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10-21-2011, 12:20 AM   #16
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I've given up dreaming of a 100-300/4 and are buying the 120-300/2.8 instead.. in Nikon mount

10-21-2011, 12:46 AM   #17
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QuoteOriginally posted by karthikv82 Quote
Does the AF work with the 2X TC ?
Yes.

As I said, works quite well, especially when you think this was taken at (effectively) 600mm handheld. With a tripod/monopod it would obviously have been sharper.




Effectively 440mm




I also have the same lens and 1.4x sigma for my newly aquired Canon 50D (bought mainly for the MP-E 65 macro) and recently tested the combo on there.


10-21-2011, 06:09 AM   #18
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QuoteOriginally posted by HGMonaro Quote
I've given up dreaming of a 100-300/4 and are buying the 120-300/2.8 instead.. in Nikon mount
For some reason, I was thinking that the 120-300mm/2.8 was upwards of $5000, and therefore forever out of reach. But I just checked, and Adorama has it for $3199. Still very expensive, and currently out of reach, but it is at least conceivable that I could save up and maybe find a used copy in the mid 2k's eventually.
10-21-2011, 06:21 AM   #19
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I use both the 1.4x and 2x sigma TCs with my 70-200F2.8 both work very well, with the 100-300/4, AF might be a challenge with a 2x TC because the native aperture is now F8 and AF only reliably works to about F6.7, BUT having said that, I have successfully stacked both my sigma TCs on the 70-200F2.8 and had AF lock in bright conditions so AF confirmation at F8 is possible.

the pitfalls with any TC at present on any pentax camera is aperture and focal length reporting.

For SR you end up with the wrong, (under compensated) setting but that may not be all that bad, Aperture reporting is a different issue however, because many pentax bodies use the known maximum aperture of the lens to meter accurately and compensate for errors in metering off the focusing screen (the K10/K20 are the worst at this) and as a result, putting a TC on these bodies causes an exposure error, which is pretty constant over the whole aperture range, necessitating EV comp settings.

Additionally I have found that with P-TTL flash, knowing the correct aperture is also important, and again this requires compensation of the flash and camera exposure settings to get it right. With these limitations understood, the sigma TCs are the best way forward.

10-21-2011, 06:32 AM   #20
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QuoteOriginally posted by Lowell Goudge Quote
the pitfalls with any TC at present on any pentax camera is aperture and focal length reporting.
...

For SR you end up with the wrong, (under compensated) setting
...

putting a TC on these bodies causes an exposure error, which is pretty constant over the whole aperture range, necessitating EV comp settings.

With all of these limitations, I wonder why Pentax doesn't take advantage of the situation to sell a TC that communicates properly with the camera body to transmit correct focal length and aperture information and works with SDM/HSM. I'm sure there are many, many people who would pay a premium for a high quality, no-hassle TC.
10-21-2011, 07:00 AM   #21
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QuoteOriginally posted by Edgar_in_Indy Quote
For some reason, I was thinking that the 120-300mm/2.8 was upwards of $5000, and therefore forever out of reach. But I just checked, and Adorama has it for $3199. Still very expensive, and currently out of reach, but it is at least conceivable that I could save up and maybe find a used copy in the mid 2k's eventually.
If it is ever released.
10-21-2011, 07:09 AM   #22
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QuoteOriginally posted by Clinton Quote
If it is ever released.
Has it not been announced in Pentax mount? Was this an error on Adorama's site then?

I just checked Sigma's website, and it doesn't seem to list the 120-300mm in Pentax mount.
10-21-2011, 07:15 AM   #23
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I pre-ordered mine on May 20, a few weeks after Adorama said I could order one. Apparently I'm #2 in line, I'll let you know how it goes (or doesn't go).

Adorama is kind enough to email me every couple weeks and inform me the lens is still on backorder. I dunno. Since I ordered it, I've got some epic glass, and I've been thinking about throwing in the towel on this glass.

Really after the surprise win on the A*1200, It's for the best (for me) that this lens doesn't show up in stock for another 6 mo


Last edited by Clinton; 10-21-2011 at 07:31 AM.
10-21-2011, 08:23 AM   #24
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WOW ... overwhelmed with the quick and useful responses Cheers. My 100-300 was a lucky buy from another forum member who was switching systems. Grabbed the opportunity 700 bargain

QuoteOriginally posted by Mike.P Quote
Yes.

As I said, works quite well, especially when you think this was taken at (effectively) 600mm handheld. With a tripod/monopod it would obviously have been sharper.
Super. I might aim to get both then ... eventually cheers for that
10-21-2011, 09:20 AM   #25
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QuoteOriginally posted by Edgar_in_Indy Quote
I expect that there will be a new version eventually, most likely with HSM and OS.
Yes, that was the speculation back then, too. There is no question that Sigma should bring out a new version of this lens, as it's just too good and reasonably priced to let fade away, but they don't usually take this long to intro an updated model. Also, I'm not sure how compelled I would be to replace mine. It already focuses really quickly, so HSM would only mean silently. Granted, a boon to birders but it's not what you would call loud now. Plus, HSM precludes the use of their TCs on Pentax, at least for AF. And then, of course, we Pentaxians don't have tremendous need for OS. I'm sure in-lens would be better for this type of lens, but how much better? Then there is the fact that many of the lens "updates" that Sigma brings out are not as optically good as their predecessors. Some are, some aren't.

I called Sigma a couple of times back when the discontinuation of this lens took place. I ended up talking to several people, all of whom told me that there were "no plans" to introduce a new version of this lens. You can take that for whatever it's worth, which ain't much. Really stupid on Sigma's part, IMO. They seem to be willing to put all of this market's eggs in the 120-300's basket, and has been said, there still hasn't been a Pentax version of that one, either, and is HSM, so no use of their TCs. Just bone-headed product planning if you ask me, which, surprisingly, they didn't.
05-05-2012, 01:44 PM   #26
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Using my Pentax AF 1.7 TC on the Sigma 100-300 f4

Has anyone used the Pentax AF 1.7 TC on a sigma 100-300 f4? I want to buy the lens if they are compatable.
05-05-2012, 02:43 PM   #27
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QuoteOriginally posted by cshepley Quote
Has anyone used the Pentax AF 1.7 TC on a sigma 100-300 f4? I want to buy the lens if they are compatable.
I had a slight problem with the combo that was remedied using the aperture ring. I liked to stop the lens down 1 stop with the TC for sharpness, if possible, but for some reason when I would pick an f stop in av mode, I couldn't get the lens to stop down to where it said on the body (and exif) unless it was 2 stops down. I found out by looking in the lens and hitting the DOF preview. (K20D) The exif showed it as 70-200mm f2.8, so that may be why. Using the aperture ring was a good work-around, but I usually used the kenko 1.5x TC on it instead. I hope this makes some sense.
05-06-2012, 09:11 AM   #28
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Thanks. Sadly, I got out bid on the sigma 100-300 f4. The search will continue.
05-06-2012, 05:05 PM   #29
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FYI: Adorama canceled my order a while ago. Said it will never be in stock.
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