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05-06-2015, 01:43 PM   #811
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QuoteOriginally posted by Stavri Quote
[SIZE=3]Thanks for the files. I am impressed not only by the IQ but the lens+K3 ISO performance- super clean files at ISO 640 on the K3 (It wasn't the case with my legacy Sigma 400/f5.6 telemacro). From a rough comparison I noticed that at ISO 1250 this lens matches the noise performance on my Sigma EX 300/f2.8 at ISO 640-800. In my estimation the lens seems to be 1/3-1/2 stop faster than a similarly spec'd 3rd party lens. (I noticed a similar thing with the DA 20-40 which people consider slow, its high ISO performance almost matched the IQ on the Sigma 18-35 Art.)
Okay, I must be having a bad day, because I'm not following you at all. What does the lens have to do with ISO performance?

05-06-2015, 01:52 PM   #812
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QuoteOriginally posted by sholtzma Quote
Okay, I must be having a bad day, because I'm not following you at all. What does the lens have to do with ISO performance?
(IMO) The sensor always "sees" through a lens of some kind, some lens optics are better than others ( the elements are better designed, polished, glued , coated, aligned etc) that you can "notice" a marginal high ISO performance increase. At iso 1000 when using my K3 with the Sigma Ex DG 300mm f2.8 for instance the produced images are noticeably cleaner then when I use the Sigma APO 400mm f5.6 Telemacro (a legacy lens) in similar settings.
05-06-2015, 02:02 PM   #813
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QuoteOriginally posted by Stavri Quote
(IMO) The sensor always "sees" through a lens of some kind, some lens optics are better than others ( the elements are better designed, polished, glued , coated, aligned etc) that you can "notice" a marginal high ISO performance increase. At iso 1000 when using my K3 with the Sigma Ex DG 300mm f2.8 for instance the produced images are noticeably cleaner then when I use the Sigma APO 400mm f5.6 Telemacro (a legacy lens) in similar settings.
To add to what Stavri wrote: It also has to do with the fact that in photo we use F/ stops (aperture size and indirectly light passing through the lens) and not T/ stops (light effectively passing through the lens). Typically, as an example, mirror lenses as the Tarmon 500/8 have a T/stop around 11 (yeah, there's a hole in there). This is an example of course but it illustrates the fact that two lenses presented as a certain f/stop does not mean they will let light pass exactly the same way (more or less).
05-06-2015, 02:11 PM   #814
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QuoteOriginally posted by vcollerp Quote
A few of my first ones.
Don't forget to post some photos on the 300mm + thread, the guys there will eat em up...

https://www.pentaxforums.com/forums/122-lens-clubs/55946-300mm-plus-lens-club...nses-1110.html

Judging by the RAW images, the transmittance on the updated coatings seems exceptional....


Last edited by Stavri; 05-06-2015 at 02:17 PM.
05-06-2015, 02:18 PM   #815
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QuoteOriginally posted by thibs Quote
To add to what Stavri wrote: It also has to do with the fact that in photo we use F/ stops (aperture size and indirectly light passing through the lens) and not T/ stops (light effectively passing through the lens). Typically, as an example, mirror lenses as the Tarmon 500/8 have a T/stop around 11 (yeah, there's a hole in there). This is an example of course but it illustrates the fact that two lenses presented as a certain f/stop does not mean they will let light pass exactly the same way (more or less).
I don't want to hijack this (important) thread, so I'll add just one more post. I understand how the amount and quality of light through a lens (clearly affected by the lens) could influence sharpness or aberrations, for example, but what on earth does it have to do with ISO performance?. The sensor has a particular response at a given ISO (including signal-to-noise) that surely is constant no matter what lens is attached.
05-06-2015, 02:33 PM   #816
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QuoteOriginally posted by sholtzma Quote
I don't want to hijack this (important) thread, so I'll add just one more post. I understand how the amount and quality of light through a lens (clearly affected by the lens) could influence sharpness or aberrations, for example, but what on earth does it have to do with ISO performance?. The sensor has a particular response at a given ISO (including signal-to-noise) that surely is constant no matter what lens is attached.
Yes the ISO performance is the same, but a lens with a faster t stop at the same aperture has the effect of exposing to the right, resulting in a cleaner image when adjusted to the same brightness levels, alternatively you can use a lower ISO with less noise.
05-06-2015, 02:59 PM   #817
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QuoteOriginally posted by robjmitchell Quote
Yes the ISO performance is the same, but a lens with a faster t stop at the same aperture has the effect of exposing to the right, resulting in a cleaner image when adjusted to the same brightness levels, alternatively you can use a lower ISO with less noise.
To add to this, the difference is likely minor and in most cases you would just tweak the exposure in post up a bit. But a lens that is just a bit brighter means you do not have to pull up a slightly under exposed picture with the resultant noise in the shadows. Or add + EV compensation if that is how you handle that.
05-06-2015, 03:37 PM   #818
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Wait, I don't get those ISO ideas at all. If we have two lenses that are f2.8, but one is is t2.8 and the other is t4 (for sake of argument), the camera would just choose a higher ISO or longer shutter to match the same EV, the same histogram curve. So you would end up with the same image, just different metering/settings. I mean, if the lens is darker, than the metering wouldn't know whether its lens or light conditions, so it would choose the settings that would give the desired overall EV. One lens and another would only expose differently if you were in M mode and kept the same shutter, aperture, and ISO. Then t4 would produce a darker image. But it would only bring more noise if you chose to set a higher ISO, or use PP to brighten it. Neither of these is affected by lens. The only way a lens could affect noise directly is if one lens would be radioactive to the point that it would affect the sensor (unlikely, I don't think thats how physics work) or if it would block incoming noise from outside of the camera. These two are both based on the premise that outside things can affect the noise performance. Now, maybe heat can affect noise, but this is usually ambient heat and sensor-generated heat, so again the lens would have next to no effect.
I am curious about this, maybe someone can link to research or an article. I did in the past think that some lenses are a little noisier than others, but I think that was just before I understood EV and didn't know that the f4.5-5.6 lens would use a higher ISO than the f2.8 lens in the same ambient light

