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Red-Winged Blackbird
Posted By: 8540tomg, 05-02-2009, 04:24 PM

Hi all,

I haven’t used my Pentax KT6-2x rear converter with my M 400/5.6 yet so I thought I'd give it a try. With the 2x on the back of this lens we are working with a focal length of over 1100mm or so and f 11.2. These numbers are so large they just seem silly. In any case it was fairly windy and a bit overcast so I had to use a relatively slow shutter speed. I've been trying to get close to some Black Birds but 400mm on its own didn't quite get me close enough. These fellows don't like you to get very close. The 400/5.6 and 2X is another story altogether. This was the best I could manage today.

Red Wing Black bird





Last edited by 8540tomg; 05-02-2009 at 04:35 PM. Reason: typo
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05-02-2009, 04:43 PM   #2
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Those are nice - If you desaturate the purple channel and darken it someone, it'll totally hide the purple fringing you've got there.
05-02-2009, 04:46 PM   #3
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QuoteOriginally posted by heliphoto Quote
Those are nice - If you desaturate the purple channel and darken it someone, it'll totally hide the purple fringing you've got there.
If I knew how I would heliphoto. I'll see what I can do.

Tom G

Last edited by 8540tomg; 05-02-2009 at 04:47 PM. Reason: typo
05-02-2009, 05:04 PM   #4
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Great shots, wonderful detail, considering how had iot is to expose a black bird properly!

05-03-2009, 02:21 AM   #5
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Nice shots. I have yet to get a decent shot of a RW Blackbird. This time of year when they are breeding makes them very hard to get close to.

Wouldn't a 2x TC on a 400mm glass give you 800mm? About 24x on a APS-C sensor.
05-03-2009, 03:10 AM   #6
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QuoteOriginally posted by wildman Quote
Nice shots. I have yet to get a decent shot of a RW Blackbird. This time of year when they are breeding makes them very hard to get close to.

Wouldn't a 2x TC on a 400mm glass give you 800mm? About 24x on a APS-C sensor.
Thanks Wildman.

They are pretty frisky this time of year. This is the best I've ever managed with these fellows. I was happy just to get them in decent focus with this focal length. I thought the detail was pretty good for an old lens although there is some purple fringe evident.

Now - about the 2X TC on the 400mm. If I were using the 2X on my old full frame film camera you are correct it would be an 800mm equivalent. I'm not an expert on this but it is my understanding the focal length of the lens is multiplied by 1.5 or so when put on a digital camera with an APS-C sensor. If this is the case the 400mm x 1.5 = 600mm. With the 2X converter added into the mix it becomes a 1200mm if I understand things correctly. Lens speed is also cut in half with the 2X in place. If I'm wrong in these assumptions and anyone can correct me on this please feel free to chime in.

In any case the net result is the 400mm and 2X combo becomes a "really long" telephoto lens. Even the slightest nudging of the camera on the tripod causes massive shake in the viewfinder. I leave shake reduction on all the time even on the tripod with this rig for that reason. It is a bit of a challenge but kind of fun to work with a "super telephoto" lens. I'm going to continue to experiment with this set up as it let's me get shots the wildlife just won't allow with a shorter lens.

Cheers

Tom G

Last edited by 8540tomg; 05-03-2009 at 04:07 AM. Reason: typo
05-03-2009, 05:15 AM   #7
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Those birds are hard to expose for sure - you got some good shots there.
05-03-2009, 05:18 AM   #8
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OK. I understand.
Your reasoning is sound as far as I know. Your were thinking in terms of magnification and I was thinking in terms of equivalent FL.

I just use a simple formula. On a APS-C sensor every 100mm of FL gives you 3x magnification. So you don't have to think about crop factor.

Thus on your 400mm with a 2x TC (2x refers to FL not magnification) you would have an equivalent of a 800mm fl glass. So 3x8=24x magnification. But either way they amount to the same thing.

05-03-2009, 05:57 AM   #9
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QuoteOriginally posted by daacon Quote
Those birds are hard to expose for sure - you got some good shots there.

Thanks Dave.

OK Wildman - I see your point now.

Tom G
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