Tamron SP 24-70 f/2.8 VC USD G2, calibrating the lens with Tap-In Console


I’ve always liked Tamron SP lenses as I think they give a lot for the money. SP, Super Performance, means they perform on a high level, more or less on the same level as first party lenses, without the same price tag. I’ve owned Tamron SP lenses for more than ten years and have been pretty happy about them, so when Tamron announced their updated version of the already very good 24-70 f/2.8 VC, I actually sold my Nikkor 24-70 f/2.8 VR to get the new Tamron. I’m not saying that the Tamron is better than the Nikkor, but it freed up some money that I could use on something else without sacrificing much of the performance (if any).

Equipment-0484

If you wonder about the Tap-In Console, I made a short article about it HERE.

This lens was my second Tamron lens to be able to use the Tap-In Console, and I would call it one of the most ingenious gadgets in the photo world, it’s also source of head-scratching. Why head-scratching? Because you might learn something about your lens that you haven’t thought about if you weren’t deep into lens design.

According to the Tap-In Utility, the 24-70 G2 should be calibrated at closest focus distance, medium distance and infinity (medium distance means half travel of the focus ring from closest to infinity), and at 24, 35, 50 and 70mm focal length. How to perform the actual calibration procedure is nowhere to be found in the documentation with the lens or the Tap-In Console, so I expected it be done at largest aperture as this is most common.

Tap-In Utility

During this time period I sent an e-mail to Tamron in Japan, Europe (Germany) and USA if they had a step by step guide on how to do it, and also how far away is enough for calibrating at infinity with both of the mentioned G2 lenses (24-70 and 70-200). Japan responded first, by forwarding it to the European department as the request was outside of their area (maybe the Tap-In Console works differently in Japan?)! Got only one response from Germany telling that: “The distance is 0,95 meter, 5 meter and by infinity more than 20 meter.” That’s it! Nothing more! Obviously, this is for the 70-200 lens, but what about the 24-70 mentioned in the same e-mail and the other questions?  Only useful information was “more than 20 meters”, which doesn’t appear in the Tamron utility and I find it strange as the furthest distance reported in the image file is 35.48 meters at 70mm focal length and 100.00 meters at 200mm!? From USA I got a couple of answers but in general they were just ramblings with no useful information and in the end, I didn’t even get an answer any more. I mean, the Tap-In Console was announced in the beginning of 2016, so I expect Tamron Customer Service knows what it is or are able to dig up an answer to provide some useful information?!

When I first got my 24-70 G2, I noticed considerably back focus at longer focal lengths that was easily visible in the viewfinder, but I just dismissed it in my mind as user error with a new lens, still the memory was lurking in the back of my head. This back focus was confirmed when I started the process of calibrating the lens late autumn last year.

0526

I mounted the camera and lens on my Manfrotto tripod and illuminated the focus target with good light, and measured 38cm from the focal plane to the target and started the calibration with Reikan Focal 2. 24 and 35mm appeared to be not so bad (+2 and +7), but at 50 and 70mm I came quickly to +20 on both!  Hm, that was unexpected, and I started thinking about the whole setup if I’ve overlooked something. The setup looked good but then I started to question the focus distance, is it the real measured distance that should be correct, or is it the distance the camera and lens think is the right one? This focus distance is embedded into the image file and can be read by an exif reader, so I found there is definitely not any accuracy in the embedded distance, but on the other hand I’m pretty sure it’s this distance the camera and lens are using.

If you want to know more about Reikan FoCal, I’ve made an article HERE.

So, after this somewhat revelation, I went back to doing another run of calibration where the camera and lens thought 38cm was (actual measurements was 41,5cm) and ended up with more or less the same at 24 and 35mm, but 50mm changed from +20 to 0, while 70mm wanted slightly more than the possible +20! Ok, didn’t see that one coming.

0527

At 1 meter, the next focus distance, the lens behaved more predictable but still massive plus values needed to get it corrected. This, together with somehow similar results from the SP 70-200 f/2.8 VC G2, made me contact the store where I bought them, explaining the behavior of the lenses and ended up returning both of them! After about a month I got a brand-new copy of both lenses, more about the 70-200 G2 in another post.

