[NecroticSoldier]

Okay... so... I now have a M1.7 how big of a light difference is 1.7 from 1.4? less than double?

[Mike Cash]

From f1.4 to f2 is one stop, so f1.7 would be somewhat less than that.

[Rondec]

The answer is less than a stop. Historically, the 50mm f1.7's didn't have quite the build of the f1.4s, although by all accounts they are probably a little bit sharper up till f2.8 anyway.

[NecroticSoldier]

From f1.4 to f2 is one stop, so f1.7 would be somewhat less than that.

Oh! so, is it worth it to get a 1.4 instead?

[flippedgazelle]

Oh! so, is it worth it to get a 1.4 instead?

Well, if the difference is around half a stop, then the answer is "no" - IMO. Especially since the f/1.4 is usually quite a bit more expensive than the f/1.7.

[NecroticSoldier]

Well, if the difference is around half a stop, then the answer is "no" - IMO. Especially since the f/1.4 is usually quite a bit more expensive than the f/1.7.

Yeah I suppose so. I can compensate that half stop anyways using diff shutter speed.

[RioRico]

my Pentax FA50/1.4: US$197 (2 years ago)
Meyer Oreston 50/1.8: US$45 (I overpaid)
Chinon-Argus 55/1.7: US$3 (a little later)
Super-Takumar 55/1.8: US$7 (same time)

What is a half-stop in light? Well, consider this:

"In 1960 the manufacturers issued new ratings for black and white films which are about double the previous speeds. This change is independent of any improvements in the film -- it is merely the result of eliminating an unnecessary "safety factor" in computing the speeds. The fact that the speeds could be changed by 100 percent without markedly affecting the results should prove how relative they are."
--David Linton, Photographing Nature, Natural History Press, 1964

100% is one f-stop. One-half stop, ain't much. On reversal film, B&W or color, it's virtually unnoticeable. On color transparency film and digital sensors, it's slightly noticeable. Going 1/2 stop from f/1.4 to f/1.2 can cost hundreds of dollars. There are reasons. But where you're at, don't sweat it.

---

Last edited by RioRico; 04-18-2010 at 02:55 AM. Reason: typo

[Canada_Rockies]

Okay... so... I now have a M1.7 how big of a light difference is 1.7 from 1.4? less than double?

f/1.7 is one half stop darker than f/1.4. The M 1.7 is lighter than the 1.4 because the glass does not need to be as large in diameter to cover the extra aperture opening, and the glass elements are most of the weight in the lens. If you are happy with the results you get from your 1.7, you won't really notice enough difference with a more expensive lens.

[NecroticSoldier]

f/1.7 is one half stop darker than f/1.4. The M 1.7 is lighter than the 1.4 because the glass does not need to be as large in diameter to cover the extra aperture opening, and the glass elements are most of the weight in the lens. If you are happy with the results you get from your 1.7, you won't really notice enough difference with a more expensive lens.

Okies, sounds good to me. Thanks guys again.

[Ira]

Justin, spend a full day with just that 1.7, doing different things with maximum aperture, minimal depth of field, etc., and vice versa. Av mode would be best for this.

If you're not shooting wide open at 1.7, then keep it around F8 to see if that's the camera's sweet/sharp spot. And try other apertures too to see your results.

You can do some great things with that lens, and will train you to frame more creatively, without the ease of a zoom.

[NecroticSoldier]

Justin, spend a full day with just that 1.7, doing different things with maximum aperture, minimal depth of field, etc., and vice versa. Av mode would be best for this.

If you're not shooting wide open at 1.7, then keep it around F8 to see if that's the camera's sweet/sharp spot. And try other apertures too to see your results.

You can do some great things with that lens, and will train you to frame more creatively, without the ease of a zoom.

Yep thanks for the advice, and hey! you remembered me name ;D! also... uhh... for some reason on my K-X AV it's aways set on 1.7 no matter where I turn. Strange eh? It only changes in M mode.

[Tuner571]

Justin, spend a full day with just that 1.7, doing different things with maximum aperture, minimal depth of field, etc., and vice versa. Av mode would be best for this.

If you're not shooting wide open at 1.7, then keep it around F8 to see if that's the camera's sweet/sharp spot. And try other apertures too to see your results.

You can do some great things with that lens, and will train you to frame more creatively, without the ease of a zoom.

