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09-19-2018, 02:08 PM - 2 Likes   #16
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Irix puts more money into advertising than Pentax does

09-19-2018, 02:45 PM   #17
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QuoteOriginally posted by Dr_who Quote
Irix puts more money into advertising than Pentax does
I find this trailer ugly but that is personal taste
09-19-2018, 06:13 PM   #18
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QuoteOriginally posted by Mike.P Quote
was unaware they did a 200mm.
they don't. they do make a couple zooms that are "macro." they used to make a 50 1:1 and currently have a 70, 105, 150, and 180 that are all 1:1. the 70 and 180 are stellar.
09-19-2018, 06:24 PM   #19
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QuoteOriginally posted by repaap Quote
It could be great option for macro. No AF really needed there.

I think so too.. plus with IBIS it could be a really nice lens for K mount.


I wonder the size and weight though.. no free lunches, I know. haha. The Sigma 150 is beefy and I can't expect this to be much different.. but maybe a little weight savings with no AF motor or IS built in?

09-19-2018, 11:26 PM   #20
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QuoteOriginally posted by Ishpuini Quote
Between my DFA100/2.8 and my Sigma EX180/3.5 I don't really need a 150mm macro, but I might be tempted if the max aperture would be interesting and if they would offer a WR package. Perhaps they might go beyond 1:1, that might be something too, esp given the working distance at 150mm.

Irix is a planned stop on my photokina itinerary anyway, so I'm hoping I'll have it in my hands soon, regardless what it is...

Wim
Off topic: do you have a ticket to photokina? If not, i am giving one away for free if you need it.
09-20-2018, 03:44 AM   #21
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150mm f2.8?
09-20-2018, 04:41 AM - 1 Like   #22
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QuoteOriginally posted by beholder3 Quote
I have not understood the need for anything between a autofocus DFA 100 mm Macro (which you can use the x1,4 converter with) and a DA* 300, for which you can also use a x1,4 converter and also can use a 25mm distance ring (with full AF).
Don't see it as an addition to the K-mount lineup... see it as the first tele and macro offering by Irix. They can select whatever focal length they please
09-20-2018, 05:23 AM   #23
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That's neat, I bet it will be a really nice performing lens! 150mm is interesting at macro distances, DOF will even be more of a challenge. This will probably make a killer portrait lens!

09-20-2018, 06:24 AM - 1 Like   #24
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At macro distance, depth of field only depends on the magnification ratio, not on the lens's focal length.
09-20-2018, 07:46 AM   #25
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QuoteOriginally posted by Mistral75 Quote
At macro distance, depth of field only depends on the magnification ratio, not on the lens's focal length.
I understand what you're trying to say, but that's simply not true. Photons don't change their behaviour because you're close to your subject. The physics is the same.

Just for fun, try to take a 1:1 picture with a 50mm macro and a 100mm macro, if you need any convincing. Or ask wikipedia how magnification is calculated
09-20-2018, 07:53 AM - 4 Likes   #26
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QuoteOriginally posted by bobbotron Quote
That's neat, I bet it will be a really nice performing lens! 150mm is interesting at macro distances, DOF will even be more of a challenge. This will probably make a killer portrait lens!
QuoteOriginally posted by Mistral75 Quote
At macro distance, depth of field only depends on the magnification ratio, not on the lens's focal length.
QuoteOriginally posted by bdery Quote
I understand what you're trying to say, but that's simply not true. Photons don't change their behaviour because you're close to your subject. The physics is the same.

Just for fun, try to take a 1:1 picture with a 50mm macro and a 100mm macro, if you need any convincing. Or ask wikipedia how magnification is calculated
Since you asked for it...

QuoteOriginally posted by Wikipedia:
Let m be the magnification; when the subject distance is small in comparison with the hyperfocal distance,



so that for a given magnification, DOF is independent of focal length. In other words, for the same subject magnification, at the same f-number, all focal lengths used on a given image format give approximately the same DOF.
Depth of field - Wikipedia
09-20-2018, 09:57 AM   #27
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See those wavy lines? It means it's an approximation. As I said, I understand what you mean. It's a simplification, which often holds but involves some risks.
09-20-2018, 10:25 AM   #28
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QuoteOriginally posted by bdery Quote
See those wavy lines? It means it's an approximation. As I said, I understand what you mean. It's a simplification, which often holds but involves some risks.
If that is what you want to say, you need to say this to each and every post about DoF or blur or whatever measurement. Simply because all computations you'll ever see on a forum are all approximations. The biggest part here is that they all make the quite shaky assumption that the lens used consists of one single lens element.
09-20-2018, 12:19 PM - 1 Like   #29
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QuoteOriginally posted by mee Quote
I think so too.. plus with IBIS it could be a really nice lens for K mount.


I wonder the size and weight though.. no free lunches, I know. haha. The Sigma 150 is beefy and I can't expect this to be much different.. but maybe a little weight savings with no AF motor or IS built in?
It will be big, but time will tell. no AF will help. if it is weather sealed, even better

---------- Post added 09-20-18 at 22:22 ----------

umm, isnt longer focal let you be little more fruther away from subject..? dof at close up will be thin.any one who shoots 1:1 on any macro notice this. wider gives more surroundings, and narrow like this more just a bug or what ever..right?
09-20-2018, 01:43 PM   #30
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QuoteOriginally posted by repaap Quote
It will be big, but time will tell. no AF will help.
How does it help? Cheaper to design thus a priori cheaper to purchase?
Usage wise AF is not a must for macros but still very nice to have
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