather than prying the cassette open in the dark). Note that too much film handling does risk scratching the negative, or even accidentally exposing some film. So I try to avoid it for anything critical. For the few times you'll use it, I don't think it's something to worry over. Film is relatively cheap compared to the anguish of messing up a good shot...


  7. How do I get exposures longer than 30 seconds?
  8. The EOS-1 can have longer exposures with the Command Back E1 and 600-series can do it with the Technical Back E. Otherwise, use Bulb mode.


  9. What's a Technical Back E?
  10. Here is some information on the capabilities of the Technical Back E (TB-E). Much, but not all, of the information comes from "How to Select and Use Canon EOS SLR Cameras" by Carl Shipman, (C)1989. The information is not taken verbatim, and the editorial comments are mine, but I'm attributing anyway (just to be safe).

    The Technical Back E is designed to be used with the EOS 620, 630 and 650. It has a sizable LCD panel which is organized with one line of 14 character cells, a "dead zone", and 3 more lines of 14 character cells. Each character cell appears to be 7x12 pixels. It has 9 buttons under an all-too-familiar 600-series type door, but longer of course. The buttons are labeled (left-to-right): Menu, Submenu, On/Off, Set, Left/Select, Right, Up, Down, Start/Stop/Clear.

    Technical Back E Capabilities:

    Notes: Memorize 4 notes of 30 characters

    Imprint: Imprint up to 3 of the following: date, time, shutter and aperture ,exposure mode, film counter, or a note

    Data Storage:

    Custom Program Curves:

    Automatic Exposure Bracketing:

    Exposure Timer:

    Imprint Data Correction:


    Keyboard Unit E:

    Interface Unit TB:

    The TB-E predates the 430EZ, so there is no control over flash exposure compensation. (Indeed, it doesn't seem to have any flash control at all.) Sounds like lots of intriguing features in there. Too bad it was so expensive ($400+). Musta been loads o' R&D for something that they couldn't have sold too many of. (Maybe it was a debugging platform for the original EOS bodies? Hmmm...)


    1. Is there any software for use with the Technical Back E other than the Canon IFU programs?
    2. Not from Canon there isn't. Unfortunately Canon will neither supply the source code for the IFU (Interface Unit) program, nor the format that they use to store data in the IFU program. However you can make the IFU program save the data it would normally print in a file as DOS text, by using a TSR utility program like which interecpts the printer calls (Interupt 17h) and redirects the data to a file. You can then work on this data to extract the fields and turn them into some sort of file which can be read by a standard database program. I've developed a program which will do this. Contact me at for more details.


  11. How do I use bulb mode without shaking my camera?
  12. For cameras with IR remote capability, use the IR remote.

    On the EOS-1, 600, and A2 series, there is an accessory called the "Remote Switch 60T3". It is a 3-terminal switch with a 60cm cord that can sense when the button has been pressed half way. It plugs into a special socket at the base of the grip. The button can be locked down by sliding the button forward. If an adaptor to a standard cable release is required, use the "Cable Release Adaptor T3". Many cable releases provide a locking mechanism. The Remote Switch 60T3 is generally regarded as more convenient since it gives better feedback as to when the switch is pressed half way, is one piece, and is faster to operate.


  13. Where is this socket on the 630, 650 or RT?
  14. The 650, 630, and RT require the purchase of a replacement grip, GR20. It is identical to the standard grip (GR30), but has the appropriate socket.


  15. How do I get long exposures on the Rebel/EOS 1000?
  16. Unfortunately, there is no elegant solution. However, there are manufacturers of accessories that place a cable release socket over the shutter release. Some take the form of a metal bar that screws into the tripod socket and holds the cable release socket in position. Others are a strap of velcro which do the same. [I believe Kaiser manufactures such an item, but I have never tried it.]


  17. How can I shoot more than 36 exposures on an EOS-1?
  18. It appears that there is no way so far. The camera cannot be made to ignore the DX-ed film length, and on film canisters without DX'ed film length, the camera will stop at 36 frames. Some hypothesize that with the faster (5fps) film transport that first appeared on the 630/RT, that Canon might worry about tearing the film off the spool. Others argue that the winder for the F1 had much more torque, that film never comes off the spool, and that Canon just plain dropped the ball. [Note that there was a bulk film back available for the F1 though.]. Al Goldis simply says to shoot to frame 35 and rewind so that a whole roll fits onto a single negative holding page. [Sounds good to me!]


