infinity settings

[Dan Cook]

I've been reading more about how to take lightning shots with my Rebel XT and one suggestion was to set it in infinity mode. How do you do that? I read on a different forum that there's an L marking or something on the lens that you move the focus ring to and that sets it. But both of my lenses do not have that.

[Dustin Wilcox]

Not sure if its the correct way to go about it or not, but what has worked for me is turning it to AF then Focusing on something in the distance for me it normally ends up being a light from a farm house, after I focus on that I just flip it back over to MF and shoot away.

[John Diel]

Check the lens switch to MF (Manual Focus) and turn the focusing ring to the infinity symbol (looks like a number 8 on it's side). You might have to move it just a tad either way to make sure it's in focus depending on the lens.

Also, as Dan stated, pick something on the horizon, zoom in on it as much as you can (again, depending on the lens) and use your auto focus (AF) to get the focus you want. Switch the lens to Manual Focus (MF) and zoom back to the wider angle you want. Re-Check the focus and make the small adjustments as needed.

John Diel

[Dan Cook]

neither of my lenses has that 8 thing.

[John Diel]

Since I don't have any EFS lenses, I can't say for sure. But if there is one, it's all the way to the right side of the Focus ring. Same ring in which the Meter/Feet scale is on.

All of my leses have this scale and notation.:)

[Dan Cook]

I've got these lenses:

http://www.buydig.com/shop/product.aspx?sku=CN5018II

and the 18-55mm kit lens. As far as I can see they don't have those markings...unless I'm blind. :eek:

[Mike Hollingshead]

I have the same 50mm and just do what Dustin mentioned. It's only going to work if you have it set on one focusing/metering point(read the manual for that). Then just set that dot on any kind of light and it should focus on it fine. Then back off to manual. If that's not an option you can do it with just manual focusing, obviously. You just have to back it slightly off the full spin. Play with it in day light to see how far off that is. It's not much, but I surely wouldn't just spin it all the way to the edge.

[John Diel]

What Mike said....

You sure there isn't a little symbol like this?? http://www.languagemonitor.com/images/infinity_symbol1.jpg

[Dan Cook]

Nope. None that I can see.

[Dick McGowan]

Nope. None that I can see.

The 50 mm doesn't have it I don't think....just put it on manual and turn it counter clockwise all of the way. Then slide it back to the right a hair to get it in focus. I think infinity is determined by the air temperature you are shooting it in, so in a warmer/colder environment, it will be at a different setting.

[Billy Griffin]

I think infinity is determined by the air temperature you are shooting it in, so in a warmer/colder environment, it will be at a different setting.


I'll be darn, I learn something new everyday on this site. It makes sense though - cold, clear air versus warm, hazy conditions. That gives me something to consider when I do the infinity settings on my lenses, yet when looking at the image, some areas appear out of focus. Good tip!

[John Diel]

Want to really learn something about Infinity and Lens refraction? See this site specific to photography:
http://photo.net/photo/optics/lensTutorial

[Dan Cook]

Link doesn't work. :(

[Stan Olson]

http://photo.net/photo/optics/lensTutorial (http://http//photo.net/photo/optics/lensTutorial)

[Dan Cook]

http://www.buydig.com/shop/product.aspx?sku=SG1770EOS

That's gonna be my next lens.

[Billy Griffin]

http://www.dpreview.com/news/0703/07030805sigma200500mm.asp

Here's my new lens! :D Kidding of course. Can you imagine carrying that thing around with you on a photo shoot? I'd need one of those Sherpas from Mt. Everest helping me!

