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10-24-2010, 10:27 AM   #16
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Thats guys for all the info and recommendations! I love forums

10-24-2010, 10:34 AM   #17
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QuoteOriginally posted by Deimos Quote
I was trying to figure out is there a focal length "standard" used for lenses that is always the same (for example 100mm is 100mm) regardless whether a lens is made specifically for FF or for APS-C, understanding that the "equivalent" field of view will be different but the focal length rating is the same on the lenses no?
That's correct, 100mm is always 100mm, regardless of the image circle projected or sensor/film size. But field of view in the resulting photograph changes depending on the sensor size. That whole "Xmm equivalent" lingo is just confusing, especially for those who never used film camera with interchangeable lenses. The industry should have switched to angular field of view a long, long time ago (or perhaps they did, but somewhere in a galaxy far, far away).
10-24-2010, 11:14 AM   #18
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QuoteOriginally posted by Deimos Quote
Yeah that I understand. I was trying to figure out is there a focal length "standard" used for lenses that is always the same (for example 100mm is 100mm) regardless whether a lens is made specifically for FF or for APS-C, understanding that the "equivalent" field of view will be different but the focal length rating is the same on the lenses no?

Clear as mud?
Focal length is an optical characteristic of the lens and it doesn't change from camera to camera. People say things like 75mm FF equivalent when talking about a 50mm on an APS camera (with 1.5 crop factor), but that's just because they want to describe the FOV and they assume familiarity with what FOV a focal length produces on 135 cameras. If you would be shooting MF, 50mm would be a wide angle. If you never shot anything else, it's a meaningless comparison and you just need to use lenses on your system to figure out the correspondence and your preferences for certain focal lengths.

So the simple rule is - if someone gives you a focal length, that's the focal length; if they mention some equivalence, they're trying to describe the FOV with respect to some system that they are familiar with and with which they expect you to be familiar too.

The only thing that you need to know is that the shorter the focal length, the wider the perspective, but how wide it is exactly depends on the recording medium.
10-24-2010, 01:13 PM   #19
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Great, that makes sense.

10-25-2010, 04:43 AM   #20
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Here's my favorite example: Cut out a picture from a magazine. Draw a 60x45mm rectangle on it. That's ~the size of a 645 frame. Now draw a 36x24mm rectangle inside that. It's the size of a 135 film frame. Now draw a 24x18mm rectangle inside that. It's ~the size of an APS-C frame. Notice: THE PICTURE HASN'T CHANGED! But smaller frames see less of it. Depth-of-field (DOF), focal point, perspective, all that optical stuff, remains the same. If you MOVE to accommodate the different frame sizes, THEN perspective and DOF change. But from a fixed position, the optical qualities remain the same.

Back to the original question: For a cheap good telephoto/macro, get a decent manual 135mm lens and some tubes. Or bellows and tubes, and enlarger lenses in the 100-150mm range. Or maybe you'll get lucky on eBay -- an M100/4 macro lens sold for US$110 a few hours ago.
10-25-2010, 06:40 AM   #21
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I ended up grabbing a new Tamron 90 DI. Got a great deal ~$380

everything seemed to indicate it was a good choice and the price was right. I considered the cosina et al also one of ray-something 150 macro attachments. Thanks for the help

@riorico yeah I love that image you find online with all the sensor sizes pasted onto it, makes great sense like that. my confusion stemmed from all of this "equivalent focal length" talk, I know some compacts even print the equivalents on their lenses... but I understand now
10-25-2010, 08:18 AM   #22
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QuoteOriginally posted by Deimos Quote
I ended up grabbing a new Tamron 90 DI. Got a great deal ~$380

everything seemed to indicate it was a good choice and the price was right. I considered the cosina et al also one of ray-something 150 macro attachments. Thanks for the help

@riorico yeah I love that image you find online with all the sensor sizes pasted onto it, makes great sense like that. my confusion stemmed from all of this "equivalent focal length" talk, I know some compacts even print the equivalents on their lenses... but I understand now
The Tamron seems like a good choice. If bying new, I'd probably go for that too based on the reviews and price. I'm currently monitoring Ebay to get an idea of second hand prices for Tamron 90, Pentax 100, and Sigma 105 (maybe Sigma 180 too, if they eventually turn up). The Cosina 100 (Promaster) is very nice IQ-wise and I don't mind the plasticy construction as MF feel is pretty good, so I'm in no hurry with this.