  19. What are all the grips for?
  20. GR-10: Optional grip for EOS 620, 630, 650, and RT. Oversized for larger hands. No cable release socket.
    GR-20: Standard grip on EOS 620. Optional for EOS 650,630 and RT. Provides a cable release socket compatible with 60T3 remote release, and Cable Release Adaptor T3 (adapts conventional, mechanical cable releases).
    GR-30: Standard grip on EOS 650, 630, and RT. Compatible with EOS 620. No cable release socket.
    GR-60: Grip extension and hand strap for EOS 10s. No cable release socket.
    GR-70: Grip extension and hand strap for EOS Elan. No cable release socket.
    VG10: Vertical Grip accessory for EOS A2/E. Adds vertical grip, input dial, shutter release, and AF selector buttons.


  21. Are the "plastic" bodies sufficiently durable?
  22. I put this question to Chuck Westfall. Here is his reply:


    This has always been a thorny question to answer. There are two key issues: (A) the weight differential between polycarbonate and metal; and (B) the reliability of engineering plastics for cameras.

    Concerning the weight differential between polycarbonate and metal, I don't think its realistic to expect the A2/E to be made any heavier than it is. Extra weight considered independently is obviously undesirable and costly. It's been a constant goal in camera design to minimize weight and cost while maintaining features and reliability.

    Concerning reliability, I prefer to let product quality speak for itself. I believe in field experience more than lab tests. So far, the EOS 10s, Elan and A2/E have not disappointed me in this regard. For example, we constantly loan out Elans and 10s's to professional photographers through our CPS loan program. (The EOS A2 and A2E will be phased into our program this year.) Pros are notorious for abusing loan equipment, but our experience has shown that both the Elan and 10s are remarkably reliable.

    Moreover, when it comes to reliability of plastics in camera body design, Canon is in a better position than most manufacturers to make the statement that they hold up quite well in the long term. We pioneered the development of plastic-bodied SLRs as early as 1978 with the AV-1, followed in 1982 by the AL-1 and in 1983 by the T50. Each of these cameras has been on the market for at least 10 years by now, with no body-related problems of any kind. To be sure, they were designed as entry-level amateur cameras, but they provided a wealth of manufacturing experience which has been used in the ongoing development of the EOS series.

    Alvin, maybe you should ask these people what makes them think that a polycarbonate body is a problem. Are they mechanical engineers? Have any of them personally run durability tests on the equipment? Where is their documented research?

    Canon Inc. has conducted a great deal of research on all aspects of the use of plastics in cameras, including resistance to heat, impact, vibration, static pressure and drop-shock. The EOS A2 and A2E (as well as other EOS cameras) have passed all these tests with flying colors.


  23. Any way to avoid fiddling with the buttons behind the little door on the 630?
  24. One can change the focus and wind modes on the 630 by going into PIC mode, setting a PIC programme, and then returning to Programme mode. It turns out that the drive and AF mode persists when going from PIC to Programme, but not vice versa. So, the programmes of interest are:

    1) Standard (one-shot, single wind)
    2) Quickshot (AI servo, continuous wind)
    5) Portrait (one-shot, continuous wind)

    [Thanks to Robert Groom for this great trick!] Note that going into the PIC programme mode resets exposure compensation. [Does this trick work for other EOS bodies? ]


  25. Why did my camera retract the film leader with the custom function set?
  26. Any shooting done in PIC mode will ignore certain custom functions. Film leader out is one of them.


  27. Why is the EF25 not completely compatible with the EOS 630/RT?
  28. Here is the answer from Chuck Westfall:

    The EF25 Extension Tube shifts the position of the prime lens's exit pupil forward by 27.25mm. This alters the angle at which incoming light is projected onto the metering cell, requiring exposure compensation. An EF25 exposure compensation program is already programmed into the EOS-1 and all subsequent EOS models. But since the EF25 was developed after the production of the 600-series (620, 630, 650 & RT) and 700/750/850 cameras, those models may produce incorrect exposures when used with this accessory. That's why it's not recommended. However, there is no damage caused by using the EF25 with one of the older EOS models. If you want to try it, I would only suggest that you make a series of test exposures to verify whether any exposure compensation is necessary for the equipment combination you intend to use.


    I've used the EF25 with a 300/4 on a 630 without problems. Exposure compensation for this combination is certainly less than 1/2 stop, if any is required at all.