I recommend that you do this as well. Even though the difference is small there is still a difference in the light coming into the camera. You will also realize that the depth of field is rather small as well with the aperture that wide open.

[NecroticSoldier]

I recommend that you do this as well. Even though the difference is small there is still a difference in the light coming into the camera. You will also realize that the depth of field is rather small as well with the aperture that wide open.

VERY small, but that allows me to do certain things my 2 can't really do.

[RioRico]

Yep thanks for the advice, and hey! you remembered me name ;D! also... uhh... for some reason on my K-X AV it's aways set on 1.7 no matter where I turn. Strange eh? It only changes in M mode.

Hey Justin (I can almost remember too!) the reason it's always at f/1.7 is because it's an M-type lens. M-types always stay wide open in the Auto modes. If there were an A setting on the aperture ring, you could control the aperture from the camera, and it would stop down automagically when you shoot. But an M-type *must* be used in M(anual) mode and preferably using the Green button to take exposure readings, in order for the lens to stop down.

In that regard, screwmount lenses on adapters are a little easier to use, except at small apertures. Except in M(anual) mode, the camera goes to Av by default. So you set the aperture ring to whatever you want, and the camera reads the light and sets the exposure. But you might get a better exposure with the M(anual)-mode Green-button trick. Your mileage may vary. All I can say is, try it out. Shooting is free. No film was wasted in the making of this experience. Whew.

Something else: Aperture and focal length interact in interesting ways. An f/1.4 lens DOES let you shoot at slightly higher shutter speeds in slightly less light, and that higher shutter speed may be the difference between an acceptably sharp keeper and an unacceptably blurry loser. But there's also DOF, the range of distance where the image is acceptably sharp. Many of us prize fast lenses because they provide a thin DOF, which helps in isolating a subject from its surroundings. Faster lenses have thinner DOF, and so do longer lenses. I'll compare wide-open shots on a 50/1.4, 55/1.7, 58/2 and see similar (but different) DOF and bokeh.

A 50/1.7 is about midway in there, but still with pretty thin DOF. I may have already recommended (and if I didn't, I should have) that you consider buying a DIRT CHEAP Helios-44 58/2 (still around US$20 on the bay). It's slightly slower but noticeably longer, wide-open sharp yet with thinner DOF, great for closer, more intimate pics than the 50/1.7. And you can use it in Av mode. Just another tool in the kit. (And it WAS the kit lens for zillions of Russian film cameras.)

[NecroticSoldier]

Hey Justin (I can almost remember too!) the reason it's always at f/1.7 is because it's an M-type lens. M-types always stay wide open in the Auto modes. If there were an A setting on the aperture ring, you could control the aperture from the camera, and it would stop down automagically when you shoot. But an M-type *must* be used in M(anual) mode and preferably using the Green button to take exposure readings, in order for the lens to stop down.

In that regard, screwmount lenses on adapters are a little easier to use, except at small apertures. Except in M(anual) mode, the camera goes to Av by default. So you set the aperture ring to whatever you want, and the camera reads the light and sets the exposure. But you might get a better exposure with the M(anual)-mode Green-button trick. Your mileage may vary. All I can say is, try it out. Shooting is free. No film was wasted in the making of this experience. Whew.

Something else: Aperture and focal length interact in interesting ways. An f/1.4 lens DOES let you shoot at slightly higher shutter speeds in slightly less light, and that higher shutter speed may be the difference between an acceptably sharp keeper and an unacceptably blurry loser. But there's also DOF, the range of distance where the image is acceptably sharp. Many of us prize fast lenses because they provide a thin DOF, which helps in isolating a subject from its surroundings. Faster lenses have thinner DOF, and so do longer lenses. I'll compare wide-open shots on a 50/1.4, 55/1.7, 58/2 and see similar (but different) DOF and bokeh.

A 50/1.7 is about midway in there, but still with pretty thin DOF. I may have already recommended (and if I didn't, I should have) that you consider buying a DIRT CHEAP Helios-44 58/2 (still around US$20 on the bay). It's slightly slower but noticeably longer, wide-open sharp yet with thinner DOF, great for closer, more intimate pics than the 50/1.7. And you can use it in Av mode. Just another tool in the kit. (And it WAS the kit lens for zillions of Russian film cameras.)

I see, I see. Well... I already have this 1.7 so... I don't plan on buying anything much soon. Yeah shooting is free ;D but I still love film. Thanks for the explanation and remembering my name almost LOL.