CANON EOS FAQ Version 2.4
Date: November 1993

Current maintainer Bob Atkins (version 2.0 and up)
Internet e-mail address
Original maintainer Alvin Shih (up to version 1.8)
Internet e-mail address

This is an attempt to address various questions about the Canon EOS camera system. It makes no attempt to address any questions about the FD-mount cameras.

All original material is Copyright © 1992, 1993, 1994, 1995 Alvin Chia-Hua Shih and Robert M. Atkins. All rights are reserved except as detailed as follows:

Permission to redistribute this FAQ via electronic means as unformatted straight ASCII text as received on the USENET newsgroup, or as the uneditied, complete set of HTML pages, is granted provided distribution is done without charges of any kind, for noncommercial purposes, and that it is distributed in its ENTIRETY including this banner and the attributions and that no alterations of any kind are made. Permission to distribute this FAQ in written or printed form, or on computer disk, or in a formatted electronic or digital form such as a word processor compatible file, or in any kind of altered or modified form must first be obtained from the current maintainer of the FAQ.

The views and opinions expressed in this document are in no way officially supported or endorsed by Canon, though we do gratefully acknowledge the help and assistance of Canon personnel (especially Chuck Westfall) in developing and reviewing some of the material presented here.

Every attempt has been made to ensure the accuracy of the information contained herein. However none of the contributors make any guarantees. Therefore, any destruction of equipment, unsatisfactory purchases, or lost shots that may result from the use of this FAQ are the sole responsibility of the reader. (That ought to keep the lawyers away! :-).

This information is derived from postings on the net as well as brochures and books. Contributors to this FAQ include (but are not limited to):

Bob Atkins          Robert French       Paul Repacholi
Changhao Boh        Al Goldis           Barry Sherman
Harald Brandt       Thomas Greve        Alvin Shih
Jim Cathey          Robert Groom        Peter Shizgal
Mike Coren          Ralph Jenson        Benson Wen
Per Danielsson      Stephen Page        Chuck Westfall
Christian Decurnex  Laszek Mazur        Uli Bodenhausen
Panos Tsirigotis    Brett Cheng

Wherever possible, credit for submitted items is given in the text. Please bring any ommisions to my attention.

Currently, this FAQ is available in plain ascii format via anonymous ftp from in the / directory.

If you are viewing this FAQ via WWW, note that clicking on the table of contents entry jumps you to the corresponding subsection. Clicking on the title of the subsection returns you to the corresponding entry in the table of contents.


