[jatrax]

Tamron MFD is 0.95m (0.32x), Pentax is 1.20m. (0.13x); right off the spec sheets.

So about 10 inches closer? Better but not likely significant for most people. Still the price is vastly different if that is important.

[Kozlok]

So about 10 inches closer? Better but not likely significant for most people. Still the price is vastly different if that is important.

The magnification ratio is 2.45x as much, so quite a lot, actually.

[amoringello]

Amazingly sharp at f2.8. I would think keeping the subject properly in focus would be difficult at that aperture, but the K1 focuses so much better than any other Pentax camera I've used. It almost magically focuses on the right spot almost every time.

100% crop, f2.8, 200mm, ISO 250 but still pretty decent.

[normhead]

The magnification ratio is 2.45x as much, so quite a lot, actually.

Especially if you are shooting on a K-1 where your normal macro lens looks more like a wide angle lens. The same "lack of crop FoV" that hits you with long lens shots, also hits you with macro.

[Winder]

I'm looking at adding a lens to my collection and was thinking of the Rokinon 135mm f2.0 as the reviews are stellar and it also performs exceptional wide open. I grew up with an old Pentax Super Program so manual focusing isn't the end of the world for me. That being said I'm also considering the Pentax 70 - 200 f2.8 and I'm wondering how that performs wide open on the K1?

I realize they're in different price ranges and one's auto focus vs. manual but I'll be using these for wedding and portrait photography. If people are having great luck with the Pentax wide open I may bite the price difference and purchase it instead.

Thanks,
Scott

It is an excellent lens all around. Sharpness is just one aspect. Everything about the lens is excellent.

[Mikesul]

It is an excellent lens all around. Sharpness is just one aspect. Everything about the lens is excellent.

Yes indeed. If the new lenses Pentax is working on are equally fine we will have an outstanding set. I one of those who think we already have an excellent selection of lenses but it would be nice to have the smooth, quick focusing of the 70-200 in more FF lenses.

[sylvainp]

In my opinion it is ok at f2.8 but not as sharp as what I'm used to with other similar lenses.

I had to return my first D FA 70-200mm because of serious focusing problem where it would front focus at 200mm when close to the subject. Cameraville had the same problem with his sample so I fear there is more of those problematic lenses out there. It's was a little bit soft at F2.8 even when focused manually.

The store I got it from tested it and sent me a replacement since they found it unacceptable. The replacement seems to have the focusing problem fixed (they tested it before sending it to me) but I need to do more test. At least this one need the same focus adjustment of -2 at 70 or 200mm when close to the subject I now need to test at 25ft and more.

I don't think it's soft at F2.8 and it's usable but at the same time it is not close to be as sharp to my Olympus pro 40-150mm at f2.8 and my old canon 70-200mm or my DA* 300mm F4 wide open ...

Considering the size and weight and the reviews I found here I was expecting the lens to be sharper wide open. Both sample I had of the lens where identical in sharpness at F2.8 at 70-135-200mm so I don't think it's isolated to my current lens and found similar softness on my shoots taken at F2.8 on flickr. I'm spoiled by the sharpness of the Olympus pro lenses I guess. My pentax D FA 24-70mm is sharper wide open too and IQ is better at 70mm when wide open.

I can live with that since most FF lenses tend to be softer wide open but what cause me problems with the pentax D FA 70-200mm is the focus breathing. I got it for portrait at 200mm like I used to do with my canon 70-200mm but when focusing close to the subject the lens is more a 135mm. In fact I get very similar fov with my old 135mm f2.8 manual lens so I get no gain from the large 70-200mm. Again, considering the size and weight I would had expected it to not suffer serious focus breathing like that. It doesn't focus very close from subject and magnification is not very high because of the focus breathing.

I don't know if I'm going to keep it since I would have better results with the da 200mm f2.8 combined with my 135mm f2.8 and my D FA 24-70mm

I really like the pentax d fa 24-70mm and it's the best 24-70mm I've had. It's made by tamron for pentax. I kind of wish the 70-200mm would had be made by tamron based on the G2 reviews I've seen.

---

Last edited by sylvainp; 03-04-2018 at 08:24 PM.

[Class A]

I'm spoiled by the sharpness of the Olympus pro lenses I guess.