With compacts the focal length equivalents to 35mm (FF or APS-C) might actually make more sense as the much smaller sensor is also much closer to the lens. These could, in principle, offer the equivalent of some 35mm (FF & APS-C) focal range with the same perspective, just not FOV. The physical focal lengths would still be different (smaller, by the factor given by sensor dimensions), though.
10-26-2010, 01:04 AM   #23
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QuoteOriginally posted by Deimos Quote
@riorico yeah I love that image you find online with all the sensor sizes pasted onto it, makes great sense like that. my confusion stemmed from all of this "equivalent focal length" talk, I know some compacts even print the equivalents on their lenses... but I understand now
It's those 'equivalences' that drive me into rant mode. I have a very nice old 5mpx P&S, a Sony DSC-V1 with 4x Zeiss optics, a superb solid little package. I'm on my third copy (I wore out the first two). The lens says, 34-134mm equivalent. Then the fine print: 7-28mm.

Well, the depth of field of a lens at 134mm is NOTHING like the DOF @ 28mm. P&S users get very thick DOF at all focal lengths. So when they acquire a dSLR and put on a mid-long zoom, they whine that the pictures aren't sharp. Of course not! That 'equivalent' lie gave them unrealistic expectations. And then the newbie forums are filled with "I wanna upgrade the kit lens" which of course makes lensmakers very happy. So I think it's a conspiracy.

10-26-2010, 08:47 AM   #24
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QuoteOriginally posted by RioRico Quote
And then the newbie forums are filled with "I wanna upgrade the kit lens" which of course makes lensmakers very happy. So I think it's a conspiracy.
except that the kitlens are not really that better nor as good as as that of other lenses that are considered better.
10-26-2010, 09:04 AM   #25
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QuoteOriginally posted by Pentaxor Quote
except that the kitlens are not really that better nor as good as as that of other lenses that are considered better.
And then we get into the "$500 lens is better than $50 lens" fight. And I will say, look at the Kit-Lens Club & Gallery here for brilliant images shot with it. Brilliant images can be and have been shot with Holgas, with Instamatics (cf Galen Rowell's mountain shots in Nat'l Geo), with magnifiers on bellows. The photographer and the subject and the light are more important than the lens and the camera.

Very well, I will stipulate: the DA16-45 is better than the DA18-55, and its hugely greater price reflects that. I will stipulate that when peeping pixels, the DA18-55 shows its weaknesses. But shoot an interesting subject in the right light with some skill, and do some PP, and print and mount and present the image correctly, and NOBODY WILL CARE that light passed through the kit lens and not finer glass. The image is not complete until it is presented and viewed.

And a perfect picture of a boring subject is still a picture of a boring subject.
10-26-2010, 09:40 AM   #26
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QuoteOriginally posted by RioRico Quote
And then we get into the "$500 lens is better than $50 lens" fight. And I will say, look at the Kit-Lens Club & Gallery here for brilliant images shot with it. Brilliant images can be and have been shot with Holgas, with Instamatics (cf Galen Rowell's mountain shots in Nat'l Geo), with magnifiers on bellows. The photographer and the subject and the light are more important than the lens and the camera.

Very well, I will stipulate: the DA16-45 is better than the DA18-55, and its hugely greater price reflects that. I will stipulate that when peeping pixels, the DA18-55 shows its weaknesses. But shoot an interesting subject in the right light with some skill, and do some PP, and print and mount and present the image correctly, and NOBODY WILL CARE that light passed through the kit lens and not finer glass. The image is not complete until it is presented and viewed.

And a perfect picture of a boring subject is still a picture of a boring subject.
Yes, but I'm still not impressed. it is just weak in comparison with other lenses. distortion, contrast, sharpness and overall has less resolution. workflow takes some substantial time as well. and there are times that post-processing does not even equate to that of what some lenses could do better.

my mistake was that I opted to get a $200 WR kit lens rather than getting a used 16-45 sold for the same amount. the DA55-300 is better than the 18-55 at 55mm. even the lowly $20 M50/2 blows the kitlens out of the water.

the preference on other better lens is not a false notion but a reality at best. although one might say it is all about marketing, but in reality, marketing is only a portion of that, but it's not plainly snake oil.
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