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02-16-2010, 02:52 PM   #16
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Added blank wall histograms showing the transmittance and contrast differences.

Steve

08-16-2010, 04:52 AM   #17
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I have a Vivitar 28mm 2.8 lens which I've had for many years, used on my K-1000. This weekend I bought a Pentax K-x body. All of my other K mount lenses (some Pentax, some not) fit on the K-x, except this lens. It seems to hang on something as I twist to lock (so I don't force it!). It does still fit fine on the K-1000. Nothing to my uneducated eye looks wrong in looking at the bayonet end of the lens. It's not a big issue as with the crop factor I wasn't planning on using it on the K-x anyway, just seems odd. Has anyone else had a similar problem?
08-17-2010, 03:55 PM   #18
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It's almost certainly a "shroud" around the aperture lever that's keeping it from locking onto the camera body. You can loosen a couple screws to remove it without any negative effect.
08-18-2010, 12:02 AM   #19
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Nice series of test shots! I agree that the Tamron is warmer. Both lenses give similar results, but I'd give a slight overall edge to the Tamron. If the lower light transmittance of the Vivitar is considered, then the Tamron's edge is more substantial, as shooting at 1/2 to 1 stop more closed would yield more DOF and better IQ under low light conditions.

In the battle of old wide angle cheapies, I think both of these would lose to the Sigma 24mm f2.8 macro. I use mine much more than I do my Tamron 28mm.

09-05-2010, 09:11 PM   #20
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Steve, I recently acquired a Tamron 02B 28mm so I dug up this comparison you did.
Thanks for dioing it, it made for an interesting read. On a different thread you asked about a M42 Vivitar 28/2.5 I also recently acquired, so today I had a bit of time and did a very brief, unscientific comparison of the 2 and for fun I threw in my Pentax-F 28mm.
With my K10D mounted on a tripod, and F-28 mounted, in AV mode and Sunny WB, I took 4 shots. 1 at f/2.8, 1 at f/4, 1 at f/5.6, and 1 at f/8. For each shot I recorded shutter speeds. Then I set the camera to M mode and took all 4 shots with each of the other 2 lenses and used the same shutter speeds as the shots from the F-28, I did adjust the shutter speeds for the 2.5/2.8 difference.

Not a great test but interesting to me. My Tamron seems darker than both the Pentax and the Vivitar. The Vivitar is cooler, and the Tamron seem quite a bit warmer than both.
Here is a link to the shots.
Picasa Web Albums - Colton - 28mm test

I hope you don't mind me posting this here.
09-07-2010, 01:00 PM   #21
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QuoteOriginally posted by Swift1 Quote

...I hope you don't mind me posting this here.
No problem Colton! It is quite an affirmation to have someone revive an old thread!


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09-07-2010, 10:33 PM   #22
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I agree with your conclusions, Colton. Also, the Tamron seems sharpest wide open. The Vivitar seems a bit less sharp than the other two overall. The difference in exposure might have affected my perception, though.
10-14-2010, 10:05 PM   #23
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A package arrived today. Four pieces of PK optics, US$9.95 BIN plus $5.95 shipping, or about $4 each total. Two KM 2x TCs, Vivitar and Albinar. An Albinar 80-200/3.9 in KM mount -- that makes my third copy, along with an Albinar Nikon non-AI and a Sears KR, those for US$9 each. I'll need to weed-out one or more of those.

And then the fourth item: a Tamron 28/2.5 (02B) in Adaptall2-KM base, serial #5223987. The focus ring was loose so I tightened the grub screws and now it's right as rain, a bit worn at the edges but functionally great. The seller didn't know what this was, just called it a Tamron 28 for Pentax. I am now very happy. One of these days I'll have to do a shootout against my ten 28/2.8's.

Oh yeah, one of those 28s (in KM mount) is labeled ACCESS P-MC MACRO (actually it has an extending front that takes it to 1:3.7). Build is quite good. Has anyone here ever heard of this?

10-15-2010, 12:33 AM   #24
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QuoteOriginally posted by RioRico Quote
Oh yeah, one of those 28s (in KM mount) is labeled ACCESS P-MC MACRO (actually it has an extending front that takes it to 1:3.7). Build is quite good. Has anyone here ever heard of this?
I think there might be some discussion of the Access lens on the "Off-Brand Club" thread.


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10-15-2010, 12:35 AM   #25
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Awesome comparison, thank you very much.

Somehow I like Tamron lens better.
10-15-2010, 03:18 AM   #26
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Very well done, Steve. My eye tended to favor the Tamron a bit overall, though as you say for most real-life purposes there's not much to choose from between the two.
10-15-2010, 05:58 AM   #27
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THANKS FOR SHARING.

I have had the tammy 24mm F2.5 since the early 1980's and one thng I have found is that it has developed over time some significant backlash in the focusing.

the performance is OK but there is a definite several degrees of rotation that do nothing at all between focusing collar and helix.

I have since added a couple of other short lenses, all of them cheap, to my collection. I have
- a Vivitar (kiron) 24mm F2 converted from Nikon AI to pentax with a flanged adaptor total cost including adaptor $6
- a Kiron 28mm F2 converted from Minolta MD to pentax with a flanged adaptor total cost including adaptor $11
- a tamron 28mm F2.5 (as tested in this thread) $13 without adaptor, but I already had one
- a vivitar 28mm F2.5 M42 mount. $9
- a sigma 28mm F2.8 macro $30

I really should do a similar comparison shouldn't I
10-15-2010, 10:06 AM   #28
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QuoteOriginally posted by Lowell Goudge Quote
I really should do a similar comparison shouldn't I
Now that sounds like a lot of fun.


Steve
10-15-2010, 10:07 AM   #29
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QuoteOriginally posted by Nesster Quote
Very well done, Steve. My eye tended to favor the Tamron a bit overall, though as you say for most real-life purposes there's not much to choose from between the two.
The same here. I have three 28mm lenses, but it is the Tamron that I use for general shooting with my film cameras.


Steve
10-15-2010, 10:59 AM   #30
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QuoteOriginally posted by Lowell Goudge Quote
I have had the tammy 24mm F2.5 since the early 1980's and one thng I have found is that it has developed over time some significant backlash in the focusing. the performance is OK but there is a definite several degrees of rotation that do nothing at all between focusing collar and helix.
That was the problem with my Tamron 28/2.5. I slid off the knurled rubber focus ring and found that two grub screws were loose and one was missing. Tending to the screws fixed the loose-focus problem.
_ _ _ _ _ _ _ _ _ _

And I should have said to Steve: GREAT COMPARISON! And thanks for the pointer on the Access 28. EDIT: I just searched that thread and found nothing about the Access 28. Bother...

Last edited by RioRico; 10-15-2010 at 03:52 PM.
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