I'm not disputing your experiences with the 70-200/2.8 but you cannot compare f/2.8 on an MFT camera with f/2.8 on an FF camera.
Stop down your 70-200/2.8 to f/5.6 and then compare sharpness. An f/5.6 setting will give you the same DOF and noise levels that f/2.8 will give you on your Olympus.

Alternatively, or rather hypothetically, you could find an Olympus 40-150/1.4 and then compare the sharpness of it, wide open at f/1.4, to the 70-200/2.8 on FF. I hope this gives you an idea how challenging getting good sharpness at f/2.8 for an FF lens is, compared to MFT lenses.

I have no personal experience with the Pentax 70-200/2.8 so I cannot speak to its quality (I'd expect it to be at least very good, if not excellent, judging from what I've heard). I can, however, point out the physics and perhaps help you to manage your expectations or manage your admiration of the Olympus lens. FWIW, I've read many times that many MFT lenses are excellent and I have no doubts that the lens you referenced is a great performer. You just also need to acknowledge that it has a much easier task.

[sylvainp]

I'm not disputing your experiences with the 70-200/2.8 but you cannot compare f/2.8 on an MFT camera with f/2.8 on an FF camera.
Stop down your 70-200/2.8 to f/5.6 and then compare sharpness. An f/5.6 setting will give you the same DOF and noise levels that f/2.8 will give you on your Olympus.

Alternatively, or rather hypothetically, you could find an Olympus 40-150/1.4 and then compare the sharpness of it, wide open at f/1.4, to the 70-200/2.8 on FF. I hope this gives you an idea how challenging getting good sharpness at f/2.8 for an FF lens is, compared to MFT lenses.

I have no personal experience with the Pentax 70-200/2.8 so I cannot speak to its quality (I'd expect it to be at least very good, if not excellent, judging from what I've heard). I can, however, point out the physics and perhaps help you to manage your expectations or manage your admiration of the Olympus lens. FWIW, I've read many times that many MFT lenses are excellent and I have no doubts that the lens you referenced is a great performer. You just also need to acknowledge that it has a much easier task.

I think you are mixing sensor size and lens design. I've adapted my pentax k and canon ef lenses on my m43 cameras with optical correction or without. When adapted FF lenses that where soft on FF where soft on m43. The lenses are what they are and the 70-200mm F2.8 is a 70-200mm F2.8 when use on smaller or larger sensor. A F2.8 lens doesn't become a F4 lense when I use apsc crop mode on the K1 right ? so it's the same thing with a olympus lens. My 40-150mm f2.8 and the 300mm f4 from olympus are exactly that but they are of smaller image circle. The same way I use my DA* 300mm F4 on my K1 and it's still a 300mm F4 lens even on a FF sensor and it work since the image circle for a 300mm lens is not really limiting on a FF sensor.

I'm not sure you understand the physic behind lens construction if you think it's a lot easier to build a m43 lens. You need to get 20 mpixel in much smaller image circle (compared to says 36mpixel in the much larger FF sensor on my K1) so the glass needed in order to get similar resolution and sharpness will need to be of higher quality.This is very easy to test when adapting FF or apsc build lenses on a m43 camera and comparing sharpness to a m43 optimized glass. The fact that olympus can make those pro lenses is quite amazing but it's also very expensive.

Anyway the 70-200mm increase a lot from f2.8 to f4 then a little bit from f4 to f5.6. It will be more than enough for most but I wouldn't call it a sharp glasse wide open compared to other offering on the market. If the lens was of a small package and lightweight I could had expected focus breathing and some softness att F2.8 but considering that it's a monster of a 70-200mm I was a little bit disappointed. Based the sharpness of my da 300mm f4 wide open I wouldn't be surprised the da 200mm at F2.8 would be sharper than the 70-200mm. It's something I will try and since the da 200mm is not a zoom It should be a real 200mm when focusing close to the subject.

[Tas]

I think you are mixing sensor size and lens design. I've adapted my pentax k and canon ef lenses on my m43 cameras with optical correction or without. When adapted FF lenses that where soft on FF where soft on m43. The lenses are what they are and the 70-200mm F2.8 is a 70-200mm F2.8 when use on smaller or larger sensor. A F2.8 lens doesn't become a F4 lense when I use apsc crop mode on the K1 right ? so it's the same thing with a olympus lens. My 40-150mm f2.8 and the 300mm f4 from olympus are exactly that but they are of smaller image circle. The same way I use my DA* 300mm F4 on my K1 and it's still a 300mm F4 lens even on a FF sensor and it work since the image circle for a 300mm lens is not really limiting on a FF sensor.

