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11-10-2015, 02:02 AM   #16

Join Date: Mar 2011
Location: westerly
Posts: 812
QuoteOriginally posted by stevebrot Quote
And how deep was the front element set on the Sears? . . . . .

I'll check it and get back to you when I have a chance.


11-11-2015, 01:23 AM   #17

Join Date: Mar 2011
Location: westerly
Posts: 812
QuoteOriginally posted by stevebrot Quote
And how deep was the front element set on the Sears? Both lens may have the same angle of view, but if your Viv is anything like mine with 67mm filter* the front element is only a few millimeters shy of the filter thread. I wonder how my Tamron 28/2.5 would fair in your test. It has 49mm filter threads. The front element is fairly small and deeply set. The dedicated hood is about 15mm deep and a full 70mm in diameter.

I can get way with a single filter with a normal thickness filter ring with no vignette and the same with hood attached.


* Kiron made fall of 1974

You were right, Steve:

On my Sears 28 the front element is several millimeters deeper than the Vivitar 28.
And my Vivitar is also Kiron made - serial # 22......

Regarding the Adaptall 28mm f/2.5, I have a copy, too. (Please don't ask me how many 28s I own! )
So I added the Tamron to my comparison test. First though, here's a group photo:
(Click on images for larger size.)

Sears 28mm f/2.8 52mm filter thread, Tamron Adaptall-2 28mm f/2.5 49mm thread, Vivitar 28mm f/2.5 67mm thread

As with my other test photos (post #11), these shots were taken with a Canon 5D, all at f/8, no hood used.
The first shot was with the lens alone.
The second has a polarizing and UV filter stacked together.
And the third used a step up ring with larger diameter polarizing and UV filters stacked.

Tamron 28

The Tamron didn't even need the step up ring. Minimal vignetting - if any

Here's a comparison of the Sears, Vivitar and Tamron - all with two filters attached, at f/8:

Last edited by .a.t.; 11-11-2015 at 11:22 AM. Reason: plurality

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