  29. Why is spot metering not recommended with the EOS 1 and EF25?
  30. Again from Chuck Westfall:

    Concerning EOS-1 spot metering with the EF25, please review my earlier reply. Even with the body's built-in exposure compensation program, the altered angle of incoming light caused by the EF25 makes that metering pattern totally useless with this accessory.


  31. Where is a good place to buy EOS equipment ?
  32. This is a tough question. Perhaps the best place to buy equipment from is a local Canon dealer where you can get personal attention and help. However, this is usually a more expensive route than buying mail order. There are lots of mail order places selling Canon EOS equipment, but not all of them are completely trustworthy and reliable. There is a monthly mail order survey posted in READ IT, BEFORE YOU PLACE AN ORDER. Not only does it list mail order experiences over the last few years, it also gives sound advice on just how to go about dealing with mail order companies. There are some stores which should be avoided if at all possible. The mail order stores which get good approval ratings (but remember, no-one is perfect) include B&H PHOTO and ADORAMA (both in New York City) and CAMERA WORLD OF OREGON. There are many other stores which give good service, but these three seem to be mentioned most often in In general, the stores advertising the very lowest "rock bottom" prices tend not to be so highly rated as those charging a few dollars more, on the other hand a higher price is no guarantee of good service!


  33. What is the repair record of EOS cameras and lenses?
  34. [Please send in any additional information on this topic to] The following repair experiences have been reported. They should give you some kind of idea how long things take, what they are likely to cost and whether any particular repair seems to be frequently required (all these only if we get enough input !).

    From Bob Atkins

    My EF28-70II quit after about 10 months of use. It seemed like some internal gears stripped, so it would not focus to infinity, the manual focus was very rough and both focus and zoom would sometimes stick (maybe broken parts jamming up the mechanism?). It was a grey market lens. It was returned to Canon (NJ) who fixed it free of charge and returned it to me in about 3-4 weeks. It has been fine ever since.

    I also had the AF adjusted on a 10s by Canon (NJ) after some focussing tests (see section 5.1) showed up a problem. The camera was returned to me in about 4 weeks with the problem fully corrected. There was no charge (warranty repair).

    Adjustment of the viewfinder screen in a 10s was a slow job, taking over 7 weeks(!) by the Jamesburg office. They did not do a good job - it was still out of adjustment when returned. It was returned to them again and this time they did it right, taking about 10 days!

    From: (Annika Forsten INF)

    My EOS-1 has a difficult problem. It goes on bc every now and then (with the booster, I never use lithiums). When I take the batteries out and then push them back inside again, the camera starts working.This happens only in southern warm countries, never here in Finland. It happens maybe once every second to fifth roll and does occur more often if the batteries are not quite fresh. It's been on service but they didn't find anything. I've had it about 2.5 years and this problem has existed for 1.5 years, ie. it started just before the guarantee went out. Also maybe related to this problem, one year ago a circuit broke and also produced the bc symptoms, but I could not revive it. Of course this happened on the first day of my trip (to the United Arab Emirates). I got it repaired after the trip.

    From: "Douglas E. Lamb"

    I sent my 3 yr old EOS 10s to Canon Canada (Toronto) to have a scratched focusing screen replaced. Within 2 days of shipping, via Courier thru my dealer, I had the estimate back. They said the mirror needed adjustment, shutter speeds were out of spec, and the auto focus required work. (In addition to replacing the focusing screen). The camera was back in my hands about 2.5 weeks later. All this cost me $186 (Cdn) + taxes. The AF appears to work better (and faster). As for the other repairs .. ?? Overall, I'm very pleased with the service.

    From: (Jeffrey Ryan Taylor)

    My only experience with an EOS repair was when I accidently scratched the focusing screen on my 10S. So I sent it in to Canon via the local camera store. It took about 3 weeks if I remember correctly and cost me approximately $80. I was happy with their service (although this was a very minor repair).I definitely had a better experience with Canon repair services than I did with Nikon (they gave me a huge hassle over some warranty work that even their regional sales rep said was a problem).

    From: ben_wen@Athena.MIT.EDU(Benson Wen)

    Okay here's what I have on EOS repairs:
    Store:S.K. Grimes, 23 Dry Dock Ave., Boston Ma.
    Equipment: Canon EOS EF24mm f/2.8
    Damage: Water, fell into dirty puddle
    Canon Authorized Repair Center? NO
    Result: Yech! They really did a bad job. They forced open the front retaining ring, I found screwdriver torque marks and a 1.5inch scratch when the technician slipped. The focus distance window was scratched from the grit that fell in the lens. It was fine when I gave it to them. Cost $70. No fee for estimate. Turnaround time less than two weeks total.

