[HenriCartierShufflebottom]

Please all be VERY SUSPICIOUS about the ephotozine.com review of this lens.

 

All negative comment is being removed and indeed (in my case) my account removed?

 

As ephotozine say themselves their review is (was) a exclusive.  Not sure whether that is the source of supression of criticism but it does bring into question the integrity of the review.

 

It would therefore be great for PHOTOZONE to do an impartial review as at least we all respect what gets done and said here.

 

Since this lens appears to promise so much a review sooner rather than later is needed and a truly independant one!

 

In addition, is anyone else in Europe somewhat unhappy about the pricing by Tamron EU versus North America?   Artificial price fixing and to the dis-benefit of the EU consumer.

[mst]

Your math skills seriously suck 

And your logic skills are simply... Well, to be expected from Brightcolours

Sorry to be harsh, but allow me to add that you both seriously lack communication and behaviour skills, especially when arguing against each other.

Klaus' point was: he has done longer tests in the past, reaching up to 800mm equivalent focal length, which is no doubt longer than 600mm on full-frame (!). The Tamron is a full-frame lens and will be tested on a full-frame camera (if at all).

When the 200-500mm lens was reviewed, full-frame tests were nothing but a distant dream here at PZ, that's why testing it on APS-C was the only option.

-- Markus

[JJ_SO]

I give up. If everybody here is so sure about equivalent focus length and real focal length are the same, there's not much of a point discussing it. To me it remains different things.


And Markus, allow me to reply, Klaus was writing about nothing else than 200-500. NOT THE SAME AS 600mm, in no case. I don't know which lenses he checked in the past, I was just looking at the Canon section of PZ. I don't want to go into skills and lack of, I think everybody can make his/her own opinion about that discussion. And by the way, Brightcolours and me are not always loosing temper when discussing together maybe we sometimes forget, the PZ forum is shared by only few participants but maybe more readers.

[Brightcolours]

I give up. If everybody here is so sure about equivalent focus length and real focal length are the same, there's not much of a point discussing it. To me it remains different things.

You need to understand that the testing target remains the same size, and needs to fill the frame in a particular manner (the corner target needs to be in the corner, the border target in the border and the center target in the center). The test targets are about lines/line pairs per image height.

This makes that for 135 format "full frame" one shoots at a shorter distance to the test targets than with 1.6x crop APS-C, for instance, with the same focal length. 

 

So, for the MTF tests, equivalent focal lengths are which dictate the testing distance. I believe that the MTF targets used are designed for 51x the focal length for 135 format (35mm film photo format). So if one were to test a 6x9 MF camera + lens with these targets, one would use a 2.4x (crop factor compared to FF) shorter distance with the same focal length than "full frame" 135 format.

 

I have some old test targets which were designed for 101x the focal length distance, which would mean an even bigger required test distance, especially with APS-C or MFT.

And Markus, allow me to reply, Klaus was writing about nothing else than 200-500. NOT THE SAME AS 600mm, in no case. I don't know which lenses he checked in the past, I was just looking at the Canon section of PZ.

Again, Klaus meant that he had tested longer lenses (meaning: lenses with a longer focal length than PZ does now) before. He did not mean longer than this particular Tamron. Due to the current testing "facilities", it is difficult or impossible for the PZ members to test 600mm, let alone 600mm on APS-C, due to the required shooting distance.

 

By the way, the test target design has another limitation: one can not test lens resolution for a lens at different distances. So, wide angle lenses can't be MTF tested for infinity (which gives at times some skewed results, like with the Voigtländer 20mm f3.5 SL II for instance), and one can not test at macro distances so the MTF tests for macro lenses show how they perform as portrait lens and not as macro lens. And for instance, lenses like my Ultra Micro Nikkor 55mm f2 and the Canon MP-E 65mm f2.8 can't be tested at all.

[Klaus]

Just to end the discussion - Markus volunteered to test the Tamron 150-600mm.

Germany in wintertime is cold enough for this ;-) The wind situation may be more tricky so it may take a while till the conditions are accordingly.

[mst]

Jeez... just how complicated things can get.

Let me quote Klaus again "I've done longer tests in the past".

To get things back down to very basic facts (and away from equivalency discussions, which are fruitless in this context): "longer" simply refers to the shooting distance required. Since the test target doesn't change, a 500mm lens on a APS-C camera requires a longer shooting distance than a 600mm on full-frame. It's as simple as that (and, yes, due to "equivalent focal length"... or cropped field of view, if the other phrase gives you headaches).

As Klaus already said, I'll test the lens on Nikon FX (and FX only). And, to add some fuel to the fire, probably alongside the Nikon AF-S 80-400 VR

However, I don't know yet when those tests will be done and published. In fact, the Tamron isn't even available over here, yet.

-- Markus

[JJ_SO]

What I simply don't understand is the reason why one lens (Tamron 200-500) is tested on APS-C and the other lens, which has the longer focal length, has to be done on fullframe. Now, if 500 is good for APS-C, why not 600? Too much of a distance to the target?

 

Other way round: Tamron says, "Di" in the lens' name is for APS-C and full frame. So, both lenses are also usable for fullframe, or I'm misunderstanding some texts of Tamron. Either way, it doesn't make much sense to compare those lenses when one was shot with APS-C body and the other fullframe. And it was the reply for the question a couple of posts ago which puzzled me.

 

But there's no need to continue. I can live with being puzzled  :blink:

 

Anyway, have fun with testing the lens. As far as I'm concerned I find lensrentals a reliable source for information about resolution of lenses and the comparison Roger already did could be enough for me to choose one of those candidates. Okay, they don't tell much about vignetting, but they usually test a whole bunch of the same lens which also gives interesting information.

[Klaus]

JoJu ... it is simple. I just don't understand why you can't get it honestly.

 

I tested the Tamron 200-500 long ago ... probably 6ish years ago. If you read the review you will notice that it was done on a 8 megapixel EOS 350D. Based on this (APS-C) camera the shooting distance was 30m(!). I finalized the test but thereafter I decided that this isn't practical anymore for the various reasons that I outlined before.

One very simple point is that the results aren't even comparable WITHIN the same system anymore - simply because of air diffusion. A 20mm is obviously far less affected than a 500mm lens.

Now as a solution we could obviously ask NASA whether we could rent their vacuum chamber used for Space Shuttle testing over in Florida maybe ...

I could have repeated the exercise on full format (at a lesser distance) - ignoring the mentioned limitations this is technically possible, of course.

 

Given the interest we decided that Markus will give it a try. However, we'll add a word of caution to the review.

 

Generally 400mm will remain the finishing line. Beyond I have issues regarding the quality control of the tests. Risking consistency is risking reputation and that's our most valuable asset.

[JJ_SO]

Let's put a stop on it. In understood those points and am thinking maybe I didn't make myself clear enough. As I said before, with those lenses it's a lot more than only lens quality to get good sharp shots out of it.

 

Lensrentals used a backlit luminescent target instead a reflective one. I also think the usual 50× focal length rule could be questioned. As you already did, didn't you? 50×800mm is 40 metres.

 

Please don't bother about borrowing NASA vacuum chambers. Not much of us use these devices often 

[Klaus]

It is 30m (APS-C: 60x focal length). 

The magnification of the test target is identical across all focal lengths. 

Technically it is possible to come closer but then you require a higher resolution test target and the error margin increases due to the more shallow depth-of-field.

We had some discussions regarding test targets based on masks used for chip manufacturing.

 

I think backlit targets would violate the Imatest guideline of testing dark grey targets - using backlit you increase the contrast between black and white quadrants.