6d w/ 105mm how far can I "zoom" in for pseudo 300mm shots?

[Brad]

I've just ordered my first dslr, a 6d with the 24-105 L lens. I've had digital point and shoots before but my last SLR was a film camera so I'm unsure of the IQ of a nice dslr.

I generally use a 300mm lens a lot, but since I just dropped almost $2800 dollars on this new setup, I really don't want to spend another grand (at least) on a longer L lens at this time. Thing is, I'm going on a nice vacation in a couple of weeks and I know that I'll be missing a longer lens.

So I thought that maybe if I just shoot with the 105 focused to "infinity" and then crop and zoom in on the finished image, I could have the effect of a longer lens without actually having the longer lens. Will that actually work? Will the image quality be good enough for that to work? Will the images be sharp and focused with this technique? I know there are a lot of variables such as available light, ISO, etc. I don't plan to blow any of these photos up very large--most of them will be snapshots on the computer but if I take some really exceptional ones they could become wall art.

Or is this a dumb idea and I should buy a longer lens?

Which leads to part 2:

If I should buy a longer lens, having never show with an L lens before and hearing that they're awesome, would I be really disappointed if I got a non-L longer lens. Would I see a ton of difference in IQ, given that nearly all will be seen just on the computer and maybe only a few blown up larger?

I also thought about maybe getting an extender as a less expensive option but they don't list this lens as being compatible.

I know this is a bit long winded but thanks for any help you can offer!

[cicopo]

Those don't look right but with all the variables of being new to RAW plus only being able to process in DPP could you please try large fine jpg & use the base setting for a few & then increase the sharpenning setting 1 or 2 positions to see what you get. If they don't improve I'd recommend doing a micro adjust on the lens & try again after that.

If you're limited to indoors see if you can get a decent shutter speed by increasing the ISO to 3200 for the test.

[cicopo]

One more thing to suspect. DID you buy a UV lens filter? If so take it off & re test. Lots & lots of complaints re filters causing softness. .

[Brad]

I have a uv filter but it wasn't on the lens on those shots.

I've been shooting everything in raw and jpeg. Here are the same shots in jpeg. The christmas, truck, and tree ones are large fine jpeg (20mb), the wall is medium fine (8.9mb).

What do you think? They don't look that sharp to me even in jpeg. Actually the truck one looks pretty good as it did in raw. Regarding lens microadjustments...the 6d is supposed to read the lens and make adjustments to the image based on the lens. Maybe that's just to take out the general design imperfections of each lens and doesn't do what you're suggesting. I'm not sure.

I should be getting the 70-300 delivered tomorrow and will take some shots outside if it's not raining. That might indicate if it's an issue with this 24-105 lens or the camera itself.

Thanks again for your help!

[Brad]

Wasn't sure what you meant here "If you're limited to indoors see if you can get a decent shutter speed by increasing the ISO to 3200 for the test."

You mean to increase the ISO to get faster shutter speed shot to eliminate the possibility of camera shake? That's a possibility of course, but as I mentioned the christmas shot was taken on a tripod with 2 second delay to eliminate that possibility.

Here's a 100% crop of a waterfall I took the other day. It was an overcast day--jpeg medium fine, f4, 1/2500, ISO 6400. Maybe this is the type of shot you wanted to see?

I'm starting to wonder if it might also be that the AF can't focus well on less well lit shots? Maybe those shots are just slightly out of focus even though the camera thought it was locked on. I'm thinking that since the shot of that truck in the sun seems to be the best quality of all--vastly different than over 100 other shots I took under cloudy skies, in the shade, or indoors in the evening. Just a thought.

[jfo]

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@Brad wrote:

tree bark - mraw (11mb), 1/60, f4, 1250 ISO, full zoom on 24-105 L, 100% blowup

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Probably blurry due to handheld shake.  The "1/(focal length)" rule might be helpful: http://my3boybarians.com/2011/10/1-focal-length-shutter-speeds-and-lens-choice-31-days-of-photo-tips...

