Infinity Focus Correction Lens Questions

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My specific scenario is I have two Konica Hexanon lenses which are said to be very high quality I want to use with my EF mount camera, but the adapters for these lenses use a focus correction lens in them to achieve infinity focus. The lenses are pretty valuable, and I would get maybe $300 if I sold them both. But really I just want to be able to shoot in lower light, and having a f/1.4 lens would really help for that. But if the focus correction lens is reducing sensitivity by one stop or more that seems like it would be better for me to just sell the lenses and use the money to get the native EF mount f/1.4 lens on the used market. But I have read the Hexanon lenses are really sharp so I don't want to do that if I don't have to. I'd probably use this lens mostly for macro or up close photos 90% of the time anyway.

[EXIF data available. Click here to show/hide.]

Camera-Specific Properties:
Equipment Make	Canon
Camera Model	Canon EOS 450D
Camera Software	Digital Photo Professional
Image-Specific Properties:
Image Orientation	Top, Left-Hand
Horizontal Resolution	350 dpi
Vertical Resolution	350 dpi
Image Created	2010:01:20 20:41:42
Exposure Time	1/60 sec
F-Number	f/5.6
ISO Speed Rating	100
Lens Aperture	f/5.7
Exposure Bias	0 EV
Flash	Flash, Compulsory
Focal Length	55.00 mm
Color Space Information	sRGB
Image Width	900
Image Height	607
Rendering	Normal
Exposure Mode	Auto
Scene Capture Type	Standard
Exposure Mode	Unknown
Focus Type	Auto
Sharpness	Unknown
Saturation	Unknown
Contrast	Unknown
Shooting Mode	Unknown
Image Size	Unknown
Focus Mode	Single
Drive Mode	Unknown
Flash Mode	Unknown
Compression Setting	Fine
Macro Mode	Unknown
White Balance	Unknown
Exposure Compensation	3
Sensor ISO Speed	65408

According to this the light sensitivity won't change even with adapters and crop factors:
http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html
>If Gertrude Stein had been a photographer she might have said "f2 is f2 is f2". The maximum aperture of a lens is constant. The f-stop is given by the focal length divided by the aperture size. If you have a lens with a focal length of 100mm and a physical aperture of 50mm, it's an f2 lens and will produce an image with a brightness determined by the fact that it's an f2 lens. Since neither the actual physical focal length nor the actual physical aperture change the when the lens is mounted on a camera, it's always an f2 lens. It doesn't matter if you use it on a full frame camera, an APS-C camera or and 8x10 camera. If it's f2, it's f2. Of course the angle of view that is recorded will be different for different formats and unless the lens was designed for 8x10, if you use it with an 8x10 camera you'll get a tiny image in the middle of a field of black, but the actual image brightness won't change because the lens will always be f2."

Does this sound right?

The young flower is orange.

>>3127320
what

You need these adapters because the EF mount has a great flange distance than the konica mount. Because its impossible to move the lens further into the camera body you need the adapter to refocus the light. They are usually poor choices because unless you buy a fancy expensive one you're effectively adding a low quality optical element to your lens. For less than $300 you can get the canon 50mm 1.4 which will give you native electronic aperture and AF. Or you could buy a mirrorless camera.

>>3127268
>pretty valuable... I would get maybe $300 if I sold them both

okay

>>3127347
I have one identical to this one:

http://www.ebay.com/itm/Konica-HEXANON-AR-21mm-f4-ex-condition-with-hood-and-case-perfect-optic-/302343126089?hash=item46650dfc49:g:MO4AAOSw-K9ZOF4x

This along with the 50mm f/1.4 which is pretty much brand new should fetch $300 overall. But I will only sell them if I can't figure out a good way to use them. I may go as far as putting them on the SLR I have to go with them and shooting film.

>>3127368
Those hexanon lenses are only good on native mount film slr:s they were intended, or mirrorless like sony a7 or fuji x-t line. It's not worth the hassle to try to use them with ef mount. And while they are ok, they will not be as good as modern native mount lenses.

>>3127275
>but the actual image brightness won't change because the lens will always be f2

f2 isn't a measure of brightness though.

He is right, the aperture wont be changed by an infinity focus adapter/teleconverter/whatever weird glass you are using, but the t-stops will change.

>>3127438
So... does this mean the lens would still be good for low-light conditions or... ?

>>3127662

Depends on how much light is lost to the adapter, and how much light gets through in the first place.

Most likely yes, it will be good in low light, but slightly worse than if no adapter/a glass free adapter was used.