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11-21-2012, 06:09 PM   #1
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Lens sharpness and TC question.

Like I mentioned in another thread, I'm using my 55-300 DA L for occasional birding with my K30 and a tripod. The problem is that I haven't got enough range. I am on a tripod and the geese are stationary in the water at about 300 feet. Now, would a Sigma 170-500 lens be as sharp at 500mm as my 55-300 at 300mm? Would the Sigma 120-400 be as sharp at 400? If I decided to use a 1.4X TC with my 55-300, can you suggest a good one that would work fine with that lens and my K30? I could also go the prime way and got some good ideas in the other thread but can't spend too much, so I'll forget about the Pentax ED monsters. Thanks for your ideas and your experience. Sorry about starting another thread but the other one was not clear enough about what I wanted to know. That's what happens whan a Frenchie from Quebec tries to express himself in English.
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11-21-2012, 06:59 PM   #2
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Mike, I'm not sure anyone can really answer that. A lens comparison to be accurate needs to be done under the same conditions with the same camera and same shooter. This is especially true when you start to get to these focal lengths because the skill of the shooter starts to be a real factor. You can hand the best 500mm ever made to someone and if they don't have the skills the images will be junk.

That said here are a few generalities from my experience:
  1. A prime will be sharper than a zoom, especially over the range you are talking about. Not that there are not some good zooms, I have the Sigma 50-500 and like it but the Sigma 500mm will blow it away.
  2. There is a big difference in skill needed from 300mm to 500mm. Most folks can do a reasonable job of hand holding a 300mm but at 500mm you really need to know what you are doing.
  3. Even on a tripod, correct balance, weighting and vibration damping are needed to get good results at this range
  4. A TC will always reduce the image quality over the same lens without one. How much is the questions. Many folks report that taking the shot without the TC and cropping usually gets just about the same image quality as taking it with the TC assuming you are using a top quality TC. Cheap TC's just forget it.
  5. There are about 100 million TC (that's just an estimate) floating around in old camera bags because people bought them and then found the image quality not good enough so they stay in the bag
  6. A good, matched TC like the Sigma 1.4x and 2x matched with the lenses they were designed for can be quite good. But just picking one up and sticking it on a consumer zoom like the 55-300 is not going to get you into Nat Geo
  7. You need to decide what image quality is acceptable to you, what you find good enough might not cut it for someone else.
11-21-2012, 07:01 PM   #3
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Tried a few TCs and found cropping a pic is always cleaner than a TC. A good choice money and quality wise
Is a Tamrom 500mm mirror. The doughnut background thing is overblown , lt rarely shows up. I use one on Pentax and a Nikon
Without SR and get great results.
If you are around Montreal you are welcome to try it before you go out and buy one. I also have a 300 5.6 Tamron and a 60-300 SP, the
60_300 is sharper open than the Pentax 55_300 stopped down. Kept it and sold the Pentax.
11-21-2012, 07:35 PM   #4
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About sharpness.

Thanks guys for your opinions. I did have a Tamron 500mm but sold it since I didn't find it as sharp as my 55-300. A friend of mine bought a new Sigma 150-500 to use on a tripod with his Canon and he gets good results. I was wondering if the 170-500 would be nearly as good. I used to have a Kenko MC7 TC but found that cropping was as good so I was wondering if a Sigma would be better. I am enclosing a picture taken with my 55-300 on a tripod. I am quite satisfied with the result because the bird wasn't very far from me. My problem is when they are 300 feet away. If the Sigma 170-500, which is affordable used, gave me similar results, I'd be happy with that. Thanks again.


Last edited by VE2CJW; 12-10-2012 at 01:07 PM.
11-21-2012, 08:07 PM   #5
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Sigma 50-500 @ 500mm f/8 1/250 Handheld. Way too slow to get it as sharp as I like but not too bad.
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11-21-2012, 08:14 PM   #6
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Just in case you were not aware here is a link to the user review section on this forum, this link goes straight to the third party part. Sigma is at the top, look under both current and legacy zooms. Pentax Lenses by Sigma, Tamron, Zeiss, and more - Reviews and Specification Database - Pentax Lens Review Database
11-21-2012, 08:16 PM   #7
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And here is a link to a nice review of the 170-500 https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/159245-sigma-1...nal-bigma.html
11-21-2012, 09:00 PM   #8
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Thanks guys. I have read a lot of reviews amd am trying to make up my mind.

