Canon 28mm EF Lens 1:2.8

Just bought that first macro lens? Post here to get helpful feedback and answers to any questions you might have.

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Jim McLeod
Posts: 25
Joined: Sat Aug 22, 2009 11:33 am
Location: Nacogdoches, Texas

Canon 28mm EF Lens 1:2.8

Post by Jim McLeod »

Hello All
I am sure this is one of those questions, where I later say, "Did I ask that?", but here goes.,

I need to know if there is any difference in using a 28mm lens rather than a 50mm except the obvious one of focal length. Back in the film days before digital, the 28mm lens gave problems as it caused distortion when shooting up close. Both lenses are Canon and are pretty much equal to me unless there is a hidden variable I am unaware of. I am thinking that it is actually the same as an effective 45mm to my DSLR (28 times 1.6). The reason for my question is that I have the old close-up lens and it would give me more magnification mounted back to back with my 70mm-210 zoom. But at my age, I am starting to get my tie wrapped around the axle at times. I would test it but my reversing ring is somewhere in the mail so would like to know in advance if possible.

Thanks
Jim McLeod

(New Member, first questions so be gentle!)

rjlittlefield
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Post by rjlittlefield »

Jim -- hello, welcome aboard! :D

Bear with me. I'm trying to pick through your posting to figure out what you have, what you want to do, and what you might be asking about.

I gather that you have a crop factor 1.6 DSLR, a 70-210 zoom telephoto lens, and a couple of old lenses -- one at 28 mm designed to be wideangle on 35 mm film, and the other at 50 mm designed to be a "normal" lens on 35 mm film.

I also gather that you're now considering using these to do high magnification macro work by reversing the 28 or 50 in front of the 70-210, and you're wondering what to expect.

Have I got that right so far?

If so, then...

The first thing you can expect, unfortunately, is quite a bit of vignetting. Zoom telephotos often do not play nicely with other lenses reversed in front of them. If that happens, you can change the vignetting somewhat by playing with aperture settings on the front and rear lenses, but most likely you won't be able to get rid of it. But maybe you'll be lucky.

In any case, the 28 mm will give you almost twice as much magnification as the 50 mm. However, this does not necessarily mean that you will be able to see more detail on the subject. The designers of the 28 mm had to make a lot of compromises in order to make it cover a 35 mm frame with anything approaching uniform resolution. As a result, its central resolution -- which is all you care about for macro work -- is likely to be worse than the 50. The 28 is also likely to vignette worse than the 50. There is no way to be sure except try them, but since you're asking about expectations, I thought I'd warn you.

Bottom line, I would expect better results from the 50 than from the 28, with each of them reversed in front of the 70-210.

Is this kinda sorta roughly in line with what you were intending to ask?

--Rik

ChrisR
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Location: Near London, UK

Post by ChrisR »

Go for it Jim, it's alot of fun trying.
My lenses of those lengths don't combine too well, I get very much the sort of problems Rik describes.
A reversing ring is a great way in to macro though, especially on the front of a cheap (10 dollars or so, on Ebay ) set of Chinese extension tubes. In fact I'd recommend two sets. The 50mm will be good, reversed. If you have a spare set, you can use part as a lens protector/hood on the reversed lens.

Both lenses will tend to work better the more you extend them (reversed). The 28 should be good for a tight portrait of a wasp :D

Jim McLeod
Posts: 25
Joined: Sat Aug 22, 2009 11:33 am
Location: Nacogdoches, Texas

Post by Jim McLeod »

Ric and Chris
It is so nice to be able to ask a question and have it answered so well. Ric you hit it right on and I thank you for getting to the point so easily as I sometimes have a bit of a problem discribing on paper what my head is thinking. I think it comes with age.

I am already greatly impressed with the group and hope to be able to give as much as I take as time goes on and I learn more.

I have a lot of questions but will do some study work on your web page. I am finding an excellent resource is to look up the memberlist and go to the associated web pages. Gooood information.
Thanks again.
Jim McLeod

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