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UV/IR Thermal or Xray Photography Humans happen to use visible light naturally but now we can go beyond the usual wavelengths we appreciate, to find out more about our world and ourselves.

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  #31  
Old October 29th, 2013, 10:49 AM
Jerome Marot Jerome Marot is offline
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The Sony seems to generate lots of excitement... but AF it with Canon lenses is not likely to be really usable. On the NEX-7, contrast AF is not really usable on lenses designed for the A mount. Of course it works with the "translucent" mirror system, but nobody is going to produce an adapter with that system except Sony and for their lenses only. So, basically, one loses AF.

Then there is the electronic viewfinder. I don't find these any good. In any case, they are not a great help for focussing fast lenses: peaking is not very accurate and the resolution is far too low to judge optimal sharpness. I think that the people who swear by them must be using lenses open around f/5.6, then it works. You can ask the display to enlarge the center of the picture for precise focus, but that means working on a tripod and who wants that with a small camera?

About tripods: I find it a real problem that Sony did not include their sensor based stabilization in the NEX line. Not only it is extremely convenient in low light, but having compared the Sony A900 and the Nikon D800 a generally unnoticed advantage of sensor based stabilization occurred to me: the A900 is generally a bit sharper than the D800 when one does not use a tripod. It is a small effect, but it shows that the higher resolution of the D800 (or A7r) is simply going to be wasted. And lens based stabilization adds another problem: it requires one to wait till the lens is stabilized, while sensor based stabilization is simply always on.

As to the Zeiss 24mm f/2.0 (SAL-24f20Z): it is one of the finest lenses available in all mounts, but is designed for the A mount. So it needs to be used on the A900/A99 or with the LA-E4 adapter. It is not compact.
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  #32  
Old October 29th, 2013, 10:57 AM
Jerome Marot Jerome Marot is offline
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Quote:
Originally Posted by Ben Rubinstein View Post
I have never been able to focus the Tak accurately on my (actually your!) 5Dc without a viewfinder magnifier used on tripod.
Responding to your old post: I realized that the Pentax Takumar 50mm has a 42mm screw mount. Do the AF indicators work when you use the Pentax Takumar 50mm on your Canon camera? If they don't, you may simply need an adapter with a chip to fool the camera. I don't know whether these exist for the EOS mount, but they do exist for the Sony/Minolta A mount. They even enable stabilization then.

(Actually, a quick google check shows that they also exist for the EOS mount.)
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  #33  
Old October 29th, 2013, 11:18 AM
Ben Rubinstein Ben Rubinstein is offline
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I do have an adaptor with a chip and it does provide focus confirmation, accurate focus confirmation with the lens. However it only gives accurate results in good light, in low light it's useless. Added to that due to the AF system on the 5D3 it only activates cross sensor focus points in the middle 3 columns and only the cross sensors are accurate. No doubt due to the low contrast of the lens wide open. I realise this is a fault of the chip, if the chip told the camera it was a specific fast canon lens the problem would not exist.
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  #34  
Old October 29th, 2013, 11:22 AM
Jerome Marot Jerome Marot is offline
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Originally Posted by Ben Rubinstein View Post
However it only gives accurate results in good light, in low light it's useless.
You could put a flash on your camera, not for the flash (which you could disable), but for the AF illuminator.
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  #35  
Old October 29th, 2013, 11:27 AM
Ben Rubinstein Ben Rubinstein is offline
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The idea is for a walk around lens with a certain look. Hardly want to drag a flash around with me to be honest. The camera is bulky/heavy enough.
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  #36  
Old October 29th, 2013, 04:16 PM
Cem_Usakligil Cem_Usakligil is offline
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Hi Ben,

Quote:
Originally Posted by Ben Rubinstein View Post
Cem thank you for your offer. Do you have any raw samples from this specific lens shot wide open? I have plenty Nex 7 samples from when I was playing with buying that great little camera. Very nice files. Very reminiscent of my 5Dc though far better shadows.
..
I am sorry but I did not realize that your request was for that specific lens, which I don't have.
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  #37  
Old October 30th, 2013, 01:51 AM
Ben Rubinstein Ben Rubinstein is offline
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Thanks anyway!
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  #38  
Old October 30th, 2013, 10:04 AM
Asher Kelman Asher Kelman is offline
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Quote:
Originally Posted by Dr Klaus Schmitt View Post
Metabones + Dr Brian Caldwell announced their new "Speed Booster",
actually a well known principle from astronomy, a focal reducer or telecompressor.

