lester_wareham

You could I guess do this, but the loss of frame edge would reduce the effective angle of view. Also the de-fish operation will significantly reduce the image's fine resolution, even barrel correction has a significant negative effect of resolution. I would think you are better of with a real ultra-wide.

I have the MT-24EX which shares the manual with the MR-14EX. I don't have another flash to experiment with but the manual gives the below:

 

Assuming type A camera, yes you can set slave C to channel 1-4 and set FEC on the slave and independently the two sides of the ring A&B (p46). So you can effectivly set the slaves ratio but adjusting the FEC over a range of +/-3 stops in 1/2 or 1/3 stop increments.

 

Not only that but (P48) you can also set slaves to group A and Group B and control them in parrallel with the ring halves. This requires flash CF 5-1.

Take a look at Bob's site http://www.bobatkins.com/photography/pmwiki/pmwiki.php/EOS/CanonTripodCollars

The 70-200 f2.8 are good lenses (there are IS and nonIS versions). The f4 version is more manageable but the loss of a stop at 200mm is a major issue from previous experience.

 

However for me the size and weight of the thing was a put off (again from previous experience) so I have gone the prime route with a 200 f2.8 and 100 f2.8 macro; Lighter cheaper smaller and sharper plus I have a real macro lens. One day I may add a 85/1.8 or 135/2 but to be honest I don't miss them for the photography I do.

Most of the reviews and tests I have seen give the edge to Canon. I have the Canon and am very impressed with it.

I guess Chris is looking for a hood that is a good match for a crop camera field of view with this lens. There is a website that lists candidate hoods but I can't remember the url.

 

I guess you need a hood for ~35mm that has the right thread size. The 35/1.4L might do the job. My understanding is the 24/1.4L hood is recommended for the 17-40 and 16-35.

There is a reasonable explanation in the Lens Work III Eyes of EOS book. It explains the basics but does not go into any interesting technical detail like how many poles the loop feedback filter has - I expect Canon treat such stuff as a trade secret. Sometimes the paternts for these things give more info amongst the weasel words, that might be worth a try.

The low light AF performance is a function of the camera and not the lens, it depends on the AF sensor sensitivity. A 1Dx may do better, cheaper to use manual focus although I don't generally find this problem.

 

Any very fast lens will not be so sharp wide open. With this lens just half a stop closed will make a large differnce. This is part of the teritory with fast lenses. No doubt if you 3-5 times as much you **might** get better performance.

 

The 50/1.4 is probably the sharpest Canon lens but does suffer some CA wide open, some people think this gives portraits a nice glow!

You should look at the whole system that you would end up with rather than just the one lens solution.

 

Having said that I would think the full frame would be essential for low noise large portraites and still life prints and good depth of field control.

 

My immediate instinct would be 5D + 85/1.2 or 85/1.8 for the potraits and perhaps something wider for the still life. 34/1.4 or 50/1.4 unless you need a perspective control lens.

I have not seen any full frame measurements of the 24-105 yet but here is one for the 24-70 http://www.slrgear.com/reviews/showproduct.php/product/143/sort/2/cat/11/page/1

I often used a spot meter with film but not for digital where you can use the histogram to get a very good idea of the exposure and use compensation to deal with dynamic range issues and reshoot. Of it is an action shot you shoot a trial shot beforehand.

This question comes up a lot. I myself have the EF 100/2.8 but I understand both are very good and sharp.

 

The 150 should give more working distance. This can be an advantage for closeups of bugs etc but can work against you with undergrowth.

 

For butterflies etc that are very difficult to get close but in the open to a 200 to 300 with tubes may be better.

 

Consider what you want to shoot, under what conditions. Do you need to handhold (bugs normally). What other lenses do you have and how would each lens fit into your system.

 

Does the new lens need to be good for general use also? I know the 100 AF is more than acceptable, I can't comment on the 150.

If you get an answer let me know, I have the same issue.

This lens is part of my general photography kit, AF speed is very acceptable. Still very sharp wide open. Good for all sorts of stuff.

You could look at the Lowepro Slingshot 200AW, combines the best features of a backpack and convinience of a sholder bag.

 

http://www.lowepro.com/Products/Sling_Bags/All_Weather_Cover/SlingShot_200_AW.aspx

 

Not sure it will fit all you need but I have some shots of my kit in it here:

 

http://www.zen20934.zen.co.uk/photography/mybags.htm

"I personally would like to see digital sensors with more dynamic range rather than more pixels."

