[madbrain]

So far, inconclusive. Some cases are worse, some appear to be better. I'm not sure how to predict!

Today I photographed a plane in flight with the 28-105mm + Pentax 1.4x converter. It was simply a test which I expected to fail, but it didn't!

Assuming this way daytime, there would have been plenty of light, so not that unexpected.

Yesterday I photographed a statue with the same combination. I thought it should be an easy success. But it failed.

How did it fail ? Bad focus ? Or acquired focus, but bad quality image ?

I think the problem is that the lenses I was trying the converter on, (28-105mm and 150-450mm), are naturally f/5.6 at the long end, which becomes problematic once the converter is on. If there is low light, the combination is pushed into noise or shake. Some failures were on a tripod with a slow shutter speed, and a 2-second self-timer which switches off SR. But something managed to shake the camera during the slow exposure.

Yes, low-light really and high f/stop throws the teleconverter off too.
If the issue is just focus, for a static subject and tripod, you can use manual focus and live view with focus peaking. That is what I did in my tests.
Depending on which tripod you have, 2-second self timer may not be enough. When I was doing my tests on tripod with the highest focal length + TC (ie. 420mm equivalent), just changing aperture with the dial, it took a long time for the image to stabilize in live view. Much longer than 5 seconds. And I used wireless remote control rather than self-timer. I waited about 3-4 seconds, plus the 3 seconds delay with wireless remote drive mode. At that point, the image was fully stable.

This won't help me much in the field, though, as I normally don't carry a tripod with me. A tripod weighs more, takes more space, and more time to setup the camera on it and shoot. I use the tripod mostly at home. So, the teleconverter won't really be all that helpful at long focal length. If it only works at smaller focal lengths, then it is just not as useful, and won't help with getting a FF superzoom replacement, no matter which lens is attached (D FA 28-105mm zoom, or APS-C superzoom).

---------- Post added 07-07-18 at 02:58 PM ----------

Something to consider as well- the crop mode does give a larger image in the frame, but not actual magnification, while the addition of a TC does provide additional magnification. But then come the downsides of the additional glass, and yet slower aperture (even higher ISO). I think a better test would be no TC and the Sigma 18-300mm lens at 300mm in FF mode, and at 200mm in crop mode, even though the FF 300mm would still have greater actual magnification. That still would not address the matter of the lens's wider aperture, and thus potentially lower ISO, capabilities at 200mm vs 300mm in dealing with lower light situations.

IMO, using higher ISO is OK on a body like the K-1 II which has very good sensor performance.
As far as the Sigma at 200mm in crop mode without TC, I did test that here :



Using the Sigma 18-300 in FF mode without TC produces very significant vignetting. I will do a few test shots now to show just how much.

Edit: those test shots are here. Just meant to show the vignetting. I shot in FF mode and square (1:1) modes, at various focal lengths - 18mm, 80mm, 135mm, 200mm, 300mm.
https://imgur.com/a/nQy9SFP

As you can see, there is significant vignetting in all of them, even in square mode. Unless you are looking for a circular image, without a TC, the Sigma 18-300 lens really doesn't fill much more than the APS-C portion of the sensor. And really, you can't expect it to, as it is an APS-C lens.

With the Tamron 1.4x TC, it fills most of the FF sensor area (not all), but you pretty much lose AF at longer focal lengths.

---

Last edited by madbrain; 07-07-2018 at 03:10 PM.

[madbrain]

As far as a walkaround zoom, I'm quite fond of my Tamron 28-300mm (A06) lens. Probably not top of the heap in terms of image quality, but I haven't noticed any glaring flaws in terms of rendering.

Thanks ! I looked up this A06 model, and it looks like it was the last version released for 35mm film cameras, at least according to Wikipedia (might be wrong!).

Tamron - Wikipedia

Lenses for 35mm SLR cameras
...
Tamron AF 28–300 mm f/3.5-6.3 Ultra Zoom XR LD Aspherical [IF] Macro (model A06, variants A06M)

But below, one can see :

Di lenses for full-frame DSLR cameras
Tamron AF 28–300 mm f/3.5-6.3 XR Di LD Aspherical [IF] (model A061, variants A061E, A061M/A061S, A061N, A061P)

DXOMark finds the following data for the Sony e-mount version on a full-frame A99 II body :
Tamron AF 28-300mm F/3.5-6.3 XR Di LD Aspherical (IF) Macro Sony

Sharpness is listed at 10 Mpix there. Much better than the other superzooms, which were evaluated in the 3-8 MPix in sharpness, depending on which body they were tested on - but mostly APS-C bodies, not full frame bodies.