I'm not sure you understand the physic behind lens construction if you think it's a lot easier to build a m43 lens. You need to get 20 mpixel in much smaller image circle (compared to says 36mpixel in the much larger FF sensor on my K1) so the glass needed in order to get similar resolution and sharpness will need to be of higher quality.This is very easy to test when adapting FF or apsc build lenses on a m43 camera and comparing sharpness to a m43 optimized glass. The fact that olympus can make those pro lenses is quite amazing but it's also very expensive.

Anyway the 70-200mm increase a lot from f2.8 to f4 then a little bit from f4 to f5.6. It will be more than enough for most but I wouldn't call it a sharp glasse wide open compared to other offering on the market. If the lens was of a small package and lightweight I could had expected focus breathing and some softness att F2.8 but considering that it's a monster of a 70-200mm I was a little bit disappointed. Based the sharpness of my da 300mm f4 wide open I wouldn't be surprised the da 200mm at F2.8 would be sharper than the 70-200mm. It's something I will try and since the da 200mm is not a zoom It should be a real 200mm when focusing close to the subject.

Cool, it might help the OP for you to post some examples of the various lenses showing what you're seeing. As they say in the classics: a picture speaks a thousand words.

[Class A]

I'm not sure you understand the physic behind lens construction if you think it's a lot easier to build a m43 lens.

I am very sure that I understand the physics. You have the typical "f/2.8 is f/2.8" misconception and I'm not here to teach you otherwise, unless you really want me to.

BTW, I never said it is easier to build an MFT lens. It is, in fact, harder, if you want the same quality. Due to the larger enlargement factor required for MFT compared to FF, every lens imperfection is magnified. Pixel densities are also typically higher on smaller sensors, aggravating the issue when pixel peeping.

What I actually said is that f/2.8 lens quality performance is easier to achieve on MFT than f/2.8 lens quality performance on FF. That is a fact.

[Tas]

Hey, here's an idea. Whilst we're waiting for the comparison images to show us what's wrong with the D-FA* 70-200, we could all have a browse of this thread: https://www.pentaxforums.com/forums/122-lens-clubs/321412-pentax-hd-pentax-d...c-aw-club.html

[sylvainp]

I am very sure that I understand the physics. You have the typical "f/2.8 is f/2.8" misconception and I'm not here to teach you otherwise, unless you really want me to.

BTW, I never said it is easier to build an MFT lens. It is, in fact, harder, if you want the same quality. Due to the larger enlargement factor required for MFT compared to FF, every lens imperfection is magnified. Pixel densities are also typically higher on smaller sensors, aggravating the issue when pixel peeping.

What I actually said is that f/2.8 lens quality performance is easier to achieve on MFT than f/2.8 lens quality performance on FF. That is a fact.

It's funny how equivalency is used for everything even when it doesn't make any sense. That is something that appeared when the shallow dof fetishism got in force so not that long ago. When I learned photography we would start with a simple lens, a light source and a sheet of paper to experiment and people from this era are the ones that won't confuse lens construction and sensor (film) size. A 120mm F4 on a 645 was a 120mm F4 and no one would call the lens 85mm F1.4 adapted on a 135 film body ... Easy to understand why and also those 120mm F4 would tend to be really soft when used on a 135 body anyway. What people would do is use a F1.4 lens on 135 to match the dof of a F4 lens and not call the lens anything else than it is (to not introduce unnecessary confusion). Why is it that in recent years peoples started to incluses everything possible in the equivalency concept I don't know but it seems to be mostly coming from pixel peepers and shallow dof fanatics around youtube and dpreview comment section.

Anyway tell me this, if I put my 300mm da F4 lens on my pentax K1, I take a picture of a subject in FF mode then switch to crop mode and take the same picture and compare both what change ?

Is DOF changed (and in which way) ?
is noise changed ?
is AF response changed (do I now have the af reaction of a f5.6 lens or a f4 lens) ?
is "light" changed ?
is exposure changed for a given iso and F-stop (let say in A-priority) ?
is a soft lens wide open now sharp wide open ?

This is a simple experiment to do for a K1 owner and it explain so much. The Northrup don't seems to be willing to test this and will try to introduce the print size in the equation to try to justify their "total light" concept. It's easy to spot a flawed concept when the authors start to add multiple variables in order to make it work.

