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07-27-2013, 02:31 AM   #1
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K30 and Teleconverters

I have the DAL 55-300 F4-5.8 ED and DAL 18-55 WR lens.

I'm going to airshows and while I'm happy with the 55-300, I could just do with a bit more length, however springing for the bigma or the 120-400 sigma lenses isn't in my budget any time soon.

so, i'm looking at teleconverters which I have found is a bizarre and confusing world that is just insane.

From the sounds of it, I don't want to go too high on the magnification so a 1.4 or 1.5 TC would be about as far to go. 2x would be too much on a 300 lens.

I've found a few threads discussing teleconverters and this thread

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/19694-tamron-t...r-pics-38.html

seems to focus on the tamron 1.4 and kenko 1.5 as the thing to go for.

both have the PZ-AF mounting so Autofocus should work.

I have found a Kenko PZ-AF 1.5 online and photos of it show it with 7 pins to the mounting ring.

the above thread discusses and seems to favour the tamron over the kenko, but there is a huge price difference between the two.

The above thread also doesn't have anything fresh in since 2010. Has anyone got experience of using the Kenko and Tamron TC's on the K30 that could comment, particularly if someone's used it with the 55-300 lens

07-27-2013, 03:15 AM   #2
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The lens database has a section on third party tele converters with reviews. Perhaps you can find some help there.

I have this Tamron converter and it works well without degrading the image quality too much. Unfortunately, it is discontinued and you'll have to search for it second hand.

I agree that you shouldn't go higher than 1.4x. Even with a 1.4x converter autofocus may not work at the long end due to the one stop light loss.
07-27-2013, 05:50 AM   #3
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Unfortunately, teleconverters don't do as well on zooms and although the 55-300 is a good lens, it's best with good light and the TC takes some of that away. This Spring when I planned to spend 3 days going to Magee Marsh to shoot birds I wanted something longer. When I knew I wasn't going to afford it, I decided to try renting from cameralensrentals.com. I rented a Sigma 5-500 for a week, with shipping and insurance it cost me a little over $100. I would not rent a lens without knowing that I could use it extensively for that period, but it worked out perfectly, I got it a few days early to get used to it and was very happy with it. A good way to try the lens out too. Of course it's not the same as owning a lens, but when you think about an expensive lens that doesn't get used that much it's a great idea. I've found that I use some lenses more seasonally.

Personally, I hope the converter on the Lens Roadmap is good and affordable, and I'm waiting to see that and the 135-370 that is on the roadmap.
07-27-2013, 06:30 AM   #4
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The TC situation is indeed complex. I agree with Ole a TC with the 55-300 is problematic. With static objects I have had some success with moving things not so much. Light is the problem and 55-300 is just too slow at the long end. YMMV.

Hopefully this will be fixed by Pentax releasing a good TC, but even then I believe TCs work better with fixed f4 and faster glass.

07-27-2013, 07:20 AM   #5
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The Vivitar Series 1 1.4x TC is cheap and work reasonably well with the 55-300. It's basically the Tamron without the PZ contacts.

Vivitar 1.4x Tele Converter for Pentax VIV-1.4X-P

https://www.pentaxforums.com/forums/lens-sample-photo-archive/153150-pentax-d...ml#post2377148

https://www.pentaxforums.com/forums/lens-sample-photo-archive/153150-pentax-d...ml#post2417817

https://www.pentaxforums.com/forums/lens-sample-photo-archive/153150-pentax-d...ml#post2421926
07-27-2013, 07:51 AM   #6
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I have a Tamron 70-300 and a Sigma 120-400 and I've found that it's easier to shoot planes with the smaller lens due to the weight issue! It's hard enough to focus on a plane doing 200+ mph without a long heavy lens taking over! I also have a Quantray 2x convertor which I gave up on as it takes away too much light. I feel your better with a shorter lens and a cropping. Having said that, the pro's were hand holding 500mm lenses, but had obviously been to the gym a lot!

The attached photo was with a Sigma 28-105.

Tuggie 76

Last edited by tuggie76; 02-08-2014 at 11:46 AM.
07-27-2013, 08:38 AM   #7
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I think you are very likely to have a hard time focusing with a TC on the 55-300mm - I've tried it, no dice. Additionally, at the long end + tc, even manually focusing, you are going to have some quality loss. Probably you can get a sharper image if you use a fast shutter at 300mm and then crop it afterwards. or keep your eyes open for a used Sigma APO 400mm lens. The manual focus one shows up on various sales locations online often enough and the autofocus 400mm macro shows up much less frequently.
07-27-2013, 12:13 PM   #8
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When I shot slides where the film is the final result, I used a TC whenever absolutely necessary. With digital - and especially with a 16mp sensor - the TC is long gone. I crop the final image instead. The gain in noise is FAR less objectionable to the loss of light, the loss of sharpness, and the gain in aberrations from the TC.

Stick with just the 55-300 and crop. Shoot wide open and use a shutter speed of at least 1/500, and preferably at least 1/1000 with a corresponding ISO.

07-27-2013, 05:54 PM   #9
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QuoteOriginally posted by JimJohnson Quote
Stick with just the 55-300 and crop. Shoot wide open and use a shutter speed of at least 1/500, and preferably at least 1/1000 with a corresponding ISO.
However if you are shooting prop planes and want the nice prop blur you see in pictures, which IMO makes the aerial shots much nicer, you don't want a shutter speed much hicher than 1/320. In other words make sure your panning skills are good or start practicing them before the next airshow.
07-28-2013, 06:00 AM   #10
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QuoteOriginally posted by JimJohnson Quote
When I shot slides where the film is the final result, I used a TC whenever absolutely necessary. With digital - and especially with a 16mp sensor - the TC is long gone. I crop the final image instead. The gain in noise is FAR less objectionable to the loss of light, the loss of sharpness, and the gain in aberrations from the TC..
For those not following the discussion on teleconverter use, use THIS LINK for the results, then scroll up a few posts to see the photos.
07-28-2013, 08:33 AM   #11
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QuoteOriginally posted by JimJohnson Quote
When I shot slides where the film is the final result, I used a TC whenever absolutely necessary. With digital - and especially with a 16mp sensor - the TC is long gone. I crop the final image instead. The gain in noise is FAR less objectionable to the loss of light, the loss of sharpness, and the gain in aberrations from the TC.

Stick with just the 55-300 and crop. Shoot wide open and use a shutter speed of at least 1/500, and preferably at least 1/1000 with a corresponding ISO.
Thank you. All along I thought I was the dummy for not recognizing the value of a TC. I used one long ago on my ME Super with a couple of lenses but in the digital age I just didn't see it as cropping is simply a click and drag of the mouse. Try THAT on a Kodachrome slide!

Perhaps I'm misunderstanding (probably) but it seems the loss of light with a TC is a bigger issue than the loss of pixels with cropping.... especially with such high pixel counts in sensors now.
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