 

In fact this is one thing you would get with more pixels. If you downsample the data to a smaller size the effective bitwidth of each pixel will increase. This fact is often used in one dimension in telecommunications systems. It is easier and cheaper to oversample the data and downsample it with a small bitwidth digitiser. In any event above 12 bits ADCs run into noise issues anyway.

 

The downsampling will also reduce the noise of the smaller sensor size averaging it out.

 

Another advantage of larger sensor size is reduced need for sharpening to compensate for the anti-alias filters. This reduces artifacts etc.

 

So there are advantages to larger sensors even if you don't need or want to store all the data.

You are right there are some bad reviews on the 16-35, there are also some good ones.

 

The 17-40 is generaly thought to be sharper at the wide end and should be better from the MTF data. However, even the 17-40 has had recent complaints about being soft on one side etc on various forum. It is difficult to know what proportion of lenses/users have this problem as of course if all is well people tend to say nothing.

 

IMHO the shorter Canon lenses seem to suffer from part-to-part variation more than other lenses in the range. I can only assume that is due to a combination to increased sensitivity to assembly tolerances at the shorter focal lengths plus the reduced margin for accetable sharpnes in the basic optical design for retrofocus lenses.

 

Even the prime lenses seem to suffer the problem. The 20mm/2.8 is not often reviwed with reliably measurements but of the two reviews I know of with had data, one is good and the other not so good.

 

Even the two primes you mention have strong views for and against.

 

It does make things a bit confussion in this range.

The already have the 10-22, nice lens.

Ivan, Can you also comment on the colour bias of the 20 and 17-40 please?

 

Some have compared the 20 unfavorably to the 17-40 and 16-35 in this respect.

Yes I get the impression the 20mm gets a bum rap also. I don't have one but I feel a lot more confident of the 20mm than the 16-35mm. The 17-40 has a better rep but is slower, however there have been a number of people complaining of soft 17-40's recently.

 

Another test is http://wlcastleman.com/equip/reviews/17-40/index.htm comparing the 17-40 and 20, to me this shows the 20mm in a good light as well.

 

I would be interested to hear from others that have compared the 17-40 @ 20 and the 20mm in a reasonably systematic way.

I may be wrong but the sharpening may be a masked HP filter rather than USM, I think I read this somewhere. I compared DPP sharpening to various PS methods and found it provides significant sharpening with minimal artifacts.

 

However I have switched to PS now and use an enhanced edge masked USM with the Canon recommended settings (0.7, 0, 300%)and a layer with blend setting to protect the highlight and shaddows for standarded capture sharpening.

Note the usual extension formula only applies to lenses focused with overall linear extension and will not be accurate with internally focussed lenses.

If you are stuck for cash get the 18-55 kit lens with the camera. The 10-22 is good and will give a ultra wide angle to normal view.

 

The 17-40 has a good reputation and should be better than the 18-55 but the 18-55 is very good for its price.

 

As a thought you should be thinking about spending to get good quality lenses, these are the most important thing for image quality. I have a 20D and it is excellent, but aks yourself if you need the 20D or would the XT be OK. You may then be able to get another lens or a better lens.

I am one that expects to move to full frame eventially.

 

The only reason I moved from film to crop digital was the availability of the EF-S 10-22. I still use the 18-55 kit lens also. This lenses are good and OK respectively. In fact the 10-22 is very sharp at the wide end.

 

So they do their job for the time being.

 

However, the EF-S 60mm and EF-S 17-85 can be covered by EF lenses so I will not bother with those.

People report doing this with good results up to 50 to 60mm of tubes, I understand this gets you to something like 2:1.

 

One of the advantages of macro lenses in general and also internal focus is the correction of aberations that become significant at smaller subject distances, this I guess will not be so effective once tubes are used.

 

The difraction limits become more significant at any higher magnifications acheived by extension (tubes in this case) becase you are effectively using a smaller part of the lens image circle to cover the sensor. This causes inverse square loss which is often figured as an effective apature. However the physical size of the focal length and apature do not change.

 

If you want very high magnifications you should look at the MP-E 65mm f2.8 MACRO PHOTO 1-5X, my understanding is the design includes a floating element to control aberations. However the inverse square light loss and magnification diffractions limits will still apply.

 

I understand that some have used tubes on the MP-E to get to 10:1, although presumable this will degrade the aberation correction as above.

 

Beyond that you are into bellows and special bellows lenses, this are normally ~20mm and fit with a special flange. Then its microscopes.

 

I suspect anything beyond the MP-E will require specialist lighting equipment.

 

Even using the MP-E must be chalenging. One of the Canon macro flashes (preferably the MT-24) would be a good idea.

 

There are experienced users on this forum that can give more info on such setups.