[Gene Moore]

I have the same 50mm and just do what Dustin mentioned. It's only going to work if you have it set on one focusing/metering point(read the manual for that). Then just set that dot on any kind of light and it should focus on it fine. Then back off to manual. If that's not an option you can do it with just manual focusing, obviously. You just have to back it slightly off the full spin. Play with it in day light to see how far off that is. It's not much, but I surely wouldn't just spin it all the way to the edge.
This is a difficult problem with auto focus lenses and I'll agree with Mike on the solution. I highly suggest you don't try to manually focus to infinity, at least with Canon EF lenses. I'm talking about not only night with lightning, but in the daylight also. I have tried manual focus to infinity with all my lenses and two different Canon cameras. I almost never get "true" infinity in manual mode, that is, a sharp horizon. I have set up my cameras on tripods and gone through many tests and can never get consistency. Unlike old camera systems where the lens decided infinity, EF lenses do focus within the camera. There are numerous instances of Canon cameras having what's called front focus or back-focus problems where the camera's focus in not dead on. This can be fixed by Canon if the camera and lens are sent in for adjustment. What this means is if you want a true infinity you need to get the camera to make that decision. As suggested for lightning try to focus on the horizon, some object or light. Move the camera sensor (only one as recommended previously) across the horizon in an up and down motion until the red light blinks and the camera beeps (if sound it turned on). Then carefully set the lens to manual, but that only works if you never touch the focus ring, any small bump and you'll be slightly off infinity and never know it...until you look at your blurred image at home. Another thing you can do is take a shot then zoom the image into the horizon or distant light to see if it's sharp: that is, if your camera model has the ability to zoom the image after its been shot. What I would love to see is Canon to adopt an "infinity lock" solution like we have on many Sony video cameras, that would solve the problem.

Gene Moore

[Dick McGowan]

This is a difficult problem with auto focus lenses and I'll agree with Mike on the solution. I highly suggest you don't try to manually focus to infinity, at least with Canon EF lenses. I'm talking about not only night with lightning, but in the daylight also. I have tried manual focus to infinity with all my lenses and two different Canon cameras. I almost never get "true" infinity in manual mode, that is, a sharp horizon. I have set up my cameras on tripods and gone through many tests and can never get consistency. Unlike old camera systems where the lens decided infinity, EF lenses do focus within the camera. There are numerous instances of Canon cameras having what's called front focus or back-focus problems where the camera's focus in not dead on. This can be fixed by Canon if the camera and lens are sent in for adjustment. What this means is if you want a true infinity you need to get the camera to make that decision. As suggested for lightning try to focus on the horizon, some object or light. Move the camera sensor (only one as recommended previously) across the horizon in an up and down motion until the red light blinks and the camera beeps (if sound it turned on). Then carefully set the lens to manual, but that only works if you never touch the focus ring, any small bump and you'll be slightly off infinity and never know it...until you look at your blurred image at home. Another thing you can do is take a shot then zoom the image into the horizon or distant light to see if it's sharp: that is, if your camera model has the ability to zoom the image after its been shot. What I would love to see is Canon to adopt an "infinity lock" solution like we have on many Sony video cameras, that would solve the problem.

Gene Moore

I've noticed on my Sigma 17-70, that it won't find infiniti that well for manual focus in the daytime or nighttime. It will even have hard times with auto and I can never get it perfect. On my Sigma 10-20, it has no problems with either, so I'm wondering if it's the lens and not the camera. I'm getting pretty tired of the 17-70 for not only this, but the autofocus isn't as good as the 10-20 (USM vs HSM). It's like night and day, and I think the 10-20 has a better all around picture. I'm pretty satisfied with the 10-20, 4 times out of 5 while chasing if I can get really close, but the 17-70 can come in handy too because of the range. If only they would build that range with the other motor and dedicate a full time manual focus like the 10-20, that would be their best lens yet.

[Mike Hollingshead]

The thing with the ultra wides is that infinity starts around like 5 feet away or something. So the depth of field will be huge from the start. On my 10-22 I've found using auto focus on the horizon leaves the marker on the lens landing in any number of spots around that infinity line. It's just a huge spacing it can land in while doing that. I thought that would be no good, since I was autofocusing on the same spot way out there, but I've seen it does not matter at all. They all look just as sharp. So with these ultra wides it's much easier to find infinity for focus.

That canon 50mm F1.8 really sort of sucks on focusing in the dark, and it doesn't help the focus ring is out on the end of the lens and very easily bumped. The other canon lenses of mine I've not had much issue with bumping things out of focus.

