All Forum Comments
Comment by George Lazarette posted on smc FA 50mm f/1.4 at 20/07/2007 - 14:31
Quote:
I'm another who doesn't used protection filters, not even with my most expensive lenses. I've never seen the point in buying an expensive lens then compromising the lens designers art by sticking another bit of glass in front.
In my personal experience, and also based on first-hand accounts I have read, the most common problems encountered with lenses are: I'm another who doesn't used protection filters, not even with my most expensive lenses. I've never seen the point in buying an expensive lens then compromising the lens designers art by sticking another bit of glass in front.
First, fungus, and the chance of this can be reduced by storing lenses in a dry, well-aired, environment.
Second: the coating being rubbed away by excessively enthusiastic cleaning over a long period. It takes a really obsessive person to do this, and to reduce the chance of getting a lens with this problem, my advice is not to buy from people who post to a certain digital camera forum which attracts such weirdos.
Third: being dropped, with consequent damage to the barrel and mechanics of the lens.
Fourth: a long way down, scratches on the front element (other than those caused by cleaning).
Fifth: close to fourth, damage done to the front element caused by a filter smashing when the lens is dropped or knocked. It must be remembered that filters are much more delicate than lens elements, and much more likely to smash. When they do, it's likely that shards of glass will be driven inwards. Lest you doubt me, there are several reports on the PDML of this happening.
There are really three sorts of people. Those who worry about their investment will tend to fit a filter, despite the fact that it affords very little protection. Those who worry about image quality will tend not to fit a filter because it may impair, very slightly, the quality of the image. And finally, those who don't worry, don't bother.
So to sum up, the sensible thing is not to fit a filter to very expensive lenses, where the optical quality is very high, and it would be a waste of all that money to risk reducing the image quality.
Instead, I suggest fitting a filter to very cheap lenses, where optical quality is not such an issue. Nonetheless, one should always fit the best filter one can afford, so if you have spent £20.00 on a second-hand Sigma, you shouldn't spend less than £30.00 on a filter.
But these are only my views, others may disagree.
G
Comment by George Lazarette posted on smc FA 50mm f/1.4 at 03/07/2007 - 10:15
Quote:
However, the zoom I mentioned in my previous post doesn't want to work; the 'top' display is flashing AF, I tried switching it across to manual but the shutter still doesn't want to play ..
Kira
You didn't mention "the zoom", you mentioned two: a 35-80 and an F 70-210.However, the zoom I mentioned in my previous post doesn't want to work; the 'top' display is flashing AF, I tried switching it across to manual but the shutter still doesn't want to play ..
Kira
Both should work, unless they are faulty. The aperture ring should be set to the A position at all times - you change aperture on the body.
G
Comment by George Lazarette posted on Newbie Pentax K100D user at 14/07/2007 - 10:31
Quote:
Adjusted levels and curves.
I do think this looks much better. Thanks for the tips!
Yes, it's now a very nice picture. The range of green tones contrasts nicely with the reddish breast.Adjusted levels and curves.
I do think this looks much better. Thanks for the tips!
He's a rather scruffy little blighter, though.
G
Comment by George Lazarette posted on My first photo post at 02/07/2007 - 17:23
Quote:
Whenever I go out I take the SMCP-DA 12-24mm, SMCP-DA 16-45mm, SMCP-FA 28-105mm, SMCP-F 70-210mm, SMCP-FA 31mm Limited, SMCP-FA 50mm 1:1.4, SMCP-FA 100mm Macro, and Sigma 135-400mm APO as a minimum to cater for 99% of my needs.
You forgot to mention the sherpas.Whenever I go out I take the SMCP-DA 12-24mm, SMCP-DA 16-45mm, SMCP-FA 28-105mm, SMCP-F 70-210mm, SMCP-FA 31mm Limited, SMCP-FA 50mm 1:1.4, SMCP-FA 100mm Macro, and Sigma 135-400mm APO as a minimum to cater for 99% of my needs.
G
Comment by George Lazarette posted on Lenses for Pentax K100D at 02/07/2007 - 13:01
Quote:
(in fact, the only photo equipment failure I've ever had has been a lens, not a body).
If you're like me, you will have had many more lenses than bodies. So it's more likely that one will be no good.(in fact, the only photo equipment failure I've ever had has been a lens, not a body).
I've had one (Pentax) lens go bad - after twenty-odd years - and no bodies. My recent concerns about the K10D seem to have been unfounded.
G
Comment by George Lazarette posted on K10d Body £449 at 08/08/2007 - 09:03
Quote:
Because if I do crop, from the tip of his nose to the tip of his tail, which is what I was after in the first place, I'm getting the same number of inches of squirrel in both situations; they take up the same space on the sensor and on the film, and I enlarge them to the same size. This is the same picture - the same print, anyway.
And if I use the same shutter speed, the visible shake will be the same too.
As Matt says, it's a rule of thumb. All I'm adding is that you need to know how to use it.
If my squirrel was Ok with film with that exposure at 6x4, it still will be with digital - I just chuck away more of the original frame with the film than I do with digital.
