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04-14-2009, 03:37 PM   #1
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Unscientific (but representative!) comparison of 50-200 & 70-300

In a couple of other threads, discussion has touched on the subject of the difference between 200mm and 300mm and the extent to which simply cropping or using a teleconverter could allow a 200mm lens to give results comparable to using a 300mm lens.

OK, I admit up front that the following is not an exhaustive study of the possibilities, it was not exactly a controlled test, it applies only to my particular copies of my particular lenses (Pentax DA50-200 and Tamron-made Quantaray 70-300, older non-Di version), yada yada yada. But I can tell you it is perfectly typical of the results I've seen every time I've made a similar comparison, and also seems consistent with what I see in others' images from these and similar lenses (eg, the real Tamron 70-300, Di version). If nothing else, take this as one data point; maybe others have other comparisons they could post.

What I've done is take pictures with the 50-200 and 70-300, both at maximum zoom, then cropped the shot at 200 to resemble the shot at 300. The shots are with the same camera (K200D), same exposure settings (f/8, 1/250", ISO 280), both on monopod with SR, same subject (the hawk!), taken seconds apart.

The shot from the 70-300 at 300mm is 2592x3872 pixels. The cropped shot from the 50-200 ends up being 1708x2552 (I constrained the proportions but just eyeballed the actual size). Even the cropped shot is of course far larger than most people's screens, and it's good for a 300dpi print at almost 6x9".

Here is an (almost) 100% crop from the the DA50-200 shot. I say almost because I wanted *both* images to have some resize applied to them, so the comparison wouldn't be thrown off by the presence of resizing artifacts in one shot but not the other so I shurnk it by a few pixels. So we'll call it 99% crop:

Now here is the a similar crop from the 70-300 at 300mm, resized to the same dimensions as the above:

What I'd observe is that the DA50-200 at 200mm seems to be capturing as much detail as the 70-300mm is showing here. The 70-300 *might* have shown more before the resize, but whatever more there might have been was lost in the resize. Meaning whatever extra detail there might have been is gone by the time you view full screen or print at any size smaller than 6x9". So there would be no advantage at all to shooting at 300mm versus shooting at 200mm and cropping unless you plan to print bigger than 6x9".

Now, if the 70-300 *was* capturing more detail but losing it in the resize, that would suggest that it would win in larger prints. But I think you may be able to get the idea from the images above that this is *not* actually the case. The 100% version of the 70-300 shot is *bigger*, but correspondingly blurrier. If I blow up the 50-200 shot larger than 100% to match the 70-300 shot viewed at 100%, the 50-200 doesn't actually show any less detail than the 70-300. the edges just look a little funkier when using a really basic resize algorithm. I'm guessing any reasonably fractal-based program could probably enlarge the 50-200 image to be indistinguishable from the 70-300 image in terms of resolution.

BTW, in shots like this, with small twigs against a bright sky, PF on the 70-300 is every bit as bad as they say. But actually, I still say this doesn't show up in "most" shots. I don't notice it on the bird, for instance - just the twigs. But bottom line,in this case, I'd say the 50-200 did *better* than the 70-300 overall - as much resolution with less PF.

Now, are other 300mm lenses better than mine? No doubt. Is a TC better than simply cropping? Maybe with some lenses and some TC's. I haven't found the Kenko 1.5 TC I have to be an improvement when used with the 50-200, but I also haven't really done a test even as good as this one.

But I guess my point is, don't automatically *assume* that just getting a longer lens is the only or even best way to get more "reach". Based on what I've seen from other people and their 70-300 lenses, I don't think any of them would perform any better here. But it would be interesting to see a similar experiment performed with the DA55-300, if anyone has both!

04-14-2009, 03:43 PM   #2
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Great post... reduced my LBA drive a bit Marc. Thanks! =)
04-14-2009, 03:49 PM   #3

Hey Marc

Wow, I thought mine was the worst PF'n sample of the 70-300... your PF looks very similar to mine in branches. The frustrating thing for me is that it is not even really high contrast areas sometimes...
Having said that, when it works well, my 70-300 is really a good copy.