I often ask to people that say a F4 lens on a m43 is a F8 lens on a FF camera, because of noise, if that lens is now of a F11 lens on my old canon 5d mk2 ? is it only when comparing different size of sensor that noise performance is part of the equivalency or also for older camera compared to newer one ? Since I need a F2.8 lens on my old FF body to get similar noise than a F5.6 on my new FF body should I start calling any lenses I put on the old body a different F-stop ? it doesn't make sense. Same thing with AF system, it see the real F-stop value not the "equivalent" f-stop value. It doesn't focus like a F8 "equivalent"lens because the sensor is smaller but like the real f-stop. It's normal it get the same intensity of light to work with. My em1.2 is better in noise performance than my friend 7dmk2 and my old 5d mkii so why would I start using fstop equivalency for noise or light with some camera but not when sensor generation or ... you see my point right ?

Back to the original question about the sharpness wide open :

There is measurements of the lense at f2.8 that show clearly that it's softer wide open specially on the long end. The ephotozine test show it clearly. Since it suffer from focus breathing you will be using the 200mm quite a lot if your subject is close to you (it will act like a 135mm lens). Stepping to F4 cure this mostly so is it sharp wide open for you or is it soft will depend mostly of you basis of comparison. This test include measurements that show this : Pentax HD PENTAX-D FA* 70-200mm f/2.8 ED DC AW Review

I had the same performance on the long end on my first and second sample of the D FA 70-200mm F2.8 I had so I tend to think this test is done right. It's very important to not confuse out of focus from softness so if you test it either focus manually with the MF helps in the camera or focus using the cdaf in live view. At F2.8 and 200mm on FF sensor it's not that hard to miss focus.

---------- Post added 03-06-18 at 08:55 PM ----------

Cool, it might help the OP for you to post some examples of the various lenses showing what you're seeing. As they say in the classics: a picture speaks a thousand words.

OP asked for opinion of user of the lens. If I was to post pictures of the lens wide open at 200mm I'm pretty sure there is a better place for this in the forum.

Sharpness is not the most concern to have with that lens for a wedding photographer in my experience since some softness is not that much of a problem but I would be a lot more worried of the usage of a lens that suffer from focus breathing like that. It's ok for sports or anything 20ft away from the lens but when shooting something close you really don't get a real 200mm.

If I was to show this with pictures I would shoot a close subject with my 135mm prime, shoot the same subject with the 200mm end of the 70-200mm and it would have almost the same fov. I don't think we really need picture to show this.

As long as he know the lens suffer from it it's his decision to go with it. On the market canon and nikon offer 70-200mm lens that doesn't do it and if you had experience with those like me ... it's a game changer for using this lens for portrait. The question is not if you can get nice portrait with it since it can but mostly why use that when you can use a 135mm f2.8 lens and get same results with 1/4 of the weight.

[Tas]

OP asked for opinion of user of the lens.

This is what the OP asked about: "That being said I'm also considering the Pentax 70 - 200 f2.8 and I'm wondering how that performs wide open on the K1?"

And as I stated above: a picture speaks a thousand words. I think it's reasonable to expect in a photography forum that examples of what you're seeing are an excellent way of backing up what you've stated. I imagine it would actually help the OP more too.

To give you an example, here's a comparison showing the DoF comparison of FF and m43: Full frame vs Micro Four Thirds: Quick DOF and Bokeh test | Mu-43.com - Micro Four Thirds User Group Sure, it's not an example with tight tolerances but the images do demonstrate what depth of field each format captures at a variety of apertures and similar equivalent fields of view. I think these examples are what Class A was trying to explain.

Softness at the widest aperture is relevant to every lens compared to stopping down, with some of the latest lenses being the only exceptions to this. But even the Zeiss Otus lenses improve by stopping down so there is more logic to find examples that the OP can check and make a decision on for their needs. But focus breathing is a different issue and was a problem with the NIkon 70-200 lenses until the latest E version which is about $1000 more than the Pentax lens BTW. To provide a better example of focus breathing in the context that both the OP and yourself refer to, I thought this would help:

You Tube

You Tube

This video can provide greater clarity to the OP regarding what the differences can look like with focus breathing. So whilst I respect that you disagree, I'd have been grateful to you if you'd been prepared to show examples, but it's your choice and I don't want this thread to be a negative experience for the OP, yourself or anyone else by insisting on examples when it's not my thread.

