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Old Jul 21, 2005, 11:33 PM   #1
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Greetings folks. Just got my 7D today.. What a beautiful camera.

I am looking for some commentary/opinions on the following lenses.
I once used them with my 700si and although they are AF lenses and work with the 7D I was curious if I should be considering some alternatives.

I have the following:

Tamron 20-40mm f2.7-3.5
http://www.photodo.com/prod/lens/det...7-35-813.shtml

Tamron 35-105mm f2.8
http://www.photodo.com/prod/lens/det...5_28-828.shtml

Sigma 70-210mm f2.8 APO
this link is not exact. I think the link must be a later version.
http://www.photodo.com/prod/lens/det...POEX-784.shtml


I am not an expert at reading the graphs, scores etc.
For those that are inclined I would welcome your interpretations of the photodo data and your opinions of these lenses.

On the subject of file formats I was curious what the general consensus was.
Do you use XFine or do you find another format sufficient for your needs?

Thanks in advance for your comments and opinions.





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Old Jul 22, 2005, 7:45 AM   #2
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Congratulations on the 7D!

As for the lenses,that Tamron SP 20-40mm f/2.7-3.5 tests better than any other wide zoom available inMinolta AF Mount, and even tests better than some widerprimes wide open (see the f/2.8 numbers for the Minolta20mm and 24mm f/2.8 primes as an example).

I just bought one of these lenses myself (but I don't have a 7D to try it on). Matt Chum (a 7D owner) has this lens, and he says it's the sharpest wide zoom he's tested on it. I saw a couple of pics he took with it for demo purposes (scene at 20mm at both f/2.8 and f/8 0, and I was impressed with the sharpness.

As for the Tamron SP 35-105mm f/2.8, this one is on my short list now. It tests much better than the newer Tamron SP 28-105mm f/2.8 on the MTF charts, and it's a smaller and lighter lens compared to the newer 28-105.

I sure wish it was internal focus with a non-rotating front element. But, you can't have everything. ;-)

It appears to suffer from some edge softness (more at wider focal lengths), but this may not show up as much with a DSLR (since it's sensor is smaller than 35mm film, it's using more a the sweet spot in a lens after the 1.5x crop). Barrel distortion may be a contributing factor here, too (looks to be bad at the wide end).

My thought is that this one would be good for when I needing something a little longer, so I'd use one as a 50-100mm zoom (which would be more like a 75-150mm on a 35mm camera), avoiding the widest lens setting.

Lens choice is tougher on a DSLR, because you need to multiply the actual focal length of a lens by 1.5x to get the 35mm equivalent focal length/angle of view.

So, that 20-40mm Tamron would function more like a 30-60mm when used on a 7D.

A popular bright zoom on the 7D seems to be the Minolta 28-75mm f/2.8D (which is made by Tamron for Minolta). This one would give you a 35mm equivalent focal range of around 42-105mm on a 7D.

Lens choice for digital is tough for me. With a 35mm camera, a good General Purpose Zoom is usually 28-70mm, 35-70mm, or somewhere in that general range.

But, because of the smaller sensor on a DSLR, these types of zoom lenses may not be quite wide enough after the 1.5x crop factor.

So, I'm probably going to reluctantly give into this same two lens combo (20-40mm f/2.7-3.5 and 35-105mm f/2.8 )as being the best combo for when I need a zoom.

Now, I have seen some user opinions of these older Tamron lenses, that seem to criticize them a bit more for succeptability to flare, etc. But, the tests at photodo.com are non-subjective (they're based on MTF charts). So, I'll go by what I see there for lens selection first, and deal with any other issues when/if they occur.

Chances are, I'd leave a prime on a camera more than a zoom anyway.

That Sigma you've gotseems to be well liked on a 7D from comments I've seen so far.

Another thing to consider when buying lenses, is that older lenses are unlikely to be ADI compatible. You'll need newer D lenses for the camera to be aware of focus distance and use this info for flash exposures.

From my perspective, it's not important. I'm not convinced that there's much difference, since the camera is using a preflash to set exposure anyway.

If I get a 7D, I'll probably go with a Metz Flash System and use Auto versus TTL mode (some Metz flashes have an Auto Mode that usesa built in sensor to measure reflected light during the exposure, eliminating the need for the preflash that Minolta's flash systems have on a 7D).

