Tamron 70-200 vs Sigma 70-200

I don't know what you are talking about as I've used Sigma TCs with every brand of lens available on Pentax, Minolta, and Canon cameras. You may have to have them rechipped for some newer bodies sometimes but they can always be made to work.
Kent Gittings

Me either as my original *ist D had no problem matching a then current Canon body in low light AF. However I always used something like a Pentax AF240FT flash in spot beam only mode when in doubt.
Kent Gittings

KentG said:

2 things.
First the Pentax 1.7x doesn't "keep" AF with any lens you put on it.
It doesn't even use the lens AF under any circumstances. It stops the
AF connection as it has no AF motor shaft pass through and does it's
own AF inside the TC. SDM does not work through it either.

Second, I've seen examples of Tamron 1.4x TC with the SDM/power zoom
contacts so those models will work fine with any Pentax SDM or Sigma
HSM lens.

Kent Gittings

Click to expand...

Not all PZ TC's work with SDM the SDM algorithm appears to need some data that the Straight through contacts don't provide.

THe Pz Teleplus (kenko) 2X does not operate SDM.

KentG said:

I don't know what you are talking about as I've used Sigma TCs with
every brand of lens available on Pentax, Minolta, and Canon cameras.
You may have to have them rechipped for some newer bodies sometimes
but they can always be made to work.
Kent Gittings

Click to expand...

For Pentax mount.....

Sigma TC's have no chip in them they are straight through electrical contacts.

Sigma TC's are matched converters and as such have rear elements that fit inside the donor lens.

If the donor lens has
1 too narrow a rear portal
2 rear focusing element retract to the mount point

Then the repercussions will be as follows
in case
1 TC wont be mountable with danger you will scratch the TC trying.

2 when you cause the rear element of the lens to retract it will smash into the tc with the obvious result.

If you are going to attempt to use the SIgma TC's you must check for this prior to use.

Hi Moving Comfort.

Thanks for posting the images.

Is it normal for the CA that is visible in the football image (post and ladies shirt)

Its perhaps a characteristic of the oof area.

Yes even at this reduced size you can see the softness at 135mm compared with your previous examples.

The berry shots almost look like a focusing error, Though the ants look fairly sharp.

In your first series the puddy cat looks soft compared with the rest ,

You have remove exif data so what focal length was this at ?

This is the copy I have now. I had a previous copy with some slight issues at 200mm, but even that one was perfect at mid-zoom.

Here's a gallery I've posted previously showing full sized face shots at several f/l:

http://zumbari.zenfolio.com/p222008672/

If you mouse over the photos, a menu pops up on the left allowing you to download the original. They were developed in ACR 5.1.

Bart
--
http://zumbari.zenfolio.com

Hi Bart

Looking at the lad (your boy ?) in the 130mm shots your so close that the left eye is in focus whilst the right eye is out of focus.

the DoF seems to extend from just before the bridge of his nose to the start of his ear.

You are right though the sharp area is indeed sharp but seems overly sharp compared with the OOF did you apply any UsM or SS.?

Maybe its like the ghosting and only affect some lenses, The lens I tested was definitely weaker in the 110-140 range compared with the rest of the range.

But as I did no formal testing may well have been a bad ghosting copy.

Your BF/FF seems no be none existent an excellent result ... is it the same across the range ?

For that shot, it's just the default sharpening settings in ACR 5.1 which I consider pretty neutral (ie., creates crisp edges without any haloing). A couple of the shots have the sharpness turned up a little bit--setting it to default wouldn't change your impression much though.

When I get the Sigma, I'll do a true apple-to-apples comparison of the lenses--no futzing with settings.

One interesting thing about this Tamron (my copy) is F/2.8 is only about 2/3 stop brighter than F/4 (basically F/3.2 and F/2.8 look identical.) I don't know if it's because my camera isn't pushing the aperture lever all the way over or if this is just the way the lens is. I also haven't done this test for longer distances (only did it for a 1m distance grey card).

Bart

awaldram said:

Hi Bart

Looking at the lad (your boy ?) in the 130mm shots your so close that
the left eye is in focus whilst the right eye is out of focus.

the DoF seems to extend from just before the bridge of his nose to
the start of his ear.

You are right though the sharp area is indeed sharp but seems overly
sharp compared with the OOF did you apply any UsM or SS.?

Maybe its like the ghosting and only affect some lenses, The lens I
tested was definitely weaker in the 110-140 range compared with the
rest of the range.