    From: Paul Nuber

    I had the plastic slider knob on manual/autofocus switch break on a 35-105 zoom. The lens was under warrantee, so I sent it to Canon repair in Costa Mesa, CA. I had the lens back in about a week. It has not failed since then.


  35. Why are there limitations on the use of the FD->EOS Macro adaptor with some EOS Cameras?
  36. The following information was supplied by Chuck Westfall of Canon:

    The Lens Mount Converter FD-EOS is not recommended for the EOS 10s and Elan (or Rebel series, for that matter) because of the non-interchangeable focusing screens used by these models. However, the problem is not macro focusing but rather exposure errors. The errors are caused by several reasons, including the offset in exit pupil position which I mentioned in previous messages about the EF25 (see section 9.14), but more importantly by the non-proportionate amount of light transmitted by the focusing screen at various apertures, in combination with the fact that the FD-EOS Lens Mount Converter lacks EF coupling pins.

    The EF25 suffers from similar problems related to offset exit pupil positioning, but is able to surmount the problems induced by the focusing screen due to its full coupling of autoexposure information. The FD-EOS Lens Mount Converter can be used successfully with the EOS 620/630/650/RT series only when those models are equipped with certain optional focusing screens (Types D, H and I), which are different (darker) than the standard focusing screen used with these cameras, and therefore less susceptible to this problem.

    Also see section 4.3 for more information


  37. How can I get in touch with Canon?
  38. You can call the 800 number (800-828-4040) for Consumer Information, publications etc. For repair info or more detailed technical help than you can get from the 800 number you can try one of the regional offices. They are located as follows (in North America):

    Headquarters        Lake Success, NY (516 488 6700)
    NJ Office           Jamesburg, NJ ( 908 521 7000)
    Atlanta Office      Norcross, GA (404 448 1430)
    Chicago Office      Itasca, IL (708 250 6200)
    L.A. Office         Irvine, CA (714 753 4000)
    Santa Clara Office  Santa Clara, CA (408 982 2500)
    Dallas Office       Irving, TX (214 830 9600)
    Honolulu Office     Honolulu, HI (808 521 0361)
    D.C. Office         Alexandria, VA  (703 642 8050)

    Canada Headquarters Mississauga, Ontario (416 795 1111) Montreal Office Lachine, Quebec (514 631 8821) Calgary Office Calgary, Alberta (403 291 4350)


  39. Why do partial and evaluative meter readings sometimes disagree when metering a uniform scene like a grey card?
  40. It seems that the evaluative metering (multi segment metering) program starts to "overexpose" scenes which are brighter than about EV15, equivalent to the "sunny f/16" exposure. This makes some sense, as the only situation where this is likley to happen is when metering something like snow under bright sun. Under these conditions you would want to "overexpose" (relative to the sunny f/16 exposure) in order to record the snow as white rather than "18% grey". Thus when comparing evaluative and partial (or spot) readings of very bright uniform subjects, the evaluative reading will call for longer exposures than the "correct" partial or spot readings. At light levels lower than EV14, spot, partial and evaluative metering of uniform scenes should all give the same exposure reading. Note that if the camera is deliberately overexposing very bright scenes like snow in direct sunlight, you might not want to "open up one or two stops" as some photgraphic books recommend - the camera is already trying to do that for you. If you want to decide how much to "overexpose", use partial metering as your "correct" exposure guide and open up from there, or switch to manual and use an incident light meter.


  41. Exactly what is the difference between "international" (grey market) and "USA" warranties?
  42. The following info was obtained from a number of Canon sources, but is not, repeat not an official quote or statement from Canon or Canon USA. You can use this information as a guide, but if warranty repair status is very important to you, you should check with Canon directly to find their current policy. If in doubt, get the USA warranty and pay the extra few dollars.

    There are basically two kinds of dealers who sell Canon photographic products in the USA. Authorized and non-authorized. Authorized dealers buy at least some of their Canon merchandise from Canon USA, non-authorized dealers do not. Theoretically at least, any USA dealer can obtain gray-market merchandise; in reality, both kinds of dealers do.

