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02-13-2014, 09:38 PM   #16
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QuoteOriginally posted by dms Quote
I don't agree w/ the last post if he is saying all extension tubes are the same. There are differences between extension tubes--cheap ones are not baffled/blackened inside to the same degree, and thus can flare badly.
That's a good point. Although I am sure he/she said with a bit of a tongue in cheek.

02-13-2014, 09:56 PM   #17
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Sorry--I can be a bit dense/too literal some times!
02-13-2014, 09:58 PM   #18
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QuoteOriginally posted by dms Quote
Sorry--I can be a bit dense/too literal some times!
Oh it's ok. I didn't mean that. You brought up a good point which I didn't think of and which probably would matter quite a bit.
People can even spot differences in flare with off-brand, or original hoods, so definitely they would see one with a poorly
blacked out insides of the macro tube! I thought that was a good point.
02-14-2014, 06:09 AM   #19
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BTW, the Raynox DCR-250 is also a pretty good option, and for me the combo of a tubes plus the Raynox is very effective on the Tamron 90 to reach quite a bit beyond 1:1. But apparently the diopters like the Raynox give more magnification on longer lenses, so for a 70mm, maybe try tubes first to see if they get you where you want to go...

02-28-2014, 05:44 PM   #20
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QuoteOriginally posted by VisualDarkness Quote
It seems like 70mm of tubes gives you a magnification of 1.05x with that lens, true macro.
You're forgetting about the K mount flange - that calculator is designed for canon DSLRs. And in any case, using 70mm of extension tubes ( taking the flange into account) with the FA77 will give you not only a very dark viewfinder but also a very short working distance. Basically, if you really need 1:1 capability, buy an actual macro lens.

There is also another problem with using a large number of extension tubes - increased diffraction. Because the lens is further away form the sensor the aperture will appear smaller, this makes diffraction a bigger issue especially when you stack multiple extension tubes, it isn't very noticeable when you are using only one tube. I did a quick comparison between the FA77 with 70mm of extension tubes and my Sigma 180mm f/3.5 APO EX both at f/11 on the Pentax K5IIs

Pentax K5IIs FA77mm f/1.8 Limited with 70mm extension tubes - Sigma 180mm f/3.5 - both at f/11- unsharpened 100% crops.

It is clear which lens is sharper.

Last edited by Digitalis; 02-28-2014 at 06:28 PM.

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