April 20, 2014, 10:13:01 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - AlanF

Pages: 1 2 3 [4] 5 6 ... 57
46
Lenses / Re: Visit Guilin, Mountain Range, in China - Lens selection
« on: March 16, 2014, 03:22:26 AM »
By coincidence I'll be there the following week on vacation, organised as a mystery tour by Chinese friends after official visits to Hong Kong and Shanghai.  I had intended to take the 5DIII plus Tamron 150-600 for nature and 24-105 for general.

 I have been trying to persuade my wife to take the 70D with the 15-85 as it could provide a back-up body and I could omit the 24-105 and we would have two cameras ready all the time.  However, she wants something small for her handbag.  She needs something without any buttons, mode dials etc that can be pressed by mistake and set off the self- timer etc. Anything foolproof to recommend (apart from iPhones etc)?

47
Watch it, Guy. The one in the white blouse is my wife, and you wouldn't stand a chance against her. 

48
Firstly, why do you say dust is flatter than sand? Dust particles are usually modelled to be spherical or cylindrical in scientific studies, ie the same shape as sand and certainly not flatter.


How dust is modeled in scientific studies isn't really relevant to it's ability to penetrate a 'dust-resistant seal'.  Neither dust nor sand are actually spherical or cylindrical, but in general dust is smaller and has a higher surface to volume ratio than sand.  Here's some household dust:



Some of it could certainly be described as 'flatter than sand'.


Neuro
An arrest warrant is being issued for your breaking US copyright.

http://images.sciencesource.com/preview/13250858/BP3016.html

Anyway, I think it is a fake, composed of cabbage leaves, chillies, potato skins and bean pods. As if an SEM gives real colours....

49
Firstly, why do you say dust is flatter than sand? Dust particles are usually modelled to be spherical or cylindrical in scientific studies, ie the same shape as sand and certainly not flatter.


How dust is modeled in scientific studies isn't really relevant to it's ability to penetrate a 'dust-resistant seal'.  Neither dust nor sand are actually spherical or cylindrical, but in general dust is smaller and has a higher surface to volume ratio than sand.  Here's some household dust:



Some of it could certainly be described as 'flatter than sand'.



Are sand particles uniform in size and shape? Aren't some of them flatter and some of them smaller? It is a geometric truism that smaller objects (of similar shapes) have higher surface/volume ratios because volume varies as length cubed and area as length squared. By modelled, I mean that the shape of atmospheric dust particles is determined by their light scattering characteristics, and they usually come out on average as spherical or squat cylinders.

50
You are a professional and need tools commensurate with your profession.

Some of your points are a little odd. Firstly, why do you say dust is flatter than sand? Dust particles are usually modelled to be spherical or cylindrical in scientific studies, ie the same shape as sand and certainly not flatter.

Secondly, you allude to your professional standard lenses as having a gold ring, and the 15-600mm not being in this class. Tamron used the gold ring cosmetically to designate its SP "Super performance lenses": see - http://www.tamron.eu/en/lenses/technology/sp-super-performance.html for a definition of them and their properties including robust outer design.

The Tamron 150-600mm is officially an SP lens: see - http://www.tamron.eu/en/lenses/overview/single/product/sp-150-600mm-f5-63-vc-usd-5.html?tx_keproducts_pi6[cam]=&tx_keproducts_pi6[vc]=false&tx_keproducts_pi6[sp]=false

The last thing I am going to do is to take my lens apart! If it fills up in the next five years with dust like a Dyson, I'll send it it back to Tamron under warranty.

51
The ultimate Tamron 150-600mm, available on eBay for only £1,000,000.

52


That sir is not any old brick wall. That is a genuine Tudor base of a chimney of Trinity College Cambridge, the Home of Sir Isaac Newton, the inventor of, among many other great things, gravity, the prism, the mirror lens telescope, and the founder of modern optics, without which we would not have "glass". Any more comments like that and I will challenge you to a duel of calculus at dawn.

Here is the full frame, showing the glorious base with the Victorian addition or restoration above.


What? I didn't know Newton invented gravity and the prism. I always thought gravity existed before he came along and the prism was a toy/curio which he bought at a county fair.

Before you challenge anyone to a battle of calculus (you failed to name Leibniz), do your homework.


I didn't name Leibniz because I didn't claim Newton invented the calculus (he did, but our German colleagues see it differently - http://en.wikipedia.org/wiki/Leibniz-Newton_calculus_controversy

You don't understand the Cambridge sense of humour (yes, we do have one). My college claims that William Harvey invented the circulation of the blood, not discovered.

