lens tele extenders
Posted 31/03/2006 - 01:27
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Matt,
That's so topical - I was out at a local Hawk watching site today and one of the guys is using an *istD with a Tamron 400mm and a Pentax 1.7 converter. He was getting exceptional shots.
I have been wondering for some time about the Pentax 1.7 with my *istDS2 and my Pentax 80-320 and Sigma 170-500.
I take it that you get full autofocus with the 1.7 and the 80-320?
Mike
That's so topical - I was out at a local Hawk watching site today and one of the guys is using an *istD with a Tamron 400mm and a Pentax 1.7 converter. He was getting exceptional shots.
I have been wondering for some time about the Pentax 1.7 with my *istDS2 and my Pentax 80-320 and Sigma 170-500.
I take it that you get full autofocus with the 1.7 and the 80-320?
Mike
Posted 31/03/2006 - 07:13
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Mike,
The 1.7xAF disengages the lens' focus, and it focuses internally.
In many ways that's a benefit because there's only a small amount of glass to move. But you have to just watch that the lens itself doesn't creep, or get accidentally moved. Adjusting the lens focus manually changes the range that the 1.7xAF can focus within.
It's great in practice but hard to explain!
Hope that helps!
Matt
The 1.7xAF disengages the lens' focus, and it focuses internally.
In many ways that's a benefit because there's only a small amount of glass to move. But you have to just watch that the lens itself doesn't creep, or get accidentally moved. Adjusting the lens focus manually changes the range that the 1.7xAF can focus within.
It's great in practice but hard to explain!
Hope that helps!
Matt
Posted 31/03/2006 - 13:53
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Matt,
Thanks I think I have the concept. Yesterday he explained that occasionally he would have to refocus the Tamron and then the converter would take over again with no problems. This appeared to happen when the hawk distance varied considerably.
Thanks,
Mike
Thanks I think I have the concept. Yesterday he explained that occasionally he would have to refocus the Tamron and then the converter would take over again with no problems. This appeared to happen when the hawk distance varied considerably.
Thanks,
Mike
Posted 14/04/2006 - 21:16
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Here's some shots with Pentax istds2, 28-70 f4, 1.7 extender, 280 ringflash.
All shot this morning, in our garden.
more on our website (photo blog section):
http://homepage.mac.com/lightexpressions/index.html
All shot this morning, in our garden.
more on our website (photo blog section):
http://homepage.mac.com/lightexpressions/index.html
Fired many shots. Didn't kill anything.
Posted 15/04/2006 - 03:58
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OK quick *summing up* questions...
Pentax 1.7x AF convertor auto focuses itself within a range set by manuall adjusting the lens that's fitted to it?
SMC 80-320 works with the above convertor on an IST D, allowing the camera to control aperture and the camera/convertor to focus?
How much light does the convertor lose? couple of stops?
Pentax 1.7x AF convertor auto focuses itself within a range set by manuall adjusting the lens that's fitted to it?
SMC 80-320 works with the above convertor on an IST D, allowing the camera to control aperture and the camera/convertor to focus?
How much light does the convertor lose? couple of stops?
Posted 15/04/2006 - 09:06
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Yes, that basically sums it up.
Think of it as a standard 2x converter (1.7x isn't far off) and then imagine it as an AF lens in it's own right. It has the same AF coupling and electronics as an F series lens. The front of the converter is effectively a KA mount (no AF coupling this time but yes, full aperture control), so any lens attached to it is set manually to infinity and the adapter does the AF work.
For close-up work, you can set the focus of the lens to a shorter distance and thereby limit the AF range and bring into focus subjects that are too close for the adapter to resolve sharply with the lens set to infinity.
I recently tried the adapter with my 75-250 f3.8/4.5 and the camera had no difficulty whatsoever, the result at the long end was soft but this was largely down to camera-shake (bear in mind that we are talking of an effective focal length of almost 640mm on my DL) and I'm sure that with the usual precautions, that can be eliminated - the AF system certainly locked on very positively.
Incidentally, the adapter is also usable with the camera in MF mode or on a manual body (a Super A or MZ-M, for example) and you can adjust the adapter's setting by turning the focus mechanism with a watchmakers' screwdriver before mounting it onto the camera.
Think of it as a standard 2x converter (1.7x isn't far off) and then imagine it as an AF lens in it's own right. It has the same AF coupling and electronics as an F series lens. The front of the converter is effectively a KA mount (no AF coupling this time but yes, full aperture control), so any lens attached to it is set manually to infinity and the adapter does the AF work.