But as I did no formal testing may well have been a bad ghosting copy.

Your BF/FF seems no be none existent an excellent result ... is it
the same across the range ?

Click to expand...

--
http://zumbari.zenfolio.com

Yes heard this before.

Posted in one of the threads where this was discussed , The conclusion was the Tamron was actually more an F3.5 lens than F2.8.

I stated at the time I didn't believe it but the evidence appears to be mounting.

i'm not experienced...just reporting what i read....so far for example my 1,7 penax cnverter works in auofocus wih every lens i have.

anyway everybody hat has he tamron and a converter shuld try i.

KentG said:

I don't know what you are talking about as I've used Sigma TCs with
every brand of lens available on Pentax, Minolta, and Canon cameras.
You may have to have them rechipped for some newer bodies sometimes
but they can always be made to work.
Kent Gittings

Click to expand...

--
http://www.pbase.com/jon1976

on the Tamron, does it mean the whole aperture range shifted 2/3 of a stop ?

lock

No--I only noticed the problem because F/2.8 is darker than it should be relative to the other apertures. What seems to be happening is it tops out at F/3.2. Setting the aperture to F/2.8 doesn't actually get me anything. So starting at F/3.5, everything seems normal.

Keep in mind I haven't made any absolute measurements. It's possible that F/2.8 is correct and all the other apertures are too bright.

Bart
--
http://zumbari.zenfolio.com

2.8 slightly darker than 3.2...

lock

awaldram said:

Mind you if absolute goodness at 200mm was my requirement I'd get the
DA* 200mm.

Click to expand...

Actually, the Tamron edges out the DA*200mm at 200mm according to some reviews (e.g. PopPhoto - there is a thread on this somewhere in this forum). Strange, but true. However, I am still leaning toward the DA*200mm for the size and quietness, as I have 50-135 mm covered.
--
Shooting since '59 and still waiting for a keeper

My Tamron 17-50 and former DA*16-50 do the opposite- that is after wide-open aperture they underexposed by 1/3EV. So for example if I shot at 1/1000 at f/2.8 and I stopped down to f/4 the camera would try to shoot at 1/640 whereas it should do 1/500. But the 1/640 expsoure was 1/3 EV too dark like it should be and if I dial in +1/3EV once I am past wide-open aperture on both lenses I would get 1/500 and I get a correct exposure that is very similar to the 1/1000, f/2.8 exposure so it seems they are both correct but the camera for some reason wants to underexpose with them past wide-open aperture.

The best way to test is to set up the camera in Manual mode (not aperture priority or any other). Set everything level - then shoot at f/2.8 at the correct exposure and simply dial in f/4 manually and the shutter speed manually at half the speed and the exposure should be very similar in the center of the image (don't look at corners since vignetting will play a part of course). When I do this - my Tamron and DA*16-50 are just fine - it's just that for some reason once past wide-open the camera actually underexposed by 1/3EV and I had to dial that in to compensate and get the correct exposure.

Cheers,
--
Sinan
http://sinantarlan.zenfolio.com/

I did the testing of the 70-200 in manual mode. However, my k10d correctly "sees" that F/2.8 is comparatively dark. If I set aperture and shutter for proper exposure at F/4. Then go to F/2.8 and double shutter speed, the exposure meter thinks the scene is 1/3 stop darker--this is spot meter.

This agrees with ACR 5, in which I have to boost the exposure slider by 0.35EV to get a match between the equally exposed F/2.8 and F/4 shots. Sort of like vignetting that extends all the way to the center of the image.

If I get a chance, I'll cross-check between my 70-200, 17-70, and 50-200.

Bart
--
http://zumbari.zenfolio.com

I had some comparison data at F/4.5, 70mm on my Sigma 17-70, Pentax 50-200, and the Tamron 70-200.

The Sigma and Pentax agree perfectly. The Tamron is 0.25EV brighter than those other two. Assuming the other two lenses are "correct" at F/4.5 (since they agree), that suggests that the Tamron is in fact too bright at smaller apertures, which implies it's pretty accurate at F/2.8 (maybe still 1/6EV too dark).

I should say there's a very small amount of rotational play in the lens when it's mounted. I'm sure this rotation will change the effective aperture setting. To deal with this mechanical tolerance, maybe Tamron has the aperture control hit the max a little early.

I don't have anything for 200mm. I'll only be able to compare with my DA50-200.

Bart
--
http://zumbari.zenfolio.com