And guess what? Indeed, the new copy behaved slightly different, but still quite similar! Head scratching, what is going on?! Could it be my camera? As it was a recall because of the shutter problem last year, I sent the camera to service and asked them to take a look at the auto focus at the same time. When the camera came back I noticed that the calibration values I’ve added earlier was consistently a couple of values off, so I’m pretty sure they have serviced the auto focus too. The camera out of the way, I continued to search for other explanations and I looked through some other calibration values I’ve done with other lenses. My 200-500 VR is pretty consistent at short and medium focus distance, the same with the Tamron 10-24 VC (in crop mode) gave me a variation of ± 2. Even the superzoom Nikkor 18-300 VR (also in crop mode) had only ± 1 throughout the zoom range. This doesn’t mean it initially was dancing around zero, simply indicating the difference between largest and smallest number throughout the focal range, all had some values into the plus side.

0528

More head scratching. Then I started thinking, what if I was able to calibrate at other apertures? Would it make a difference or would it stay the same through the aperture range? My calibration software, Reikan Focal was able to set desired aperture, so I run through the calibration at f/2.8, f/4, f/5.6, f/8 and f/11 at all focus distances, and at all focal lengths mentioned above.

Below is a print screen of the results and I really didn’t imagine that it would be like this, referring to the beginning of the post when I wrote you might learn something new. As we can see here at focus distance of 38 cm, quite good at 24mm, but from 35mm and on there is a massive swing from plus to minus values, especially at 70mm.

24-70 0.38 meter

Further we see more or less the same at focus distance of 1 meter, very good at 24mm, but from 35mm and on, a large swing from plus to minus. Although not as much as at 38 cm focus distance.

24-70 1 meter

And finally here are the numbers from infinity. Considerably less of a spread and almost surprisingly tidy. The solution that worked for me, was to set the focus a hair to the left of the middle of the infinity mark on the lens, flip the switch to manual focus and then aim at the focus target and walk away from the target while looking at the focus confirmation in the viewfinder. When walking too far away, the dot starts blinking. Then take a few steps towards the target until the dot is stable. In my mind this is the outer end of the infinity limit, because you can walk surprisingly close before the confirmation dot start blinking again at the closest end.

24-70 infinity

NA at 50 and 70mm means there where no conclusive answer as the curve was almost straight between -20 to +20, making it a hit or miss the give any number at all.

Honestly, I’ve never imagined that the plane of focus would move so much and for so many reasons. Not only does it move at different focal lengths, it moves at different focus distances and with different aperture too! My first thought would be, is this normal, does all or most other lenses behave like this too?! Unfortunately, I don’t have any of Nikon’s f/2.8 pro zooms available anymore, so I took my next best thing, the Nikkor 16-35 f/4 VR and here are the results from this lens.

16-35 0.50 meter

And here the still popular Nikkor 50 f/1.4D

50 3 meter

A short explanation of the letters after the values. I’m using Reikan Focal software to help me determine the correct value, and Focal are using four words to tell how good or the quality of the final value is. The best is Excellent, then Good, then Acceptable, and finally Poor. If I get an Acceptable or Poor result, I normally do another run to confirm the first one, and sometimes even a couple of more runs if there is a big difference in the values and in the end calculate the average value.

I won’t say that this is normal behavior of all lenses based on only those mentioned here, but at least it looks like it’s not so uncommon? Later I will do similar tests of the 24-120 f/4 VR and the 200-500 f/5,6 VR to see if it’s more prone in shorter or longer focal lengths.

Update; here are the numbers from the Nikkor 200-500 VR at 5 meters. I’m not sure if this revealed much of a pattern though.

200-500 5 meter

So then comes the big question, how to choose witch value to add in the lens when it varies from huge plus to massive minus values? Well, that’s a very good question! For me though, I buy f/2.8 zooms to use them at large aperture, so I will aim the final calibration at f/4 and then it will be close enough at f/2.8, f/4 and f/5.6. If there is something like the 24-70 G2 at 70 mm at 38 cm, I will probably make a compromise between f/2.8 and f/4, and keep that in mind when wanting to use the lens at smaller apertures and close to 70 mm (like using live view could be a solution).