Dan if you are getting that for chasing, I'd consider the canon 10-22 or the sigma 10-20 instead. I don't see my 17-40 being on for chasing as much anymore now that I have the 10-22.

[Dan Cook]

Yeah it would be used for chasing; I'm also thinking of the 17-70 one to replace the default Kit lens for every day shooting.

[Brett Roberts]

I've noticed on my Sigma 17-70, that it won't find infiniti that well for manual focus in the daytime or nighttime. It will even have hard times with auto and I can never get it perfect. On my Sigma 10-20, it has no problems with either, so I'm wondering if it's the lens and not the camera. I'm getting pretty tired of the 17-70 for not only this, but the autofocus isn't as good as the 10-20 (USM vs HSM). It's like night and day, and I think the 10-20 has a better all around picture. I'm pretty satisfied with the 10-20, 4 times out of 5 while chasing if I can get really close, but the 17-70 can come in handy too because of the range. If only they would build that range with the other motor and dedicate a full time manual focus like the 10-20, that would be their best lens yet.
I also have mixed feelings about my Sigma 17-70. The autofocus is rather disappointing, and not a whole lot better than the kit lens in terms of speed or accuracy. I think mine backfocuses slightly, and probably needs to be sent in for calibration this winter (when I rarely do any shooting). Sharpness is an improvement over the kit, but on the other hand, sometimes I feel like the color saturation is not up to par with images I see posted online from the 17-40L and other more expensive lenses (and yes, I realize post-processing plays a major role, but the sky and particularly foliage colors out-of-camera on the Sigma just seem a bit off and dull).

[Dick McGowan]

I also have mixed feelings about my Sigma 17-70. The autofocus is rather disappointing, and not a whole lot better than the kit lens in terms of speed or accuracy. I think mine backfocuses slightly, and probably needs to be sent in for calibration this winter (when I rarely do any shooting). Sharpness is an improvement over the kit, but on the other hand, sometimes I feel like the color saturation is not up to par with images I see posted online from the 17-40L and other more expensive lenses (and yes, I realize post-processing plays a major role, but the sky and particularly foliage colors out-of-camera on the Sigma just seem a bit off and dull).

Yeah, the color to me, is off, almost too much saturation on mine (mine doesn't look dull, just weird). I briefly owned the 17-40 and my copy was blurred on the left side, so I sent it back not wanting to deal with the calibration for it, knowing it could come back the same way. The focus on it was as quick as the 10-20 and had the full time manual focus too, but my copy had problems.

The Sigma 17-70 is definitely sharp, but not as much as the Sigma 10-20. I highly recommend this lens to anyone that likes to take structure shots. It really opens a new perspective on a photo of a storm taken from up close. The price isn't too bad, and you get a nice lens hood for it also. Sometimes 10 mm isn't enough...I shot this one (http://i6.photobucket.com/albums/y230/DickTwister/colyier4web.jpg) at 10 on 5/22 and it wasn't nearly enough.

I'd like to get something like Canon's 24-70L or 24-105L, but those, like the 17-40L were made for full frame sensors, not 1.6 crops like the Rebel XT that I own. I'm sure it just depends on what copy you get, because I've heard both good and bad stories. Plus, they run well over a grand (or used to I haven't checked in awhile).

[Dan Cook]

So Mike would you reccomend getting the Canon 17-40L instead of the Sigma 17-70 as a replacement for the Kit lens?

