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02-11-2008, 06:57 PM   #91
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QuoteOriginally posted by jgredline Quote
Actually, I very happy with my 135-400Sigma APO that is also F/5.6 @ 400. The image quality to me is amazing.
Yeah, ebay is really the only place to get one. I got mine a year ago for a BIN price of $449. Just last week one went for $653 in Pentax mount. Just to give an idea how over inflated Pentax long glass prices are I tracked a one in Nikon mount that sold for $273!

John

02-11-2008, 08:21 PM   #92
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TC talk

Have the Kenko 1.5 teleconverter. Seems pretty good quality. Seems that Tokina, Tamron, Kenko, Phoenix converters are all made by same company. Tokina and Phoenix look identical- have compared them. Think the Tamron 1.4 tc has 4 elements and the Kenko 1.5 has 5. This would explain the greater length of the Kenko.
Strange tc tales.
1. Mentioned this before. Kenko will not work properly with the Pentax A400 5.6 mf lens. There is one less contact on one side of tc than other. This causes the f stop to read out as 2.8! Meter is totally confused. Why they built a converter that has a pin running to nothing on the other side is anyones guess. Also have the same problem with older Phoenix 2X tc.

2. Have a Promaster 1.7 tc that looks just like the Tamron 1.4/Kenko 1.5. It is slightly longer than the 1.5 Kenko. It has matching front and rear contacts and works fine with 5.6 lenses! It appears older than the new Kenko. So why redesign the mount on the Kenko to not work with f5.6 lenses? Strange.

3. Friend has 2x Phoenix that won't af with certain high speed lenses (2.8). MF is fine. Tried a new Phoenix (has been redesigned - hadn't noticed). It afs fine with the troublesome lenses in the exact same conditions. It even afs along with the Kenko 1.5 used together at the same time. What could possibly cause the other 2x to not focus? It does fine on other lenses. Does the converter actually add info to the lens/camera setup?
4. Off subject slightly. Using a Canon EOS with a tc is strange if the lens is a t mount. If the tc has the electrical contacts that mate to an EOS body and the other end ( lens) doesn't see contacts the combo freaks out and refuses to shoot - no matter the mode ASMP! First thought the contacts were shorting out against t mount. Not so. The electronics just can't handle this situation. Would really suck using on telescope!
thanks
barondla
02-11-2008, 08:48 PM   #93
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Well, I am convinced that the Tamron 1.4tc is far different that the Kenko 1.5TC..
At the end of the day, the quality ''may'' be the same, but certainly the kenko needs to have the ISO set at 800 or even 1600 to work properly..Of course this leads to noise that is not so noticeable when shooting animals, but when shooting people, ot is quite obvious..

Here I caught three Canadian geese all trying to mate..
ISO/1600 during the day !!!


ISO/1600 during the day !!!


ISO/1600 during the day !!!


Here is a photo of my son..
ISO/1600 shows a ton of noise...I tried ISO / 800 and it simply would not auto focus..


Same pic after about 5 minutes in CS3..Still not very usable...


So, the Tamy 1.4 as far as my opinion goes, is the way to go...Why? I don't really know, I just know what I have seen and experienced with my own eyes...
02-12-2008, 03:57 AM   #94
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Here are a few I made with the Kenko 1.5x TC on my Pentax F* 300. All handheld. I had hardly any AF issues and used ISO 400:







Yes, it does alter the bokeh, as can be seen here:



So far, I am more than happy with the Kenko!

02-12-2008, 04:04 AM   #95
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QuoteOriginally posted by jgredline Quote
Well, I am convinced that the Tamron 1.4tc is far different that the Kenko 1.5TC..
At the end of the day, the quality ''may'' be the same, but certainly the kenko needs to have the ISO set at 800 or even 1600 to work properly..
Just so you know: the ISO setting is totally unrelated to the AF speed. If you use ISO 100 or ISO 3200 does not matter at all, the AF speed and AF problems will stay the same. What lens did you use in your shots?
02-12-2008, 08:10 AM   #96
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QuoteOriginally posted by Asahiflex Quote
Just so you know: the ISO setting is totally unrelated to the AF speed. If you use ISO 100 or ISO 3200 does not matter at all, the AF speed and AF problems will stay the same. What lens did you use in your shots?
ASA
Those are some really nice pics!! The lens I used was the Tamron 75-300, so it was not a good lens, but the same lens works well with the tamron 1.4TC...

As far as ISO, I am aware that it holds no bearing on Auto focus speed as that comes down to the lens build, but at lower ISO's the pics would not come out..Well, they would, but where extremely blurry and dark. Simply not enough light.
02-12-2008, 09:36 AM   #97
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Javier - I still think there's something fundamental about exposure that you are not understanding. So the ISO setting has NO bearing on autofocus speed, not sure where you got that from.

