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Messages - jrista

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1621
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 03:26:56 PM »
@Dilbert: I refer you to Neuro's answers for all the spherical aberration stuff. Canon DOES purposely leave in spherical aberration by design, as it is a desirable effect in many circumstances.

As for your assuming, you assume that people are trying to justify what Canon does, when in actuality people are simply explaining what Canon does. You assume that people here "worship" Canon, when in fact some people are simply fans, others are simply customers and might otherwise not care about the brand. You assume a whole hell of a lot about people here man, and then you lash out at them with thinly veiled hostility and nasty words based on your INCORRECT assumptions.

All I'm saying is...might not want to assume, you would look like less of a donkey's rear end in the end.

1622
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 12:15:32 PM »
There. Is. No. Such. Thing. As. A. Perfect. Lens.

There. We have that settled.
Well said :)

Oh, if one could wish... These debates are never settled...closed minds cannot handle alternative points of view. :P

1623
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 11:45:19 AM »
My 35 Art´s AF is drifting again (a third AFMA with Focal showed a further 4 step adjustment, on top of the 7 steps I got between the one I did when I got it and Christmas), so I must admit I am a bit skeptical to that part of sigma. But since so many are happy with it, I hope my AF problem is a one-off.


I have a technical query here:

As far as I understand, the purpose of AFMA is not to 'fix' defective lenses, but calibrate a specified lens to a given camera to account for manufacturing tolerances.
Once the AFMA is done, the camera knows how much to compensate for this lens, and everything is hunky-dory.

But in what condition can AFMA drift as is happening in Eldar's case? Is it because something is moving within the lens and a gap is getting bigger or a cog is becoming more loose?

I am particularly interested since I just acquired a 35A (so far it looks like it is focusing right on target as shown below- spot focused on "6" using a peripheral point and center point respectively), I haven't run it through FoCal yet.

AFMA is purely a camera body firmware thing. It only reconfigures the body, it does nothing with the lens. Drift is a pretty odd thing, but I'd like to know more. Spherical aberration can result in the focal plane shifting when you stop down or open up. Since lenses usually focus wide open, then stop down for the shot, spherical aberration can result in your focal plane ending up in an unexpected place.

The Canon 50mm f/1.2 and Canon DSLR bodies include firmware that compensates for this. There is a known component of spherical aberration in that lens (by explicit design), so the focus shift caused by it can be mathematically compensated for. When you have your aperture setting tighter than f/1.2, the firmware will focus the lens with a compensation shift to ensure that once stopped down, the focal plane is where you want it to be.

If the Art 35 has some spherical aberration, it is highly unlikely that such a focus shift is compensated for. That would require paired firmware between the lens and body. Assuming that is actually the problem. If the focal plane is shifting at the same aperture, then that is a different problem, and likely due to the lens, rather than the body.

1624
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 11:38:05 AM »
I'm pretty sure that you can introduce spherical aberration through plugins or other software components if you really so desire. What you can't do is correct for poor image quality at capture time.

Actually, spherical aberration is an effect in three dimensional space. You can simulate some aspects of soft focus in post, however those effects never fully replicate a TRUE soft focus. Neither can you change the nature of boke blur circles in post. Blur circles created by a lens with spherical aberration have a very specific aesthetic (brighter outer ring, with a clear spherical gradient to the center...it's a highly desirable trait for many photographers and cinematographers.)

The aesthetic effect caused by a lens with spherical aberration is not one that can be fully or easily replicated artificially in post. You can approximate some aspects of it, but for someone who likes the effect, those approximations NEVER measure up, and it is always obvious when it is a post-processed effect vs. a real optical effect.

Anyway, in the main the comments above about justifying Canon's current design and product are more about trying to ensure that people who worship Canon find a way to present Canon's offering as good and justified so that they feel good about owning Canon products. That's it. I'm sure someone will argue here that this comment is wrong, but you don't see anyone saying that they wish the 70-200/2.8 II had soft focus like the 50/1.2L and so on.

It has nothing to do with justifying or worshiping Canon. Your assuming something, then using your assumption to put words in peoples mouths as an attempt to win an argument. That's kind of you staple there, Dilbert. :P Why not try to put up a legitimate argument sometime, eh?

It simply has to do with exposing people to opinions other than their own. There is more than one way to design a lens, and there are reasons for designing lenses differently.  I honestly do not think it would be good for every 50mm lens on the market to have exactly the same specs, offer the same exact IQ, produce the same aesthetic. It's better to have a diversity of options, because not everyone photographs the same things in the same ways that you do.

1625
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 11:28:55 AM »
"In the case of the 50L (both of them), it was an intentional design decision by Canon."