But my feelings are like what you have shown here. My DA 50-200 holds up well on crops, especially with the K20d. So I will almost always choose it over the 70-300 just because of the PF...
04-14-2009, 03:58 PM   #4
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That hawk must like you Marc
I think it takes a really sharp lens to make good use of a TC (especially if you try it on a k20d) The kenko does work well on my new sigma 100-300mm f4, but I bump up the contrast and saturation a tad to make up for the loss. They do seem to magnify imperfections don't they.

04-14-2009, 05:16 PM   #5
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50-200 v 55-300

Just the sort of quick 'n dirty test I like!
I just took a couple of shots with my 50-200 and 55-300.

55-300 full frame at 300

50-200 cropped.

55-300 - tight crop right of frame

50-200 - tight drop of same

You be the judge.

Incidentally I had the Tamron 70-300 but found it was a tad soft at the long end - just where you want it to be sharp. The 55-300 is much better in that regard and doesn't have much pf either.
04-14-2009, 05:48 PM   #6
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Yep, that DA55-300 looks like a real improvement! I'd also be curious to see how it compared with the the 50-200 at 200. The 70-300 I have is not as good at 200 as my 50-200, so maybe it shouldn't be surprising that by 300 the 50-200 can still match it just by cropping. The 55-300 also has the advantage of being half a stop faster than the 50-200 at some focal lengths, and of course has quick shift which no 70-300 has.

Anyhow, I don't doubt there's sample variation and measurement variation involve, and that someone else will be able to show an example of a 70-300 outperforming crop of a 50-200. But I rather doubt any controlled test would actually show a significant advantage to the 70-300's on average.

From what I've been seeing, I think people choosing a 70-300 over the 50-200 because they think 200 won't be long enough are probably making a mistake. Between the resolution issue, the larger size, slower focus, lack of quick shift, lack of the 50-70 range, and the PF in the Tamron versions, the *only* advantage of the 70-300's would seem to be price, and it's a fairly narrow advantage. Hold out for the 55-300 if you really need more reach.
04-14-2009, 06:19 PM   #7
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Hi, Marc,

Thanks for sharing your comparison of the DA 50-200 versus the Tamron 70-300. Before I got my 55-300mm I have been considering to get the Tamron to fill the gap at the long end. I have both DA 50-200 and 55-300mm but I have not made any comparison as you did. However, based on the images I captured with the 55-300mm, it is a stellar performer with quick focus and excellent IQ.

Keeping in mind that at around or less than 200mm, the 55-300mm can give you f4.5 aperture whereas the DA 50-200mm will be at f5.6. I also did not notice any major CA or PF in the high contrast edges by looking at the image you have shown here (Tamron).

If I have a chance I will do the similar comparison in the future. Again, thanks for sharing your thoughts on this.

04-14-2009, 08:35 PM   #8
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prodigital2000 has a truckload of 50-200's!


I smell a DA 50-200 revival forming!


04-14-2009, 08:36 PM   #9

Ritz has a bunch too...

The local ritz closeout had 4 da 50-200's
04-16-2009, 08:58 AM   #10
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I have a Sigma 70-300 and have had decent results after figuring out the limitations and staying within the area where I know it will work ok. I also have a 200mm f4 Takumar which is a much better lens and crops with the Tak are much better quality than the 70-300. I have a Vivitar 2x teleconverter in M42 that I have used on the Tak and so far the results have been disappointing. Again, much better image with a crop. I really need a decent AF zoom and the 55-300 looks like a good choice for a moderate price and once I get all of my daughters end of the year college bills paid I am planning on getting one if I can swing it without resorting to plastic. For most of us it always is the choice of making due with what we can afford vs. what we would like to have.
04-16-2009, 09:10 AM   #11
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The Tamron 70-300 is sharper than the 55-200 up to 200mm. It also softens noticeably after 280mm. Try the test again at 200mm vs. 280mm to see what I mean...
04-16-2009, 09:43 AM   #12
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I'll throw some more fuel on the fire in a week or so with comparison shots between my 200 and 300 lenses and TC's.

In the mean time, does anyone have any opinions on the Tamron 75-300 vs. the 70-300's? I'm finding my 75-300 LD to be slightly but noticably sharper than the 70-300 LD (non-DI).

