October 25, 2014, 03:41:11 PM

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Messages - AlanF

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46
EOS-M / Re: Recommendations for lens to supplement EF-M 22mm?
« on: September 01, 2014, 12:45:51 AM »
There is only one sensible choice, the 18-55mm kit lens, white box.  It is a very good lens and built for the EOS-M, and versatile. At $100-150 it is a value king.

47
Pricewatch Deals / Re: Deal: EOS M w/22mm f/2 STM $249
« on: August 30, 2014, 04:45:38 PM »
Concorde Lafayette ?  8)

Brilliant! It's now called Hyatt Regency Etoile.

48
This stuff just gets too technical for me, so let me ask a question.

I'm standing on the side of the road on a sunny day and I'm looking at a bald eagle that is 75 meters away sitting at the top of a tree.  In my camera bag is my 300mm 2.8 lens, a 7D and 5D3.

I'm shooting handheld.  I don't dare move closer for fear that I scare him off.

If I'm trying to produce a final/edited image that "fills the frame" with as much detail, sharpness, and overall IQ as possible, which body do I attach to the 300mm?

A fully grown bald eagle is 1 m long. The size of the image on the sensor for a 300mm lens 75 m away is 4 mm. corresponding to 930 pixels on the 7D or 640 on the 5DIII. 300mm is too short for a decent image. I would use the 300 mm + 2xTC on either camera as 1860 px on the 7D or 1280 on the 5DIII would give an excellent image. You didn't have the 2xTC in your bag, I know but that is bad planning.

Alan, my friend...I'm laughing now, didn't you see the part where I said "too technical for me". :D  ;D

It's a hypothetical situation.   Which body should I grab?

OK I'll leave out the technical stuff for you:  75 m is too far away for a 300mm for good photos of anything smaller than an ostrich so my answer is grab neither and just enjoy looking at the eagle. But, if all you want is to publish a thumbnail on the web, it won't make much difference whatever you choose.

49
Pricewatch Deals / Re: Deal: EOS M w/22mm f/2 STM $249
« on: August 30, 2014, 09:58:40 AM »
Arrived in a foreign city last night, having decided to pack the EOS-M + 18-55mm instead of the 24-105mm (5DIII and 150-600 are the other gear).

A competition for all of our US members, two photos from my hotel window:
What is the continent; what country and what city?

For Europeans: name the hotel.

Both fully automatic jpegs, no fancy stuff.

50
This stuff just gets too technical for me, so let me ask a question.

I'm standing on the side of the road on a sunny day and I'm looking at a bald eagle that is 75 meters away sitting at the top of a tree.  In my camera bag is my 300mm 2.8 lens, a 7D and 5D3.

I'm shooting handheld.  I don't dare move closer for fear that I scare him off.

If I'm trying to produce a final/edited image that "fills the frame" with as much detail, sharpness, and overall IQ as possible, which body do I attach to the 300mm?

A fully grown bald eagle is 1 m long. The size of the image on the sensor for a 300mm lens 75 m away is 4 mm. corresponding to 930 pixels on the 7D or 640 on the 5DIII. 300mm is too short for a decent image. I would use the 300 mm + 2xTC on either camera as 1860 px on the 7D or 1280 on the 5DIII would give an excellent image. You didn't have the 2xTC in your bag, I know but that is bad planning.

51
Pricewatch Deals / Re: Deal: EOS M w/22mm f/2 STM $249
« on: August 30, 2014, 05:32:54 AM »
Bought one in UK at £199 with the 18-55, and bought cheaply the 22mm plus adapter. Only used it a few times but can say it is lovely piece of kit, which gives excellent results, in spite of negative reviews about focus speeds. Its AF worked fine with the 300mm f/2.8 + extenders but struggled with the Tamron 150-600mm at 600mm, though fine at 400mm.

Both the "kit" lenses are excellent.

52
Thanks Jon for sharing your calculations. To support experimentally what you are saying about diffraction limited aperture, the Canon SX50 has 1.54 µM pixels, giving a DLA of f/2.5. Its widest aperture at f = 1200mm effective is f/6.5, 2.6 x the dla, yet it really does still out resolve most cameras with larger pixels, as Don Haines will confirm.

53
Photography Technique / Re: Is RAW worth it?
« on: August 29, 2014, 12:51:30 PM »
RAW is worth it as long as it doesn't make you lazy.

Too many people use RAW as an excuse to be sloppy with lighting and lazy with "automatic" exposure.

These folk must love spending time on a computer fixing their mistakes then. Sounds like a nightmare to me.

Less time in post means more time chilling out in front of the telly with a beer in my hand.

I prefer to chill out behind my tele. Do you have a beer belly to go with your telly?