I am not trying to be rude or adversarial, but I can learn more myself when people show me what they're seeing and as it is not uncommon to find people making negative comments about gear (and fair enough if there's a problem) most people don't post examples so the value that can be placed on those comments are comparatively diluted.

Hope the above clarifies that I'm not seeking an argument.

Tas

[Class A]

A 120mm F4 on a 645 was a 120mm F4 and no one would call the lens 85mm F1.4 adapted on a 135 film body

You are right that renaming a lens in that manner is not helpful.

It does, however, make a ton of sense to refer to a 50/1.8 APS-C lens as a "75/2.8 FF-equivalent" lens. Why? Because to all purposes and intents, the APS-C lens will allow you to take the same images that a 75/2.8 lens will allow you to take on FF.

As to why people started to suddenly use "FF currency" (for focal length and widest f-stop) for APS-C lenses, my believe is that prior to the introduction of the digital APS-C format, it was not at all common for regular photographers to use one and the same lens with different formats. The economics of digital sensors produced the phenomenon of "crop sensors" that worked with lenses that were originally intended for a larger format. This consequence of reusing a mount that is strictly speaking too big for the sensor format used, naturally invited questions like "What do pictures taken with a 50/1.4 FF lens look like on a crop sensor camera?". The answer is, of course, they'll look like as if you were using an FF camera (something that the vast majority has been doing so far and hence were familiar with) with a 75/2 lens. This gave people a way to understand what to expect from a 50/1.4 on APS-C.

You can blame the industry's convention to label lenses with their focal length instead of with their AOV. If a 50mm lens were labelled "46.79°" then it would have been possible to simply state "This 46.79° FF lens, will look like a 32.17° lens on APS-C". This would have avoided unhelpful responses like "50mm = 50mm" and "f/2.8 = f/2.8" because no one challenges the fact that the AOV changes when one crops. What most people do not seem to understand is that the idea is not to claim that a 50mm "becomes" a 75mm lens. As a matter of fact, it is correct that the focal length doesn't change. However, it is 100% valid to say that the 50mm lens on APS-C is equivalent to a 75mm lens on FF. So the correct wording is that it is an "75mm FF-equivalent" lens.

Anyway tell me this, if I put my 300mm da F4 lens on my pentax K1, I take a picture of a subject in FF mode then switch to crop mode and take the same picture and compare both what change ?

The most obvious change will the the AOV. You'll see a lot less in the cropped frame. This, for obvious reasons, makes it non-trivial to compare images/settings, as it will always remain an apples and oranges comparison in which you can only pick your poison but never do a straightforward comparison.

A much more helpful question is what the difference between two images is that are shot on

1. K-1 in FF mode with a 300mm lens at f/4.
2. K-1 in crop mode with a 200mm lens at f/2.8.

The answer is (practically) none (let's ignore ISO settings here). I'm writing "practically" because technically the f-ratio should be f/2.67 for the 200mm lens, not f/2.8.

The above assumes that both images will be looked at the same size. If you were to enlarge both by the same factor, you'd get images of different sizes which, again, would make comparisons difficult. You didn't specify the viewing conditions for your thought experiment, but the only fair comparison is to assume that both are printed at the same size or that they are viewed at different magnifications on a screen.

Is DOF changed (and in which way) ?

If we assume the same output size then the image taken with the crop mode engaged will show shallower DOF. Yes, that's correct, if you keep the lens and settings constant and only crop, but maintain the same output size, the image taken with the "smaller sensor" will have the shallower DOF (ignoring for the moment, that the image contents are different). This is contrary to the common wisdom that FF cameras produce shallower DOF. The latter piece of wisdom, however, only applies, if one uses the same settings, and equivalent lenses (i.e., a longer focal length on the FF camera).

Perhaps try reading this article on camera equivalence. The author is a Physicist with a PhD. Anyone claiming that equivalence arguments are nonsense or are made by people who do not understand the physics behind lenses, or are promoted by "...pixel peepers and shallow dof fanatics around youtube and dpreview comment section...", should be aware that the science is supporting equivalence, not "50mm = 50mm".

P.S.: I'm not using the "Physicist with a PhD" reference to claim correctness of his arguments. I'm only pointing out what anyone disagreeing with the arguments can expect to be up against when claiming that physics is on their side. Of course, his arguments are correct, BTW, I'm merely pointing out that I'm not trying to make an "argument from authority".