For close-up work, you can set the focus of the lens to a shorter distance and thereby limit the AF range and bring into focus subjects that are too close for the adapter to resolve sharply with the lens set to infinity.
I recently tried the adapter with my 75-250 f3.8/4.5 and the camera had no difficulty whatsoever, the result at the long end was soft but this was largely down to camera-shake (bear in mind that we are talking of an effective focal length of almost 640mm on my DL) and I'm sure that with the usual precautions, that can be eliminated - the AF system certainly locked on very positively.
Incidentally, the adapter is also usable with the camera in MF mode or on a manual body (a Super A or MZ-M, for example) and you can adjust the adapter's setting by turning the focus mechanism with a watchmakers' screwdriver before mounting it onto the camera.
Die my dear doctor, that's the last thing I shall do!
Posted 07/02/2010 - 20:46
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New member with a question for you guys. Is there a teleconverter that will work with a Sigma 150-500 mm zoom? I am using A Pentax K7 which I am really pleased with.
Jim
Pentax K7, Pentax 18-70 f4, Sigma 10-20, Sigma 105 Macro, Sigma 150-500, Tamron 70-300, various Cokin Z pro filters.
Remember,wherever you are. "Take only photographs and leave only footprints."
Pentax K7, Pentax 18-70 f4, Sigma 10-20, Sigma 105 Macro, Sigma 150-500, Tamron 70-300, various Cokin Z pro filters.
Remember,wherever you are. "Take only photographs and leave only footprints."
Posted 07/02/2010 - 21:47
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If you want a lens longer than 500mm, which equates to 750mm on a 35mm camera, and is therefore quite long already, I would suggest you look out for a mirror lens or an old Takumar 1000mm. Both in M42 mount.
G
G
Keywords: Charming, polite, and generally agreeable.
Posted 07/02/2010 - 21:50
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Mike-P wrote:
WOW .. 4 years on .. how did you manage to dig this thread up?
Probably through the search engine.
WOW .. 4 years on .. how did you manage to dig this thread up?
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 07/02/2010 - 22:13
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I have the Sigma 170-500 and have tried it with 1.5x Kenko and 1.7x Pentax TC's. Most of the time you have to use MF as not enough light gets through for AF to work. A friend has tried the 150-500 with a 2x TC on a Canon, and found the same thing.
Barrie - Too Old To Die Young
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
Posted 08/02/2010 - 07:23
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Thanks all, will see if I can get hold of a Pentax 1.7x, anybody got any ideas?
Jim
Pentax K7, Pentax 18-70 f4, Sigma 10-20, Sigma 105 Macro, Sigma 150-500, Tamron 70-300, various Cokin Z pro filters.
Remember,wherever you are. "Take only photographs and leave only footprints."
Pentax K7, Pentax 18-70 f4, Sigma 10-20, Sigma 105 Macro, Sigma 150-500, Tamron 70-300, various Cokin Z pro filters.
Remember,wherever you are. "Take only photographs and leave only footprints."
Posted 08/02/2010 - 09:25
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Most people would suggest not bothering with a teleconverter with a zoom lens. There are a small number of exceptions, mostly fast expensive zooms like the Sigma 100-300 or various f2.8 70-200s.
There's a chap called JinFinance on ebay who often has 1.7x TCs for sale. You have to keep emailing him weekly until he gets some stock in because he sells out very quickly.
There's a chap called JinFinance on ebay who often has 1.7x TCs for sale. You have to keep emailing him weekly until he gets some stock in because he sells out very quickly.
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 08/02/2010 - 22:27
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Kimbo wrote:
Incidentally, the adapter is also usable with the camera in MF mode or on a manual body (a Super A or MZ-M, for example) and you can adjust the adapter's setting by turning the focus mechanism with a watchmakers' screwdriver before mounting it onto the camera.
Hi,Incidentally, the adapter is also usable with the camera in MF mode or on a manual body (a Super A or MZ-M, for example) and you can adjust the adapter's setting by turning the focus mechanism with a watchmakers' screwdriver before mounting it onto the camera.
Why would one want to adjust the 1.7AF's settings, I presume focus setting, when using it with a manual lens ?
Greg
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5870 posts
24 years
Sussex,
UK
http://www.ephotozine.com/gallery/showlargepic.cfm?photoid=447534&start=0&am...
The contrast was reduced quite a bit by the convertor, but Capture One and Photoshop rescued the image. I was mighty pleased with the sharpness, given the riddiculous focal length! (On a Manfrotto MN444 tripod)
Matt