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Focal lengths that can be image-stabilized on Sony A-Mount
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PostPosted: Sun Nov 01, 2015 11:16 pm    Post subject: Focal lengths that can be image-stabilized on Sony A-Mount Reply with quote
Several models of A-mount Sony cameras, such as A900, A850, A77, A65 and A99, allow focus confirmation and image stabilization of old lenses, provided you use a proper "chipped" adapter. Unfortunately, most of those "intelligent" adapters on the market come programmed to focal length of 50mm only. To overcome the 50mm limitation, I've been writing a code of my own so I could program a chip to other focal lengths. To make the story short, I discovered that all these focal lengths that can be programmed:

6mm 7mm 8mm 9mm 10mm 11mm 12mm 13mm 15mm 16mm 17mm 18mm 20mm
22mm 24mm 26mm 28mm 30mm 35mm 40mm 45mm 50mm 55mm 60mm 70mm
75mm 80mm 85mm 90mm 100mm 105mm 110mm 120mm 130mm 135mm 140mm
150mm 160mm 180mm 200mm 210mm 230mm 250mm 280mm 300mm 330mm
360mm 400mm 420mm 460mm 480mm 500mm 560mm 600mm 650mm 700mm
800mm 840mm 900mm 1000mm 1100mm 1200mm 1300mm 1400mm 1600mm
1800mm 2000mm 2200mm 2400mm 2600mm 2800mm 3200mm 6553mm

Interesting that the table is bigger than the list of FLs one can enter manually on A7II or A7RII.

The table above is for Sony A99, but I think it also applies to other A-mount models. I've never seen a table with all possible focal lengths published elsewhere. I dare say that the complete table of FLs was known only by Sony's engineers until now.

The most important is that I have now all my lenses, with focal lengths from 16mm to 1600mm, with image stabilization! How about taking a hand-held picture with a 16mm fisheye using shutter speed as long as 1/2 second and still having a perfectly sharp picture? Life can be beautiful!

To show the effectiveness of the image stabilization, take a look at the picture below:

Full Image:



Pixel level (crop 100%)




Position: standing without support
Camera support: handheld
Camera model: Sony A99V
Lens: APO Sigma 400mm F5.6
Aperture: F5.6
Shutter speed: 1/20s
EFCS: on
ISO: 4000
WB: Auto
Environment: indoor
Illumination: 100W incandescent lamp, 2800 °K
Focus: on the clock number

If you can check the numbers and letters on the clock, you will see they are sharp even when viewed at pixel level.

For a 400mm it is generally recommended that a shutter speed of at least 1/400s be used for sharp image. The image stabilization allowed me the use of shutter speed 20x lower (exposure time 20x longer). Amazing!

The image is JPEG as came from the camera except for an exposure correction of +1EV. If you look at the EXIF data, you may notice the F22 aperture value, which is the fixed value that the adapter chip sends to the camera. The actual lens aperture is F5.6.

You may also want to check the A99 noise intensity for ISO 4000.



NOTE: This is possibly my last post in this forum. It will be clearer after I post further information in Photographer's Cafe later.

Thanks for reading.

Greetings to all.


PostPosted: Mon Nov 02, 2015 3:52 am    Post subject: Reply with quote
Like 1

Good to see you can make the stabilization works on all your lenses.


PostPosted: Mon Nov 02, 2015 7:58 am    Post subject: Reply with quote
Welcome back Gerald. Like 1


PostPosted: Mon Nov 02, 2015 5:48 pm    Post subject: Reply with quote
calvin83 wrote:
Like 1

Good to see you can make the stabilization works on all your lenses.


Hi Calvin

Of course, image stabilization is more important for telephoto lenses, but wide-angle, ultra wide-angle and fisheye lenses also benefit greatly from IS. In order for image stabilization be effective, the focal length setting should be off by no more than ~ 20% of the actual focal length.

It is interesting to know that some very expensive lenses, as the Canon EF 11-24mm f / 4L USM that costs almost $3000, have no image stabilization. Not because IS is not desirable, but because with it that lens would be even bigger, heavier and more costly than it already is.

As side information, the Sony A99 uses the focal length setting and the sensors of movement in the camera body to stabilize video. In this mode, the image sensor stays locked so image stabilization is purely electronic.



cyrano wrote:
Welcome back Gerald. Like 1


Thank you, cyrano! Glad to hear from you!


PostPosted: Mon Nov 02, 2015 6:20 pm    Post subject: Reply with quote
Very interesting, though I've never looked deeper in the possibilities of IS with MF lenses on my A850 up to now. Even my chipped M42 adapter lies around somewhere unused... Wink

The simple reason behind is that I really prefer to use rather Minolta AF lenses on my A850 body with rather rare exceptions and with those lenses it works anyway as designed.

In this respect Pentax has introduced a much simpler option on my K20D: You just have to tell the camera (using up/down button) which FL is used. No chips needed.
My other cameras don't support in-body IS at all.

