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View Full Version : Here's kind of an off-beat combo ...



DonSchap
12-28-2007, 10:02 PM
I was playing around with some strange single lens ideas for a "walk-around" lens. Obviously, the 18-250mm f/3.5-6.3 was a good idea ... but what if you already had an 17-50mm f/2.8 zoom ... and really didn't want to add another $450 lens to the pile. What might work?

Why not a 17-50mm f/2.8 and a 2x T/C combo? Now, I'm not a big fan of the Teleconverter, but what the heck ... some folks don't give a care ... they just want an image, to heck with new glass. The constant f/2.8 makes it truly doable without any loss of autofocus at any point during the focal range, you're just doing it at a base aperture of f/5.6 instead.

Let's look at this on the SONY, just for grins. By adding the 2x T/C ... yes, you tend to slow the autofocus response, but not too much. You wind up with a 34-100mm f/5.6 lens. The lens increases in length by about an inch ... and IQ is not too terribly mangled.

Minimum focus distance ... normally 8 inches at 50mm, shortens to 6 inches at 100mm (w-2x), which is kind of an amazing facet to this.

Sample images:

@ 50mm & External ETTL flash
31906

@ 50mm + 2x T/C & External ETTL flash
31907

I mean this is really close-shooting, but it tends to confirm to me that if you are shooting indoors ... six-inches is getting pretty darn close. The MACRO lenses, indeed, get closer ... but, this definitely is a real close-up, Mr. Deville. :rolleyes:

Obviously, everything becomes twice as big ... and if you are strapped for room in your "on-the-run" camera bag ... this could be a good fall back idea. If definitely gets you into that "gap" of 50-70mm (short telephoto area) ... that a 70-300mm f/4-5.6 simply cannot manage. You are no darker than 5.6 anywhere in the entire range, either. The 70-300mm 70mm setting meets up with the 2x T/C + 17-50mm lens at about 82mm indicated.

Now, consider a 1.4x T/C ... loss of only one-stop of light ... the focal range goes from 24-70mm and it should become the "perfect" bottom end to the 70-300mm f/4-5.6 telephoto lens, with a base aperture of no more than f/4 throughout the range. Unfortunately, in real life, the 1.4x T/C + 17-50mm lens winds up about 5-8mm shy of the 70-300mm's 70mm setting and is roughly 62-65mm at the extreme long end, but then again ... that's a lot closer than you'd be at only 50mm.

Anyway ... just a few thoughts for beginners trying to make due with the one or two lens bag ... a 1.4x and/or 2x T/C should probably be part of it.

Just a footnote: The 18-200(250)-type and 70-300mm lenses do not play well with T/Cs.

sparkie1263
12-29-2007, 11:10 AM
I have a Quantaray 70-300 Macro I tried taking some macro shots. I have a lock on my lens for macro but I cannot get real close. The closet I can get and till focus clear is about 3 feet. Is that about right for this lens. Here are 2 shots I tried.

coldrain
12-30-2007, 05:10 AM
Be sure to turn off SSS when using a teleconverter too.