Canon TS-E24mm f/3.5L

Scuff wrote in post #6648312
Using my rough and ready chart,

Please explain.

Lester Wareham wrote in post #6648377
Very nice.

I was wondering if you could just use the maths to apply the tilt, looks like you can. Was this just focus by eye or does the focus confirm light help any?

Hi Lester

I have posted this chart before, but to save searching...... I use it most of the time as a quick and dirty reference which helps me visualise the focus plane more accurately.

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Here is a shot that demonstrates how well flare is controlled with this lens. It also has a Hoya Pro-1 UV filter on the front......

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Scuff wrote in post #6648419
Hi Lester

I have posted this chart before, but to save searching...... I use it most of the time as a quick and dirty reference which helps me visualise the focus plane more accurately.
.....

I was able to confidently focus just using the viewfinder on this one, but do use the focus confirmation lights more on the 90 TS-E.

Right you can derive that mathematically and the angle of the planes of acceptable focus, see http://www.zen20934.ze​n.co.uk/photography/ti​ltshift.htm . Of course the actual angle of ideal focus depends of the focus distance, that looks right for infinity focus (lens to image distance == focal length).

For a simple lens:

Can the focus confirm be relied on in your experience or do you focus by eye?

Scuff wrote in post #6648452
Here is a shot that demonstrates how well flare is controlled with this lens. It also has a Hoya Pro-1 UV filter on the front......

Again great shot. Have you noted any vignetting problems at maximum tilt or shift with a filter fitted?

Hi Lester

In my experience I can trust the focus confirmation, I tend to use it with the 90 more than the 24.

There is some vignetting at the extremes, which I would expect. I try to stay 'out of the red' as far as possible and therefore do not consider it a problem.

Thanks.

Just picked up my mint, used copy an hour and a half ago. There aren't nearly enough samples from this lens, so I thought I'd throw up a few quick and dirty samples to showcase it's technical merits while I learn to use the thing.

These were all shot on a tripod.

1 -- using it as a REALLY high quality 24mm prime. 1/100 f/7.1

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Lester Wareham wrote in post #6651776
For a simple lens:

[GIFS ARE NOT RENDERED IN QUOTES]

Lester, I was wondering if you could give me a bit of assistance with the above chart.

I have read/re-read the articles that the chart is taken from & are getting a better handle on the mathematics behind the operation of the lens.

From the above I understand that the angle of the SF plane changes dependant upon the focus distance for a given amount of tilt but can you give me an explanation of the figures one the right hand side (which are the key to the coloured plots on the graph)

What I am trying to ask: what do the numbers e.g. o.029 or 0.042 represent?

I have just got the 24 and am finally getting the chance this weekend to play with it outside (weather permitting:rolleyes

Mark Vuleta wrote in post #6862764
Lester, I was wondering if you could give me a bit of assistance with the above chart.

I have read/re-read the articles that the chart is taken from & are getting a better handle on the mathematics behind the operation of the lens.

From the above I understand that the angle of the SF plane changes dependant upon the focus distance for a given amount of tilt but can you give me an explanation of the figures one the right hand side (which are the key to the coloured plots on the graph)

What I am trying to ask: what do the numbers e.g. o.029 or 0.042 represent?

I have just got the 24 and am finally getting the chance this weekend to play with it outside (weather permitting:rolleyes

Sorry for the delay in getting back to you.

The numbers you indicate are the distance from the lens rear nodal point to the centre of the image plane centre in metres.

So at 0.024 (24mm) an object point in the centre of the optical field will be in perfect focus at infinity. At 0.048 (48mm) an object point in the centre of the optical field is at life size magnification M=(A-F)/F where A is the distance on the distance from the lens rear nodal point to the centre of the image plane centre and F is the focal length.

So it is a way of noting the focus distance in a tilt independent way. Of course all the models make the simplifying assumption of a thin lens with, by definition, unity pupillary magnification.

So the focus distance of the object side centre of optical field of view from the lens front principle node will be given by the classic lens equation using the distance labels of the analysis 1/Z=1/F-1/A.

So you see the focus plane tilts less as you focus closer, plus the angular separation between the planes of acceptable focus (depth of field) gets smaller.

