August 22, 2015 at 3:13PM

0

Some help with adapting different lens focal lengths to Micro 4/3...

Hey, it's me again. Kid with the Pentax and the winter movie, except the movie never got made, and the Pentax is dead. I've decided to invest in the Panasonic GH4, because, well, I think it's a good investment. I'm not here to debate over the camera choice itself, so don't try to bring that up. :)

I currently have 3 lenses, with adapters, that I plan to use on my GH4 once I buy it. Just some cheap vintage glass I found on ebay, since I found a couple people on here saying just to do that. Don't worry, I won't stick with them forever, they're just to get me up and shooting.

My deal is, I need help converting the lens focal lengths to micro 4/3, so I know what my actual focal length is, so I don't end up buying the same (cheap vintage) lenses later.

My lenses are:
Minolta MC f1.7 at 55 mm Prime for Sony Nex
Minolta MD f3.5 at 135 mm Prime (I'm assuming for the same mount)
Industar f2.8 at 53(?)mm for M39 mount

All have the correct adapters for their respective native mounts to Micro 4/3. So now my question is, what are my actual focal lengths? If you can get me answers for each one, and/or direct me to a page that has some kind of conversion tool/table, it would be super appreciated.

Thank you all in advance.

13 Comments

Compared to a lens mounted on a Full Frame sensor camera like a Canon 5D or a Nikon D810, you would take the focal length of your lens and double it when mounting it on a Micro 4/3 camera.

So a 55mm lens becomes a 110mm lens, a 135mm lens becomes a 270mm lens, and a 53mm lens becomes a 106mm lens. So all of your lenses become equivalent to telephoto lenses when mounted on a GH4 camera.

Abelcine created a very handy FOV calculator that helps to understand how different focal length lenses work with different camera formats.

http://www.abelcine.com/fov/

Just choose the camera formats you want to compare and then choose the lens you want to mount on these cameras, and the Abelcine calculator will show you what the field of view would look like. For your GH4 camera select the Panasonic AF100 camera which is also a Micro 4/3 camera and uses a sensor with a similar size.

August 22, 2015 at 8:35PM, Edited August 22, 8:37PM

3
Reply
Guy McLoughlin
Video Producer
28864

Thanks Guy! I remember that doubling formula for full frame to M4/3 from an article on this site awhile back. Also I think that calculator will come in very handy.

Only thing though, I'm not sure what sensor sizes these lenses were meant for. I really don't know if they're meant for full frame or not.

Torsten Pearson

August 22, 2015 at 9:01PM

>>>I'm not sure what sensor sizes these lenses were meant for.

The Minolta lenses were definitely made for Full Frame 35mm film cameras, and I suspect that the Industar is also made for Full Frame 35mm film cameras.

About the only pre-digital lenses that were NOT made for Full Frame 35mm film were the Olympus PEN-F lenses that were made for Half-Frame 35mm film cameras. ( equivalent to APS-C lenses in the digital world )

August 22, 2015 at 11:29PM

0
Reply
Guy McLoughlin
Video Producer
28864

Thank you!

Torsten Pearson

August 23, 2015 at 1:47AM

Does it matter that these lenses are really small? Like smaller than my 18-55 for my pentax? these are like really small lenses. I don't know if theyre for full frame or not.

August 24, 2015 at 10:18PM

20
Reply
avatar
Torsten Pearson
Writer-Director-Editor
464

The exterior dimensions of the lens are related to optical physics and are not directly related to what size sensor they cover.

Your "actual focal lengths" are 55mm, 135mm, 53mm. Use those focal lengths to calculate depth of field.

Everybody likes to use full frame photography as a reference. That's fine if you grew up shooting 35mm photos or video on a 5Dii/iii and really know focal lengths for those cameras. If you don't think in 35mm still photography terms, the comparison means nothing. If your background involves shooting video or motion pictures on 35mm or 16mm film, the full frame comparison simply causes confusion.

Guy refers to the field of view (FoV) which changes based on the sensor size. The GH4 sensor is about half the height and half the width of a full frame sensor. So, to compare the FoV of the GH4 with a full frame camera, double the focal length, as he did above.

Is there a reason you chose a 53mm lens and a 55mm lens? Are you planning on buying more lenses?

August 26, 2015 at 1:28AM, Edited August 26, 1:31AM

0
Reply
Charlie K
1214

I grew up shooting on a camcorder until just 3 years ago when I got my Pentax, and I haven't learned or known anything about sensor size until researching the GH4. So all I know is whatever you tell me lol.