I find it interesting that the 75-300 is still in production while the 70-300 was "upgraded(?)" to the DI version. Was the 75-300 that much better to begin with and didn't warrant the marketing expense of changing both. Or, could it be the 75-300 was already at DI standards and they didn't want to have the two lenses compete in marketing for the digital market?

Let IQ be the judge. There might be gold in those undervalued 75-300's if my suspicion is correct.

Unfortunately, I don't have a 70-300 DI here to compare it with.

But I DO have a bunch of non-AF, mid-range zooms and some Adaptall 2's I haven't gotten around to yet. If anyone with a spare DI's interested in a mid-range zoom comparison project maybe we could work out a short term swap.

04-16-2009, 02:01 PM   #13
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QuoteOriginally posted by kenyee Quote
The Tamron 70-300 is sharper than the 55-200 up to 200mm.
That could be - I haven't compared them in the middle of the their ranges. I would note that right *at* 200mm, I see them equal by f/6.7, but the 70-300 may well be better at f/5.6. Also, my 50-200 is impressively sharp in the 50-70 range and I have to say, I probably use the 50-200 more at either end of the range than anywhere in the middle, so I'd be reluctant to give that up that 50-70 range.

It also softens noticeably after 280mm. Try the test again at 200mm vs. 280mm to see what I mean...
Interesting - I'll try that next time I'm in the mood to compare again!
04-23-2009, 12:16 PM   #14
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Took a while to get back to this. But I did spend some time yesterday making boring test shots with the 50-200, 70-300, and M200/4, with and without Kenko 1,5 TC. Unfortunately, I don't have any good samples to post. Because frankly, they are all over the map. I think the best I can say right now is that depending on what scene I am shooting, the light, the aperture, and which way the wind in blowing, I think I could find evidence for or against any assertion anyone wanted to make about any of these lenses. Which is to say, the differences are largely less than measurement error.

About the only incontrovertible statement regarding IQ I can make is that the Tamron has bad PF with twigs against the sky - which we all know. A major issue shooting birds in trees, a much more minor issue in virtually all other situations (which is why it had never bothered me before).

Some other *general* observations:

- I'm not noticing the 70-300 perform noticeably better at 200 or 260 or 280 than at 300. Certainly not so much better that you'd be better off shooting shorter and cropping. On the other hand, it can be pretty good at 300 in situations where PF is not an issue.

- 50-200 still looks better overall @ 200 than either of the others. But while cropping the 50-200 to match the 70-300 @ 300 is usually about a wash if you are not viewing at 100%, there *are* cases where it has captured more detail that gets lost in any downsizing. Which is to say, for screen or small prints, there no difference between cropping the 50-200 @ 200 versus using the 70-300 @ 300, but there *are * cases where on larger prints the 70-300 @ 300 will win. Not by much, but it's there.

- M200/4 + 1.5 TC is definitely bit worse than 70-300 @ 300 when comparing f/8 for both (and by f/8 on the 200*1.5 combo, I mean, aperture ring at 5.6). However, the 200*1.5 combo sharpens up pretty dramatically when you stop down another half stop, whereas the 70-300 has already pretty much maxed out sharpness at that point. Results are actually pretty similar with both lenses at peak sharpness, at least in terms of center sharpness. But out of focus areas look much less pleasant on with the 200*1.5 combo. The contrast also disturbs me on the 200*1.5 combo in busness areas of light & shadow - harsh and yet hazy at the same time in way that's hard to describe.

What have I learned? That these are all decent but unexceptional lenses. i still like the 50-200 for its size, reasonably quick AF, quick shift, 50-70 range, and how it works with the Raynox. I acknowledge that the 300 end of the 70-300 *can be* better than cropping the 50-200 in some cases. And I still love the MF ring of the M200/4. Someday I'll borrow a 55-300 and do this some more, but right now, I'm kind of burned out on all this.
04-23-2009, 12:49 PM   #15
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IMHo you have a soft copy of the Tamron, mine is sharper than the 50-200 at 300mm. In saying that, apart from sharpness (negligable) and reach, the 50-200 is a better lens in every other respect, particularly colour where it smacks the Tamron upside the head.

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