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Author Topic: NEX7 as Surrogate  (Read 3784 times)
OnyimBob
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« on: March 06, 2013, 02:43:55 AM »
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Interesting article Michael.
I started digital photography in 2004 with a Nikon D70. I loved it - a toy I never tired of playing with .... until I then succumbed to the wiles of a Pentax K20 - and I loved her too!
Then I went on a trip to Japan with the full Pentax kit and came home swearing I would travel light from then on (I'm in my late sixties).
And so I took Michael's then recommendation and purchased the NEX7.
The K20 has not left the bag for more than 12 months.
The Sony is a delightful camera - read Michael's reviews to find out why.
It is almost the perfect camera for me .... (I've heard the NEX7N is due to be announced shortly too)!
Sorry Michael, it's no surrogate - it's the real thing. Smiley

On a serious note, each camera above has had a lot more megapixels than the one before - a factor for print size - but the real benefit of the NEX is it's size and ease of use - the Tri-Navi controls are magic!
Cheers, Bob.
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Hans Kruse
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« Reply #1 on: March 06, 2013, 04:35:55 AM »
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Thanks for a great article. One correction on live view: The Canon DSLR's from the Canon 5D mkII and forward has electronic first curtain. They do not close the shutter and reopen it for starting the exposure. The end of the exposure need the shutter to close and reopen for the next shot. This also btw. means that live view is a better alternative than MLU to avoid vibrations. The old Canon 1Ds III does the same thing as the D800 in live view.
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VidJa
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« Reply #2 on: March 06, 2013, 01:43:05 PM »
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Thanks Michael,

Although I probably will never be able to own a Leica, nor any Leica glass, you convinced me to seriously reconcider my plans to buy a D7100 in favour of a nex 7(n)

 I was flipping through my (finally) up to date lightroom catalog and noticed that I did much more candid and street photography with my first camera digital camera, a swivel coolpix 995 (oh my only 3 mp), and even some first landscapes are stlll among my favourites.

Cheers Vic

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ErikKaffehr
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« Reply #3 on: March 07, 2013, 12:31:15 AM »
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Hi Michael,

A good article indeed, just a few small comments.

1) I have peaking on mu Alpha 77 and Alpha 99, but I feel it is very inaccurate. What settings work best for you?

2) Large aperture lenses are known to have focus shift. So best focus at say f/1.4 differs from say f/4. Stopping down farther covers up the focus shift with increasing DoF. So I guess that focusing at shooting aperture is most accurate if using a fast lens.

Best regards
Erik

Interesting article Michael.
I started digital photography in 2004 with a Nikon D70. I loved it - a toy I never tired of playing with .... until I then succumbed to the wiles of a Pentax K20 - and I loved her too!
Then I went on a trip to Japan with the full Pentax kit and came home swearing I would travel light from then on (I'm in my late sixties).
And so I took Michael's then recommendation and purchased the NEX7.
The K20 has not left the bag for more than 12 months.
The Sony is a delightful camera - read Michael's reviews to find out why.
It is almost the perfect camera for me .... (I've heard the NEX7N is due to be announced shortly too)!
Sorry Michael, it's no surrogate - it's the real thing. Smiley

On a serious note, each camera above has had a lot more megapixels than the one before - a factor for print size - but the real benefit of the NEX is it's size and ease of use - the Tri-Navi controls are magic!
Cheers, Bob.
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Fine_Art
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« Reply #4 on: March 07, 2013, 12:50:05 PM »
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I am also very attracted to NEX for it's adaptability.
  • It would let me put a very small secondary in my Dob telescope greatly boosting contrast
  • focus peaking and live view make telescope focusing easy
  • it will take all my lenses adapted
  • it will take any lens I want like the Canon T/S
  • I can use a tilt adapter with any of my full frame lenses on APS-C
  • there is no 1/2 stop light loss like the Alpha SLTs

The downside is loss of fast autofocus, especially screw drive, for all my lenses.

« Last Edit: March 07, 2013, 12:52:11 PM by Fine_Art » Logged
Fine_Art
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« Reply #5 on: March 07, 2013, 01:03:58 PM »
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Hi Michael,

A good article indeed, just a few small comments.