QuoteOriginally posted by vcollerp Quote
A few of my first ones.
Wonderful! Looks like the lens is a winner, at least in good hands!

05-06-2015, 03:41 PM   #819
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QuoteOriginally posted by f1monza Quote
Will here is the jest of it all.
I have used sigma lenses with
Canon bodies. Seems Sigma and Tamron will discontinue making lenses for Pentax bodies.
According to Sigma and Tam on
Both companies decided not enough volume sales by Pentax owners. What ever you decided on make it quick. Soon Pentax owners are going to be left in the dark.
Including myself.
I too have owned Sigma lenses on my Canon. I did prefer the L lenses from Canon. May just convert back to Canon. Not enough support for PENTAX owners.
Just when I was getting the hang of my K5iis.
So weird... f1monza, can you please tell us where you emerged from and why you chose to spend your energies on a forum whose brand you clearly see as dead in the water? Seriously, I have no idea and would like to know.

[Disclaimer: Have not read most recent 5ish pages. Maybe he answers my question...]
05-06-2015, 03:46 PM   #820
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QuoteOriginally posted by filoxophy Quote
[Disclaimer: Have not read most recent 5ish pages. Maybe he answers my question...]
Nope. f1monza seems to have left the building.
05-06-2015, 04:02 PM   #821
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QuoteOriginally posted by jatrax Quote
Wow. A little speechless, those are fantastic. I would be proud of any of them. And you are just learning the lens? I cannot wait to see what you do with it with some experience.

I guess my only comment is why on earth would Ricoh release the pictures they did when they could have released pictures like these?
(His first day with the lens) Isn't that something.....
05-06-2015, 04:05 PM   #822
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QuoteOriginally posted by filoxophy Quote
So weird... f1monza, can you please tell us where you emerged from and why you chose to spend your energies on a forum whose brand you clearly see as dead in the water? Seriously, I have no idea and would like to know.

[Disclaimer: Have not read most recent 5ish pages. Maybe he answers my question...]
Same thing here, I just passed to watch the great pics in the las two pages and ended up to see your post.
f1monza is ready to jump back to Canon because Sigma and Tamron are no longer supporting Pentax K-mount.
Then he say that he preferred Canon L-series lenses with Canon body anaway.
So, why not stick with Pentax and use only Pentax lenses?
Really weird post...
05-06-2015, 04:33 PM   #823
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Great pictures, and thanks a lot for the RAW files !
05-06-2015, 07:05 PM - 1 Like   #824
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I am SO impressed with these images. I have just picked up a part time job as a jail (gaol) guard and with She Who Must Be Obeyed's reluctant approval it is ALL going to CAMERAS and LENSES.

Waiting for the other shoe to drop, so to speak, before I choose between the K-3 and K-3 II. I do have the Pentax cable 5P, so I can hook up an external flash easily enough (I also have the AF540FGZ). The GPS is about $250 when it's not built in. The high res for landscapes using the sensor shift system might be useful. The better shake reduction is attractive.

Right after the K-3 (II?) comes the 150-450. I will finally, with some sorrow, retire my lovely old M 400/5.6. The new lens allows for things coming closer without having to switch lenses and the reduced CA and PF is a great advantage. There is no speed loss at f/5.6, and maybe a bit higher T/stop with the newer coatings.

The series of pictures combining the K-3 and 150-450 ARE ABSOLUTELY STUNNING! And I know I am shouting -- aren't you?
05-06-2015, 11:21 PM - 3 Likes   #825
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+1,


just to show the serious housing/features for this lens :








p.s. : Hama ***** HTMC UV filter added from my own stock
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