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| 02-10-2008, 08:18 PM | #76 |
| Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.  Originally posted by Outlaw  Whoa!! Nice shots Javier. I've used a Sigma 2x TC with the Bigma and its hunts viciously except in very good light. Initially wondered what I was doing wrong but after reading this thread, all has become "clear" . .so to speak. I often need to MF too and I wonder if this is true of all 2x TC's or jst the Sigma. Has anyone tried the Sigma 2x with a DA*50-135 yet? That will be my next lens. Rob I'm actually very surprised a 2xTC would autofocus with the Bigma at all. I'm sure you know this but when you use a TC you loose the light needed for the camera to autofocus. So when you use a 2xTC your loosing 2 stops of light, seeing as the Bigma is 6.3 at the long end your already starting out with an f/12.6 lens. I would have guessed that a f/12.6 lens would never autofocus even in good light  I guess what I'm trying to say is that the hunting your talking about has nothing to do with the Sigma TC specifically, any 2xTC attached to the bigma would hunt just as much. I *think* the difference in autofocus between the Tam 1.4 and Kenko 1.5 is the .1 difference in magnification... loosing just that little amount more of light is causing more hunting. I hope that made sense.... John | |
| 02-10-2008, 08:41 PM | #77 |
| Originally posted by palmor I *think* the difference in autofocus between the Tam 1.4 and Kenko 1.5 is the .1 difference in magnification... loosing just that little amount more of light is causing more hunting. | |
| 02-10-2008, 11:16 PM | #78 |
| Originally posted by jgredline Rob Thanks for the kind words...I have not had the opportunity to use anything longer than the 1.5TC...Can you post some photos using the sigma TC? I would be curious to see them. John | |
| 02-11-2008, 09:30 AM | #79 |
| Originally posted by palmor I have photos with that TC.. but attached to a Sigma 70-200 EX.. not sure if that is the combo you'd be interested in seeing examples from. If it is I can post some. John I would love to see them and also I would be very interested in hearing your thoughts on the Sigma TC.. | |
| 02-11-2008, 09:44 AM | #80 |
| Originally posted by jgredline John I would love to see them and also I would be very interested in hearing your thoughts on the Sigma TC.. . First my thoughts on the TC. Since this TC and the Sigma are a matched pair they work very well together. The loss of IQ is minimal while focusing is just a tad slower (the 70-200 if a very fast focusing lens by itself). The thing about the Sigma TC's is that the front element sticks out so they are not compatible with all lenses out there. If your lens has a rear element that is close to the end of the lens (if that makes sense) there is a chance that it could come in contact with the Sigma TC, damaging one of both of them. For the 1st time last week I tried the Sigma TC on my Tokina AT-X 400 f/5.6. With this setup there is no AF so it was all manual focus. The results where OK, I wouldn't use it for anything that I wanted the best quality out of, but for that owl sitting on a branch way out of reach I may be tempted. I didn't process any of those since I was only fooling around but I can try to take some shots in better light and see how they come out. Anyway onto the photos. These where all taken with the 70-200EX and Sigma 2xTC. Both lens and TC are the older non DG versions. Shouldn't make a difference but I mention it just in case it is important. I don't have any direct comparisons at different f-stops since I'm not much of a pixel peeper... I just go by my results that I get in real world shooting. There are more examples in my birds Gallery on my pbase site (link in sig). Pentax K10D ,Sigma 70-200mm f/2.8 EX APO IF Taken with Sigma 2x TC Stats based on TC: 1/1500s f/8.0 at 400.0mm iso400  Pentax K10D ,Sigma 70-200mm f/2.8 EX APO IF 1/2000s f/8.0 at 400.0mm iso400 (used 2xTC)  Pentax *ist DS ,Sigma 70-200mm f/2.8 EX APO IF Taken with Sigma 2xTC  Pentax K10D ,Sigma 70-200mm f/2.8 EX APO IF 1/750s f/4.0 at 200.0mm iso400 (with Sigma 2xTC)  Pentax K10D ,Sigma 70-200mm f/2.8 EX APO IF 1/60s f/7 at 400.0mm iso200 (with Sigma 2xTC)  | |
| 02-11-2008, 11:22 AM | #81 |
| 02-11-2008, 12:05 PM | #82 |
| Originally posted by Clem Nichols John: I don't have the eyes of a pixel peeper, so my opinion may not be worth much, but I really don't see how you could expect better sharpness even without the TC. To my less-than-expert eyes, those look razor sharp. I'm having a hard time waiting for the Sigma 70-200 f2.8 with HSM to become available. For those who might be considering the Tamron 1.4TC, Cord's website now says to call for availability. I ordered one on Wednesday, 2/6. It was charged to my credit card on that date, and an automated e-mail said it would be shipped within 2 business days. Assuming that neither Thursday nor Friday was some kind of a government holiday that I haven't heard about, it should have already been shipped, but it doesn't indicate it on their website. I'm thinking they may be having trouble finding one. I'm also thinking that this thread was good for their business. CN Thanks Clem. I think that its more of a testament to the 70-200 lens then the TC. TC's will just magnify any imperfections that the lens has and that Sigma really doesn't have any IMO. Here are a couple of shots without a TC from that lens, I think these are even sharper with slightly better feel to them (can't put into words what is better other then sharpness but there is something.. just slight). Thanks again John   | |
| 02-11-2008, 12:53 PM | #83 |
| 02-11-2008, 12:59 PM | #84 |
| 02-11-2008, 02:42 PM | #85 |
| Originally posted by jgredline Palmor Thanks for the photos...They are really nice... I think it is important to note, that TC's are indeed going to take away some quality..even if the eye can't see it...TC's are not meant to replace lenses, but to enhance their use... For example...My Tamron TC 1.4 has a permanent home on my sigma 70-300 apo = 420mm, but if I know I am going birding or long lens specific, I will take my 135-400 or my bigma... | |
| 02-11-2008, 03:50 PM | #86 |
| Originally posted by palmor Yup, I agree 100%. The IQ of the Sigma 70-200 and TC combo is good but I actually never use it anymore. I moved to a 400mm prime lens that I think gives just as good if not better IQ and is faster focusing and much lighter. CN | |
| 02-11-2008, 03:53 PM | #87 |
| Originally posted by Clem Nichols Just out of curiosity, which 400mm prime are you using? Thanks. CN A couple of examples Bald Eagle photo - palmor photos at pbase.com Bald Eagle photo - palmor photos at pbase.com Bald Eagle on roof top photo - palmor photos at pbase.com John | |
| 02-11-2008, 03:58 PM | #88 |
| Originally posted by palmor The Tokina AT-X 400mm f/5.6 (latest version with the tripod colar). Great lens, very light and sharp stopped down 1 stop. A couple of examples Bald Eagle photo - palmor photos at pbase.com Bald Eagle photo - palmor photos at pbase.com Bald Eagle on roof top photo - palmor photos at pbase.com John | |
| 02-11-2008, 04:05 PM | #89 |
| Originally posted by jgredline Hmmm, Where one might go to purchase one? | |
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