1) I have peaking on mu Alpha 77 and Alpha 99, but I feel it is very inaccurate. What settings work best for you?

2) Large aperture lenses are known to have focus shift. So best focus at say f/1.4 differs from say f/4. Stopping down farther covers up the focus shift with increasing DoF. So I guess that focusing at shooting aperture is most accurate if using a fast lens.

Best regards
Erik


If the lens has focus shift it will still have it on your regular camera. Going to NEX is not going to make it worse. Just be sure your adapter is well machined to very high tolerances by testing focus wide open. If there is back focus or front focus at any corner the planes on the surfaces are not parallel. Center FF/BF should be the same as the same lens on your regular camera.
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ErikKaffehr
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« Reply #6 on: March 07, 2013, 01:24:57 PM »
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Hi,

Focus shift is a problem of lens design, it does not depend on adapter.

It essentially means that optimal focus shifts wit aperture.

http://diglloyd.com/articles/Focus/FocusShift.html

Focus shift is well known problem in optics and essentially all large aperture lenses suffer from it.

Best regards
Erik


If the lens has focus shift it will still have it on your regular camera. Going to NEX is not going to make it worse. Just be sure your adapter is well machined to very high tolerances by testing focus wide open. If there is back focus or front focus at any corner the planes on the surfaces are not parallel. Center FF/BF should be the same as the same lens on your regular camera.
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Fine_Art
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« Reply #7 on: March 08, 2013, 01:21:57 PM »
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Hi,

Focus shift is a problem of lens design, it does not depend on adapter.

It essentially means that optimal focus shifts wit aperture.

http://diglloyd.com/articles/Focus/FocusShift.html

Focus shift is well known problem in optics and essentially all large aperture lenses suffer from it.

Best regards
Erik



You have to read the first sentence.
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DaveCurtis
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« Reply #8 on: March 08, 2013, 01:29:57 PM »
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Nice read Michael.

That 28-35-50 tri-elmar looks interesting. I wonder why Leica stopped building them? 

Looks like the ultimate 'street' lens in terms of versatility.
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ErikKaffehr
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« Reply #9 on: March 08, 2013, 02:00:29 PM »
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Hi,

The first sentence of what? Sorry for asking but I don't know what article or posting you refer to.

Anyway, focus shift is caused by different amount of spherical aberration at different apertures. The best focus moves when stopping down. So if you focus correctly at say f/1.4 and shoot at f/4 your subject will be slightly out of focus.  The example below is from Photozone.de and shows a Leica Sumicron 50/2.5 at full aperture and at f/5.6 as you see best focus at f/2.5 is on the '20' mark while best focus at f/5.6 is between the 18 and 19 marks.

http://www.photozone.de/sony-alpha-aps-c-lens-tests/546-leica50f25nex?start=1

To me it seems that you are discussing something else.

Best regards
Erik



You have to read the first sentence.
« Last Edit: March 08, 2013, 02:11:05 PM by ErikKaffehr » Logged

KLaban
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« Reply #10 on: March 09, 2013, 05:09:23 AM »
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I'm looking for a platform that will get the most out of the Leica M lenses, wides, 18mm & 21mm included.

It would seem there is no surrogate.
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ErikKaffehr
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« Reply #11 on: March 09, 2013, 09:10:41 AM »
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Hi,

The Leica lenses are not really designed for digital sensors. The Leica M will probably have solutions to address some of those issues, like offset microlenses and thin IR filters and no OLP-filtering.

I presume that future M lenses are designed with digital sensors on mind.

Best regards
Erik


I'm looking for a platform that will get the most out of the Leica M lenses, wides, 18mm & 21mm included.

It would seem there is no surrogate.
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Jim Kasson
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« Reply #12 on: March 09, 2013, 10:54:33 AM »
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The Leica M will probably have solutions to address some of those issues, like offset microlenses and thin IR filters and no OLP-filtering.

I presume that future M lenses are designed with digital sensors on mind.