[Dustin Wilcox]

I have quickly learned to hate the lens Market. About the time I think I have settled on a lens to purchase, I read or hear a bad review on it, not to mention once one finds one they like, there is always a slightly better one for only $100 more so I begin to consider it, only to then again consider the next step up for only another $100 more; it seems that process continues until your looking at several thousand dollar lenses. Already purchasing a new HD camcorder and SLR camera this year combined with quickly approaching college season my budget lacks the ability to afford the lenses I really want. I have quickly realized when one brings $500 to the camera shop they are not going to walk away with much glass, at least quality glass and I really hate spending that kind of money still knowing what I have is crap compared to what else it out there. Regardless of my complaints I am in need of two lenses a telephoto for wildlife needed by this fall, and a wide angle for chasing which can wait till next year. After shopping around the cheap lens market I have decided since I will use it more, I might as well stick a little more in the wide angle lens. While they are cheap telephoto lenses and not the best quality I think I am going to pick up either a Canon EF 75-300mm f/4.0-5.6 III USM or the Sigma 70-300mm f/4-5.6 SPO DC Macro currently leaning towards the sigma, anyone have any experience with either? While not as urgent as the zoom lens I want to pick up either the Sigma 10-20mm or the Canon by next Spring hmm... sounds like a good Christmas gift!!

Anyone have any experience with this lens? http://www.bhphotovideo.com/c/product/389308-REG/Sigma_795101_28_300mm_f_3_5_6_3_DG_IF.html
That’s quite a range at a pretty low price, f/3.5 and 300mm in the title doesn't sound bad for the money, that is if you want to overlook the fact that after f/3.5 it reads-6.3; I would consider this over the 70-300mm I mentioned above but I'm sure it becomes quite the ISO hog one you get much over 200mm.

[scott r currens]

So Mike would you reccomend getting the Canon 17-40L instead of the Sigma 17-70 as a replacement for the Kit lens?

On Gene Rhoden's radio show Hank Baker highly recommended the Tamron 17-50mm F/2.8 Lens. He said something to the effect that its performance is the equivalent of a $1500 Canon lens. I wasn't in love with my Canon 17-40L lens so I sold it and got a new Tamron 17-50 lens.

My first impressions of the Tamron were not good. It is a smaller lens that looks and feels cheaper than the Canon lens I sold. I thought I had made a mistake until I started taking pictures with it. The auto focus system works much better with this lens and the images I am getting from it are crisp and clear, Not soft and out of focus like I was getting half the time with the Canon lens. I haven't taken a ton of pictures with the Tamron yet but so far I like it a lot.

The best thing about the Tamron lens is the price, it was only $379 on Ebay.

[Dan Cook]

On Gene Rhoden's radio show Hank Baker highly recommended the Tamron 17-50mm F/2.8 Lens. He said something to the effect that its performance is the equivalent of a $1500 Canon lens. I wasn't in love with my Canon 17-40L lens so I sold it and got a new Tamron 17-50 lens.

My first impressions of the Tamron were not good. It is a smaller lens that looks and feels cheaper than the Canon lens I sold. I thought I had made a mistake until I started taking pictures with it. The auto focus system works much better with this lens and the images I am getting from it are crisp and clear, Not soft and out of focus like I was getting half the time with the Canon lens. I haven't taken a ton of pictures with the Tamron yet but so far I like it a lot.

The best thing about the Tamron lens is the price, it was only $379 on Ebay.

Scott can you post a couple images you took with this lens? I want to see what the end result looks like. :)

[Gene Moore]

On Gene Rhoden's radio show Hank Baker highly recommended the Tamron 17-50mm F/2.8 Lens. He said something to the effect that its performance is the equivalent of a $1500 Canon lens. I wasn't in love with my Canon 17-40L lens so I sold it and got a new Tamron 17-50 lens.

My first impressions of the Tamron were not good. It is a smaller lens that looks and feels cheaper than the Canon lens I sold. I thought I had made a mistake until I started taking pictures with it. The auto focus system works much better with this lens and the images I am getting from it are crisp and clear, Not soft and out of focus like I was getting half the time with the Canon lens. I haven't taken a ton of pictures with the Tamron yet but so far I like it a lot. The best thing about the Tamron lens is the price, it was only $379 on Ebay.

