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Messages - neuroanatomist

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1
Lenses / Re: Advice: extension tubes Macro
« on: August 20, 2014, 08:11:31 PM »
Is the air in the Canon tubes better than the air in the Kenko tubes?  For most applications, the Kenko tubes are just fine (the only reason I went with Canon tubes is that my main use is to reduce the MFD of a supertele, and I wanted to be sure of the mount strength - not an issue of concern for macro lenses).
For starters math is not my strong point.  Just curious as to how much the MFD is reduced on a 600mm lens when using extension tubes.  I currently have two setups.
1. 300/2.8 w/ 2x TC, MFD ~ 10ft.
2. 600/4(non-IS), MFD ~ 20ft.
Will an extension tube(s) get my 600 MFD to ~10 ft?
My slight understanding of the math says no.
Thanks for any enlightenment you may provide.

An EF 25 tube will get your 600/4 to an MFD of ~15 feet.

2
Lenses / Re: Image quality with or without filters
« on: August 20, 2014, 07:45:35 PM »
Here is a great test; http://www.lenstip.com/113.1-article-UV_filters_test.html

They did some thorough testing, but I'll repost some caveats about interpreting their results in the context of use on a dSLR:

Just be aware of how LensTip's scoring is derived.  One factor (25% of the scoring) is how effective the filter is at blocking UV light, and that is irrelevant for dSLR users.  In fact, in one sense better UV blocking is worse, because some of the deep blue light is also lost.

Hoya, Zeiss, and B+W all publish their transmission curves. No filter has a perfectly vertical cutoff on a transmission curve - most good commercial multicoated filters that 'block' wavelengths ramp from ~0% transmission to their max of >99% over a 25-125 nm range (although some of the longpass and bandpass filters I use in microscopy are close to vertical, with a slope covering <5 nm - and they come with a price tag commensurate with that performance). 

The Zeiss has the steepest slope of the three, ramping up over the 410-435 nm range (it's cutting out some blue light, which is considered to start at 400 nm). The Hoya has the least steep slope, running from 350-460 nm or so, meaning its passing some UV in the 350-399 nm range, and blocking a bit of blue light as well.  The B+W is intermediate, ramping up from 360-430 nm, but at 400nm (the start of the visible range) the B+W UV transmission is >90%, and the sensitivity of the CFA blue channel on the sensor is very low below 420nm anyway.

Of course, while that might be good to know if you're shooting film, none of that matters if you've got a dSLR.  The dSLR's sensor is insensitive to UV light, so there's no difference between a UV filter (be it the 410 nm Zeiss or the 360 nm B+W) and a clear filter that fully passes the long end of the UV spectrum.  I have empirically tested my 7D and 5DII for UV sensitivity with calibrated UV/Vis light sources and some of those precise bandpass filters mentioned above (running a lab that has such equipment comes in handy sometimes) - there's no need for a UV filter.  I do use UV filters for protection (B+W MRC or Nano), instead of clear - but that's only because every time I've needed to buy one, the UV version was cheaper than the clear one (although that's not the case with all brands or in all geographies).

For the Lenstip tests, I recommend looking at the test results, not the summary table.  For example, compare the top scoring Hoya with the 3rd place B+W - the Hoya scored 90% (36/40), the B+W scored 83% (33/40).  But, when you look at the subscores which they provide that sum to a possible 40 pts, you see that B+W loses 1 pt for visible transmission, 1 pt for flare, and 5 pts for UV transmission.  The Hoya loses 2 pts for visible transmission, 2 pts for flare, and gets 10/10 for UV transmission.  But for a dSLR user, UV transmission is irrelevant...meaning that for a dSLR user, the B+W is the better filter according to Lenstip's testing, since it's better on both visible light transmission and flare.

3
Third Party Manufacturers / Re: D810 users are seeing spots
« on: August 20, 2014, 06:04:10 PM »
Does anyone here remember how long it took Canon to address issues with the 5D Mark II? It definitely wasn't this quick!

What problems were those?  I can't find any Canon Service Notices (firmware updates notwithstanding) for the 5DII...


4
Reviews / Re: What Happened to DxO?
« on: August 20, 2014, 05:57:28 PM »
Have you been to France, or anywhere else in Europe, during the month of August?   ;)

Well, I know there are actually some folks at DxO working hard, but I guess the website team is all on holiday...

5
Site Information / Re: Smartphone Blunders
« on: August 20, 2014, 05:55:27 PM »
For me, the clue was that it said "EOS M" on the top plate, instead of "EOS M3"...   ;)

6
EOS Bodies / Re: 5D3 No Longer in Production
« on: August 20, 2014, 03:40:04 PM »
Oh dear there's going to be terrible anguish, spitting feathers and general sabre rattling if the 7DII doesn't have some sensor fabrication advance similar to the Exmor. But you know I'm not really sure how much pressure there is on Canon to catch up on this. It would seem that 99% of Canon users (generically speaking) are not bothered about that particular aspect of the sensor, including many well respected professionals; certainly judging by sales there are many other features which the buying public seem to want. Certainly the amount of people using variable ISO now surprises me, but on the other hand given the performance of a camera such as the 6D I suppose that shouldn't be surprising. And when using variable ISO who wants their DR to drop by a stop or two between ISO 100 and 800 ?