54
Thanks Jon.  What I tried to do was put some numbers behind the long running debate and help me in my choice of gear. 20% is the difference between a 600mm and a 500mm lens, which is useful, but a 500 on a crop is not equivalent to an 800 on FF in terms of resolution.

I am very happy with both my 5DIII and 70D. For much of my time, I take bird photos where the little charmers occupy far less than the crop sensor area and so the 70D represents phenomenal value. For birds in flight, the 1.6x wider field of view for the same lens makes it easier with the FF. And, as others point out, FF is less demanding for hand-held work. The factor of 1.6 in field of view increases the effects of camera shake by approximately 60% for crop for a gain of 20% gain in resolution.

55
I'm sure this thread is full of bad information all around, and I'm not even going to read the previous posts.

What can one say to that?

56
That might be true in a testing scenario, but few of us shoot in those. Factor in AF, handholding, higher than base iso, less than ideal aperture or shutter speed etc etc etc and the differences become minimal, as so many people who have owned both have attested to.

That doesn't mean there is no point to a 7D, 70D 7D MkII, as a compliment to a 6D etc one might work very well, but the resolution thing really is a red herring unless you are using a heavy tripod, 10X live view manual focus blah blah.........


What the estimates tell you is that even if you have a heavy tripod, base iso etc you will gain only a small increase in reach, and not 60%.

edited for asking my question within the quote - sorry

Reach or resolution?

In the following context they are the same: if you can achieve 1.6x greater resolution with the crop, a subject 1.6x further away will have the same apparent resolution as for the FF and so you have 1.6x the reach.

57
I did the same calculations for the Nikon D800 and D7000. You would expect them to have virtually identical resolving powers since their pixel sizes are 4.88 and 4.78 µM, respectively. And that is what I calculated, giving some credence to the calculations I did for the Canons.

MTFcrop/MTFff with identical lenses is close to 0.63 for all lenses (on the dpr widget), compared with 0.66 expected from the relative pixel heights of both sensors. The relative resolving power of the crop, given the 1.5x less field of view is:

R = 0.945   (compared with R= 1.02, calculated from the ratio of pixel sizes).

The 36.6 mpx ff beats out the 16 mp crop since, when cropped it is at least as good as the crop sensor and has all the advantages of FF when not cropped.

58
That might be true in a testing scenario, but few of us shoot in those. Factor in AF, handholding, higher than base iso, less than ideal aperture or shutter speed etc etc etc and the differences become minimal, as so many people who have owned both have attested to.

That doesn't mean there is no point to a 7D, 70D 7D MkII, as a compliment to a 6D etc one might work very well, but the resolution thing really is a red herring unless you are using a heavy tripod, 10X live view manual focus blah blah.........

What the estimates tell you is that even if you have a heavy tripod, base iso etc you will gain only a small increase in reach, and not 60%.

59
Here is a way of calculating the effective extra reach or resolving power of a crop body versus FF, which will amuse the geeks among us.

Measure the MTF of a lens on the crop (= MTFcrop) and the same lens on the FF (= MTFff). The ratio of the MTFs, MTFcrop/MTFff, gives the relative resolving power of the bodies with that lens. However, the crop body can be placed 1.6x further away to give the same field of view. Therefore, the true effective relative resolving power, R, is given by:

R = 1.6x MTFcrop/MTFff.

Photozone lists measured MTFs for a set of lenses on the 5DII and 50D. I calculated their ratios for the Canon 200mm f/2.8 II, 85mm f/1.2 II and 35mm f/2 at wide apertures below the DLA. MTFcrop/MTFff is very close to 0.726 in all cases.

This gives R for 50D/5DII = 1.16.

So the effective extra reach is 16%.  (Based on the ratio of their pixel sizes, a value of 36% is expected.

The dpreview widget gives values for the 5DIII and 7D only for a few lenses. I did the same calculations with the Tamron 150-600mm (between 150-400mm), the Canon 200-400mm and the Sigma 50mm f/1.4 A at wider apertures below the DLA. In all cases, MTFcrop/MTFff is close to 0.742.

This gives R for 7D/5DIII = 1.19.

So, the effective extra reach is 19%. (Based on the ratio of their pixel sizes, a value of 45% is expected).

There are always arguments about using MTFs quantitatively, but I think in this particular calculation it is reasonably valid to use them. It fits in reasonably well with experience - Jon has shown there is better resolving power in photos of the moon with the 7D, but it doesn't look 45% better. And my own experience is that the 7D and 70D aren't much better than the 5DIII, certainly not 1.6x.

60
The 300mm f/2.8 II is my favourite lens and I preferentially use it on birding trips at home. But, the Tamron 150-600mm is good enough and is just so convenient for travel when I have to fly for a holiday. But, if I were to go on a specialist birding trip abroad or go on safari again I would take the 300 + extenders on the 5DIII and the 70-200 f/4 IS + 70D.

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