There has been much written about the 17-50 Tamron lens and sharpness, mostly favorable. Here is a good source comparing it to the lens I want, (but can't afford right now) the Canon 17 -55 IS:

http://www.wlcastleman.com/equip/reviews/17-85compare/index.htm

I think most photographers tend to look for sharpness first in a lens often dismissing other important factors that may affect the image. Note that Castleman does go into the autofocus issue. In my opinion nothing ruins a picture faster than bad focus with camera movement second and sharpness/ contrast third. With film cameras the focus was very seldom an issue, but now with autofocus, especially in poor light it's become a very important consideration. If this lens purchase is for storm chasing a large percentage of images may be taken in less than favorable lighting conditions, thus inviting infinity problems. Here's a number to think about. I lost five tornadoes to bad (infinity) focus problems in 2004-2005. Most of these problems came from a Tamron lens, some from Canon, so I did some lens trading and improved my technique in the field. Check out the following statement from Castleman that deals directly with the equipment side of the problem, I think it's most interesting.

Autofocus Accuracy Under Variable Ambient Light
Lenses were tested at 50mm under tungsten modeling light at 1 meter working distance. Each lens was focused at infinity and then refocused on the right mannequin eye and the shutter released. The test was repeated 20 times for each lens, and the percentage of in focus images were recorded. The tests were run under good modeling lighting (ISO 800, 1/100th sec @ f/2.8) and low light conditions (ISO 800, 1/40th sec @ f/2.8). When autofocus problems were identified under low light conditions. The tests were repeated.

Canon lenses showed the best performance with an EOS 400D Digital Rebel XTi under low light.
The Tamron lens had the worst performance under low light (and very noisy autofocus motor).Looking at the table beside this paragraph, Tamron scored only an 82-85 percent focus success in low light. I love the resolution numbers for the Tamron, but this focus issue alone (combined with my previous problems) will keep me from purchasing it.

Gene Moore

[Mike Hollingshead]

So Mike would you reccomend getting the Canon 17-40L instead of the Sigma 17-70 as a replacement for the Kit lens?

I know nothing about the Sigma and have had no problems with my 17-40L.

[Dick McGowan]

While they are cheap telephoto lenses and not the best quality I think I am going to pick up either a Canon EF 75-300mm f/4.0-5.6 III USM or the Sigma 70-300mm f/4-5.6 SPO DC Macro currently leaning towards the sigma, anyone have any experience with either? While not as urgent as the zoom lens I want to pick up either the Sigma 10-20mm or the Canon by next Spring hmm... sounds like a good Christmas gift!!



I own the Sigma 70-300 f/4-5.6 non APO. Jayson Prentice on this board has the APO version which is better in terms of quality (and slightly more in price), so you might ask him. I picked mine up for $130 after shipping, and it's okay. Sharpness on it is decent from 70-200, but from 200-300 it's not quite as sharp, and the colors aren't near as good either. But I just bought it to "practice" with it, before I bought a decent telephoto. The autofocus sounds like a tank and is pretty hard to do on something moving at 300, handheld, not to mention only 5.6 at 300 mm which is nearly impossible in low light.

I have a few examples of the Sigma 70-300 f/4-5.6 non APO here (http://stackedplates.blogspot.com/2007/01/sledding.html) and here (http://stackedplates.blogspot.com/2007/01/cardinals.html) I don't really use it that much. If you are wanting a really good telephoto for the price, pick up Canon's 70-200 f/4L non IS. The image stabilizer is more money.

So Mike would you reccomend getting the Canon 17-40L instead of the Sigma 17-70 as a replacement for the Kit lens?

Dan,

Here is a comparison between the kit lens, the 17-40L f/4.0, and the Sigma 17-70 f/2.8-4.5. As Scott and Gene mentioned about the Tamron being 2.8, so is the Sigma at 17 mm and nearly the same price (I paid 350 on BH with the discount code). A guy ran a test on them all and posted on my blog, and is here (http://stackedplates.blogspot.com/2007/02/canon-17-40-f4l-vs-sigma-17-70-2845.html)

[Dick McGowan]

I guess I should also mention that the Sigma 17-70 f/2.8-4.5 was designed for 1.6 crops (Rebel, Rebel XT, etc) and I don't believe the Tamron was. (Not saying it won't do a good job) The Sigma is also 70 mm vs. Tamron's 50 mm and the Sigma also has macro capabilities. I'd like to see a comparison between these two in terms of quality because, like Brett, I'm having issues with the 17-70.