    No matter what a salesdroid may tell you, all Canon equipment passes the same quality control. There is no such thing as a substandard Canon camera, made in Korea, and imported as "grey market". Grey Market Canon equipment is just as good as "USA" equipment. However, there are (or can be) warranty differences and it is possible that manuals might not be in English (though they usually are). There may be additional problems with equipment never intended for sale in the USA, like the EOS 10QD, since replacement parts might not be available here very easily.

    If a customer purchases grey-market Canon merchandise in the United States from a non-authorized Canon dealer, Canon USA has no obligation to provide that customer with warranty service. (But they might, see below).

    If a customer purchases grey-market Canon merchandise in the United States from an AUTHORIZED Canon USA dealer, Canon USA will usually provide warranty service on that item, even without a legitimate Canon USA warranty, as long as the customer can produce a legitimate bill of sale showing the description and serial number of the merchandise.

    If a customer purchases grey-market Canon merchandise purchased OUTSIDE the USA or Canada, then once again CANON USA has no obligation to provide warranty service.

    On the other hand, Canon merchandise purchased outside the USA or Canada, but WITH A LEGITIMATE CANON WORLDWIDE WARRANTY is different. In this case Canon USA Factory Service will honor warranty repairs on such merchandise.

    Note that Canon USA warranties are issued by Canon USA, Inc., an independent sales subsidiary of Canon Inc., the manufacturer of Canon products. Canon Inc. issues no warranties. If a gray-market item is repaired at no charge by Canon USA, Canon USA loses money on the deal. They are probably not pleased to pay their technicians to repair gray-market goods sold by authorized Canon USA dealers, but in the long run, it seems that they think that it is better to honor the warranty than to lose the dealer or customer, so repairs are usually performed at no charge to the customer. With a non-authorized dealer, there's nothing to lose as far as Canon USA are concerned, except for the possibility of future customer sales through an authorized dealer. Again it seems that even with grey market equipment bought from non- authorized dealers, warranty repair may be performed at no charge - just don't bet on it. It doesn't seem to be a legal obligation on Canon's part and they do it just to be nice to customers. This could change at any time, so be warned. There are no reports on of Canon refusing to repair grey market goods under warranty at this time (09/93), but things could change. Again, if you are worried about such things it might make sense to pay the extra few dollars and get the USA warranty version of whatever you are buying. Typically, USA warrantied items are about 10% more than "grey market" equivalents, but it all depends on the store.

    Extended warranties are available on all Canon EOS bodies for about $40 (discount). This extended warranty is offered by Canon (not by the camera store or any 3rd party) and is only available on Canon USA products (i.e. not on grey market goods). Whether or not it is a good idea depends on you. It will certainly be cheaper than any out of warranty repair. It adds 4 years to the existing Canon 1 year warranty, so you are covered for 5 years. It's like any form of insurance - a gamble. If your camera breaks, it's worth it, if it doesn't, it isn't. Presumably Canon do not lose money on the deal, so they are betting the cameras will not break .


  43. What is that status of "discontinued" and "out of production" items. Are there potential problems in buying a discontinued EOS camera, like an EOS 630?
  44. Chuck Westfall of Canon USA has supplied the following information:

    Production status on any given product is determined by Canon Inc., the manufacturer of Canon products. Discontinuation of sales on any given product is determined by each independent Canon sales company (e.g., Canon USA, Inc., Canon Canada, Canon Europa, Canon Singapore, etc.), based on stock on hand.

    The EOS RT was technically "out of production" before it ever went on sale. It was a limited-production piece at the outset. (Only 25,000 were manufactured at the end of the EOS 630 production run, and Canon Inc. announced this information in its press releases at the time.)

    The EOS 10s was a North American model of the EOS 10 and 10QD, which were sold in Europe and Japan, respectively. Regardless of which version we're talking about, this model has been out of production for quite some time, though the exact dates are confidential. In the USA and Canada, the EOS 10s is still a current model as long as stock remains, but the camera will be discontinued from our catalog when the stock is sold out.

    Canon warranties are issued by the sales companies, not the manufacturer. On the other hand, spare parts are supplied by the manufacturer to the sales companies. Technically, Canon Inc. can stop supplying spare parts after a certain (Japanese) legal time limit based on the end of production, which as we know is often not the end of sales by the sales companies. In practice, there is rarely any problem, but theoretically there may well be a gap of a year or two, or maybe even three in some cases between the end of production and the end of sales. When this occurs, it's the sales company's responsibility to adhere to local laws governing such matters, which can and do vary according to location. For instance, spare parts for cameras in the USA must be maintained for a certain amount of time (note: I think this is 8 years - RMA) after the end of sales for a given product. If Canon USA cannot repair a product within the legal time limit because of lack of spare parts, we will offer the customer replacement merchadise from our current stock. In practice, this almost never occurs.


