Vivitar 100mm f3.5 with the new Brevis35?

V

vj_jasper

Active member
hi all, i am considering a 100mm Vivitar to put on a Brevis35 via the Canon fd style connection (hope that sounds sensible? if not, please feel free to mention :))

Timur has mentioned issues with telephoto lens if they do not have a backfocus, the lens will not remain in focus during a zoom..

how do i know if the Vivtar has a backfocus .. or any lens, how do i know if they will zoom through and maintain focus?

thanks for any info

jas
 
You are confusing telephoto with zoom. Telephoto refers to focal length, zoom refers to the ability to change focal length.

If you are looking at a 100mm lens, then it is telephoto, but not a zoom.

Beyond that, all lenses will "have a backfocus". The issue you're referring to has to do with whether or not the 35mm adapter is properly calibrated and set up precisely so the lens mount is at the exact distance from the ground glass that it needs to be. If the adapter is set up properly, then your zoom should track.

Alternately it is possible that any given zoom lens can also introduce backfocus/focal flange issues if the mount is, for some reason, not properly attached or has been adjusted. However, it's much more likely that your adapter's backfocus/focal flange distance will be off than it is that your lens will be significatly off.

Finally, if you find a Vivitar zoom, you should be aware that Vivitar made a series of variable focal length lenses that aren't, technically I guess, zoom lenses. They provide a variety of focal lengths but are NOT set up to maintain focus throughout and they can not be set up to do so. They're called Varifocal lenses.

Oh, also, you might find that a 3.5 lens is too slow, even though the Brevis does very well with both light loss and vignetting.
 
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A 3.5 will be fine with a Brevis. Dennis used to shoot with a slow vivitar zoom if i'm not mistaken. Outside it'll be fine, interior just make sure you have adequate light.
 
As a rule, slow zooms work better than slow primes on our adapter. In other words, an f3.5 zoom at 28mm will show less edge falloff than a 28mm prime at f3.5. Strange but true.

We've got a Canon 28-200 zoom f3.5 that works very well on the adapter. For sharpness, it's nowhere close to our 80-200 Nikon f2.8D zoom, but it works :-)

Most zoom lenses (properly collimated on the adapter) do maintain focus as you zoom in and out and this is a great way to check focus. The same technique (zoom in, set focus, zoom out to frame) is pretty much the norm for the B4 zoom lenses and ENG cams. I've got a very inexpensive 28-70 Vivitar that does not maintian focus when zoomed and this is a irritation. The best thing you can do is google for lens reviews regarding any particular lens. Chances are you'll learn a lot about the lens this way :-)
 
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