But the point is to select an appropriate lens so that you fill the frame. Any discussion about shake presupposes that you are using the whole frame. If you are going to discard a third of the 35mm image, then you are not using the camera to its best advantage.George Lazarette wrote:
When you print the two pictures, provided you don't crop, the squirrel will be considerably smaller in the 35mm print. It will appear to be sharper.
Agreed. I've never disputed this, in any of the ways you've expressed it. If I've appeared to, then I'm sorry.When you print the two pictures, provided you don't crop, the squirrel will be considerably smaller in the 35mm print. It will appear to be sharper.
Quote:
The squirrel may be the same size on the film/sensor, but you are not getting the same picture, so the comparison is invalid.
This is where we differ.The squirrel may be the same size on the film/sensor, but you are not getting the same picture, so the comparison is invalid.
Because if I do crop, from the tip of his nose to the tip of his tail, which is what I was after in the first place, I'm getting the same number of inches of squirrel in both situations; they take up the same space on the sensor and on the film, and I enlarge them to the same size. This is the same picture - the same print, anyway.
And if I use the same shutter speed, the visible shake will be the same too.
As Matt says, it's a rule of thumb. All I'm adding is that you need to know how to use it.
If my squirrel was Ok with film with that exposure at 6x4, it still will be with digital - I just chuck away more of the original frame with the film than I do with digital.
I quite agree that in your scenario your squirrel would be the same size, and equally shakey or unshakey. But because you are prepared to throw away a large part of the 35mm image, your argument is like saying that if you chop the legs off a racehorse it's no faster than a snail. True, but not particularly relevant to racing.
G
Comment by George Lazarette posted on Tokina 500mm mirror lens + use with DL2 at 02/07/2007 - 13:29
Quote:
If some shutter speed with some lens (say 1/400s with a 400mm lens) is enough to render a picture of a distant squirrel enlarged to say, 6x4, shake free on film, surely the same exposure on digital, with the same lens, will be enough to render the same squirrel at the same size on the print also shake free, since the size of the squirrel is the same on either film or sensor, and is enlarged to the same size.
I don't see why I need 1/600s when the image of the squirrel is the same size, and it's being enlarged the same amount.
Granted, it's a different percentage of the frame, but I don't want the whole frame.
The squirrel may be the same size on the film/sensor, but you are not getting the same picture, so the comparison is invalid.George Lazarette wrote:
A picture taken on 35mm film with a 75mm lens will be equivalent to a picture taken on digital with a 50mm lens. But the final 10x8 print from the digicam will have to be enlarged more than the 35mm image. And the enlarging will accentuate the shake.
George, I understand this perfectly, but with respect, you keep saying effectively the same thing, and not addressing my point.A picture taken on 35mm film with a 75mm lens will be equivalent to a picture taken on digital with a 50mm lens. But the final 10x8 print from the digicam will have to be enlarged more than the 35mm image. And the enlarging will accentuate the shake.
If some shutter speed with some lens (say 1/400s with a 400mm lens) is enough to render a picture of a distant squirrel enlarged to say, 6x4, shake free on film, surely the same exposure on digital, with the same lens, will be enough to render the same squirrel at the same size on the print also shake free, since the size of the squirrel is the same on either film or sensor, and is enlarged to the same size.
I don't see why I need 1/600s when the image of the squirrel is the same size, and it's being enlarged the same amount.
Granted, it's a different percentage of the frame, but I don't want the whole frame.
When you print the two pictures, provided you don't crop, the squirrel will be considerably smaller in the 35mm print. It will appear to be sharper.
G
Comment by George Lazarette posted on Tokina 500mm mirror lens + use with DL2 at 02/07/2007 - 12:43
Quote:
I absolutely understand the enlargement issue.
With long focal length lenses (which is when you have to worry more about shake), however, at least in my experience, the intention is often to photograph something a long way away, not to compose for the whole frame.
So if I want to take a picture of a distant animal, for instance (or Dan's tennis ball example), I'll want to choose the longest lens I have, and then enlarge the animal part of the image to a suitable sized print.
In this case, the image of the animal in the camera will be the same size whether it's film or a digital sensor. If I then want the animal blown up to a 12x8 print, it seems to me that the amount of shake will be the same.
I said it was simple because it is. You have unfortunately tried to make it far more complicated than it is. It doesn't mean you're stupid, but it does make it difficult for people who are trying to help you see the wood for the trees that you have planted. In fact, you will be irritated with yourself when you finally see how simple it is!George Lazarette wrote:
It really is very simple. The smaller the recording medium (film or sensor), the more you have to enlarge the image, and when you enlarge the image you enlarge the blur.
I hate it when people say "it really is very simple", since even if you're less paranoid than I am, it's not hard to hear, or at least imagine, the sigh in their voice, and the unstated "you fool" at the end.It really is very simple. The smaller the recording medium (film or sensor), the more you have to enlarge the image, and when you enlarge the image you enlarge the blur.
I absolutely understand the enlargement issue.