  45. Can I get a service manual for my camera/lens?
  46. Yes you can. Canon have service manuals for just about everything. HOWEVER, be warned, EOS cameras and lenses are VERY complex. Special tools are required for almost any kind of service operation. It is almost certain that you will do more damage than good if you attempt any kind of repair. You will certainly void any kind or warranty you may have. In my opinion you should regard these manuals as intersting technical reading and NOT as a guide for repair. The 10s manual contains a lot of specifications about the camera and operating modes as well as repair info. The 630 manual is not such a good deal as it covers only the differences between the 630 and the earlier 620/650. It has a lot of technical info on the 630, but refers back to the 620/650 manual for most of the repair/adjustment proceedures. Neither the 10s nor 630 manuals cover electrical adjustments. There is a seperate manual for that (CY8-1200-071). If anyone has more info on any other manuals, please send it to me (

    These manuals are available from the Canon USA Parts Center (908- 521-7230), but The Canon USA Parts Center do not accept credit cards. If you do not have an account with them, they will ship UPS COD ($4.50 extra). You can try the Canon 800 number (800) 828 4040, but at times they can be very hard to deal with. They told me that the 10s manual was only available on Microfiche, cost about $1 per page and would take 3-4 weeks to get. This is WRONG. It is printed on paper (120 pages) and cost as shown below. The people on the 800 number can be very dense. Finally the Parts Center in NJ put me in contact with Jeff (Dawson?) at the 800 number who had all the correct info, took my credit card number and said the manual would be shipped from stock via UPS. In fact it took about 2 weeks and arrived via US mail, but at least it arrived.

    I'd appreciate hearing about the contents of any manuals you do order (email

    Model                                          Parts No.     List Price
    T50                                            CYA-0006-000  $35.00
    T60                                            CY8-1200-070   40.00
    T70                                            CYA-0007-000   35.00
    EOS 850/750                                    CY8-1200-046   40.00
    EOS 630                                        CY8-1200-051   40.00
    EOS-1/POWER DRIVE BOOSTER E1                   CY8-1200-056   40.00
    EOS 10s                                        CY8-1200-062   40.00
    EOS 700                                        CY8-1200-063   40.00
    EOS SYSTEM ELECTRICAL ADJUSTMENTS              CY8-1200-071   30.00
    EOS REBEL /S                                   CY8-1200-072   40.00
    EOS REBEL II /SII                              CY8-1200-090   40.00
    EF-M                                           CY8-1200-085   40.00
    EOS ELAN                                       CY8-1200-086   40.00
    EOS A2                                         CY8-1200-100   40.00
    EF 50/1.8 (I), 28/2.8, 15/2.8                  CY8-1200-033   30.00
    EF 35-105/3.5-4.5, 35-70/3.5-4.5, 70-210/4     CY8-1200-034   30.00
    EF 28-70/3.5-4.5, 100-300/5.6 & 100-300/5.6L   CY8-1200-036   30.00
    EF 135/2.8 SF, 300/2.8L                        CY8-1200-037   30.00
    EF 50-200/3.5-4.5 & L, 50/2.5 MACRO & CONVRTR  CY8-1200-038   30.00
    EF 35-135/3.5-4.5                              CY8-1200-040   30.00
    EF 200/1.8L, 600/4L, EF 1.4X EXTENDER          CY8-1200-047   30.00
    EF 24/2.8, 100-200/4.5                         CY8-1200-048   30.00
    EF 28-80/2.8-4L                                CY8-1200-050   30.00
    EF 50/1.0L                                     CY8-1200-059   30.00
    EF 80-200/2.8L, 20-35/2.8L                     CY8-1200-060   30.00
    EF 35-80/4-5.6 POWER ZOOM, 35-135/4-5.6 USM    CY8-1200-066   30.00
    EF 100/2.8 MACRO, 70-210/USM, 100-300/USM      CY8-1200-068   30.00
    EF 35-80/4-5.6, 80-200/4.5-5.6, 35/2           CY8-1200-073   30.00
    EF 35-105/4.5-5.6                              CY8-1200-075   30.00
    EF 400/2.8L                                    CY8-1200-076   30.00
    EF 50/1.8 (II)                                 CY8-1200-077   30.00
    TS-E 24/3.5L                                   CY8-1200-078   30.00
    EF 75-300/4-5.6                                CY8-1200-079   30.00
    EF 100/2 USM                                   CY8-1200-080   30.00
    EF 14/2.8L USM                                 CY8-1200-081   30.00
    EF 28-80/3.5-5.6 USM                           CY8-1200-082   30.00
    EF 200/2.8L USM                                CY8-1200-087   30.00
    EF 300/4L USM                                  CY8-1200-088   30.00
    EF 500/4.5L USM                                CY8-1200-089   30.00
    EF 35-80/USM                                   CY8-1200-092   30.00
    EF 35-105/USM                                  CY8-1200-093   30.00
    EF 80-200/USM                                  CY8-1200-095   30.00
    EF 75-300/USM                                  CY8-1200-096   30.00
    EF 20/2.8 USM                                  CY8-1200-097   30.00
    EF 85/1.8 USM                                  CY8-1200-098   30.00
    EF 28-105/3.5-4.5 USM                          CY8-1200-102   30.00
    EF 35-350/3.5-5.6L USM                         CY8-1200-103   30.00
    EF 20-35/3.5-4.5 USM                           CY8-1200-105   30.00
    300EZ, 420EZ                                   CY8-1200-035   30.00
    430EZ                                          CY8-1200-053   30.00
    ML-3                                           CY8-1200-039   30.00