If you want a mathematical duel, here is my second (taken on Monday night at iso3200, f/4 24-105)

53
As someone who’s currently building up a collection of kit, I’d like to thank Alan F for his brick wall shots.  I can clearly see that the L glass plus a 2xTC offers better IQ than a third party, 1/3-of-the-price lens. 
I own a Sigma 150-500 and as I have just bought a 70D I’m looking at improving my IQ for keeper’s sake. 
I was considering the Tammy but I now know that I need to go “L”.
Next question is regarding the 300L f4 compared to the 400L 5.6, and just to add further debate, how does the 100-400L stack up against either of these if they had an added TC, and also against the big new Tammy?
I know it’s a big ask but I think it’s valid as there have already been a lot of comments on this thread regarding all these lenses, so if you could make a top ten list of best IQ how would it look???
(e.g. below)
 1st = 300L, 2nd = 300L + 2xTC, 3rd = 400L, 4th = Tammy 600mm, 5th = 400L + 2xTC etc etc, yada yada yada :o
The tamron beats the 300f4L and with the 2x tc it's not even in the same game

Yes. The Tamron is at its best between 200 and 400mm, and really superb at 300mm. It is as good as a good copy of the 100-400 at 400mm, and much better in the corners - it fares well against the 400 f/5.6L over the whole frame. The 400 L is very good with a 1.4xTC, the 300L f/4 is not as good. The 100-400  has crippled AF with a TC, and is f/8. The Tamron has rendered those older lenses obsolete. I am afraid you have to spend 5x more on the 300mm f/2.8 to beat it.

54
I did another comparison of the Tamron 150-600mm @600mm versus the Canon 300 f/2.8 II + 2xTC III on a 5DIII. A Tudor chimney overlooking my garden has very nice detail and shading in the bricks and mortar. In this collage of 100% crops of 800x700, which are testing the resolution at the limits, you can see that the Canon does have the edge, but the Tamron does very well.

I have made a personal decision to never take or comment on "brick wall of shame" crops. Maybe stating that goes against my conviction but I hold fast.

That sir is not any old brick wall. That is a genuine Tudor base of a chimney of Trinity College Cambridge, the Home of Sir Isaac Newton, the inventor of, among many other great things, gravity, the prism, the mirror lens telescope, and the founder of modern optics, without which we would not have "glass". Any more comments like that and I will challenge you to a duel of calculus at dawn.

Here is the full frame, showing the glorious base with the Victorian addition or restoration above.

55
I did another comparison of the Tamron 150-600mm @600mm versus the Canon 300 f/2.8 II + 2xTC III on a 5DIII. A Tudor chimney overlooking my garden has very nice detail and shading in the bricks and mortar. In this collage of 100% crops of 800x700, which are testing the resolution at the limits, you can see that the Canon does have the edge, but the Tamron does very well.


56
Software & Accessories / Re: BlackRapid FAIL - grrrrrr
« on: March 11, 2014, 02:03:54 PM »
Having read about Black Rapid failures and also having had the camera body fall off the lens, I made a very simple safety back up strap that holds the body to the strap using the strap lugs. The Black Rapid is screwed into the tripod foot of the lens as usual. I put a small hand strap through one of the camera body lugs and attached it to the Black Rapid strap via a key ring that can slide up and down. If the body falls off the lens, it is retained by the strap. If the connector or fastener to the tripod fail, then the lens is saved by the camera lug holding both of them. I have tested the system, and it works.

57
Animal Kingdom / Re: BIRD IN FLIGHT ONLY -- share your BIF photos here
« on: March 11, 2014, 07:54:23 AM »
Lapwings in flight
1/5000, f/5.6, iso640, 300mm f/2.8 II + 2xTC, 5DIII
Full frame compressed to 2400x1600.

It is remarkable that all of the lapwings are in focus. This where my 300mm combo beats my Tamron 150-600 as it sharp across the whole frame at 600mm.

58
I own the three mentioned Canon lenses and I had ordered the Tamron to replace my 100-400 but then cancelled after reading about AF issues. Also I really don't use my 100-400 as the 300II and converters is portable enough for me. I've had the 600II since October 2012 and use it mainly for spring migration when the birds are skittish and far. Most often with the 2xTC attached. But I also use it bare and at 840 also when appropriate. I've had the 300II since Nov 2013 and have used it with both TCs and it is a phenomenal lens and I use it instead of my 100-400 now as a "portable" solution. I got the 200-400 just a month ago to take to Antarctica in November and I brought it to Borneo for birding and wildlife(orangutans). That is where I am typing this from now. I have found it very versatile for the mammals but wish I had my 600 for the small birds but there was no way I wanted to travel with the 600 through SE Asia. I have used the 2-4 with 1.4 external and had good success at 784mm or really at 800mm if you use the square root of 2 to get 1.4.  Only issue has been the low light of the jungle and needing the 1DX to save shots with ISOs from 6400-25600 being used in the deeper jungle!!!

