Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Nov 26, 2003, 2:35 PM   #11
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Regardless of what their plans are, it looks like a lot of cameras (Canon) have been sold this season... Even this popular 50-500mmF4-6.3 EX APO is on backordered status!
NHL is offline   Reply With Quote
Old Nov 27, 2003, 5:03 AM   #12
Junior Member
 
Join Date: Nov 2003
Posts: 20
Default

Ok, now my Christmas wish list has got another number. Looks like the Sigma 50-500 is something I gotta have!

Since I live in SA, the Kruger park is one of my favourite playgrounds, so a telephoto is a necessity.

I think I've settled on the following arrangement:

Sigma 17-35
Canon 28-135
Sigma 50-500

Doesn't seem like I've missed too much in terms of focal length range here chaps. If anyone has any bad experiences with any of these, I will be very much appreciated if you can let me know. Otherwise it's time to start saving up for these puppies!
Ugly Kid Joe is offline   Reply With Quote
Old Nov 27, 2003, 7:01 AM   #13
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Well... from your selection you are pretty much covered (the lenses are identical to what I have); However what I've found was the 70-200 f/2.8 is a must have!

Take a look at your lenses selection they are mostly f/5.6 or higher at the long which will limit your shutter speed in the shade or cloudy days, but the best feature in a constant f/2.8 is its shallow DOF which can really pop your subjects from their blurry background. Beside with a matched teleconverter of 1.4x or 2x you're still within the range of the other Sigma. IMO the EX 50-500 f/4.5-6.3 is a secondary lens while the EX 70-200 f/2.8 is a prime... (beside it looks like this lens is on backordered too!)

Man they are selling like hot cakes... :P
NHL is offline   Reply With Quote
Old Nov 27, 2003, 7:24 AM   #14
Junior Member
 
Join Date: Nov 2003
Posts: 20
Default

Sound advice, thanks mate! My research on the 70-200 has shown nothing less than excellent reviews, and I hadn't considered the DOF in my original lineup, and now I have a complete set to aim for, so it's time to save up some cash. Any camera is only as good as its lens after all.

Please be so kind as to furnish one more piece of advice... what tripod? I am very green in this area, so is there any particular make that you can recommend. I will be lugging it around attached to my backpack (which is a Lowerpo Mini Trekker - very nice!)
Ugly Kid Joe is offline   Reply With Quote
Old Nov 27, 2003, 7:37 AM   #15
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Bogen - Manfrotto?

... There's others of course, but the amount of accessories available for theses tripods are limitless! BTW I'll go for the Carbon one with all the gears you're carrying. :lol: :lol: :lol:
NHL is offline   Reply With Quote
Old Dec 2, 2003, 11:27 PM   #16
Junior Member
 
Join Date: Dec 2003
Posts: 8
Default

I have both the Canon 28-135 IS and the Sigma 24-135 F2.8 lens. I also have a Canon 10d with the front focus problem and unfortunately the Sigma 24-135 is bitten with the problem at 24 mm (24 only) at F2.8.

Other than that I have somewhat of a proble with the Sigma because while it is sharp it is a VERY high contrast lens and tends to produce shots that look cooler in colors than my other lenses. I have my other lenses in the Sigma shop being rechipped but Sigma New York said that the 24-135 is to new to them to have specs or replacement parts so they can't rechip that lens.

I don't know if these comments will pertain to the rebel but I thought I should let you know. I hope to keep the lens because yes - F2.8 is great and 24 is much better than 28. You wouldn't think 4mm could make such a difference but with the 1.6 multipliter it does.
bruceperson is offline   Reply With Quote
Old Dec 3, 2003, 10:12 AM   #17
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Quote:
I have both the Canon 28-135 IS and the Sigma 24-135 F2.8 lens. I also have a Canon 10d with the front focus problem and unfortunately the Sigma 24-135 is bitten with the problem at 24 mm (24 only) at F2.8.
... While I agree with you that it might be a body problem, but I'm not familiar with how you measure this:

1- Lenses: Take the EF 28-135mm IS USM, set it at 135mm and focus it on an object about 1.5m away and record the distance scale. Now change the zoom position to 28mm and focus on the same object, notice the distance scale on the barrel is now only 1m! I don't have a Sigma 24-135 F/2.8 lens so I can't try this, but with my 17-35 f/2.8-4.5 I don' t notice this problem, which is typical with high ratio AF zoom, ie the distance changes as the zoom is varied. What this means if you focus at 1 focal lenght and zoom in/out to crop, you'll end up with front/back focus (the fine print in the lens manual has a warning regarding this effect). This is usually a trade-off in adopting a varifocal design to keep a lens affordable and compact!
The other thing that does not make sense in the description is at the wide angle the problem should be less not more even at f/2.8 since the DOF is so much larger at the WA than at the tele where the DOF distance could be in the inches/centimeters (and not feets/meters). The Sigma 70-200 f/2.8 for example does not change focusing distance as the zoom is varied... which is why you're not seeing this.

2- Camera: The distance between the lens mount to the sensor plane could be different from the distance to the AF sensor behind the prism. In this case what you see as sharp focus in the viewfinder could be misaligned during manufacturing with the sensor; However with this case the front or back focus should remain constant and will not change with the lenses or focal lenght, and Canon can adjust for this (that's why they ask you to send a lens in as well just to be sure it's not a problem with a problematic mount).
NHL is offline   Reply With Quote
Old Dec 3, 2003, 2:08 PM   #18
Junior Member
 
Join Date: Dec 2003
Posts: 8
Default

Quote:
Originally Posted by NHL
Quote:
While I agree with you that it might be a body problem, but I'm not familiar with how you measure this:.
...