This diagram shows the effect for a 24mm lens with A=32mm and 8 degree of lens tilt at f8. The red lines on the left indicate the image and lens planes and the blue lines show the wedge shaped depth of field.

Thanks Lester

Now that my brain has got over your post (it eventually made sense to me:rolleyes.

I have spent a bit of time trying to understand the maths of the lens for two reasons.

Firstly, I struggle with focusing the lens due to poor eyes and the small viewfinder on the 30D. I am tossing up as to whether to get a split screen for the camera or get a 1DsM11 (secretly leaning towards the second option:o)

And the second reason, just to attempt to improve my technical knowledge although it seems the more I learn, the less I know.

As a follow up question, is there some form of table that I could convert the decimal figures to equivalent focus distances (or could you point me to the appropriate formula). Maths & algebra not being my strong point (point me to a leaking water pipe or a blocked drain & I'm your man!, maths, not so much)

As a matter of interest, do you know how accurate are the charts in respect to "thin lens"verses the actual practical lens?


Sorry for all of the questions, I think I will like the beast but would just like to get the best out of it.

(did have good weather this weekend but too busy to play )

Mark Vuleta wrote in post #6880658
Thanks Lester

Now that my brain has got over your post (it eventually made sense to me:rolleyes.

I have spent a bit of time trying to understand the maths of the lens for two reasons.

Firstly, I struggle with focusing the lens due to poor eyes and the small viewfinder on the 30D. I am tossing up as to whether to get a split screen for the camera or get a 1DsM11 (secretly leaning towards the second option:o)

And the second reason, just to attempt to improve my technical knowledge although it seems the more I learn, the less I know.

As a follow up question, is there some form of table that I could convert the decimal figures to equivalent focus distances (or could you point me to the appropriate formula). Maths & algebra not being my strong point (point me to a leaking water pipe or a blocked drain & I'm your man!, maths, not so much)

As a matter of interest, do you know how accurate are the charts in respect to "thin lens"verses the actual practical lens?


Sorry for all of the questions, I think I will like the beast but would just like to get the best out of it.

(did have good weather this weekend but too busy to play )

Actually I thought Scuff's diagram above was fairly handy
https://photography-on-the.net …p?p=6648419&pos​tcount=107

The maths is on the web site, it is all trig and similar triangles, nothing remotely exotic.

As for the difference between the thin lens simplification and a real lens the following points come to mind:

1. The front and rear nodes will be separated by the nodal separation rather than being coincident, this will tend to add a bit to the overall image plane to subject plane distance.

2. Real SLR lenses are often slightly retro or telefocus and exhibit a non-unity pupillary magnification. This will effect the depth of field calculation a little, but I would ignore that.

3. Due to the nodal separation, when the lens is tilted one or both nodal points must I guess undergo some rotation depending exactly where the tilt axis point is set. Additionally looking at the construction the focus helicoid is in front of the tilt mechanism, so presumably some rear nodal point rotation will be introduced by focusing nearer than infinity. This might manifest as some apparent image shift when the lens is tilted, but I am guessing, perhaps an owner can comment.

The above points may explain some differences between my calculated focus plane tilt and those in scruffs diagram.

I think playing around with numbers for the thin model is probably interesting but trying to deal with all the practical points is fraught with difficulty, particularly as many of the variables will not be precisely known.

Thanks Lester

I'll have a bit more of a read on the site. (although it makes me more like your location under your avitar )

Then, its time to practice, practice & practice.

I do have an angle viewfinder with a 2X magnification which is making it easier to focus so that may be the way for me to go in the meantime.

Thanks for your assistance

Cheers

Mark

Has anyone found this lens to be soft in use?

MaDProFF wrote in post #6925182
Has anyone found this lens to be soft in use?

The only softness I've seen is corners when used with max shift -- if you avoid the ranges marked with red on the lens, sharpness is very good. I find the centre sharpness to be best between f/5.6-7.1, but still very good up to f/13.

Anywho, a few pics from today.

13 second exposure, shot with 10 stop ND and 4 degrees tilt and a bit of shift up.

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