Mike Chaney's Tech Corner

Since it's so quiet on the forum, which leads one to believe that we know it all and there's nothing left to ask; ;-)

I wanted to know, and I am not a scientist so go easy on the answers, when I shoot (example: a face and shoulders) with a lens of 100m, and do it again with a different lens set to 100mm, and a third , why there are subtle differences in the renditions.

I have a 100-300, and a 70-200, and a 28-135,  they really are not alike. The nose is different in each for example.

I can do the same thing at 50mm using a 50mm lens, and the 28-135 at 50 mm.

Any theories or factoids?
Fred

How do you keep "the nose" absolutely still?  And how do you focus at exactly the same point with all three lenses?

Thanks for the reply.
This is not scientific. It's a perception.
Like taking a shot of a person using a wide angle lens versus a 100mm lens. The images have different perceptions.

I'm sort of asking: Do you get the same "feeling", and if so, what about the lens difference causes it?

Fred :-[

It's perspective.  Actually, this is an old photo school teaching.  Back then it was done with 4x5, so much easier to learn.  IF you take the same subject and shoot it to the same size with different focal lengths, the apparent perspective will change.  It's just all about light physics with the different concave, convex, plano-convex, etc. lenses.  I'd ask you to go stand nose-to-nose wih your wife and stare at it but she might think you've been drinking ;D ;D.  It's harder to do since our brain compensates too much, but can be done.

The old PJ days were a 24 or 28mm, 85mm (portrait), 105 (basketball), 180 and 300 (football, baseball, police actions, etc.)  Only a few could afford a 21mm.  The 50mm stayed in the bag EXCEPT for boxing.  

There is a flip side to the perspective thing.  If you shoot a given subject to the same size at the same aperture (assuming an accurate lens) the Depth of Field will be identical.  

An aside to all this.  Watch closely at breaking news where all the TV guys are jamming in (we call it a media circus).  You can see the distortion.  The TV guys get in close because they go to wide angle.  Those C lenses have incredible DOF so they don't have to focus!!  AND they want their guy to jam the Mr. Microphone in the guy's lips.  That's why you see the still guys cramming in and trying to shoot Hail Mary's.

In a controlled situaton where we know each other we usually agree to ALL stay back.  

There is a really strange anomaly in the business.  The best video guys were still shooters--they don't zoom.  They shoot a bunch pieces and put a story together.  Likewise, some of the best still guys came from film/video.  They get the horizon lines straight.

Thanks, Seth
I knew I see a difference but was it only me?
I think I see it more when shooting a large blossom. 17mm will flatten the blossom, and the 50 to 150 makes it come alive.

Thanks again,
Fred

That's where I go to a macro.  More of a flat field, but DOF is a whole new animal.  I do a lot of back lit flower petals with the macro (when the ground is dry.)  Fill flash if it needs it to keep it HDR.

That has just got to be my next lens  8)
I'm wondering about the Canon 60mm EF-S f2.8 or a longer 100mm f2.8. The greater subject distance with 100m  seems to be a good idea, especially for small creatures.
Terry

Terry-

Tell you what.  I have a 60mm but REALLY wish I had the 100mm.  Well, 105 with Nikon.  Both systems are a 2.8 and have USM/VR respectively.

The downfall for me would be having to get further "under" a flower.  DOF would add to the issue.  I do have the Nikon RC1 macro flash setup to bail me out.

That sort of thing is always a downfall for me when I get home with dirty clothes, my wife does not appreciate it at all ;D
Thanks for your comment on the 60 vss 100 f/l
Terry.

Hmm, I always got away with it with my girlfriend.  I told her I was out "working."  Probably because she was a photog too, huh?

And to make things a bit more confusing, Canon is apparently in the process of releasing a new "L" macro which is largely similar to the older 100mm macro except with IS and presumably some other optical upgrades.

It's expensive, but it looks like they updated the USM to be a bit quicker. I'm not necessarily sure whether it's a worthwhile upgrade over the older 100mm, but it's nice to see a lens in the gulf between the 100mm and the 180mm lenses.