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 1 
 on: May 05, 2015, 09:23:59 PM 
Started by Frank Kolwicz - Last post by Frank Kolwicz
I've been struggling with erratic focus and image sharpness with my 600/4 and the 1.4 and 2x extenders mostly because I'm an old fart and learned photography in the pre-computer age when photographers were made of iron and so were cameras (figuratively speaking).

An F1 coupled with an FD600/4.5 didn't care how you put the extenders on, so why should these new gimcrack computer thingies care? They're supposed to be smarter than ol' dumb-ass hardware, right?

Actually, no. They are only smarter in a stupider way, in that the complexity of doing one job well makes them vulnerable to how you do your job and attaching teleconverters is a prime example.

In order to avoid confusing the now very sophisticated software, you MUST put the teleconverter on the lens before you attach the camera so that it's tiny brain records the system as a whole. And it doesn't matter if the camera is on or off, you still have to feed it the pablum with the right spoon - lens/converter THEN camera. Likewise  in reverse, perhaps, when removing the converter, although I haven't tested that, yet.

I'm not sure where the little darlings are going wrong, perhaps it is in confusing the microfocus adjustment, but I rather doubt that since when it gets screwed-up, it is plain that there is no plane of truly sharp focus in the images, everything is soft and microfocus should not throw the lens that far out of whack.

If it were up to me, since the telextenders are only intended for the big prime lenses, the manuals for those lenses would all have a warning on the top of the first page in big letters as well as everywhere in the text that refers to the extenders, focus, microfocus adjustment, AF and anything else remotely relevant, not just a routine reference on page 139 or somewhere, as if it wasn't all that critical. And it would include a full explanation of why it is so (I hate authoritarian "Thou shall nots").

 2 
 on: May 05, 2015, 09:24:03 AM 
Started by Fotobuff - Last post by Bob Atkins
I'm not aware of an IS version of the EF 17-40. No doubt if they do ever bring out a MkII version with IS, the price will go up by about 50%, so be careful what you wish for!

The  Tamron SP 15-30MM F/2.8 DI VC USD is the only EF compatible superwide zoom for full frame that has IS that I can think of. If you wanted APS-C, then there's the Canon EF-S 10-18mm f/4.5-5.6 IS STM, which at $249 is quite a bargain and is the equivalent of a 16-29mm in full frame terms. It's rather slow though.

 

 3 
 on: May 04, 2015, 09:41:08 PM 
Started by Fotobuff - Last post by Fotobuff
Thanks. Does yourr 17-40 lens have IS ? Probably not but it seems that IS has recently been introduced in the 17-40. I may be wrong.

 4 
 on: May 04, 2015, 07:27:35 PM 
Started by Fotobuff - Last post by mjperini
For what it's worth, I own a lot of Canon lenses and the 17-40 is one of my favorites. I don't know if I got a particularly good copy of the lens but my results are frankly amazing from a picture quality / price standpoint.     I also own the 17mm T/S f/4  which is a world class lens, and for most things I pick up the 17-40.  Good luck

 5 
 on: May 01, 2015, 09:49:52 PM 
Started by Fotobuff - Last post by Fotobuff
Thanks for the comprehensive survey. I think the best option for me would be to increase my budget. I may have to wait a little but perhaps it will be worth it.  Cheesy

 6 
 on: May 01, 2015, 12:58:19 PM 
Started by Fotobuff - Last post by Bob Atkins
The Canon 17-40/4L is around $800, so I assume you're looking for something significantly cheaper.

That does seriously restrict your choices, especially since you're looking for something with full frame coverage, not just APS-C. Sigma don't have a full frame (DG) series lens with that type of zoom range that's any less expensive and Tamron don't have anything in their Di (full frame) lineup either.

Your only real option would be the Tokina 17-35mm F/4 AT-X Pro FX at around $450. I think the Canon 17-40 is sharper, and it gives a little more zoom range, plus it has faster focusing. The Tokina may have lower vignetting and distortion, but both of those can be corrected in software anyway.

Persoanlly I'd go for the Canon 17-40/4L if I could afford it. The Tokina 17-35mm F/4 AT-X Pro FX is $350 cheaper though, so if that's a deal breaker, it's not a bad lens and probably the best you can do if ~$500 is your absolute limit.

As for new lenses, yes, there are some in this range but they are either for APS-C format only or they are more expensive than the Canon 17-40. The new Tamron SP 15-30MM F/2.8 DI VC USD looks very nice, but it's $1200.

 7 
 on: May 01, 2015, 12:33:26 PM 
Started by KeithB - Last post by Bob Atkins
A few people are reporting seeing some sort of dust or debris sandwiched in the filter stack that covers the sensor. Seems like it was probably a manufacturing defect such as dust in the air in the assembly room.  Not all cameras are affected. but some certainly are. The effect on the image is small, but it can certainly be seen, especially when shooting at small apertures.

I'd expect Canon to offer a free fix for any camera showing this problem sometime in the very near future. Either a sensor unit replacement or a cover filter replacement if it's not bonded to the sensor itself (it is in some cameras).

 8 
 on: April 30, 2015, 10:51:41 AM 
Started by KeithB - Last post by KeithB
This just in from LensRentals:
http://www.lensrentals.com/blog/2015/04/canon-t6-sensor-issue

 9 
 on: April 29, 2015, 01:42:41 AM 
Started by Fotobuff - Last post by Fotobuff
Hi!
I am trying to get a uwa lens like 16-35 or 17-40 mm for my Canon EOS 6D. I would like to keep the cost down so I will forego IS and will not insist on a constant aperture lens (f/4 or F/2,8) and I am willing to consider third party manufacturers as well. I would like to know what choices are available in the market and at what price ?  Color fringing and vignetting , especially at the wide end is, of course, to be minimum and auto focus must work well in different light conditions. I believe some new lenses have come recently in the market.

Thanks and regards

 10 
 on: April 08, 2015, 04:16:31 PM 
Started by mjperini - Last post by Bob Atkins
Well, at $2400 it's a VERY expensive 1" sensor fixed lens still camera. To me it looks like something designed primarily as a 4K HD video but that can also shoot decent stills.

A few years ago Canon showed a mock-up of their "camera of the future". It was a still/video camera with such high resolution and so many pixels that the image could be cropped to mimic the effect of a telephoto lens without quality loss. It was their "vision of the future" but they had no date attached. Probably around 2030 or so.

In 2010 they showed a concept camera which they described as a"Multi-purpose camera - a compact and lightweight camera which supports both video and still image capture with ultra-high definition 4K resolution.  Suitable for both work and professional use it features a newly developed CMOS sensor that enables video shooting at high frame rates in excess of 60 frames per second". That sounds a lot like the XC-10.

I strongly suspect that we will be seeing 4K video on the next generation of what we think of as still DSLRs too (5D MkIV maybe?). I wouldn't be surprised to also see it on digital rebels at some point. It's just a matter of software and processing speed. APS-C sensor have more than enough pixels for 4K video.

The EOS 1D C is the real 4K video plus stills camera, but it's $8000.

Note that there are other similar cameras around. For example the  Sony FDR-AX100/B (http://www.adorama.com/Refby.tpl?refby=rflAID012417&sku=SOFDRAX100B) is $1700, has a 1" Sony Exmor sensor and shoots 4K video and 20MP stills.

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