  47. What's a Vertical Release Button and how do I get one?
  48. A Vertical Release Button screws into the remote release socket of some EOS camera bodies (see below) and makes it a little easier to shoot verticals than using the regular shutter release button.

    From Chuck Westfall (via ACS): [comments from RMA]

    The Canon vertical release button is available exclusively through Canon Professional Services, and is not sold through dealers. CPS USA sells it for $12.00. [Item Code is SSC-E0482] call CPS at 516-328-4840 [I also have 516-328-4831 for CPS] for price and ordering information. BTW, the vertical release button fits any T3 socket, so it's compatible with T50, T70, T80 & T90 cameras as well as the EOS-1, EOS 5/A2E/A2, and the EOS 620/30/50/RT series when those cameras are fitted with optional grip GR-20.


  49. Can I use a linear polarizing filter with my EOS camera?
  50. While you can use a linear polarizer, it's not recommended. A circular polarizer is required for maximum exposure accuracy. The use of a linear polarizer could result in maybe up to a stop of over/under exposure. With print film this would probably be acceptable, but with slide film it would not be. Use a linear polarizer if you must, but don't blame me or Canon if it causes problems.

    Technically, a circular polarizer is required because of the partly reflective mirror. The light reflected by this mirror to the metering system and the part transmitted to the AF sensor (and spot meter in the EOS-1) is related to the polarization of the incoming light. Depending on the angle of polarization, linearly polarized light will be reflected or transmitted with different degrees of efficiency. The efficiency of reflection and transmission of circularly polarized light is a constant, independant of how the circularly polarizing filter is set. Check any physics text under "Brewster's angle" for more about polarization dependant reflection.


  51. What are the plots in the "Lens Work" book?
  52. From what I have been able to gather, these plots are the calculated MTFs of the lenses, neglecting diffraction effects. Thus they are not true MTF plots. For example the absolute maximum MTF of a lens at f/8 and 30 lp/mm is about 0.85. It cannot be 1.0. If the plot indicates an "MTF" of 1.0, what it means is that the lens is diffraction limited. i.e. all aberations have been eliminated and the only limitation on resolution and contrast is diffraction. I don't know if the plots take things like flare into account, but I assume not. The consequence of this rather strange way of doing things is that you can't really tell if the lens is better or worse when stopped down from full aperture to f/8! You can tell if the lens aberrations decrease (they always do), but you can't tell if the increased difraction more than makes up for the reduced aberrations. To get true MTFs you have to multiply the plots by the MTF of a diffraction limited lens at the relevant apertures (wide open and f/8) and relevant number of lp/mm. This is not a big correction in most cases. You can use 0.85 for f/8 at 30 lp/mm for example. It may cause more problems in the section on 2x converters, where the effective aperture with an f/8 lens and 2x coverter is f/16. The diffraction limited MTF for an f/16 lens at 30 lp/mm is about 0.75.

    The plots are useful for seeing general trends, judging astigmatism or for comparing two lenses at the same aperture, but remember that they do not appear to be real MTF plots.


