promaster macro

[okobojichick]

I have a promaster lens for my film rebel.  Can I use it on my digital rebel?  Called support and he said it could damage the camera - hmmm - didn't damage my film camera.

[cicopo]

If it has an EF mount it should fir fine. It may not provide perfect optics by today's standards but if has AF it's most likely an EF style lens.

[TCampbell]

I very much doubt it could actually damage the camera... but you could have other issues.  Here's why.

When Canon introduced digital cameras, the sensor size was reduced a bit from the size of a single frame of 35mm film.  This kept the costs from being ludicrously expensive (a real barrier to consumers).  So it was actually remarkable when Canon was able to market DSLR cameras to consumers that actually cost less than $1000 for the body and at least one kit lens.

A side-effect of these smaller sensors, was to reduce the lens expense further by taking advantage of the fact that the sensor is physically smaller (this is only true of the "APS-C" sensors... there are digital "full frame" sensor cameras and this doesn't apply to those).  Since the sensor is smaller, the image circle projected by the lens could ALSO be smaller.  That allowed Canon to engineer lenses where each lens element was a bit smaller, reducing the degree of various optical problems, which in turn allows them to use fewer correcting elements, etc.  This makes it possible to make a smaller and lighter lens and NOT actually sacrifice image quality at all (although those lenses cannot be used on "full frame" bodies for a variety of reasons -- not least of which is that the lens isn't designed to project an image circle large enough to fill the frame as well as some physical problems with back-focus distance and clearance of the reflex mirror.)  These smaller lenses intended only for use on small sensor bodies (bodies that have "APS-C" size sensors... so named because the sensor is roughly the same size as a single frame of "Advanced Photo System - Class" size film).

HOWEVER... you don't own a small-sensor camera.  You own a film camera.  That means your lenses have to be the same type used on digital "full frame" bodies -- these are the EOS "EF" lenses (not EF-S).  EF lenses can actually be used on any Canon EOS camera... film or digital.... full-frame or crop-frame. 

So that's the good news.

Here's the caveat:  Canon does not share the workings of the electronics which are used for communication between the lens and body.  Third party lens makers have to "reverse engineer" to make these lenses work.  They generally test the lens for compatible with the "current" crop of cameras. 

BUT... from time to time, Canon will introduce a new camera which takes advantage of their own connectivity rules, but for which the 3rd party lens maker was unaware.  You can end up with a new camera that wont work with an old 3rd party lens... but will work with an old Canon EOS lens.  Sometimes 3rd party lens makers allow you to send the lens in and they reprogram it -- but this is by no means a guarantee.  Sometimes you end up just having to cut your losses and move on.

Incidentally... your digital Rebel body can use EITHER the "EF" or the "EF-S" lenses ... both are fully compatible.

[ebiggs1]

"Called support and he said it could damage the camera"

I am going to agree with the advice from Canon on this one. Owning around 2O FD lens and older EF lens I have tried about as many possible combinations as there is. For whatever reason I did have one old EF "film" lens that hit the mirror on my Canon EOS 1D, DSLR.

Now consider the fact that the old lens is not up to digital quality and has a slight possibility it could hurt your Rebel, is it really a good idea? Hmmmmm......

[cicopo]

With the above opinion carrying some weight INSPECT the rear of the lens to see it the rear element or any other parts would be inside the mirror box area when mounted. If the actual mount is the only section of the lens which will be inside the mount on the camera I can't see a risk, BUT if some part of the lens extends past that mount then yes it might. Can you stand the lens on a flat surface with the rear cap off? Is it sitting on the mount flange? (there may be a slightly higher section where the electrical terminals are so it's not sitting perfectly flat but that's not much higher than 3/32 inch & won't be inside the mirror box area). If you can the mirror wouldn't be able to hit any part of the lens once mounted.

[ebiggs1]

I have no idea what a " promaster macro" lens is. But on these very inexpensive lenses, most notably on zooms, the rear element can extend back beyond the tube of the lens itself. This usually happens when the zoom is in it's shortest focal range. Some of them even extend on focus adjustment.

This idea is bad, but if you must, (like the above warning) do inspect it very carefully and at all zoom and focus ranges.

Not in this case but on old FD lenses have a aperture lever can and will contact parts inside the mirror box on certain DSLR's.

Just be very careful. 

[TCampbell]

"promaster macro" is vague.  It would help if we could know specifically which lens this is.

On an "EF" lens (or compatible -- a lens designed to work with either "film" or any DSLR body including full-frame bodies), the rear-most thing on the lens should be those electronic contacts.  

Nothing should protrude into the camera body farther than those contacts.  If anything DOES protrude farther back than that, then *some* bodies can have clearance problems with the reflex mirror swings up.  

EF-S lenses (for APS-C bodies) do have a rear element that protrudes back into the body a bit farther, but they can get away with it because APS-C bodies also have physically smaller mirrors which do not require as much clearence.  Those lenses cannot be used with any camera body other than bodies with APS-C sensors.   Canon designed the mount on their non APS-C bodies so that the EF-S lenses wont even be able to mate to the mounting flange -- if a lens does not want to mate to the mounting flange, then don't force it.  The design which prevents those lenses from mating is deliberate.

[okobojichick]

Thanks for all the info.  The lens is a ProMaster Spectrum 7.  On the side is says AF Macro and around the lens itself it says MC Macro Lens, 100 mm, 1:3.5.    Does that additional info help?  OkobojiChick

[TCampbell]

I am a bit suspicious that this may be for a non-EOS film camera (i.e. Canon "FD" mount lens).  I did some searching for this lens, and every hit I can find for Canon mount is for Canon "FD" mount.

Here's a photo I took of two lenses.  The one on the left is an "FD" mount lens for Canon film camera (pre EOS film camera).  The one on the right is an EOS mount lens.  

Notice the EOS mount (on the right) has several electronic contacts -- these communicate with the camera body.  The lens on the left (the FD mount lens) has no electronic contacts, but does have a few metal tabs which the body can use to mechanically control the aperture or detect when the lens is set to manual vs. auto-aperture.

Incidentally, the lens on the right happens to be the Canon EF 100mm f/2.8L IS USM Macro.  (If anyone is curious, the lens on the left is a Canon FD 35-105mm f/3.5-4.5)

 If you look at the back of your lens and do not see the electronic contacts, but instead see those metal tabs, then you have an FD mount lens... not an EOS mount lens.

[ebiggs1]

Tim, I have both those lenses!  

A little off subject but sorta on topic. This is a shot with a "converted" FD 135mm f2 L. Shot with my 1D Mk II.

How I miss auto focus. 

The FD 135mm f2 was/is one of my most favorite lens (of all time) so I had to see if it could come along with me to the world of digital. This is done with the Ed Mika FD to EOS adapter. However this adapter is $150 bucks, so it may not be a wise choice for an inexpensive lens i.e. a ProMaster?