I do understand the difference between full frame and micro 4/3 now and why the FoV changes, thank you.

The only reason I chose these lenses is they were cheap, and I knew I could get adaptors for them. I just wanted to get shooting on my Panasonic as soon as I could.

Torsten Pearson

September 6, 2015 at 3:25PM

And yes, I do plan on buying more. I need some wider angle lenses now.

Torsten Pearson

September 6, 2015 at 3:25PM

The Industar is on an M39 mount which means that it has come off a rangefinder camera not an SLR. That mount places the lens much closer to the sensor (and thus the mirror for an SLR camera). People who have an Industar 69 have an additional problem as I have posted about on my Facebook page. https://www.facebook.com/pages/Cave-Art-Films/348651878657791. Quoting myself " These lenses were designed for the Chaika camera and for no particular reason the standard M39 mount is actually 1.3mm closer than usual. This means that the lens is closer and so it will not focus to infinity and the markings on the focusing ring are incorrect.

The often used technique is to open up the lens and tinker with the focusing threads and end stops. Apart from being possibly free, it is completely STUPID. You are hacking up a classic lens to bodge it to fit. The proper way to do it is to thin the adapter to your camera by 1.3mm so it all works as it should. The only disadvantage to this is that it would thow off any other lens used with that adapter.

If you have access to a lathe, all well and good or you could use a grinder and take away a bit at a time until you hit the infinity focus point. I think that this is also STUPID. Why? S G Webb and Son in Stevenage Hertfordshire will remove EXACTLY 1.3mm from my adapters for £5 for the pair, ready tomorrow morning. £5 to do the job properly."

I got my Industar 69s from a guy in Lugansk, I believe the Industar factory was in the Ukraine and the Ukranians and Polish have a large selection of M39 and M42 lenses on ebay.

It's worth looking in second hand shops, car boot sales, street markets and pawn shops for lenses as they often go there very cheap, sometimes with the film cameras. I bought an Olympus OM 24mm from Cashconverters for £40 to sell on and got £121 for it on Ebay. I bought an old OM10 camera with a 50mm prime and 2 zooms plus a lot of accessories for £20 locally. I also got 2 50mm OM primes for £17 for the pair from a street market.

Canon FD lenses are very popular as are the Nikkors at all sorts of focal lengths. Old Soviet lenses are popular although some of them with mass production over several decades in large factories seem to have never made 2 the same. M42 Super Takumars have a legendary reputation. Your Minoltas are supposedly highly underrated and good lenses can be picked up very cheaply.

I do find it astonishing that a search on YouTube for all these lenses shows videos that look remarkably good.

September 9, 2015 at 2:24AM, Edited September 9, 2:28AM

0
Reply
avatar
Julian Richards
Film Warlord
1035

Thanks for the reply. So you're saying it's possible to get my Industar to fit my sensor better? Do i want it closer or further away from the sensor?

Torsten Pearson

September 13, 2015 at 11:43AM

Torsten,

No. Only the Industar 69 which is a 28mm lens made only for the Chaika camera which for no real reason has the lens mount closer to the film. Soviet build quality is such, though that it is possible that a particular lens may not reach its full range ie not focus close enough or have an infinity focus. That said, the Soviet designers knew this and built a certain amount of extra play in the system. I would advise you to check that you have an infinity focus.

September 13, 2015 at 5:32PM

0
Reply
avatar
Julian Richards
Film Warlord
1035

I do have infinity focus, the image is just cropped.

Torsten Pearson

September 14, 2015 at 9:34AM

ehm... you do nothing, be cause crop not change focal lenght, but focal angle, which is a very different thing. If you change focal you change perspective view of planes, if you change focal angle you change your ability to shoot a larger or smaller plane, but NEVER the crop can change focal lenght, you cannot change the shape of internal lenses or distance between eachother.
The website of abelcinema linked over show you the focal angle, or field of view of lens cropped, but when you shooting and want some certain effects of perspective, you must read number on lens, and forget every other stupid urbans legend that run on web.
never a 25mm (large angle) could be a 50mm (normal) if you try to do a portrait with a 25mm you find big distortion...
a simple test that everyone can do?
grab a camera with crop, put a 50mm, one eye see in camera, one eye out, you could same perspective, without difference. try with 25mm, you see a many big difference about plane distance and more...

August 12, 2016 at 5:51AM

0
Reply
avatar
Carlo Macchiavello
Director
341

Your Comment