  53. What is "depth of field" and how does the "Depth-of-Field" mode work?
  54. From Chuck Westfall:

    Depth-of-field is commonly defined as the range in front of and behind a sharply focused subject in which details look acceptably sharp in the final image. It occurs because at any given viewing distance, the eye cannot distinguish between a blur circle (circle of confusion) smaller than a particular size and a sharply focused point in the image. For this reason, depth of field is not a precise mathematical figure unless an arbitrary viewing distance, a specific image magnification and a permissible blur circle diameter (circle of confusion) are agreed upon.

    According to the International Center of Photography's Encyclopedia of Photography,

    "At the average close focusing limit of 10 inches (25 cm), the human eye cannot distinguish between a dot and a circle 0.01 inch (0.25mm) in diameter; this is the maximum possible size of the circle of confusion."

    Canon computes depth-of-field data for EF and FD lenses on a permissible blur circle diameter of 0.035mm at the film plane. Using this guideline, the blur circle could be enlarged approximately 7 times before its size would exceed 0.25mm. This degree of enlargement is slightly larger than a full-frame blow-up of a 35mm frame on 8 x 10 paper.

    If you want to calculate depth-of-field for any given magnification/aperture combination, just plug the desired numbers into the following formula:

    NL = H/ (n + 1)
    FL = H / (n - 1)
    NL = depth-of-field from subject to near limit,
    FL = depth-of-field from subject to far limit,
    H = Hyperfocal distance, and
    n = Hyperfocal distance divided by lens-to-subject distance.

    Hyperfocal distance is calculated from the formula:

    H = F squared divided by (aperture value times c)
    F = focal length and
    c = permissible blur circle diameter.

    The important thing to grasp from this explanation is that it's the combination of permissible circle of confusion, image magnification and viewing distance that determines depth of field. If we settle on 0.035mm as the permissible circle of confusion, then the depth of field calculations should be valid for a 7 x 10 image at a 10-inch viewing distance. By definition, changing the viewing distance must affect depth of field; moving closer would require a smaller image magnification, while moving back would allow a greater image magnification.

    Let's move on to the specifics of the EOS Depth AE mode. The photographer determines the foreground and background limits for depth-of-field using the camera's autofocus system. The camera memorizes the defocus amount between the two points and sets an intermediate focusing point approximately 7/17 of the way from the near point to the far point. Then the CPU calculates the necessary aperture value to produce depth of field which will cover both points at a 0.035mm circle of confusion. Then the exposure metering system calculates the shutter speed value required for correct exposure at that aperture.

    The presence or absence of distance encoders in the lens is irrelevant for the purpose of EOS Depth AE calculations. Keep in mind that the first EF lenses with distance encoders were the EF 35-135 USM, 70-210 USM & 100-300 USM, introduced in 1990; OTOH, Depth AE was introduced at the beginning of the EOS series, with the EOS 650 in 1987.

    One of the fundamental principles of phase detection autofocus is that the AF system uses subject contrast to detect and calculate a defocus amount at the film plane. Another way of saying this would be that the AF system detects whether the accurate focusing plane is in front of or behind the focal plane, and by how much. The precision of this system is more than adequate for highly accurate AF calculations.

    In any case, the EOS Depth AE calculations involve adding the defocus amount for DEP 1 to the defocus amount for DEP 2 to ascertain the total defocus amount. It then becomes a simple matter to place an intermediate focusing point 7/17 of the way from the near point to the far point. The 7/17 figure was selected by the EOS Depth AE system designers based on its accuracy for "normal" subject distances, not extreme close-up photography.

    Now we come back to another fundamental principle of the EOS autofocus system. Remember that the defocus information is essentially raw data, in the sense that lens characteristics, such as focusing extension amount and helicoid rotation pitch or cam movement will vary according to individual lens types. For example, a telephoto lens has a longer focusing extension amount for any given change in focusing distance than a wide-angle lens; similarly, the rotation pitch of a macro lens is more coarse than that of a standard lens. Therefore, each EF lens is provided with a CPU that translates the raw data of defocus amount from the camera into the required amount and direction of focusing extension in the lens.

    At the same time the focusing position is established, the EOS camera's CPU calculates the aperture value required to bring DEP 1 and DEP 2 within a 0.035mm circle of confusion. This calculation is also extremely accurate because it is based on the total defocus amount at the film plane as previously described.

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