Camera Labs

I'm sure this has been asked before but I don't know how to phrase this in the search. I'm new to DSLR of course. I'm in Afghanistan right now and having a new T2i sent home to be waiting for me. When I go on vacation I'll be visiting my dad and he has an OLD canon 35mm. I know it is old because I remember trips as a kid in my single digits and I'm almost 37 now. He has some nice glass one I remember is a BIG tele-photo. I don't remember the specks and I'm sure that would help a lot in asking if they would work together. I googled old canon zoom lenses and I found a pic of a 85-300 that looks like it, but it has been 20-yrs since I've seen it. If they work together, besides crop factor (which I still don't fully understand) is there any other issues I may have. I'm pretty sure there is no auto-focus which would suck. I hope it works, I remember being at the lake and taking good pics of ducks on the other side from where we were.

The first thing I'd find out is whether the lens has the same mount type as your camera i.e. EF. I've never heard of an 85-300mm Canon EF lens so it may be an older lens mount, in which case you will need an adapter.

The crop factor is a simple concept. Using Canon as an example, most Canon crop-frame bodies such as the 550D/T2i use the APS-C sensor, which is smaller than the 35mm sensor you have on full frame Canon bodies such as the 5D or 1Ds. At a given focal length for the two sensors, the image will be cropped on the APS-C sensor as it is smaller so you get 1.6 times less coverage than the 35mm sensor. For example, if you have a 550D and the 5D both with the same lens set at a focal length of 50mm, the 550D will look as though it's zoomed at 80mm i.e. 50mm x 1.6 crop factor. It's not a true focal length of 80mm on the APS-C, it's just an equivalent caused by the smaller sensor.

If you look at the image below, the coloured portion is roughly what you'd see with a Canon APS-C sensor body at a given focal length and the black and white section is what you'd see with a 35mm (full frame) sensor at the same focal length.



The same image is entering the lens so to speak but the smaller APS-C sensor captures less of the image than the 35mm sensor.

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Bodies: Canon EOS 550D w/ Magic Lantern
Lenses: Tokina AT-X 116 Pro DX f/2.8, Canon EF-S 15-85mm f/3.5-5.6 IS USM, Canon EF-S 18-55mm f/3.5-5.6 IS, Canon EF 50mm f/1.8 II, Canon EF 70-300mm f/4-5.6 IS USM
Accessories: YongNuo Speedlite YN-468 Flash, Neewer Macro LED Ring Light, Meike Battery Grip, YongNuo RF-602 Wireless Flash Trigger & Receiver YongNuo WR-128 Wireless Remote Control

Ok, now I have it, Thanks! So if I have a 5D and 550D next to one another with the same lens zoomed to the same amount I'm not going to have as much "surface area" in the picture of the 550D.

Some people joke about having a dyslexic moment, I am honestly dyslexic and there are so many number I have to think about, ugh. I'm going to have to make a cheat sheet to keep in my camera bag.

Thanks again

don't bang your head with crop factor, if you got the lens, you got them and there is no changing them.. if you find them to wide buy more tele lens, if you find them to narrow buy wider lens (in general its how it works for people that don't use same lens on film or full frame and aps-c cameras..)

all you need to know is what mount are the lenses you got, will they auto focus and meter the exposure with you camera..

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Hi hikingmike,

May I wish you a warm welcome to the CameraLabs forum.

A good resource when researching older lenses is the Canon Camera Museum's Lens pages. If the lens in question is an 85-300mm then almost certainly it uses the FD mount. While you can get adapters allowing use of FD lenses on EOS bodies there's a gotcha in that, apart from a very few which included optics and which were manufactured by Canon for the professionals to use while they transitioned to the EF lenses, none of them to my knowledge allow the FD lenses to focus on distant subjects. The problem is that EF lenses are designed with a spacing of 44mm from the flange to the focal plane while FD lenses were designed with a figure of 42mm (source).

FD lenses can still be used provided focus at infinity isn't needed but they are probably more trouble than they are worth. Sorry.

Bob.

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OM-D E-M5 + ED 12-50mm, H-PS14042E, H-F007014E, L-RS014150E, M.ZUIKO DIGITAL 45mm 1:1.8.
Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.

Thanks for that link to the museum and all the info. From looking, I'm pretty sure it is the 85-300. I found an adapter that gets ok reviews for $28.00 so I would not expect much from it. If I get my dad out of the house and go play, I'll risk a $28.00 purchase. Let you all know in Mid July if it works. I'm just excited to finally get my first DSLR