11-21-2012, 09:29 PM - 1 Like   #9
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What I have found is that in good light a 300mm slower lens will give you great results cropped. But as light decreases, you start stretching the iso a bit and quality after cropping drops off significantly. A longer lens with iq close or even not quite as good can end up giving you better quality because you don't have to crop as much as the iso increases.

Some examples from my 170-500. I got it through KEH. It isn't as sharp as I would like and has issues with flare. The second one illustrates what I said above; I don't think this is cropped iirc, and it was quite poor lighting. With the 300mm I would have had to crop it substantially losing detail through high iso softness.

I look at longer lens not to mean I can shoot things far away, rather the frame gets filled at the same range as I would get with the 300. I find 300mm just too short. I regularly use a manual 400 f4 Tamron and like the length. 500 makes it harder to find things in the viewfinder which can be an issue with small birds. But when you get them you have lots of pixels to play with.




Last edited by derekkite; 11-21-2012 at 09:35 PM.
11-22-2012, 07:36 AM   #10
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Good description of my problem.

Derek, you have clearly described my problem. Most of my experiments were done near sunset or on an overcast day with the geese quite far away on the water, good recipe for disaster. Since I have only 300mm to shoot, I had to crop and the result was worse. Looking at your pictures with the 170-500, I can't say that I'm impressed since they look a lot like most of my cropped pictures. I don't think I'll go with a long zoom but will probably explore longer older primes. Thanks for the clear explanations. I'm including a picture taken with my 55-300 that was cropped to get the effect of 600mm. It's not too bad but I need to get closer but there is a limit to cropping. Take care.
Mike.

Last edited by VE2CJW; 12-10-2012 at 01:07 PM.
11-22-2012, 09:02 AM   #11
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I tried a Sigma 150-500mm OS HSM. I returned it because it was unacceptably soft at 500mm. My definition of unacceptably soft is that it was not sharp when cropped to 100%. It was sharper than my 55-300 at 300mm, but fell off noticeably at longer lengths. Note that I don't consider the 55-300 sharp enough for pure telephoto shooting. I only use it when I don't expect to crop the images.

I used an A*300mm for about a year, with and without a Kenko 1.5X TC. This combo was sharp, the only down sides being MF of course, and a little too much CA at times. I didn't find it shorter in practical use than the 150-500mm, because the Sigma is an IF lens and loses range at subject distances below infinity. I just bought a DA*300 f4. I haven't used it enough to say much except that it's pixel sharp and the CA control is amazing. Unfortunately AF with the PZ capable Kenko is pretty hopeless, so I'm back to AF most of the time when using the TC. I'm waiting anxiously for the Pentax 1.4X.

I can recommend the A*300 with Kenko 1.4X, or the more complementary but pricier Pentax 1.7X for AF, or of course the DA*300. I like having the ability to use 300mm @ f4 and 420mm @ 5.6, because it's more versatile. It's a constant struggle in Northern Ontario to keep shutter speeds up and ISO down. I often have to go down to f.4 just to get a useable shot.
11-22-2012, 11:06 AM   #12
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Unless you are willing to spend a couple of thousand dollars on decent glass for the reach you require, I'd suggest you work on technique-related ways of getting closer to birds. Building or procuring a lightweight blind can be low budget and your exiting consumer-level tele zoom will work quite well.

At a certain point you will have to decide how "occasional" your bird photography pursuit is--or will be. Over time, the progression in one's skills, and desire (I'm not including shooting for money here) will lead to sizable costs and most likely a camera brand change. That can take years (as it did for me), but I find it smarter to try to map it out in phases for the future.

You also have to be cognizant of the serious weight and size requirements excellent lenses entail. At cool birding spots I've run into a handful of shooters who use jogging strollers or carts to shlep their gear. Alternatively old timers show me their permanently shifted posture from humping 500-600mm lenses plus heavy tripods and gimbal heads miles up the trail repeatedly.

My body just cannot handle that, so I've made do with a more compact set of tools, and just try to work on technique to partially overcome their (and my own) limitations.