If any of you have been wondering about the order of calibration, I’ve come to the conclusion to start in one end of the focal length and work your way through all focal lengths to the other end, witch end you start should not matter. When it comes to focus distance, I’ve been thinking it would be a good idea to start in the middle, then each end and then reconfirm the middle again in the end. Reason for this is that if you need to add “bigger” numbers at one or several focus distances, it may affect the neighbor distance as well (not sure about this though, but this way will take care of it if it does). I mean if you start in one end of the focus distance, then the middle and in the end the last, you need to reconfirm the middle and the first to be sure all are good. If you start in the middle, then both ends and finally reconfirm in the middle, you will have less work. Calibrating a lens is time consuming enough as it is.

Another short update: I’ve been playing with the Tamron SP 15-30 f/2.8 VC lens last days, and I think I’ve come across a rule of thumb on how to calibrate at infinity, finally. Some may say it’s quite obvious, and I think I’ve been partly fooled by the name “infinity”. In this context it’s not “endless far away”, and when I finally accepted that fact, the pieces started to fall into place more easily. A common thread with all Tamron SP f/2.8 lenses I own, is that the longest reported focus distance correlate somewhat with the focal length. Take the focal length in half and replace millimeters with meters, like 15mm will be 7.5 meters, 70mm will be 35 meters and 200mm will be 100 meters. This is more or less exactly what the longest focus distance reported from the lens and camera, that are embedded onto the image file. In practical terms it means how far away is needed to get to the longest focus distance. It’s just trial and error, as the real measured distance is hardly only a guideline. Take a photo of the focus target and see what is the reported distance in the file and move accordingly if needed. I also think it’s a good idea to not move too far away, only enough and then some. Means if you exactly reach longest focus distance at a certain distance, add a few % so you are sure it is actually enough (I’ve seen reported focus distance move quite a bit between calibration runs without the actual distance have been change).

I guess when you’ve read so far you have a feeling the whole story is somewhat negative, and I agree. But remember what this is, a post about calibrating the lens, not about how it perform in daily life. So I think this slight negative angle is justified, I think Tamron could have provided better user manual on how to do the calibration. In their tech pages online they could also have explained the behavior of the lens at different lens designs without giving away any design secrets.

As mentioned this is not a post to talk about the performance of the lens, but I will say I really love Tamron lenses and how they make the photos look, so don’t let this post scare you away from any of the fantastic SP lenses from Tamron. I will not hesitate to buy another Tamron lens in the future.

Equipment in use for the calibration:
Reikan FoCal 2 calibration software on my PC.
Reikan focus chart printed in highest quality on 120g non glossy paper for close and medium distance, printed in A2 size for infinity.
Tamron Tap-In Console and Utility.
Nikon D750.
Tamron SP 24-70 f/2.8 Di VC USD G2.
Manfrotto 475B tripod.
Kirk BH-3 ball head.
2x Dynaphos soft-boxes with total about 450 watts of low energy lights for illumination of the focus chart indoors and daylight outdoors.

Conclusion is easy for me, but I don’t have any proof to give you guys, so you’ll have to trust me when I say that the lens performs as expected from a Tamron SP lens after calibration. When all values had been added to the lens and I went outside to do some final test shots, focus looks to the best of my judgement to be spot on. As I don’t have any before photos, I can’t show you any, but here is one after.

Focus-0989

NB, the values mentioned throughout this post is only valid for my lenses together with my camera, do not expect they will fit your lens and camera, they might end up making your lens worse! So, do your own calibration and find your own values. I posted those values only to prove the point, not to give the final answer.

If you have some comments or questions, let me hear from you in the comments below!

Thanks for visiting!

 

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11 comments

  1. Hi,
    I read an article last week that was about calibrating the Tamron SP 24-70mm f2.8. They were saying that when calibrating at a set distance, let say .38m. Once they had set 24mm (say +5)and moved on to the 35mm and set that number (say-3), they had to go back to the 24mm and re-calibrated it as the software had changed the calibration . It still was at (+5) but the focus point had moved sometimes up sometimes down. So it turned out to be a trail and error over the 4 focus lengths until all calibrations aligned. It seems a lot of trouble. Have you in you calibrations experienced any thing like this.