Anyway, thanks for sharing. Your example is rather impressing.


PostPosted: Mon Nov 02, 2015 10:30 pm    Post subject: Reply with quote
How is this different to the programmable chips that have been available for years?

http://www.eadpt.com/eadpen.htm


PostPosted: Mon Nov 02, 2015 11:37 pm    Post subject: Reply with quote
Computer programmers will recognize that last odd-looking focal length that doesn't seem to fit with the other numbers in the sequence.

6553mm reminds one of 65535 -- a special number in computer programming (convert to binary to see why).

So those are the allowable settings use 6mm for least IS and 6553mm for maximum IS, yes?

The settings are near optimal (say Sony) for those focal lengths. However, these settings do not take into account, for example, close focusing and macro lenses, which achieve higher magnifications than the lens lengths Sony calibrated.

I.e, it is magnification rather than focal length which determines how to set IS. For example, a 90mm macro lens used a 1:1 magnification is going to require more IS than the Sony 90mm setting gives...


PostPosted: Tue Nov 03, 2015 12:38 am    Post subject: Reply with quote
iangreenhalgh1 wrote:
How is this different to the programmable chips that have been available for years?

http://www.eadpt.com/eadpen.htm


I never had a James Lao's adapters, so I cannot say much about them. What I know is that the most advanced adapter can be programmed to four different focal lengths. In contrast, the chip in my adapter can be programmed if I want to all 73 values of focal length in the table. No doubt an adapter for all those focal lengths is possible but it wouldn't be much practical.

I have programmed several adapters so far: a "universal" for 10 FLs, a dedicated for wide-angle (16, 17, 20 and 28mm), one for normal and short telephoto (50, 80, 135 and 200mm), and one for super-telephoto (300, 400, 600 and 800mm). Each time the lens release button is depressed, the focal length switches to the next value.


PostPosted: Tue Nov 03, 2015 12:59 am    Post subject: Reply with quote
visualopsins wrote:
Computer programmers will recognize that last odd-looking focal length that doesn't seem to fit with the other numbers in the sequence.

6553mm reminds one of 65535 -- a special number in computer programming (convert to binary to see why).

So those are the allowable settings use 6mm for least IS and 6553mm for maximum IS, yes?

The settings are near optimal (say Sony) for those focal lengths. However, these settings do not take into account, for example, close focusing and macro lenses, which achieve higher magnifications than the lens lengths Sony calibrated.

I.e, it is magnification rather than focal length which determines how to set IS. For example, a 90mm macro lens used a 1:1 magnification is going to require more IS than the Sony 90mm setting gives...



Maybe the 6553mm value in table is just a "code stop", I don't know. Any way, it is the value that appears on the camera display, but perhaps the largest focal length that can be effectively stabilized is "only" 3200mm. Sadly, I don't have a 3200mm lens to test such extreme focal length.

The intriguing number you referred is 2^^16 - 1, or 1111111111111111b, right?

To stabilize a 90mm macro lens working with a scale 1:1, you should set the focal length to 180mm. For this type of application, a 5-axis IS system would be ideal.


PostPosted: Tue Nov 03, 2015 1:02 am    Post subject: Reply with quote
Gerald wrote:
iangreenhalgh1 wrote:
How is this different to the programmable chips that have been available for years?

http://www.eadpt.com/eadpen.htm


I never had a James Lao's adapters, so I cannot say much about them. What I know is that the most advanced adapter can be programmed to four different focal lengths. In contrast, the chip in my adapter can be programmed if I want to all 73 values of focal length in the table. No doubt an adapter for all those focal lengths is possible but it wouldn't be much practical.

I have programmed several adapters so far: a "universal" for 10 FLs, a dedicated for wide-angle (16, 17, 20 and 28mm), one for normal and short telephoto (50, 80, 135 and 200mm), and one for super-telephoto (300, 400, 600 and 800mm). Each time the lens release button is depressed, the focal length switches to the next value.


You only need to programme a single FL, one for each lens, that is, unless you're swapping adapters between lenses and I don't see the point in that when they are a couple of dollars from China now.

Looks like your solution is the same as Laos, his can be programmed to a great number of FLs.


PostPosted: Tue Nov 03, 2015 1:15 am    Post subject: Reply with quote
Like 1 Congrats


PostPosted: Tue Nov 03, 2015 1:46 am    Post subject: Reply with quote
Attila wrote:
Like 1 Congrats


Attila,

Would you please tell to whom was the thumbs-up?

Thank you.


PostPosted: Tue Nov 03, 2015 1:48 am    Post subject: Reply with quote
To you Gerard, sorry it wasn't clear.


PostPosted: Tue Nov 03, 2015 1:59 am    Post subject: Reply with quote
Thank you very much, Attila.

Like 1

I will take the liberty to understand your gesture as the signal I was expecting.

Best Regards

Gerald


PostPosted: Tue Nov 03, 2015 2:48 am    Post subject: Reply with quote
Happy Dog
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