M
11-22-2012, 11:21 AM   #13
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QuoteOriginally posted by Miguel Quote
My body just cannot handle that, so I've made do with a more compact set of tools, and just try to work on technique to partially overcome their (and my own) limitations.
Which more compact tools? I've been looking at the Q again now that there's a lower price and a Pentax adapter. I could get a similar FOV to my 300 and 1.5X TC using the Q and a 135mm lens, gaining two stops of light, but the IQ just seems too much of a step down.
11-22-2012, 11:40 AM   #14
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Birding is almost a curse, you end up spending thousands of dollars on lenses. I was looking at some shots I took last winter with my 2.8 300mm tamron 107b, the earliest version. Many times I was at 2.8, 1/30 iso 320. Higher iso the sharpness falls off dramatically. Tough to get shots without movement either of the subject or camera, even on a monopod.

Shooting long on water is tough. The 55-300 controls CA and flare quite well. You won't find that with older lenses and iq over water will be hard to get. The Sigma 500 zooms seem to be ok,

Maybe I'll list what I've tried:

55-300 pentax. Too slow for most of the shooting I do here. We are in a valley and it is plain dark for 6 months. In good light a pretty fair lens. Focus hunting sucks, makes me want to throw it somewhere.
Tamron 23a 60-300 adaptall. Cheap, can be had for about $60. Nice and sharp and a lens that gives you a smile when using it. Couldn't get a decent shot on water though.
m42 300 f4 Pentax. Abberations were something fierce. Sharp but out of focus colors just wierd. A bit better on water. Sold it.
500mm Tamron mirror. F8 is too slow. Not too bad for sharpness, oddly tough to handle. Sold it.
Pentax 300 A* f4. I really try hard to like this lens but can't. When I get a good shot it is amazing, but CA and lack of sharpness makes me leave it at home. Lack of tripod mount limits it to light where handholding is ok.
Tamron 107b 300mm 2.8. Oddly effective in low light but as light increases you have to stop down severely to control CA. Works well with a 140 tc. They say the 60b and 360b are better optically. Useless for water; can't control the stray light that bounces off the waves.
Tamron 400 f4 adaptall. The best of the bunch. Love the length and gives clear shots stopped down. Not good on water, need to stop down to f11 to avoid stray light and CA.
Sigma 170-500. Not as sharp as I like, but very nice to handle. Again a lens I try really hard to like but quality is just not there. Focus is quick.

I dream of a Sigma 500 f4.5 and probably will buy one next year. I will get myself an autofocus 300mm f4 either sigma or pentax in the next little while. Most of the year a 300 2.8 is almost a necessity, so am considering a sigma 300 2.8 and a tc. Not sure if it would be satisfactory though.

Bah. A gambling or cocaine habit may be cheaper than this hobby
11-22-2012, 02:13 PM   #15
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QuoteOriginally posted by audiobomber Quote
Which more compact tools?
Within the context of my post, my Canon 7D + the 100-400mm L lens is significantly easier to go five miles with than the 500mm f4 L lens or a Nikon 200-400mm or 600mm lens. I can carry it across my body ready to shoot, or the push/pull design allows it to fit into the top compartment of my Kata pack. I couldn't do it with a K20D + the Bigma either, and the image quality for birds (or sports) between both kits with vastly different in favor of the Canon.

QuoteOriginally posted by audiobomber Quote
I've been looking at the Q

While the Q really intrigues me as a street or fun art shooting tool, I cannot fathom using it for high-quality capture of moving objects like birds. Both the shutter lag and being required to use the LCD rear viewfinder I would find way too frustrating. Image quality further compounds things.

QuoteOriginally posted by derekkite Quote
Maybe I'll list what I've tried
A core problem with relying on Pentax for birds (and sports) is that most solutions for higher-quality are a little kludgy, or have limited availability (like scrounging for used TCs of various quality). Few can point to three lenses and say "go order one of these from B&H, or look at Craigslist." Of course, Canon and Nikon solutions are really expensive for the most part, and it entails dealing with a whole 'nother camera mount. So that's why I recommend folks to seriously evaluate how important bird (and sports) shooting is to them because the implications are also serious.

M
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