    Like

    • Hi nelgnej and thanks for sharing.

      No, not between focal lengths, but focus distances. Between focal lengths at same focus distance I’ve had no trouble. But o’boy I’ve had my share of disappointment at different focus distances at same focal lengths. My best guess is that the lens wasn’t set accurately at the right focal lengths every time, but there I’m just guessing…

      Do you have a link to the article?

      Ove

      Like

      • Hi Ove,

        Here is part of and email I received from Tamron Service Australia about the problem of rechecking previous adjustments.

        “Yes that can happen performing focus shift adjustments on Tamron lenses can be very time consuming, the other thing that happens is if you input a too high a number to bring a distance correct it can influence the focus curve and alter the other results this is one reason why you have to go back and forth and check. Prime lenses are a lot easier to adjust but zooms more difficult and time consuming.”

        Plus it is mention in the YouTube Video https://youtu.be/XrR-R0Jp6M8.

        In the end I gave up on Reikan Focal as the tests were not consistent. I ended using the method used in the video. I connected to Lightroom and used it to trigger the camera. Starting at 24mm took the shot, and removed the Lens did the adjustment to the lens, (did not use the fine tune in the camera), re-took the shot to check adjust again at 24mm @ .38. If correct the moved on to 35mm, used the same procedure, once 35mm adjustment was correct I then checked 24mm again and adjusted accordingly if necessary, then recheck 35mm. Once 24mm and 35mm were correct then move on to 50mm and repeat the whole process again. While it is very time consuming I found the end result was excellent.

        Liked by 1 person

      • Hi Glen.

        Thanks for sharing the email and the youtube link. For the email, I’m a little surprised that they (Tamron) obviously know how tricky it is to calibrate zoom lenses, but has absolutely zero information about the process on their websites (or at least last time I checked). As touched into in one of my articles, I sent a similar email to Tamron Europe, USA and Japan. Tamron Europe has yet to answer, Japan forwarded the email to Europe, with a copy to me, as I belonged there and never heard more from them too. Tamron USA replied in manners that showed they had no idea what I was talking about. After some emails back and fort trying to explain in different ways, they got silent. Sometimes I really regret I put my head into this hornet’s nest. It would be a blessing to live in bliss….

        I don’t want to be negative, the performance of the Tamron lenses are very good when the focus is in the right place, but I truly wish they would have done the calibration process a bit easier and at least provided a step-by-step guide that worked.

        Best
        Ove

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      • Come to think of it after looking at the video you linked to, he is using the markings in the focus window on the lens. This is something that definitely didn’t work for me, but that shouldn’t influence between focal lengths?! Curiouser and curiouser, as the cat said….

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  2. Hi! I read your article but I had a much easier time with calibration. I placed camera & lens and target on a flat table, placed a book under the camera & lens to level it with the target, I moved my target back or forth so that the lens displayed the exact distance as illustrated in the TAP-in console software, f/2.8 only, one focus point, adjusted closest distance then middle distance and dismissed infinity altogether. My lens became stunningly sharp as a result. I had to go as far as +9 at the middle distance for about all focal lengths. Was I just lucky?

    Liked by 1 person

    • Hi Ed, and thanks for your comment, much appreciated.

      I’m both envy and agree, this is how easy it should have been, but this way didn’t work for me. It could be the combination of lens and body, who knows. At medium distance this should work fine though, but out of curiosity, did you measure the actual distance at medium and closest? What body do you use?

      Dismissing infinity could maybe work with the shorter focal lengths, but for the 70-200 infinity definitely needs to be addressed. Your way though, could be an interesting experiment doing somewhere in time to see how it correspond with measured distance…

      Like

  3. As a Canon user I can tell you that if you have a canon that has Microdeadjustment built in then use that method. I purchased the tap in console and its just a waste of time. I spent 8 hours trying to get focus sharp with the tap in and finally gave up. I then calibrated using my in camera microdeadjustment and got this lens tack sharp at all distances and focal lengths in 30 minutes. Please people, if you have in camera adjustments use them as the Tap In is a piece of garbage.

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