Of course, there is no data for this lens in Pentax mount on K-1 or K-1 II . And I still have my doubts about DXOMark's methodology - reporting sharpness as a single number for a zoom lens with variable apertures.

The A061P is the Pentax version. I just ordered one from Amazon for $199, missing the hood and front cap. I hope this is a working copy. It won't have as much magnification as the Sigma 18-300 APS-C, but it will at least illuminate the entire sensor.
I couldn't find any review of the Pentax version of this lens.

The A061 in general is a really old lens, and the reviews I can find are on other bodies.
For example, Tamron 28-300mm f/3.5-6.3 XR Di AF Review in Canon mount. This is a fairly negative review. I'm not sure how much of it really still applies to current bodies. The Canon 5D and 1Ds Mark II must have been quite a bit more expensive than my K-1 II is today, and with much worse sensors back then. It's hard to imagine any lens bad enough that you would be reduced to printing only at 5x7 and below.

A lot of user reviews (such as Amazon, or even here on Pentaxforums in the lens database) seem to mix up the A06 (non-Di) and A061 (Di) versions. Ie. people are giving bad reviews of the non-Di version for the Di lens. I don't know how much better the later really is.
Not sure when I will actually receive the Tamron A061P - hopefully by next weekend. I won't have time to do elaborate tests during the week like I did last thursday with the Sigma 18-300 .

[h4yn0nnym0u5e]

Re: shake, I think the SR mechanism does not work properly with the TC. It just passes the electronic focal length info from the lens. But that is off by a factor of 1.4 when using the TC. So, for handheld shots, better not use the TC.
Actually, SR was disengaged completely for this shot. It was taken handheld even though the camera was still in "remote control, 3s" drive mode. So the shake is easily explained - not by the TC, but by user error?

Slightly OT, but do note that you can turn off the SR disengagement with remote, if you want. I do, as I've lost more shots due to accidentally having no SR than to it over-compensating when on a tripod... See custom settings menu page 3, item 21, or p56 of the manual.

Cheers

Jonathan

[madbrain]

Slightly OT, but do note that you can turn off the SR disengagement with remote, if you want. I do, as I've lost more shots due to accidentally having no SR than to it over-compensating when on a tripod... See custom settings menu page 3, item 21, or p56 of the manual.

Cheers

Jonathan

Thanks. I'm aware of this option. I chose to leave it as default. Usually I notice the red blinking light for remote trigger. This one time, I just didn't pay attention.

[madbrain]

Not sure when I will actually receive the Tamron A061P - hopefully by next weekend. I won't have time to do elaborate tests during the week like I did last thursday with the Sigma 18-300 .

Received it today. Unfortunately, it's model A06, not A061 as it was advertised to be. A06 is the non-Di version, unfortunately. So, I'm sending it back. This is getting tedious as it's the 3rd FF K-Mount superzoom that I buy which is not as advertised. First one was defective, second one was a Canon mount, third one wrong model. Sigh.

[Mallee Boy]

Been for a walk with my A061 Tamron 28-300 while the car was being serviced. Unfortuneatley I probably could not have picked a worse day, dull, cloudy and flat un-interesting light. I took the old f 35-80 along as well.

the Tamron was dis-appointing, in this light where it was shutting itself down (I shot in P Mode) to get a useable shutter speed, images were soft and often showed a hint of motion blur. The 35-80 ran rings around it. Remember this is letting the camera do the work and hand held. However, next day, bright light, lots of contrast around and the Tamron was much better.

[timw4mail]

Been for a walk with my A061 Tamron 28-300 while the car was being serviced. Unfortuneatley I probably could not have picked a worse day, dull, cloudy and flat un-interesting light. I took the old f 35-80 along as well.

the Tamron was dis-appointing, in this light where it was shutting itself down (I shot in P Mode) to get a useable shutter speed, images were soft and often showed a hint of motion blur. The 35-80 ran rings around it. Remember this is letting the camera do the work and hand held. However, next day, bright light, lots of contrast around and the Tamron was much better.