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@Brad wrote:

christmas - full raw (24mb), 1/30, f4, 400 ISO, full wide on 24-105 L, 100% blowup, on tripod and 2 second shutter delay to eliminate shake

....

 It seems to me that nothing is very sharp unless there's a lot of light, more specifically sunlight, because in the christmas shot it was fairly bright in the house even though it was evening. I'd say there was a good 800-1000 watts of lights on in the room.

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Indoors needs a lot of light.  I've never shot film, so can't say whether this is different than what you're used to, but indoors at f/4 (I also use a 24-105mm) needs a lot higher ISO or faster lenses.  Household light is pretty dark for a DSLR; stage lighting or adding flash are the two situations where I get proper exposure.

What is the historgram saying for these shots? http://www.learn.usa.canon.com/resources/articles/2012/understanding_histograms.shtml

[cicopo]

The leaves in the waterfall shot look good, so there is hope. Yes I wanted you to jack the ISO up for faster shutter speeds. Need to eliminate any user issues as well as things like a UV filter before pointing a finger. You may want to read up on what others are saying here plus check their samples.

http://photography-on-the.net/forum/showthread.php?t=1252637

You may also want to try out DOFMaster just to see how shallow the DOF is in the shots your comparing. If you're shooting wide open or near wide open the DOF can be very shallow when the camera to subject distance is close.

http://dofmaster.com/dofjs.html

[Brad]

Thanks for reminding me of the 1/focal length rule. I'd totally forgotten about that. I agree that some of the issues with those shots could be hand shake.

With film, ISO 400 film was about the highest you could go before you got a lot of noise so I had been keeping the ISO setings lower on this camera. I realize that you can go a lot higher with digital so I reset the auto high setting to 25600 so I could get some faster shutter speeds.

Results are below. They're still a bit mixed in my opinion. I shot them all above the 1/focal length  rule and some 2x or 3x or more above that, so in theory that would eliminate the camera shake issue.

I went outside and shot 100+ photos about an hour before sunset. The ones in sunlight seemed bettter if there was a decent amount of contrast, but even in good light, if there was not much contrast (e.g. tree bark, green leaves, etc.) then the results were still not sharp and clear.

BTW I got the 70-300mm f/4-5.6 IS USM today so some of the shots below are with it. The rest are with the 24-105 f4 L. All are large fine jpegs straight from the camera, blown up to 100%.

santa1 Indoors daylight, no interior lights on, 24mm focal length, 1/30, ISO 1000

santa2 Indoors daylight, with interior lights on, 105mm focal length, 1/125, ISO 6400

santa3 Indoors daylight, with interior lights on, 300mm focal length, 1/320, ISO 10000

santa4 Indoors daylight, with interior lights on, 300mm focal length, 1/640, ISO 20000

wall1 outdoors, 105mm focal length, 1/500, ISO 100

wall2 outdoors, 270mm focal length, 1/500, ISO 100

treebark1 outdoors, 70mm focal length, 1/125, ISO 25600

street1 outdoors, 24mm focal length, 1/80, ISO 100

[Moderator removed image due to containing private/personal information]

treebark2 outdoors, 300mm focal length, 1/320, ISO 25600

license1 outdoors, 300mm focal length, 1/320, ISO 25600

leaves1 outdoors, 70mm focal length, 1/320, ISO 25600

leaves2 outdoors, 300mm focal length, 1/320, ISO 500

Most of them still don't seem that sharp to me. What do you guys think?
I checked out the links you posted (thanks) and most people are raving about how good the low light performance is on the 6d but I'm just not seeing it.

Here's a link to where someone compares a few different cameras one of them being the 6d. My images are not as sharp as them as far as I can tell.
http://www.etherpilot.com/photo/test/misc/6d_5d3_d600_colfix.jpg