Neuro could you please guide me where I could read more about this? Find this so difficult to believe. Thx.

In the press release Canon state that their target market is portraits, etc, which accounts for weak corner sharpness.

Hmmmm. Ok.
But they do not provide a sharp lens to people who want to shoot sharp portraits and sharp landscapes and sharp street and sharp journalism photos at wide apertures?

Are there not many uses to a sharp 50mm lens at wide f stop?

This is just not going down well with me. Am not being obstinate but find this logic incomprehensible.

I'm curious why Canon HAS to make such a lens. Do you think Canon could do it cheaper than Zeiss, and that's why you want Canon to make one? There are SIGNIFICANT difficulties in making a lens sharp, corner to corner, at f/1.2. It would be EXTREMELY difficult to do so. It is even difficult to do it at f/1.4, which is clearly evident by the $4000 price tag the Otus has.

Why is it that you can't simply be satisfied with the fact that Zeiss has offered the exact kind of lens you want? Too expensive? If Canon made something similar, it wouldn't be any cheaper. If they made and f/1.2 version of the Otus, it would likely be significantly more expensive.

As for the rest of Canon's 50mm lenses, the 1.8 and 1.4 are VERY old lens designs, and the 50/1.2 is even getting a little dated. They were designed and built in an era where sensor resolution was lower than it is today. Canon surely has updates in the pipeline, and I'm sure when those new lenses hit the street, they will be competitive. Whether Canon chooses to compete with the Otus, or with the Sigmas of the world, is yet to be seen...but I would bet money that Canon ignores the Otus and sticks with what will sell in massive amounts: Something cost effective and affordable.

1626
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 16, 2014, 02:48:30 AM »
But but what about the people who want a good quality 50mm and are willing to pay appropriate money?

And don't you think lots of people will buy the Sigma?

Canon DOES have the 50/1.2 lens. You can't deny the quality of that lens, despite it's spherical aberration, which as it so happens to be, is a DESIRABLE trait in a portrait lens for many photographers. Not everyone screams for perfect corner to corner sharpness. Sometimes, having soft corners is beneficial to guiding your viewers eyes to the subject...which tends to be near the center of the frame.

I've always admired photos taken with the Canon 50/1.2 and 85/1.2 lenses. They have a specific aesthetic appeal that is just WONDERFUL for portraiture specifically, and for a variety of other types of photography as well (such as street.) I find it ironic how so many people write off the Canon 50/1.2 and 85/1.2 lenses as if they don't even qualify to be included in the lineup for comparison.

So, what about the people who want quality? Canon offers a VERY high quality 50/1.2 lens that offers STUNNING and very aesthetically appealing results. You should give it a try sometime. Oh, and you'll spend about half as much on that as you would on an Otus...you won't get razor sharp corners, but it's HALF as much as an Otus.

So. Am I to infer that if Canon comes out with 50/1.2 II that is sharper and has better corner to corner sharpness then you would not DESIRE to use it?

I'm sure a lot of people would. I'm also sure that a lot of the people who currently love the soft-focus traits of the current 50/1.2 would be bummed if Canon copied the Otus design with razor sharp focus corner to corner. It's better to have a DIVERSITY of lenses with different traits, than for all manufacturers to make exactly the same things that behave exactly the same way.

I think the center performance of the 50/1.2 and 85/1.2 needs to be improved...in the grand scheme of things, it's a bit soft, and doesn't need to be. I do, however, hope Canon keeps the soft focus traits in place if they release a 50/1.2 II and 85/1.2 II. If I want a lens with perfect sharpness, I can always get the Otus...if Canon copies the Otus, then I'm suddenly left WITHOUT the option of buying a lens that purposely leaves in a certain amount of spherical aberration for artistic flare.

1627
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 16, 2014, 12:13:38 AM »
And jrista with regard to the composites, now you are just showing off.  Good work.

LOL. Yeah, a little.

Thanks. ;)

1628
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 10:58:26 PM »
Two more composites:




1629
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 10:57:14 PM »
That definitely looks like IS messing with your stability, Lloyd. You gotta turn IS off when doing astrophotography with a camera lens.

The good looks great! You got Spica and Mars along with the eclipsed moon. I was hoping to do that, but decided I didn't want to interrupt my imaging sequence to do it.

1630
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 04:43:37 PM »
Some great shots by Jrista and Slyham.

I have not had time to fully sort through the photos I took last night with my 800mm and the 150-600, but most of the ones taken during the full eclipse had too much motion blur.  As the moon got darker, I just increased exposure time.  This was a mistake.  The moon moves rather quickly across the sky and the longer exposure introduced blur.  On the small screen of the camera they looked deceptively okay, but when I downloaded them to the computer you could tell the moon had moved a good bit even during a one second exposure.

