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05-28-2013, 07:47 AM   #16
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QuoteOriginally posted by CheepShot Quote
The 50-500 OS is razor sharp with a good 1.4x tc. I'm sure the 500mm is as well. Incredibly nice lens.

Actually, Nikon bodies D7100 and up do AF up to F8. Kenko teleplus pro 1.4x tc's send a fake signal to the body allowing af in good light on others.
Geeeeze !

I've had my share of using different long lenses with tc's and I have yet to find one such combo which will give "razor sharp" results at the long end. That goes for Sigma and Pentax lenses.

Got some samples of razor sharp (Sigma) images with a tele-zoom lens with a TC ?

JP

05-28-2013, 08:28 AM   #17
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QuoteOriginally posted by jpzk Quote
Geeeeze !

I've had my share of using different long lenses with tc's and I have yet to find one such combo which will give "razor sharp" results at the long end. That goes for Sigma and Pentax lenses.

Got some samples of razor sharp (Sigma) images with a tele-zoom lens with a TC ?

JP
Ya, I too would love to see some razor sharp images with a TC on this lens [on the long end] - looking at a couple of res-charts (including sigmas own technical mft chart for this lens) I can't see anywhere but on the short end of this lens [and only within a couple of stops] where it is razor sharp and that is without a TC.
05-28-2013, 11:38 AM   #18
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I may have read this wrong...but a 500mm lens on an ASP-C cropped sensor would translate to about 750-775 mm...35mm film equivalent. My 55-300 lens at 300mm on my ASP-C bodies translates to about 450- 462mm...35mm film equivalent.
05-28-2013, 12:56 PM   #19
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QuoteOriginally posted by stormtech Quote
This has my attention also. I know this phenomenon has been proven with the DA* 60-250 at distances less than infinity - the reason being I am told is because it is an internal focus (IF) lens.

I never even thought of the Bigma suffering from the same thing. This gets me to wondering now if I am just better off shooting my FA* 300 4.5 with 1.4x TC which equates to 420mm.

Going to have to do a couple test shots to see for sure......
Instead of going further off topic here, I did a down and dirty test of the two lenses toady - I posted my findings here:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/226250-compari...00-4-5-tc.html

05-28-2013, 01:59 PM   #20
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QuoteOriginally posted by stormtech Quote
This has my attention also. I know this phenomenon has been proven with the DA* 60-250 at distances less than infinity - the reason being I am told is because it is an internal focus (IF) lens.

I never even thought of the Bigma suffering from the same thing. This gets me to wondering now if I am just better off shooting my FA* 300 4.5 with 1.4x TC which equates to 420mm.

Going to have to do a couple test shots to see for sure......
All internal focusing lens show this behaviour, to have a shorter fl at near distances. The nominal fl is only valid for infinity.

Ben
05-28-2013, 05:36 PM   #21
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I stand corrected. My test was several months ago against a Tamron 60b with the 140f tc. I've sold the Bigma and can't duplicate the results. When I get a chance, I will try and find a couple shots with the Bigma and a cheap Tamron 1.4x tc. I am pretty sure there are a couple posted on my flickr acct.
05-29-2013, 11:06 AM   #22
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QuoteOriginally posted by jpzk Quote
Geeeeze !

I've had my share of using different long lenses with tc's and I have yet to find one such combo which will give "razor sharp" results at the long end. That goes for Sigma and Pentax lenses.

Got some samples of razor sharp (Sigma) images with a tele-zoom lens with a TC ?

JP
Is the 50-500 OS Sharp with a TC? Take a look yourself, please take in to consideration that I do this for enjoyment and in no way am I professional photographer or reviewer. In my humble opinion, the Sigma 500mm F4.5 is an exceptional lens that outclasses the Bigma at 500mm. Staying on topic.

Here's a shot that is approximately a 100% crop with the Sigma 50-500os and a cheap Tamron-F AF 2X TC
Bald Eagle | Flickr - Photo Sharing!

Here's another approx 100% Crop eagle shot with the 50-500 OS and a Tamron-F AF 1.4X TC
Bald Eagle | Flickr - Photo Sharing!

Here's another eagle shot at 50mm with the Sigma 50-500 OS followed by another at 500mm cropped 100%
Eagle over-looking Fox River | Flickr - Photo Sharing!
Eagle in previous image | Flickr - Photo Sharing!

Here's another eagle shot with the 50-500 OS at 500mm followed by a 1000mm F10 Rubinar Reflex
500mm 50500os | Flickr - Photo Sharing!
1000mm F10 Rubinar (Old Russian Mirror Lens) | Flickr - Photo Sharing!

Sigma 500mm F/4.5 taken with a Pentax-Q
http://www.flickr.com/photos/23755697@N04/8881638308/

Last edited by CheepShot; 05-29-2013 at 11:21 AM. Reason: Added another shot
05-31-2013, 08:09 AM   #23
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Original Poster
thanks all for your responses

im currenty contemplating what lens to get (i have budget for either)

given i have the 70-200 f2.8, i was thinking potentially the 50-500 zoom would be more useful given its been pretty highly rated... but the LBA inside of me is asking me to go for the sigma 500 ...

if you do end up doing a comparison sometime down the road, i am very patient to wait and see your conclusions

thank u!

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