Yeah, a rainy day is not great news with a superzoom.


One thing I found interesting: I have an older Tamron 28-200mm lens (171D) that is faster on the long end, but slower on the wide end. ( I think it's basically a autofocus version of the Adaptall 28-200mm (71A))

171D (28-200): 3.8-5.6
A06 (28-300): 3.5-6.3

Considering how much better the image quality is on the A06 though, I can live with the slightly worse autofocus performance.

[madbrain]

Yeah, a rainy day is not great news with a superzoom.


One thing I found interesting: I have an older Tamron 28-200mm lens (171D) that is faster on the long end, but slower on the wide end. ( I think it's basically a autofocus version of the Adaptall 28-200mm (71A))

171D (28-200): 3.8-5.6
A06 (28-300): 3.5-6.3

Considering how much better the image quality is on the A06 though, I can live with the slightly worse autofocus performance.

Would be interesting to compare all these.
I haven't tried my A06 yet, still waiting for return label from the Amazon seller.
I ordered an A061 from Japan as I couldn't find it anywhere else. Will not have both on the same day to compare directly on tripod as I did before with other lenses.

Rain is not a major concern for me. I am rarely in those conditions. Would use the D-FA 28-105 if I was.

[madbrain]

So I got the Tamron A061 28-300mm XR Di FF lens . Seems to be OK. I didn't do any exhaustive IQ comparison tests yet. Probably this weekend. It seems slightly slower to focus than the Sigma 18-300 APS-C.

Took a whole bunch of cat pics at night in borderline lighting conditions.

One of them was the following at 180mm, f/5.6, ISO 16000 .



Not all the picture were this sharp. It seems worse on wide end than tele end. But will have to conduct more tests.

[clickclick]

ISO 16000

Did you mean 1600 or is it 16000?

[timw4mail]

Did you mean 1600 or is it 16000?

The noise suggests to me that 16000 is likely.

[clickclick]

The noise suggests to me that 16000 is likely.

Yes, in the table leg especially, but the kitty's face looks pretty nice. So just wanted to verify. If 16000, I should push more with my K1. I usually use 3200 as my upper end.

[madbrain]

Did you mean 1600 or is it 16000?

I really meant 16,000 .

[madbrain]

So, I just compared the Sigma 18-300 in APS-C and the Tamron 28-300 XR Di in FF. This time I shot the inside of the piano again.

Comparing the field of view, it is close (but not exactly the same) for the FF lens at 300mm and APS-C lens at 143mm. But obviously the FF lens offers much more resolution for the same field of view.

I get more center resolution with the 28-300 FF . At the longest focal length, the strings on the piano take up more pixels in the FF image at 300mm than the same strings in the Sigma APS-C image also at 300mm (450mm in FF equivalent).

I can't quite say which one is sharper as the focus is very critical and only part of the strings are in focus. The live view & manual focus helps with that, but it's not possible to get exactly the same section of strings to be in focus on both lenses. I would need to be shooting parallel to the strings, and I'm shooting at an angle.

I can't do it with my tripod, even with the pistol head. The camera can face straight down and is high enough, but doesn't extend into the piano - it can only shoot the floor this way. I would need an extension between the tripod head and camera. And I don't think I would trust it to hold the camera. Maybe cinematographers would know what kind of rig is suitable. I don't have it.

Anyway, the point is that the very old FF lens still provides more resolution when zooming close.

The focus speed difference is very major, however. The Tamron is very slow to focus in CDAF. The K-1 II ends up doing 2-3 revolutions of the focus ring before finding focus on the strings, and this can take >10s with the Tamron lens, and is quite noisy. With the Sigma lens, it still can take 2-3 revolutions, but it is much faster, and also almost completely silent. In PDAF (not in Live view), the AF speed is much more tolerable, and the difference isn't nearly as dramatic.

What remains dramatic is the sound of focusing. One of my cats certainly noticed when I was using the Tamron lens last night and autofocusing. Her ears did something funny :


My cats don't seem to mind the very slight noise of the Sigma lens as much.

[clickclick]

I really meant 16,000 .

Thanks! Really think it looks pretty good. I need to do more experimentation with higher ISOs. You are using a K1 II though, so I probably would have to do some work in post with my K1 to match how good your noise levels are.