I just now did a little research on the issue and saw a web site which recommended that for lunar photography you should take 250 and divide it by the mm of your lens to get the maximum exposure time to avoid blur.  See http://www.amlunsoc.org/photography.htm   For my 800mm lens, that would be no more than a 30th of a second and about a 40th of a second for the 600mm.  (this seems to be similar to the 500 or 600 rule applied to star photography) Or I could do it right like jrista and get an equatorial tracking mount.  Unfortunately, I would also need Mr. Spock to help me operate it.

It is a good thing there may be a few more of these events coming up.  Time to crank up the ISO and open up the lens if I am going to use the long lenses to photo the next one.

Equatorial mounts are a lot easier to use than that. They sound very technical, but they are actually simple and elegant devices. All you would really need to do is use the hand controller, set it to lunar time tracking (vs. sidereal, which is the default used for stars), pick the moon to point, center (there is always a bit of pointing error), and start imaging. Once you set it, you can pretty much forget it. The only extra bit of work is the meridian flip...once the moon passes the meridian (from east to west crossing the imaginary "12 o'clock line" overhead), you need to tell the mount to goto the moon again, and it will flip the mount to the inverse orientation...then you can image for the rest of the night.

1631
Lenses / Re: Sigma vs Zeiss vs Canon
« on: April 15, 2014, 03:52:27 PM »
But but what about the people who want a good quality 50mm and are willing to pay appropriate money?

And don't you think lots of people will buy the Sigma?

Canon DOES have the 50/1.2 lens. You can't deny the quality of that lens, despite it's spherical aberration, which as it so happens to be, is a DESIRABLE trait in a portrait lens for many photographers. Not everyone screams for perfect corner to corner sharpness. Sometimes, having soft corners is beneficial to guiding your viewers eyes to the subject...which tends to be near the center of the frame.

I've always admired photos taken with the Canon 50/1.2 and 85/1.2 lenses. They have a specific aesthetic appeal that is just WONDERFUL for portraiture specifically, and for a variety of other types of photography as well (such as street.) I find it ironic how so many people write off the Canon 50/1.2 and 85/1.2 lenses as if they don't even qualify to be included in the lineup for comparison.

So, what about the people who want quality? Canon offers a VERY high quality 50/1.2 lens that offers STUNNING and very aesthetically appealing results. You should give it a try sometime. Oh, and you'll spend about half as much on that as you would on an Otus...you won't get razor sharp corners, but it's HALF as much as an Otus.

1632
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 03:46:47 PM »
Wow jrista! That's a really awesome triad shot! Well done sir.

What equipment do you shoot with? Especially which tripod head? I've got a decent enough Benro with ball-head, and it worked, sorta, but I kept wishing it was geared in some way or another to fine tune.

Thanks. :)

I used a Canon 7D, EF 600mm f/4 L II lens, but the equipment that really allowed me to get the kind of detail I did during totality was the Orion Atlas equatorial tracking mount. I did not have to jack my ISO way up to 3200 or 6400 to get images during totality...I kept it at ISO 100, tracked in lunar time, and simply increased my exposure times. At full moon, my shutter was 1/250th. At maximum totality, it was 8s to 15s. Since I was tracking the moon itself, I could expose for that long of a time without experiencing blur due to the moon transiting across the frame.

1633
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 03:42:56 PM »
Here are mine taken with my T1i and 55-250 mm.

Great shots, nice and crisp.

1634
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 03:41:43 PM »
I finally managed to get some processing on my images done. Out of 200 frames, I've picked 17 that encompass the total sequence from first shadow to last shadow. Still working on that composite. In the mean time, here is my Totality Triad composite, all spiced up:

Well, that's mildly...freaking awesome!  Can I buy a print of that off ya?

Sure! I am actually trying to build a storefront site for my photography. I don't have it rolling yet, but I'll send you the link when I do. I guess I could do something ad-hoc, through paypal, if you really wanted a print right now. I use a nice high quality printer that can ship directly from print lab to my customers. Just let me know.

1635
Landscape / Re: Total Lunar Eclipse - #1 of 4 - April 2014
« on: April 15, 2014, 03:38:48 PM »
jrista, you really have mastered astrophotography and these shots are amazing!

Thanks. I've been imaging the moon a LOT longer than I've been doing deep sky astrophotography, and I'm more of a master of the moon than I am of astrophotography. Maybe at some point I'll be as good with AP as I am with the moon, but at the moment, I'm still a noob compared to some astrophotography wizards.

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