Now, I don't own a 7D, but I'm thinking about getting one (so, I've started buying some lenses while deciding). I'm also spending a bit of time looking at availableflash systems.

Personally, if I were you, I'd stick with the lenses you've got for zooms, unless you have a pressing need for something else. Of course, a few lighter primes are always nice versus the need to lug around larger zooms.
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Old Jul 22, 2005, 8:49 AM   #3
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P.S.

If you wanted something smaller and lighter as a walk around lens (and don't really need f/2.8 brightness), Konica-Minolta is releasing some new lenses soon (should start shipping in about a month).

Something like the new 18-70mm would give you a 35mm equivalent focal range of 27-105mm after the 1.5x crop factor/multiplier on the 7D. These new lenses are designed specifically for DSLR models (hence, they can be smaller and lighter), and cannot be used on a 35mm SLR:

http://www.steves-digicams.com/pr/km...lenses_pr.html
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Old Jul 22, 2005, 11:31 AM   #4
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Thanks JimC that really helps a lot.

I'll start with the 20-40mm and see if I get similar results.

I do have a 3600D flash arriving today and that will round out my kit.
I am somewhat concerned about what I've read from some owners who have lamented flash compensation issues although it appears that this is more of an issue with the 5600D flash.
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Old Jul 22, 2005, 11:42 AM   #5
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deadhead wrote:
Quote:
Thanks JimC that really helps a lot.

I'll start with the 20-40mm and see if I get similar results.

I do have a 3600D flash arriving today and that will round out my kit.
I am somewhat concerned about what I've read from some owners who have lamented flash compensation issues although it appears that this is more of an issue with the 5600D flash.
Yep... A lot of 7D owners have been sending their cameras and flashes back to KM for calibration. The problem appears to stem from the strength of the preflash that KM requires for flash metering purposes.

I'm leaning towards buying one of the KM DSLR models now. The only major issue I've got with them is the flash system design (preflash). But, I can get around that by using a 3rd party flash system like Metz (Auto versus TTL mode doesn't require a preflash with some flash models).
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Old Jul 23, 2005, 4:45 PM   #6
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the 'preflash' is used for autofocus and can be turned off!
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Old Jul 25, 2005, 8:29 AM   #7
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bernabeu wrote:
Quote:
the 'preflash' is used for autofocus and can be turned off!
I'm not talking about an AF preflash.

With Minolta's flash system on a 7D, a short preflash occurs a split second before the main flash. The camera uses this preflash to determine the correct flash burst length during the main flash (since itdoes not meter from the sensor during exposure). So, some film 7 owners are not thrilled about this behavior. ;-)

With the compatible external flash models Minolta offers with this camera, the preflash will always be there, unless you go to manual mode.

Some people don't notice it (preflash a split second before main flash). But, a small portion of the population will always see it andblink with it. There are quite a few threads about this subject floating around the internet (can't disable the preflash using a Minolta flash like the 5600HS-D with the 7D unless you switch to manual mode).

So, 7D owners that need to take lots of group photos have found that some other flash systems will not use a preflash in non-TTL auto modes. Some of the Metz units with newer firmware are able to see the camera's aperture setting, and regulate the flash strength by monitoring the reflected light during the exposure (using the built in sensor in the flash).

Unfortunately, Minolta doesn't offer a flash that works this way with the 7D, so a preflash is required.


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Old Jul 25, 2005, 2:01 PM   #8
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you can turn it off by going to ADI mode (if you have a 'D' lens)
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Old Jul 25, 2005, 2:03 PM   #9
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bernabeu wrote:
Quote:
you can turn it off by going to ADI mode (if you have a 'D' lens)

Well, I asked around, and some 7D owners told me that it can't be turned off, even with a D lens.IOW, regular TTL versus ADI TTLstill has the preflash, and you can only get rid of it going tomanual mode on the flash.

But, perhaps they were misinformed. Here is what I've been told:

Quote:
KM digital cameras use a pre-flash, whether they're a D-lens or not. For film cameras, this is different.

Film: TTL = no pre-flash, ADI = pre-flash
Digital: TTL or ADI = pre-flash

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Old Jul 25, 2005, 4:26 PM   #10
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i will bow to your professional expertise, but, i'm darned if i can see a preflash when using ADI
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