[Brandon Goforth]

Another thing to consider is that the 17-40L is weather sealed, and that would seem to not only protect from moisture, but from dust as well. I too am close to upgrading to a Rebel XTi and 17-40L lens, and I've been debating between the 17-40L, Sigma 17-70, and Tamron 17-50. It seems like there are good and bad copies floating around from all 3, but if you can get a good copy of the 17-40L, it seems that overall it would be the better choice, given the images I've seen, the build quality, and the fact that it's weather sealed. By the way, you guys that own an XTi, have you had any problems with under-exposure? Seems like there have been some complaints about this.

[Brett Roberts]

I have quickly learned to hate the lens Market. About the time I think I have settled on a lens to purchase, I read or hear a bad review on it, not to mention once one finds one they like, there is always a slightly better one for only $100 more so I begin to consider it, only to then again consider the next step up for only another $100 more; it seems that process continues until your looking at several thousand dollar lenses. Already purchasing a new HD camcorder and SLR camera this year combined with quickly approaching college season my budget lacks the ability to afford the lenses I really want. I have quickly realized when one brings $500 to the camera shop they are not going to walk away with much glass, at least quality glass and I really hate spending that kind of money still knowing what I have is crap compared to what else it out there. Regardless of my complaints I am in need of two lenses a telephoto for wildlife needed by this fall, and a wide angle for chasing which can wait till next year. After shopping around the cheap lens market I have decided since I will use it more, I might as well stick a little more in the wide angle lens. While they are cheap telephoto lenses and not the best quality I think I am going to pick up either a Canon EF 75-300mm f/4.0-5.6 III USM or the Sigma 70-300mm f/4-5.6 SPO DC Macro currently leaning towards the sigma, anyone have any experience with either? While not as urgent as the zoom lens I want to pick up either the Sigma 10-20mm or the Canon by next Spring hmm... sounds like a good Christmas gift!!
Completely agree with you on the love/hate relationship with DSLR photography. I should've waited to get into this hobby until after college!

I've had the Sigma 70-300mm APO DG for a couple years now. For the price, it probably can't be beat. If you have the budget to get something better like the 70-200 f/4L or even EF 70-300 IS, I'd recommend going that route instead. The Sigma is capable of producing good images in the 70-200mm range stopped down some, but the autofocus is downright painful in its slow speed and loudness. The "macro" function is interesting and has yielded great results for me on a few occasions, but, like the lens itself, is cumbersome to use for various reasons. Finally, and most importantly to me, it seems to have somewhat poor contrast outdoors, even with the hood on. As I'm sure you know, you generally get what you pay for with lenses, and at < $200 for the Sigma, you can't expect a whole lot.

[Gene Moore]

By the way, you guys that own an XTi, have you had any problems with under-exposure? Seems like there have been some complaints about this.

As a matter of practice I now run my XTi at + 1/3 stop overexposure. Sooo, sounds to me there is some truth to the complaint. That said, it's not so clear cut. The XTi has three metering choices, center weight average, evaluative metering and partial metering. The last one, partial metering tends to be the most selective to the center of the frame and yields the darkest exposure of the three choices. Also, it's most often my selection for chasing because the center weighted average often gives me over exposed sky and perfect ground, generally that's not what I want.

Gene

[Mike Hollingshead]

One complaint I could make about the 17-40L is that it seems that it doesn't have the greatest contrast in the world. My canon 10-22 EF-S seems to have much better contrast. The 10-22 is also sharper.