I also use the 300mm f/2.8 II plus TCs. The AF on the Tamron on the 5DIII and 70D is not far behind the 300mm with 2xTC and is very acceptable. The Tamron's AF is not a problem for my Tamron or for most of the others who have posted. The reproducibility and consistency of the Tamron AF is far better than that of the 100-400.

59
The lens is moisture resistant.

Wonder what that means?

Rubber lens flange gasket. Presumably the sliding tube has a gasket and the front lens is sealed. Definitely not for scuba diving or zooming in and out in a thunderstorm.

60
I bought a new Tamron 150-600mm lens a month ago. I am a professional photographer and am not biased towards or against Tamron vs. Canon, as I own prime L-grade lenses from both companies.  Unfortunately, this lens is not weather sealed, and after using the lens for two weeks outside, the amount of internal dust was atrocious.  Regardless of being meticulous and using a blower at all times, the lens quickly absorbed dust onto the frontal glass element internally, including moisture, via the cork-screw barrel that retracts into the upper chamber.   Closely inspecting the markings on the lens, I saw that it was manufactured in China, as opposed to Tamron's traditional Japan manufacturer, which was a big shock, so quality control has definitely been compromised in order to sell the lens at $1069 :-\

Additionally, image stabilization for action shots (specifically bird shots) is not reliable.  Even though the proper autofocus point speed and tracking can be adjusted in the Canon 5D Mark III to compensate for the lag, shutter speed has to be at least 1/2000th+ of a second in order to prevent motion blur for hand held action tracking shots (coupled with f/6.3 on a cloudy day and ISO 1000-2000, this creates photos worthy of entry level DSLR bodies and stock lenses - which means not good!). Unlike my Canon 100-400mm f/4-5.6 L lens, which has 2 modes of image stabilization and creates very fast and stable shots, the Tamron 150-600mm lens only has an on/off VC switch with no additional stabilization mode selection settings.  Gimbal shots are naturally improved, but AF adjustment at 15m to infinity is still sluggish when trying to focus on objects 200ft and further (creep still occurs with the limiting switch).   I called Tamron directly, and their technical support team confirmed that their teleconverters are not compatible with this lens as Tamron engineers have officially discontinued all TC's and did not design this lens with the 1.4x or 2x in mind.  Additionally, they confirmed that both converters should not be used with the lens, as unpredictable results can occur and are not guaranteed to work properly. 

Static shots are amazing with very comparable MTF chart optical clarity to Canon, and portability of the lens is great :); nevertheless, I need a fast and reliable lens for shooting Ospreys, Eagles, King Fishers, Herons, etc.  Sorry everyone, but this lens is not quite the "big white killer" that many individuals thought that it would turn out to be.  I too thought that this was the lens that would allow me to save several thousand dollars; however, I have now returned the Tamron 150-600mm lens for a full refund and consequently have to save up in order to purchase the real Canon 600mm f/4.0 L II (weather sealed, improved pre-set focus ranges, stabilization modes, etc.).  I am not even going to touch the "Sigmonster" 800mm f/5.6, given that it too is not weather sealed and that other professional birders have complained that the focus ring breaks over time, has a fragile body shell, and is extremely sluggish to maneuver; being confined to a gimbal for the majority of the time.   In the end, you get what you pay for! :-\

The lens is moisture resistant. I have had no problems whatosever of dust entering the lens. The VC works fine, and in my hands is about 3 stops as opposed to the 4 stops on my 300mm f/2.8. Yesterday I went for a walk with it on my 5DIII and suddenly saw a bird of prey in the sky. The lens locked on immediately and I got 4 or 5 equally sharp shots in a row at 1/1250 s - below is the full frame reduced to 2400x1600 and a 100% crop. The crop is as sharp as you would expect for that small size. I usually get 100% keepers for 1/600 s and above, as listed elsewhere. As for being made in China, if that is a sign of poor quality I had better dump my iPhone and Macbook Air and iPad etc.


Pages: 1 2 3 [4] 5 6 ... 57