As for your follow-up comments about low ISO shots coming out blurry and dark, well the blur probably would be caused by needing to use a slower shutter speed due to the lower ISO (either camera shake or motion blur), but why would they be darker?

You do realize that if lower the ISO one stop (1600->800), to keep the image the same brightness, you'd have to either slow down the shutter one stop (such as 1/500s->1/250s) OR open the aperture one stop (f/8->f/5.6). P/Av/Tv mode take care of this for you (forget about AUTO-ISO, I never use that and don't really know how it works) In Manual mode, you have to do this yourself.

So there should be NO change in brightness when changing the ISO if you are using P/Av/Tv and not dialing in any EC.
02-12-2008, 09:49 AM   #98
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QuoteOriginally posted by egordon99 Quote
Javier - I still think there's something fundamental about exposure that you are not understanding. So the ISO setting has NO bearing on autofocus speed, not sure where you got that from.

As for your follow-up comments about low ISO shots coming out blurry and dark, well the blur probably would be caused by needing to use a slower shutter speed due to the lower ISO (either camera shake or motion blur), but why would they be darker?

You do realize that if lower the ISO one stop (1600->800), to keep the image the same brightness, you'd have to either slow down the shutter one stop (such as 1/500s->1/250s) OR open the aperture one stop (f/8->f/5.6). P/Av/Tv mode take care of this for you (forget about AUTO-ISO, I never use that and don't really know how it works) In Manual mode, you have to do this yourself.

So there should be NO change in brightness when changing the ISO if you are using P/Av/Tv and not dialing in any EC.
I agree. There is allot to learn still...This is why I am quick to point out my Amateur status.
Yes, I am well aware of how shutter speed, ISO and EV works hand in hand..I just don't have steady enough hands to pull that off...I did try a slower shutter speed.. I did not have a tripod with me and no shake reduction in the camera, so I compromised best I could with what I had...I agree about the ''auto iso''. I try and stay away from it...

Perhaps, you and some of the the folks who trully have an understanding of exposer can start a thread on it...Certainly, I would love to follow along and learn more...

02-12-2008, 09:50 AM   #99
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I was looking at the latest road map and unless, I am missing something, I see a ''new'' TC coming as well...
http://www.digital.pentax.co.jp/en/lens/roadmap.pdf
02-12-2008, 10:01 AM   #100
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Javier, what mode were you shooting in when you took those dark shots that needed extra ISO? Where you in "M"?
02-12-2008, 10:02 AM   #101
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It's spelled "exposure"

Did you ever read Peterson's "Understanding Exposure" ?
02-12-2008, 10:18 AM   #102
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QuoteOriginally posted by Miserere Quote
Javier, what mode were you shooting in when you took those dark shots that needed extra ISO? Where you in "M"?
I used ''p'', then switched to TV and kept slowing down the shutter speed until the photo was not underexposed, but then it was blurry. I then tried using Av mode and basically opened it up as much as possible, same result..I did not try ''M'' mode as I am not familiar enough to use that...Cranking the ISO was the only thing that worked for me with what I had...

Now here is the thing. With the Tamron TC 1.4 this is not a problem. Conventional settings work...With out the TC at all, it was great, ISO 200 perfect.. Maybe the Kenko TC i have is bad?, but then again it the Kenko works good with other lenses...
02-12-2008, 10:21 AM   #103
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QuoteOriginally posted by egordon99 Quote
It's spelled "exposure"

Did you ever read Peterson's "Understanding Exposure" ?
Sure did, a few times..I even converted it over to PDF so I have a copy on my lap top.., (Sorry, I can't share it though, as I respect the authors right to make a living and copy right laws)
02-12-2008, 10:30 AM   #104
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The problem with Tv is that if you hit a certain shutter speed (say 1/400s) and you're at a certain ISO (say 400) and it needs f/4.0 for proper exposure but your lens only opens to f/5.6, then you're scr*wed! I THINK the f-stop will blink in the viewfinder to indicate that you will underexpose. One reason why Tv mode can trip you up. Obviously if you're in Av mode, the shutter speed can be adjusted to ensure proper exposure. I guess Auto-ISO would raise the ISO for you in that Tv scenario, but I'd rather be in control.
02-12-2008, 10:59 AM   #105
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QuoteOriginally posted by jgredline Quote
Sure did, a few times..I even converted it over to PDF so I have a copy on my lap top.., (Sorry, I can't share it though, as I respect the authors right to make a living and copy right laws)
I just got this book Sunday, and started reading it last night. Looks like it will be very helpful. Like you (and I don't mean this as derogatory in any way), I'm having a problem understanding exposure. I can only get better.
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