With long focal length lenses (which is when you have to worry more about shake), however, at least in my experience, the intention is often to photograph something a long way away, not to compose for the whole frame.
So if I want to take a picture of a distant animal, for instance (or Dan's tennis ball example), I'll want to choose the longest lens I have, and then enlarge the animal part of the image to a suitable sized print.
In this case, the image of the animal in the camera will be the same size whether it's film or a digital sensor. If I then want the animal blown up to a 12x8 print, it seems to me that the amount of shake will be the same.
Look at it this way. If you can see camera shake in a print, but then make a much smaller print of the same image, you will be unable to see the shake. The less you enlarge, the less obvious the shake is, and vice-versa. Obviously, smaller images need to be enlarged more.
A picture taken on 35mm film with a 75mm lens will be equivalent to a picture taken on digital with a 50mm lens. But the final 10x8 print from the digicam will have to be enlarged more than the 35mm image. And the enlarging will accentuate the shake.
There is no more to it than that. Stop coming up with all these different scenarios; you are only confusing yourself.
G
Comment by George Lazarette posted on Tokina 500mm mirror lens + use with DL2 at 02/07/2007 - 10:57
Quote:
However, if you enlarged the ball on the film negative and the ball on the sensor image to the same size, by this argument the visibility of the shake would be the same, which is what I thought.
I think I understand. If this was George's argument as well, then it boils down to the fact that if you make two different enlargements of the same sized image, you'll see anything that's out of focus more easily on the larger enlargement.
In this case, the print from the 200mm on digital has been enlarged more than the one from the 300mm on film. Comparing the shake in these two situations is much harder, since with two lenses, you have two lengths, and two masses, so it's harder to know which one is going to shake more.
It really is very simple. The smaller the recording medium (film or sensor), the more you have to enlarge the image, and when you enlarge the image you enlarge the blur.Daniel Bridge wrote:
And for your supplementary question Chris, the answer is yes, exactly the same distance.
Going back to your first question, you're right in that an object will be the same 'size' on film or digital, but imagine that you took a photo of a tennis ball, using a film body and a K10D, using the same lens, all things being equal.
That ball forms an image on the film and sensor that's, say, 5mm across.
Ok, so far, this is exactly as I had it.And for your supplementary question Chris, the answer is yes, exactly the same distance.
Going back to your first question, you're right in that an object will be the same 'size' on film or digital, but imagine that you took a photo of a tennis ball, using a film body and a K10D, using the same lens, all things being equal.
That ball forms an image on the film and sensor that's, say, 5mm across.
Quote:
We then blow up prints from both to 12" x 8". The film is 36mm along it's longest edge, so to get that to 12" takes about 8.3x enlargement. The digital image is only 24mm along it's longest edge so needs 12.5x enlargement.
The image of the ball is similarly magnified, so is 41.5mm across on the print made from film, and 62.5mm across on the digital one.
Any camera shake is magnified by the same amount, so if it's not quite noticable on the print from film, it might be visible in the digital one.
Yes, absolutely. You've made a bigger enlargement of the ball, by blowing up a smaller angle of view (with digital) to the same size print as the larger angle of view (with film). So any shake will be more visible because it's a bigger enlargement.We then blow up prints from both to 12" x 8". The film is 36mm along it's longest edge, so to get that to 12" takes about 8.3x enlargement. The digital image is only 24mm along it's longest edge so needs 12.5x enlargement.
The image of the ball is similarly magnified, so is 41.5mm across on the print made from film, and 62.5mm across on the digital one.
Any camera shake is magnified by the same amount, so if it's not quite noticable on the print from film, it might be visible in the digital one.
However, if you enlarged the ball on the film negative and the ball on the sensor image to the same size, by this argument the visibility of the shake would be the same, which is what I thought.
I think I understand. If this was George's argument as well, then it boils down to the fact that if you make two different enlargements of the same sized image, you'll see anything that's out of focus more easily on the larger enlargement.
Quote:
Now, if we want the ball to be the same size on the prints, we don't need such a long lens for the digital shot, so we could use a 200mm on digital and a 300mm on film
Sure. If you're aiming for the same sized print, off the whole of the available frame from digital and film respectively, you need to get the same angle of view, so that means different lenses.Now, if we want the ball to be the same size on the prints, we don't need such a long lens for the digital shot, so we could use a 200mm on digital and a 300mm on film
In this case, the print from the 200mm on digital has been enlarged more than the one from the 300mm on film. Comparing the shake in these two situations is much harder, since with two lenses, you have two lengths, and two masses, so it's harder to know which one is going to shake more.
So, on Pentax digital, the old advice to choose a shutter speed that is no slower than a reciprocal of the focal length (300mm lens means 1/300) needs to be amended so that the shutter speed becomes one and a half times the reciprocal - 1/450 for a 300mm lens.
G
Comment by George Lazarette posted on Tokina 500mm mirror lens + use with DL2 at 02/07/2007 - 09:11
............. Well, they had one in stock so it would have been daft not to.
G