[Gene Moore]

One complaint I could make about the 17-40L is that it seems that it doesn't have the greatest contrast in the world. My canon 10-22 EF-S seems to have much better contrast. The 10-22 is also sharper.
Mike, I just recently got my new EF-s 10-22 from B&H. Like you stated, the contrast (color saturation) is drastic, wow. That said, I'm not happy with the sharpness. The main problem is at 10mm....where I need it the most. It's quite sharp from the center to the left side of the frame, but soft to almost fuzzy on the right side. I believe that is attribuited to decentering of an element, at least that's what I've read. Certainly something I can't fix with a screwdriver and pliers. Sooo, ugh...do I keep it and send it to Canon, or back to B&H and maybe get something worsehttp://stormtrack.org/forum/images/icons/icon13.gif. I've heard stories both ways, Canon fixed one of my lenses, but others complain they come back the same.

I hear great things about the Sigma super wide angle, but there is also a big ruturn percentage on those too. Maybe these wide angle zooms are difficult to assemble correctly? I borrowed my chase partner's 10-22 EF-s this last spring and it was spectacular all across the frame.

Gene Moore

[Mike Hollingshead]

I'd certainly send it back to BH for a trade. I did that with my 100-400L. If you happen to get another bad copy you can then send that to Canon. I'd just trade it in first. My 10-22 is the sharpest lens I own, and all over the image...even at 10mm.

[Cris Schroeder]

I initially had issues with my XTi underexposing images. I generally shoot in evaluative metering mode and the issue has gotten better.

Look at the histograms of your underexposed images. I've found that most of the underexposed shots from the XTi were shot in high-contrast situations. The camera does a great job of squeezing the shadows and highlights into the image. However, if you have some bright highlights (like bright cloud) it will underexpose to keep from blowing them out. The shadow data is there but you need to pull it out using a RAW converter.

I shot a couple of hundred frames at Arches NP, Mesa Verde NP, and the San Juan Mountains a couple of weeks ago. The Mesa Verde shots were the toughest as the mesas and cliff dwellings were in shadow and there were building thunderstorms in the area with bright sunlight. My straight JPEG conversions of the RAW files looked horrible, with the mesas grossly underexposed. I converted some of the better images twice, once for the sky and once for the mesa. Then I combined the two in Photoshop and used contrast masks to blend them together. The results were really good, considering my crappy Photoshop skills. Just for fun I ran the RAW converter on a couple of images I shot using about 2 stops of overexposure. I was able to reduce the exposure in the converter and bring out a nice blue sky/white cloud image where the JPEG only shows a white sky.

To sum up a long story, the XTi will underexpose but it does it to squeeze as much of the contrast range as possible into the image. If you shoot in RAW mode, you can do a double-RAW conversion and recover both the shadow and highlight info. Unfortunately if you shoot in JPEG mode they just look dark.

I’ll try to post a few images tonight if anyone is interested.

[Gene Moore]

Manual focusing that is.....

This also relates to other threads where night focusing is an issue. Some of the recommendations include going to manual focus, but I stated I could seldom get an accurate focus with some lenses. Now I believe I know the reason why and I'll put it to those interested in this subject. I have in hand a copy of the new 2007 Canon EOS system book that lists all the available products and lenses. In the lens section there is a breakout of particular lens features like circular aperture, inner and rear focusing, AF stop feature and so on....there are many. Of special interest is a feature called "Full-Time Manual Focusing" or FT-M as listed under each lens. Now, here is the kicker; some of my lenses and some I've used belonging to chase partners do correctly manual focus, some do not. Looking at the list the ones I could not use to get a good manual infinity focus did not have the FT-M feature. Example, my EF 50mm f1.8 lens will not manually focus well nor would my kit lens EF 18-55 f 3.5-5.6 (that I no longer have). Neither had the FT-M feature, but my EF 85 f 1.8 USM will and it does have FT-M. I could list more lenses but you get the idea. Why is this so?? Canon states "these lenses can manually tweak focus without switching out of AF mode." That is, within the lens I think there is a better coupling design with the autofocus system. Anyway, it's my opinion when buying a Canon lens that may be used to manual focus this feature should be included. All the L lenses have this feature and most of the high end lenses with IS also include this feature. Hope this helps those of us that stumble around in the night with tripods.http://stormtrack.org/forum/images/icons/icon10.gif

Gene Moore