That is because those who are bothered by it will be/are moving to other manufacturers. If Canon are fine with bleeding off their market base, then sure, they won't care. If all depends on if the assumption that Canon are cool with losing market share to more progressive manufacturers is true or not.

I suspect they are not cool with that happening.

You skipped a step.  No, Canon doesn't want to lose market share.  But...you are assuming they are, in fact, losing market share.  Where is your evidence to support that assumption?   It seems equally if not more likely that those who are bothered by a ~2-stops less low ISO DR and switched from Canon to Nikon are outnumbered by those Nikon users hoping for the true replacement to the D700 that never came, and so bought a 5DIII instead. 

As for 'more progressive manufacturers', your definition of progressive is almost as biased as DxO's Scores.  DPAF...not progressive?  Fluorite elements in supertele lenses, you'd think a progressive company like Nikon would have used them decades ago like Canon did...instead Nikon called them too fragile, only now they're touting the benefits of fluorite in their newest supertele lenses.  Limiting the definitions of 'innovative' and 'progressive' to mean achieving more low ISO DR is typical of the biased DRivel posted by the crew of CR Forum DRones. 

7
...something bigger and better even more outrageously priced.  :o

8
Lenses / Re: Canon EF24-105mm f4 IS USM time for a refresh?
« on: August 20, 2014, 10:31:22 AM »
The 24-105 makes for a cheaper kit, but Canon now sells kits with the 24-70/4 IS, too.

I don't think the Sigma 24-105 delivers significantly better IQ than the Canon 24-105, and the Canon is cheaper (as a new white box lens).

9
Third Party Manufacturers / Re: D810 users are seeing spots
« on: August 20, 2014, 09:16:51 AM »
like the last gen's 1Ds series oily mirrors fiasco on canon's side, nikon learned and that is always good.

Nikon had to learn the hard way.  Did the country with the world's second-largest economy forbid Canon from selling a defective dSLR model in their country? 

10
Lenses / Re: Canon EF24-105mm f4 IS USM time for a refresh?
« on: August 20, 2014, 07:22:05 AM »
The refresh was called the 24-70mm f/4L IS.   ;)

11
EOS Bodies - For Stills / Re: connect ST-E3-RT with Canon SR-N3 cable?
« on: August 20, 2014, 07:13:46 AM »
As Graham says, the SN-R3 is for triggering the camera shutter from the flash, and it's only needed with pre-2012 bodies, your 1D X can be remote-released directly via the hotshoe.

You should be able to connect the camera's PC terminal to the 600's PC port (or hotshoe if you have the PC-to-shoe setup) and it will fire as a 'dumb' flash.  The ST-E3-RT cannot be triggered except via a hotshoe connection (direct or via an off-camera shoe cord like the OC-E3).

12
Canon General / Re: A Rundown of EOS 7D Mark II Information
« on: August 19, 2014, 08:36:31 PM »
It's pretty amazing how one single thing, not having two additional stops of low ISO sensor DR, is all it took for everyone to forget all the other innovations, technological advancements, and general leadership in the industry Canon has made throughout their history as a photography company.  ::)

Certainly not everyone.  Not the majority of dSLR buyers.  Mostly, just the DRones conveniently forget.  ???

13
You don't get it do you? Unless your relation has broken the laws of physics his 4"x4" panel is not going to "soften the light" any more than any other 4"x4" piece of diffusion material.

Go learn about light before you get in a fight with people that know what they are talking about. There is nothing your relation can do with his £120 kit that I couldn't do with a 69c piece of foam paper, the bottom of a milk carton, and a book of Rosco swatches ($2.95). For under $5 I get a quart of milk and better performing flash modifier than your relations.


I'm not in a 'fight' with you. Don't get too excited mate, this is a discussion. One in which my corner is backed by a knowledgeable source and who i'd trust over any forum lurker. Here, read the preview: https://www.kickstarter.com/projects/2101747734/bouncelite-the-revolutionary-flash-diffuser/description
He's only a distant relation but I know the inventor has 30 years experience as well.


I don't get why you don't get that softness has to do with size ?

...It's not a discussion, it's denying facts ...


Well, he's defending a relative.  And maybe he's a backer...   ::)

14
Canon General / Re: A Rundown of EOS 7D Mark II Information
« on: August 19, 2014, 05:29:47 PM »
EF mount and the Rebel line are the only innovations you can think of?

How about image stabilization, ultrasonic motors, a relatively inexpensive full-frame digital body, and high-def video in SLRs?

How about eye-controlled focus, and diffractive optics?

How about DPAF?  Etc.

I think AvTvM's definition of innovation means making the exact specific camera he wants...

15
Brits, particularly most Londoners, generally don't get the George C. Parker reference, when you talk of bridges like that they are much more likely to think of Roberto Calvi.

I wasn't aware that he sold bridges.  Still, one might think the reference to PT Barnum in the same sentence might have given a clue, even if he never actually spoke the phrase attributed to him, "There's a sucker born every minute."  Looking at the kickstarter site, that's 253 minutes worth of suckers. 

Ok, they're called backers.  That reminds me of an even more obscure cultural reference - a film adaptation loosely based on a play with which I suspect at least a few Brits might have passing familiarity, as it was written by the Bard of Avon.

MICHAEL: Yeah, well, what we need is a backer.

CAMERON: What’s that?

MICHAEL: Someone with money who’s stupid.


For the curious, some Google hooks might include Heath Ledger, Julia Stiles, and the number 10.

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