  1. Canon Publications:
    1. What kinds of publications are available?
    2. How do I order Canon publications?
    3. I need a manual for my Canon camera. How do I get one?
    4. I didn't manage to get all of the publications I wanted.The person on the phone didn't seem to understand.
  2. Nomenclature:
    1. Acronyms:
    2. Model Number Equivalencies:
  3. Flash:
    1. Other than the 430 EZ, what are my options?
    2. What's the difference between "meter" and "feet" versions of the 430EZ?
    3. Why doesn't the AF illuminator on my flash work with my 10S/A2?
    4. Body-Integral Flash Questions:
      1. How does red-eye reduction work?
      2. Can I get red-eye reduction with slow sync flash?
      3. Can I use red-eye reduction with 2nd curtain sync?
      4. How do I get a smaller aperture with more DOF using my built-in flash?
      5. When does the internal flash charge?
    5. On the A2, what does CF16 do?
    6. Can I get an off-camera flash cord for my 630/RT?
    7. Why doesn't the A-TTL preflash out-of-range warning work on my camera?
    8. Is there an after flash underexposure warning?
    9. How do I change the fill-flash ratio?
    10. A-TTL Questions:
      1. Why doesn't Canon use distance information for flash exposure calculations?
      2. Is it OK to block the A-TTL sensor (with a softbox, say) with using plain TTL flash?
      3. Is it OK to block the A-TTL sensor (with a softbox, say) when using A-TTL?
      4. Why does blocking the A-TTL sensor give me smaller apertures?
      5. Why can't I use A-TTL with the off-camera TTL accessories?
      6. Can A-TTL cope with filters over the flash?
      7. Can A-TTL be used with filters over the lens?
      8. Is the A-TTL program affected by flash exposure compensation?
      9. Why didn't Canon put the A-TTL sensor in the body?
    11. Is there a faster way to mount the flash?
    12. How can I find out more about using flash with my EOS?
    13. In A-TTL, how can you read the subject distance with the light reflected (what is the physics law) ?
    14. Can spot metering be used for the ambient exposure with the EOS 5/A2 (like partial metering with the 10s)?
    15. Are there 5 vertical sections of the TTL sensor in the EOS 5/A2?
    16. How is ambient light metered in A-TTL and TTL flash photography with the EOS 1?
    17. How does the camera-flash communication differ when the flash is on and off the camera?
    18. Why don't you recommand the use of "C"-size NiCd batteries in Battery Pack TP ?
    19. What about the use of flash with the EF-M?
    20. Why doesn't the flash work on my Elan when the film speed is set to ISO 5000?
    21. Can I use a non-Canon, non-dedicated flash with my EOS camera?
    22. Does the PC adaptor offered by CPS confer some kind of electrical isolation to protect the camera?
  4. Lenses:
    1. Lens Specifications?
    2. Why does Canon offer so many different lenses, some of which seem quite similar?
    3. Can I use my FD-mount lenses on EOS bodies?
    4. Can I use EF-mount lenses on FD-mount bodies?
    5. Why have the focusing motor in the lens?
    6. Doesn't the motor in the lens make the lenses more expensive?
    7. Manual focusing with USM lenses?
    8. Can small animals hear USM lenses?
    9. Is there any way to focus a USM lens without making any ultrasonic noise?
    10. Canon lenses look too expen$ive. What about third-party?
    11. Why didn't Canon think of using distance information (like some other nameless company :-)?
    12. So which lenses are worth getting?
    13. What does the "II" mean?
    14. What about the Tamron 28-200/3.8-5.6?
    15. My lens cap is too loose. What can I do?
    16. Tell me all about teleconverters!
    17. Is the Tamron TC officially endorsed by Canon?
    18. My lens pulls its filter threads inside the lens barrel and/or the filter threads turn during focusing. How can I use a circular polarizer?
    19. How can I use a rubber lens hood if my front filter threads retract?
    20. What are TS-E lenses?
    21. Why are TS-E lenses so expensive?
    22. Why should I use an EOS-1 with TS-E lenses?
    23. How much magnification can I get using EOS lenses?
    24. What is a good, fast,cheap, small, light telephoto lens for an EOS camera?
    25. Brief review of the Sigma 21-35 for EOS
  5. Focusing:
    1. Manually focusing doesn't give me the AF confirmation light. What's wrong?
    2. Why is the manual focus throw so short?
    3. What techniques are there for precise manual focus on an AF lens?
    4. Why do some lenses have ranges on the MF/AF switch?
  6. Viewfinder:
    1. I wear glasses. Can't see all of viewfinder and/or the information display. What can I do?
    2. Why can't I focus on both the viewfinder image and/or the information display?
    3. What's the eyepiece cover for?
    4. How do I get dust out of the viewfinder?
    5. How do I change the focusing screen in the 630?
    6. Do the optional EOS 630 focusing screens affect exposure?
    7. Which manual focusing aid is most useful?
  7. Bodies:
    1. What's an EOS RT?:
    2. What's an EOS 1 HS?
    3. Why can't I get eye-controlled focus to work at the store?
    4. Is the EOS Rebel/1000 any good?
    5. What's an EF-M? The Rebel is only $30 more!
    6. Can I use IR film in bodies with "Quiet Drive"?
    7. What is in those bar codes?
    8. Can I write my own barcode programs?
    9. What about "obsolete" models? Are they any good?
    10. Is there any way to reprogram an Elan to leave out the film leader after rewind?
    11. What's the difference between a Rebel S and a Rebel
    12. IIS?
    13. What viewfinder screens are available for the A2/A2E?
    14. What's an EOS 500/Rebel X?
    15. How can I change default metering modes on a 630 or 10s?
    16. Should I get a 630, 10s or Elan?
    17. Why doesn't the EOS-1 have mirror lock-up?
  8. Batteries:
    1. Bodies:
      1. Why don't I get as much life out of my batteries as my manual would have me believe?
      2. I just got my camera and have been fooling around with it. I've already lost two bars on the battery check, and I haven't even run any film through it! What's happening?
      3. What are the "hard numbers" on battery use?
      4. I'm down to one flashing bar. Do I have to throw the battery away?
      5. If I let the battery die, will I lose my film count or custom function settings?
      6. Does the VG10 draw power?
      7. Is there anything I can do to increase the shooting capacity of my A2E? It ate a battery in 6 rolls!
      8. Are there any differences in lithium batteries?
      9. How can I keep my camera running in the cold?
      10. What else should I know about battery consumption?
      11. Are there any rechargeable batteries (2CR5s) for EOS cameras?
      12. What is a BP-5?
    2. Flash:
      1. The 430EZ eats batteries too quickly. How can I get more flashes out of my 430EZ?
      2. What if I want a LOT more flashes and/or faster recycling(because of fast action and/or cold weather)?
      3. What about non-Canon high-voltage packs?
      4. High voltage packs look too expensive. What are my options?
      5. I don't have a high-voltage jack on my flash. What are my options?
      6. What is a low-voltage pack?
  9. Miscellany:
    1. Can I get warranty service, even if I didn't buy it in this country?
    2. How do I leave the film leader out?
    3. Where do I get a film leader retrieval tool?
    4. How do I get exposures longer than 30 seconds?
    5. What's a Technical Back E?
      1. Is there any software for use with the Technical Back E other than the Canon IFU programs?
    6. How do I use bulb mode without shaking my camera?
    7. Where is this socket on the 630, 650 or RT?
    8. How do I get long exposures on the Rebel/EOS 1000?
    9. How can I shoot more than 36 exposures on an EOS-1?
    10. What are all the grips for?
    11. Are the "plastic" bodies sufficiently durable?
    12. Any way to avoid fiddling with the buttons behind the little door on the 630?
    13. Why did my camera retract the film leader with the custom function set?
    14. Why is the EF25 not completely compatible with the EOS 630/RT?
    15. Why is spot metering not recommended with the EOS 1 and EF25?
    16. Where is a good place to buy EOS equipment?
    17. What is the repair record of EOS cameras and lenses.
    18. Why are there limitations on the use of the FD->EOS Macro adaptor with some EOS Cameras?
    19. How can I get in touch with Canon?
    20. Why do partial and evaluative meter readings sometimes disagree when metering a uniform scene like a grey card?
    21. Exactly what is the difference between "international" (grey market) and "USA" warranties?
    22. 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?
    23. Can I get a service manual for my camera/lens?
    24. What's a Vertical Release Button and how do I get one?
    25. Can I use a linear polarizing filter with my EOS camera?
    26. What are the plots in the "Lens Work" book?
    27. What is "depth of field" and how does the "Depth-of-Field" mode work?

[ Jump to End: Miscellany | Next Section: Publications ]