Erik,

You have quite rightly pointed out some hardware fixes to problems with some existing M-series lenses. My tests indicate that some errors are somewhat correlated with ray angle. One way to make things better with new lens designs would be to go to a retrofocus layout to get the ray angle of incidence to the sensor closer to normal (in the geometric sense of the word). However, that would mean giving up the desirable compactness of the M-series lenses.

I'm sure there will be people who will cringe at the very suggestion, but I think a fruitful avenue for the Leica M camera designers will be firmware that's aware of the vicissitudes of each lens when coupled with the sensor of that model camera, and will make appropriate corrections. I think Leica does some of that already. I think it's working pretty well in the RX-1. I suspect from the relative lack of corner color, that Sony is doing some corrections for the 16mm lens in the NEX-7.

Some firmware corrections may cause a loss of resolution, but sensor resolution vs time is still on a pretty steep slope, and soon we'll have sensors that can out-resolve the lenses, at least in the corners, where there will be the greatest need for correction.

A drawback for Leica of putting most of their efforts behind a firmware-based approach might be that there would be little reason for its customers to go out and buy new glass. However, there's a base of customers who have large investments in Leica lenses, and the company would be well-advised to do what it can to keep those people in the fold. If the price of getting the best results is buying new lenses, many people might take the opportunity to jump ship to another vendor.

The issue of third-party glass is thorny. Leica won't want to do things to encourage its customers to buy Zeiss lenses. They could come up with a scheme that allowed customers to load plugins into the camera, but that doesn't sound like Leica. My guess is that the corrections for third-party lenses will be done in programs like Lightroom, and that Zeiss will make available Lightroom correction plugins for each body/lens combination that has a large enough customer footprint.

It's an exciting time to be a photographer.

Jim
« Last Edit: March 09, 2013, 10:57:30 AM by Jim Kasson » Logged

Fine_Art
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« Reply #13 on: March 09, 2013, 11:56:25 AM »
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Hi,

The first sentence of what? Sorry for asking but I don't know what article or posting you refer to.

Anyway, focus shift is caused by different amount of spherical aberration at different apertures. The best focus moves when stopping down. So if you focus correctly at say f/1.4 and shoot at f/4 your subject will be slightly out of focus.  The example below is from Photozone.de and shows a Leica Sumicron 50/2.5 at full aperture and at f/5.6 as you see best focus at f/2.5 is on the '20' mark while best focus at f/5.6 is between the 18 and 19 marks.

http://www.photozone.de/sony-alpha-aps-c-lens-tests/546-leica50f25nex?start=1

To me it seems that you are discussing something else.

Best regards
Erik




No worries, I pressed quote which did not put my quote in your quote.

I was referring to this "If the lens has focus shift it will still have it on your regular camera. Going to NEX is not going to make it worse." -me
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michael
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« Reply #14 on: March 09, 2013, 12:19:45 PM »
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Nice read Michael.

That 28-35-50 tri-elmar looks interesting. I wonder why Leica stopped building them?  

Looks like the ultimate 'street' lens in terms of versatility.


It's a fantastic lens. Regrettably Leica had to stop making them because they proved to be too difficult (expensive) to manufacture from a mechanical perspective. A cut-away drawing shows how incredibly complex the mechanism is. Total Leica overkill as usual.

Michael
« Last Edit: March 09, 2013, 02:11:46 PM by michael » Logged
KLaban
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« Reply #15 on: March 09, 2013, 12:48:58 PM »
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The Leica M will probably have solutions to address some of those issues, like offset microlenses and thin IR filters and no OLP-filtering.

Erik, I'm sure you're right.

The best platform for the range of the existing Leica M lenses is surely the Leica M.
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ErikKaffehr
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« Reply #16 on: March 09, 2013, 08:53:33 PM »
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Hi,

Michael mentioned that the best way to focus a lens was at full aperture and than stop down. This may be less true with large aperture lenses, it is probably better to focus them at shooting aperture, which is no problem with the NEX-7 in good light.

That was the reason I mentioned focus shift. This will also apply to the Leica M.

Best regards
Erik




No worries, I pressed quote which did not put my quote in your quote.

I was referring to this "If the lens has focus shift it will still have it on your regular camera. Going to NEX is not going to make it worse." -me
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