Lenses: Yes I'm familar that if you go by the lens barrel the the distance to target is different at telephoto than at the wide angle setting of a zoom lens. I am trying to say that if you focus (using center AF) at an object 30 feet away at the widest angle setting (most depth of field) at the most open F-Stop (most limited depth of field for that mm setting) using a non-canon lens, my camera will produce an image where the 30 foot object will be out of focus and objects 20 feet away will be in focus. It is wrong. Canon lenses do not seem to do this although they typically start at F3.5 so they naturally have a greater depth of field that 2.8 lenses so this problem is not as noticable with Canon lenses.

Camera: Yes I thought of that difference between prism and cmos sensor, but then my Canon 24-70 L F2.8 should also have the problem and it doesn't. I believe that the camera communicates to the lens in some way about the maximum aperature, when to stop focus or some other matter that Sigma, Tamron, and perhaps other third party lens makers have yet to figure out on the 10d.

Canon sent their dealers a letter this fall essentially saying as much and that they did not intend to cooperate in any way with third party lens makers and that in the case of digital (specifically the Canon 10 d), would not support third party lenses at all. That is why I might have to sell all my non-Canon lenses and either just take what Canon has to offer or consider moving to Nikon (but I don't know if thier policy re. third party lens makers is any better). This is just so Apple and Microsoft of Canon.




1- Lenses: Take the EF 28-135mm IS USM, set it at 135mm and focus it on an object about 1.5m away and record the distance scale. Now change the zoom position to 28mm and focus on the same object, notice the distance scale on the barrel is now only 1m! I don't have a Sigma 24-135 F/2.8 lens so I can't try this, but with my 17-35 f/2.8-4.5 I don' t notice this problem, which is typical with high ratio AF zoom, ie the distance changes as the zoom is varied. What this means if you focus at 1 focal lenght and zoom in/out to crop, you'll end up with front/back focus (the fine print in the lens manual has a warning regarding this effect). This is usually a trade-off in adopting a varifocal design to keep a lens affordable and compact!
The other thing that does not make sense in the description is at the wide angle the problem should be less not more even at f/2.8 since the DOF is so much larger at the WA than at the tele where the DOF distance could be in the inches/centimeters (and not feets/meters). The Sigma 70-200 f/2.8 for example does not change focusing distance as the zoom is varied... which is why you're not seeing this.

2- Camera: The distance between the lens mount to the sensor plane could be different from the distance to the AF sensor behind the prism. In this case what you see as sharp focus in the viewfinder could be misaligned during manufacturing with the sensor; However with this case the front or back focus should remain constant and will not change with the lenses or focal lenght, and Canon can adjust for this (that's why they ask you to send a lens in as well just to be sure it's not a problem with a problematic mount).
bruceperson is offline   Reply With Quote
Old Dec 3, 2003, 5:38 PM   #19
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Quote:
I am trying to say that if you focus (using center AF) at an object 30 feet away at the widest angle setting (most depth of field) at the most open F-Stop (most limited depth of field for that mm setting) using a non-canon lens, my camera will produce an image where the 30 foot object will be out of focus and objects 20 feet away will be in focus.
Can you see the sharpness in the viewfinder at 24mm? Or are you saying the central AF in the viewfinder indicates that it's sharp, but when the shutter is released Canon intentionally "skew" the lens in the resulting image... I can see this in AI focus, but in one-shot AF, the focusing in the viewfinder ceases when the picture is in focus. If it's off by 10 ft you should be able to see this in the viewfinder as well... Are you saying the viewfinder(ie in focus) and the final picture(ie out of focus by 10ft) do not match, which sounds like a camera alignment problem?

Did you try to focus manually to verify this? It does not do this on my Sigma 17-35 f/2.8-4.5 EX which is mostly spot on. :?
NHL is offline   Reply With Quote
Old Dec 3, 2003, 9:59 PM   #20
Junior Member
 
Join Date: Dec 2003
Posts: 8
Default

[quote="NHL"]
Quote:
Are you saying the viewfinder(ie in focus) and the final picture(ie out of focus by 10ft) do not match, which sounds like a camera alignment problem?

Did you try to focus manually to verify this? It does not do this on my Sigma 17-35 f/2.8-4.5 EX which is mostly spot on. :?
Now I think you have it. Since these tests are conducted in the range of 17-28 mm for this effect to show it is hard to show precise focus in the viewfinder. But YES. What I see in the viewfinder is not what I get on the image (with non-canon lenses). I have the pictures to prove it. I also have just finished today a test using a brand new digital rebel and it behaves with these problem lenses in the same fashion.

One interesting note was that for this test I varied the program mode from Manual->AV->TV->P and I found that Manual mode actually made the effect somewhat better. It did not cure it but there was a difference.

I think I will probably have to sell all my non-canon lenes like my two favorite Tamron lenes and all my Sigma lenes unless the Sigma rechip works that I'm having done now. I should know by the end of the month. Then I'll just have to wait for Sigma to get replacement parts for the 24-135 lens so it too can get rechipped.

Since the problem also exists with the Digital Rebel I guess there is no use in sending my 10d back to Canon. They would probably just say that everything is in spec. By the way, my Canon 24-70 2.8 L back focused on the Rebel. Strange I'll have to do more testing on my 10D.

Best Wishes.
bruceperson is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 3:26 PM.