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12-08-2015, 02:17 AM   #16
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Anydbody have an idea of what the 2x would be like with the DFA 90mm Macro.

I am thinking of getting the 2x

12-08-2015, 10:16 AM   #17
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QuoteOriginally posted by donesteban Quote
Did you put the lens itself to f/16? My 645D doesn't translate the apperture when adding the converter, I still can put the 20/4 to f/4 according to the camera. But in combination with the 2x convter that's f/8 wide open. So if my camera shows f/16 in combination with the 2x converter, there is f/32 in fact. This will soften the image, too, don't stop the lens further down than f/8 when usng the 2x converter! If a lens is not sharp enough at f/8 in combination with the converter, don't use it with the converter, as stopping further down will kill sharpness anyway. Just try your 200/4 at f/32 without converter.
The 1.4x converter allows to stop down the lens up to f/11, making it a bit easier for the lens.
Excellent point and I did do that so it was stopped WAY down, more than I was trying for. That would have probably contributed to IQ problems too. Next time I get a chance I'll give it another go taking all of this into account.

Thanks!
12-08-2015, 01:08 PM   #18
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FYI-- Diffraction formulas show that f/32 will yield no more than 42 Lp/mm (1340/focal ratio, 32), so that is part of your problem.

Last edited by desertscape; 12-08-2015 at 01:13 PM.
12-16-2015, 12:30 PM   #19
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I must be the odd duck. I have a field day when using the 2x tc with my 200mm and 400mm. it's strictly manual focus, but I 've worked hard building my skill at manual focusing. I even get good results stacking the 1.4x and the 2.0x. last summer I shot a bunch at a civil war re-enactment. I have my share of sharp images, soon i'll post a few at this posting.

12-16-2015, 04:57 PM   #20
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QuoteOriginally posted by bull drinkwater Quote
I must be the odd duck. I have a field day when using the 2x tc with my 200mm and 400mm. it's strictly manual focus, but I 've worked hard building my skill at manual focusing. I even get good results stacking the 1.4x and the 2.0x. last summer I shot a bunch at a civil war re-enactment. I have my share of sharp images, soon i'll post a few at this posting.
I made some mistakes when I tried it so I'd like to try again but I can't lift my 645D kit at the moment. I'll try again when I can!
01-10-2016, 12:46 AM   #21
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I use the 200mm and the 400mm with the 2x tc "a lot" I use a monopod a lot and as many tips and tricks as I can. with my 465D there is no live view. my manual focusing has gotten pretty good. when i'm careful there is no IQ degration to speak of for me.
01-10-2016, 09:30 PM   #22
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here are a few samples from my 200mm + a 2x tc.
Attached Images
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PENTAX 645D  Photo 
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PENTAX 645D  Photo 
01-11-2016, 11:34 AM   #23
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I tested my 400A with the 2X TC and decided to crop as the IQ was horrendous so I share your findings Matt. this was some time ago so don't have images and crops handy but it really wasn't even close.

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