Close-up lense question - DPChallenge Forums

Sigma 50-500mm f/4.0-6.3 EX DG HSM for Canon EOS

07/24/2005 07:44:47 PM · #1

I found a set of close-up lenses for a good price on an online auction site, and I'm thinking about buying it.
But since I don't know much about anything, what do the numbers +1 +2 +4 and +10 mean?
+1 what? +1 spell points?

Pioneer

Canon EOS-350D Rebel XT

07/24/2005 08:01:22 PM · #2

Hello, I have close up lenses that fit on my 28-300 lens and they are multiplied by +1 +2 or +4 times magnification. I assume the + 10 would be ten times better. I have used them and stacked my 1-2- and 4 all together and they work pretty good

07/24/2005 08:15:26 PM · #3

Ok, thanks.
I'm seriously considering buying this set along with some other stuff from the same seller. He sells a lot of no name brands, but I've heard from others that it's quality stuff.

So now I will have spent more money on photo gear this month than what I spent buying the camera and the first three lenses :-)

kyebosh

Canon EOS-20D

Canon EF 80-200mm f/2.8L

07/24/2005 08:30:39 PM · #4

if you want good closeup filters go with the canon made ones. The 250D and the 500D.

Canon EF 17-40mm f/4.0L USM

07/24/2005 08:36:47 PM · #5

Four filters for a quarter of the price of one 250D isn't much of a waste even if they suck. But if I can't get any good results with them, I'll take a look at the canon filters for my next "shopping spree" :-)

LoudDog

Canon EOS-350D Rebel XT

07/24/2005 08:46:26 PM · #6

I have the Hoya set and love them. Be sure to get a decent brand and not the no-name brands on Ebay as I've heard they are not very good. My set was used and came with a Hoya CS and ploarizer and was a whole $17 (used on Ebay). They are a fun toy for a low price.

Canon EF 100mm f/2.8 USM Macro

07/24/2005 08:48:08 PM · #7

Hmm... That's even better than the price for this set... Maybe I should try to find a similar deal for a Hoya set instead.

Spork99

OM System OM-1

07/24/2005 09:05:13 PM · #8

I have the Hoya set and they are decent enough, you lose some corner sharpness , but with the 10D, since you are using the sweet spot anyway, it's not too bad.

It's not as good as my Sigma 105 Macro, but it'll do.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

07/24/2005 09:25:41 PM · #9

For the record, the +1, +2 etc refer to "diopters"; they are a universal unit of measurement in the optical industry. The larger the number, the greater the magnification. The actual amount of magnification they provide varies depending on the lens they are mounted to. There is no "direct equivalent. The formula, if I recall correctly, is this:

diopter power x (focal length of the lens in meters + the magnification of the lens itself)

In other words, if I have a 100mm lens that is focused to 1:1, its focal length in meters is .10 meters and the magnification is 1; so 1 2-diopter lens on a 100mm macro focused at 1:1 magnification delivers 2 x (.10 + 1.0) magnification, 1:2.2 magnification (if I managed that right off the top of my head).

If your base lens is not a true macro lens (presumably the case) then let's assume it can focus to 1:2; the formula then becomes 2 x (.1 + .5) or 1.20; you will be shooting at 1:1.2 magnification, slightly larger than life size. If the lens will focus to a mgnification of 1:3 (more typical) then 2 x (.1 + .33) = .86, and you will get a magnification of 1:0.86.

These figures are assumeing 2.0 diopters, they will vary by the actual amount of diopters used of course.

The Canon and Nikon diopter lenses are actually 2-element lenses, and they are significantly crisper throughout the field of the image than the less-expensive, single-element diopters.

It's been a long time since I had to deal with this stuff, so don't climb all over me if I have the details wrong; the principle is accurate, I think.

Robt.

Robt.

Sony 24-70mm F4 Vario-Tessar T* FE OSS

07/24/2005 09:37:15 PM · #10

That sounds like more numbers than I can fit in my head at one time :-)

Let's see if I can remember any of the math classes I missed in school...

50mm lens, 1:1.8 magnification, 2 diopters. That would be 1:1.21
And that would mean... One centimeter in real life becomes 1.21 centimeters in the photo?

kyebosh

Canon EOS-20D

Canon EF 80-200mm f/2.8L

07/24/2005 09:37:33 PM · #11

Originally posted by bear_music:

diopter power x (focal length of the lens in meters + the magnification of the lens itself)

In other words, if I have a 100mm lens that is focused to 1:1, its focal length in meters is .10 meters and the magnification is 1; so 1 2-diopter lens on a 100mm macro focused at 1:1 magnification delivers 2 x (.10 + 1.0) magnification, 1:2.2 magnification (if I managed that right off the top of my head).

The problem here is that 1:1 is more magnification that 1:2.2. I think you meant 2.2:1.

Also yes, the canon ones will be much better.

Bear_Music

Samsung Galaxy S24 Ultra

07/24/2005 10:15:15 PM · #12

Originally posted by kyebosh:

Originally posted by bear_music:

diopter power x (focal length of the lens in meters + the magnification of the lens itself)

In other words, if I have a 100mm lens that is focused to 1:1, its focal length in meters is .10 meters and the magnification is 1; so 1 2-diopter lens on a 100mm macro focused at 1:1 magnification delivers 2 x (.10 + 1.0) magnification, 1:2.2 magnification (if I managed that right off the top of my head).

The problem here is that 1:1 is more magnification that 1:2.2. I think you meant 2.2:1.

Also yes, the canon ones will be much better.

Yeah, probably. I am not good at math and these ratios screw me up. Can soemone who knows the relationship of ratios to magnification more intuitively recalculate based ont he formula I just gave? The formula is accurate, I'm sure. You'll be shooting at a magnification of 1.2 x life size, I just screwed up the ratio expression of that.

Robt.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

07/24/2005 10:16:54 PM · #13

Originally posted by Incarlight:

No, IF you had 1:1.21, then 1.2 cm in real life becomes 1 centimeter in the "film" (the sensor, for us). if it were 1.2:1, then you'd be correct.

Robt.