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Messages - Fleetie

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31
Lenses / Re: How to fix zoom creep on EF-S 17-55mm f/2.8 IS USM Lens?
« on: September 09, 2013, 07:25:35 PM »
I use black electrical insulating tape on the barrel of my 24-105L. It's still working fine; I'm pleased with the fix.

32
EOS-M / Re: EOS M and Vintage Glass
« on: September 09, 2013, 07:06:27 PM »
Does anybody know if OM lenses rest wide open, or rest at set aperture?
Seen a OM tilt adaptor to EF-m, just windering about practicalities (i.e. am I stuck wirh a wide open aperture always, or can I control it, I know there is an aperture ring on less, I just recall someting anout the shutter being cocked bon OM bodies)

Thanks
With my cheap OM to EOS adaptor (no chip; purely a mechanical piece of machined metal), there's a little screw/pin in the right place, so that the OM lens stays at the aperture you set. So when the shutter goes, the OM lens' aperture doesn't need to change. Also it helps with metering, cos the camera has no way of knowing what aperture the lens is set to anyway, so it pretty much has to work this way.

I've used my OM lenses quite happily on both my 7D when I had it, and my 5D3 now.

This comparison I did might be of some small interest, but the only aim at the time was to discover things about which lens was fastest/brightest, and what the bokeh was like. It compares about 5 different OM 50mm lenses and the Canon 50mm f/1.4 lens.

https://www.facebook.com/media/set/?set=a.4505135767033.1073741834.1849695638&type=1&l=eb457b7c51

On an OM *body*, obviously, the iris DOES move when the shutter goes. So when you're composing, it's wide-open, and when you fire, something in the body (a pin or lever, I guess) actuates the lever on the lens to stop down the iris.

In "Program" modes on OM bodies, you set the lens to the most-closed aperture you want to allow the body to use (typically f/16, the slowest aperture), and then the camera will "decide" what aperture to set the lens to when you fire, so it's more advanced in that case than just opening/shutting the iris. It also decides what shutter speed to use. I don't know what the algorithm is, i.e. whether it favours the fastest shutter speed it can get (using max aperture at the expense of DOF), cos I never use the program modes.

Back to the EOS M, I am waiting very impatiently for the high-end one to come out, which assuming I still have a job and am still alive and well enough to bother, I will probably buy as soon as I find one available. I intend to get the EF adaptor and use my 50mm f/1.8 (i.e. very small/compact) with it, sometimes. I think it'll be fun! Just bring the damn thing out, already!

33
EOS-M / Re: EOS M and Vintage Glass
« on: September 08, 2013, 04:29:16 AM »
SQUARE bokeh?!

That's the first time I've seen that!

34
EOS Bodies / Sensor & Electronics Cooling
« on: August 27, 2013, 11:32:16 PM »
Peltier cooling is a good idea except.... Kiss "GOODBYE" to battery life. You can't just switch the peltier cooler on for the duration of the exposure. It has to be given time to cool things down - during which time the camera's battery takes a beating.

It's a shame, for it's the perfect solution otherwise. Apart from dew issues, which I'm sure could be resolved with the ingenuity a company the size of Canon could muster if it wanted to.

OR:

Maybe a little orifice - similar to those found on steam irons used for ironing clothes have - bearing the inscription : "Pour LN2 Here -->" !

35
EOS Bodies / Re: Play Arkanoid on your Canon dslr :-)
« on: August 15, 2013, 08:15:14 AM »
What a complete waste of time and resources. For goodness sake.

Still, I believe these ML people are doing it for fun, and no-one actually pays them directly.

I've never felt tempted to put ML on my 5D3, though I would like to see focus peaking from Canon.

37
Canon General / Re: Just For Fun!
« on: July 13, 2013, 10:56:17 PM »
"Just my $0.02"

FFS I am sick of seeing that on here. It ADDS NOTHING and makes the offenders look like arses.

It's got to a point now that I just skip any post I see with that in. If people admit their opinions are worthless and are so damn keen to tell me it, then I won't bother reading it. GRRRRRR! This really does frost my Kelvinator.

---

Also: "+1000".  I MEAN, WHY?

WHY?

---

Also : Quoting huge pages and pages of text in quote boxes (Jrista) and then putting 1 or 2 lines of text at the bottom of it all. Were those 2 lines of text worth my scrolling through all the mostly-irrelevant preceding rubbish? I don't think so.

38
Very good point about the sensor acceptance angles.  I'm also wondering if periferal illumination correction also might have had an effect in this case.
No, because I always leave it switched off. And I just turned on the camera to double-check, and it was, and is, off.

The jpgs are SOOC, too.

39
The 'sneaky' ISO boost with fast primes it done to compensate for loss of light transmission through the microlenses over the sensor pixels that occurs at high incident angles of light. As such, it's specific to digital (vs. film), and more boost is needed for smaller pixels.  The issue has been documented (and quantified) by DxOMark.  It's not just Canon, by the way - Nikon and Sony do it, too.

http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues

Thanks, Neuro.