See here: Metabones - Metabones and Caldwell Photographic introduce Speed Booster

White Paper is here: http://www.metabones.com/images/meta...te%20Paper.pdf

Test is here: An adaptor which claims to make your lens, faster, wider and better!! This is NOT an April Fool’s! | Philip Bloom

****

Done that before for my sort of photography, see on my BLOG: Photography of the Invisible World: Search results for reducer

without reducer/telecompressor:


with reducer/telecompressor:

overall system changed from f4 to f1.6 and the focal length from 84mm to 34mm!

I must say, I owe you a belated congratulations on using the concept before the Metabones adapter was available. But then, it's hardly surprising, as you understand optics so well and have one of the largest collections of superb specialty lens for UV, IR and visible photography.


The Trade name, Metabones™ distracted me, I must admit, from the fact that you were doing this well before Caldwell's partnership with this company gave them a product! Kudos to you. I should pay more attention to the details of your posts!



Asher
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  #39  
Old October 30th, 2013, 10:23 AM
Asher Kelman Asher Kelman is offline
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Now, can we get such focal length reducers that increase the effective aperture using MF lenses on full frame 35mm cameras, like the Sony A7?

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  #40  
Old October 30th, 2013, 10:36 AM
Ben Rubinstein Ben Rubinstein is offline
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You're not the first to be wondering it however I'm not sure that there is such a great need. The MF lenses in general are either less sharp or stupidly expensive and far less prolific or special/niche/interesting than the 35mm lens market which the speedbooster opened up to those using crop cameras. There are not that many lenses which would be worth the bother to be frank given the native choices already available.

I do have a Mamiya lens adaptor with about 10mm of rise and fall. Never got round to using it though, to be frank, spherical stitching is less bother

What I do think there is a market for is adaptors to use large or medium format lenses on a Hcam type board with a mirrorless camera to allow movements for stitching using wider lens circles. Niche, especially in an age of native 36 megapixel cameras, however I have little doubt that Stefan, the man behind the Hcam is thinking about it right now. When I used the camera fusion adaptor the main problem was mirror box shading. The problem was solved with mirrorless crop cameras but it was still a faff. Now with FF mirrorless, the whole concept of flat stitching becomes far more interesting.
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  #41  
Old October 30th, 2013, 10:40 AM
Jerome Marot Jerome Marot is offline
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Quote:
Originally Posted by Asher Kelman View Post
Now, can we get such focal length reducers that increase the effective aperture using MF lenses on full frame 35mm cameras, like the Sony A7?
There is no technical reason why it should not work. There are plenty of commercial reasons why it would be a tough sell. Basically, Metabones can sell their adapter because lots of APS-C users already have plenty of old 24x36 lenses in their drawers.
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  #42  
Old October 30th, 2013, 09:46 PM
Asher Kelman Asher Kelman is offline
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Quote:
Originally Posted by Ben Rubinstein View Post
You're not the first to be wondering it however I'm not sure that there is such a great need. The MF lenses in general are either less sharp or stupidly expensive and far less prolific or special/niche/interesting than the 35mm lens market which the speedbooster opened up to those using crop cameras. There are not that many lenses which would be worth the bother to be frank given the native choices already available.
Ben,

One does not need "many lenses", LOL. There are some really great MF lenses that could be used and obtainable for a modest price. The increase in MTF will make up for the fact that the lenses might be marginally less sharp than canon's best primes. Also the peripheries will likely take a hit, but for me, thats no issue as I'd like this geometry of edges being less important anyway! If you didn't feel that too, you wouldn't be in love with the Super Takamur Multicoated ~50 mm Pentax lens!

[QUOTE=Ben Rubinstein;147298]I do have a Mamiya lens adaptor with about 10mm of rise and fall. Never got round to using it though, to be frank, spherical stitching is less bother [/quote[ I went for the Pentax 6x7 lenses with the Zörk shift adapter for my 5DII. Again, I have not used it once I discovered how easy it was to take adjacent, overlapping shots handheld.

Quote:
Originally Posted by Ben Rubinstein View Post
What I do think there is a market for is adaptors to use large or medium format lenses on a Hcam type board with a mirrorless camera to allow movements for stitching using wider lens circles.

What is that board? I have discovered the brilliant Hcam with its ability to take any lens and any MF back, but haven't seen the board you refer to. However, it would be a brilliant tool!

The Fusion adapter is wonderful, but has a lot of slack and I need tape to keep it aligned in the portrait position.

The motorized HCam has gotten my juices flowing!

Asher
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  #43  
Old October 31st, 2013, 01:21 AM
Ben Rubinstein Ben Rubinstein is offline
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Hi,

I was talking about a theoretical hcam type board for mirrorless cameras. I spoke to Stefan from Hartblei last night after writing this but he was rather busy preparing for a roadshow, he did say that the new Sony's were a game changer.

I just don't think there are that many affordable MF lenses which have something that comparibly priced 35mm lenses do not if you are already adapting. The choices are so vast in the 35mm world that there is little in the MF world which would excite in comparison unless you are looking for the larger lens circle or are interested in the more modern and super expensive options which don't have an aperture ring anyway. The one I would love to buy is the RZ 110mm but it is bellow focused, I couldn't focus it on a regular camera. Shame as it has a georgous rendition and feel. I'd love to use it for stitching.

If you are interested in the HCam I can put you in touch with Stefan, super incredibly nice guy who has been a good friend as I learnt the repro business in which he is one of the world experts.
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  #44  
Old October 31st, 2013, 02:33 AM
Jerome Marot Jerome Marot is offline
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Quote:
Originally Posted by Asher Kelman View Post
One does not need "many lenses", LOL. There are some really great MF lenses that could be used and obtainable for a modest price. The increase in MTF will make up for the fact that the lenses might be marginally less sharp than canon's best primes. Also the peripheries will likely take a hit, but for me, thats no issue as I'd like this geometry of edges being less important anyway! If you didn't feel that too, you wouldn't be in love with the Super Takamur Multicoated ~50 mm Pentax lens!
Let me explain why the adapter would not be a commercial success with a simple example.

On APSC-C cameras, people may want to adapt a 35mm f/1.4. The adapter makes this a 24mm f/1.0 lens. It will have the apparent field of view and apparent depth of field of a 35mm f/1.4 on a 24x36 camera. It is f/1.0, so very fast. Photographers fantasize about this kind of mythic aperture values.

Let us suppose that an adapter would exist to adapt medium format lenses on 24x36 cameras. I want to get the same field of view as above, so I would use a 50mm medium format lens. That lens becomes a 35mm with the adapter. So far, so good.

There is one difference, though: 50mm medium format lenses typical aperture is f/3.5-f/4. So, with the huge medium format lens on the adapter, I produce a 35mm with an aperture of f/2.5-f/2.8. It is slower than a typical native 35mm lens. A faster 35mm f/2.0 typically costs less than the metabones adapter and is much smaller, lighter and more convenient.

Remember: medium format lenses are not very fast.
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  #45  
Old October 31st, 2013, 02:45 AM
Ben Rubinstein Ben Rubinstein is offline
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and they're big, not as sharp on a FF sized sensor, don't particularly have any special renderings that you cannot get with a natively 35mm lens, etc, etc.
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