I do remember years ago reading that the Leica M9 has special angled microlenses to mitigate this effect; I think it was the same effect.

It still does seem a little "sneaky" of the camera to not show the modified ISO used.

I'm not going to lose sleep over it; it's something interesting I learned today. I still like my 5D3!

40
I don't need to do anything of the sort.

I took several shots in both conditions, and the result was unambiguous.

Rotation does not change the angle of lens axis to plane of sensor. The lens is still mechanically mounted hard up against the flange, so no angular movement is possible. Clearly you have not tried this, or it would be obvious to you that mechanically, the mount is identical to the connected case.

You might "need" to. So please do.

In fact, let's have more people do this.

41
One day I might do another, similar test of the same lenses, but this time to compare their sharpness wide-open.

But don't hold your breaths; round tuits are scarce here.

42
Of course, you would expect the f/1.2 lens to be brighter than a f/1.4 lens but this is NOT what Fleetie observed. When the camera communicates with the lens, it boosts its internal ISO (without telling you) so that the f/1.4 image becomes brighter than the f/1.2.

No. That's not exactly what I am saying:

YES, the "connected" Canon image is definitely brighter.

But even the connected image is less bright than the Zuiko 50/1.2 image. That was not what I found last time, but this time I was more careful to keep lighting constant than last time.

The Zuiko 50/1.2 image is the brightest one I got (IMO).

43
Yes, I know about T-stops. That's partly what prompted this test. See the "50mm lenses that don't suck wide open" thread.

I'd been meaning to do a more scientific test of all my 50mm lenses like this for a while now, so tonight I finally got a round tuit.

Last time I did a similar but less rigorous test like this, the Canon f/1.4 seemed more transmissive, i.e. brighter, than the Zuiko 50/1.2.

But no, Zuiko 50/1.2 is much brighter, as you rightly say, one would expect.

44
Do you have simulate exposure or whatever it's called turned on for LiveView? When it communicates with the lens it may get more information and so might also apply the peripheral correction information (which generally will affected the outer portions of the frame, not the overall frame).

As for Olympus f/1.2, it should be brighter than a f/1.4. You're talking a full stop there, no duh it'll be brighter.

No, I never use "simulate exposure".

I know it should be brighter but last time I tested it, it came out looking slightly dimmer than the Canon 50/1.4 lens. but no, the results here are clear.

BTW, how on Earth do you get that f/1.2 is a FULL STOP wider than f/1.4?! No, it's not!


45
I did these tests this evening. I was as careful as possible to keep room lighting the same for each shot.

See the thread about "50mm lenses that don't suck wide-open", which made me get off my butt and do these tests.

Note that the aim for these tests was only to compare lens brightnesses (T-stop) and bokeh, with all lenses wide-open.
The scene is too dark to determine relative sharpnesses.

I tested the Canon 50mm f/1.4 wide-open, both connected and NOT CONNECTED electronically, by rotating lens in body while holding the lens-release button down. Mechanically it is still completely mounted, but the camera cannot communicate with the lens, so does not know what it is, so it cannot "decide" to sneakily increase the ISO.

Canon 5D Mark 3
Manual
t=1/15s, ISO400 (nominal)

Focus was on the same point on the lantern, using live view, magnified x10.


RESULTS:

Dude was right. The "CONNECTED" Canon 50mm f/1.4 image is noticeably brighter, and I took the picture both ways, several times, and the results were completely repeatable. So it seems that the 5D3 DOES sneakily SEEM TO boost ISO without telling you, if it detects that the 50mm f/1.4 lens is connected. When I review the images on the camera, they all say ISO400.

Dude was also right that the Olympus 50mm f/1.2 is significantly brighter than the Canon 50mm f/1.4 wide-open, EVEN brighter than the "CONNECTED" image. That makes me feel slightly better about having dropped just shy of £400 on this (perfect, mint, unmarked) example of this lens, back in Jan. 2010!


Here's the album on FB:

https://www.facebook.com/media/set/?set=a.4505135767033.1073741834.1849695638&type=1&l=7e5db91bd2

Here are the files on Dropbox, including raw files:

https://www.dropbox.com/sh/rhtr3k0ru902sbr/yMKl0KWANf?lst

The tests I did were:

Zuiko (Olympus) 50mm f/1.8 - Dimmest, as expected

Zuiko 50mm f/1.4 Silvernose

Zuiko 50mm f/1.4 Non-Silvernose (later model) VERY SLIGHTLY brighter than Silvernose

Zuiko 55mm f/1.2 - Has the "biggest" bokeh / OOF blur. NOTE! This is a 55mm lens, not a 50mm one.

Zuiko 50mm f/1.2 This is the brightest of them all

Canon 50mm f/1.4 NOT CONNECTED, because lens was rotated to disengage electronic contacts

Canon 50mm f/1.4 CONNECTED - Should be same, but IS BRIGHTER

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