Blind test: 18-155 vs 32mm

I liked the poll nnowak did in this post so decided to add a similar test with the 18-155 and the 32. There should be a clear IQ difference between the two.

Nothing scientific, but this is what I did:

1) Placed the camera on a tripod.

2) Set the camera to f8, ISO 200 and AV mode.

3) Shot some test shots with the 32mm

4) Changed lenses to the 18-155

5) Set the focal length to 32mm (this took a couple tries so the scene changed slightly) and fired test shots

6) Uploaded these SOOC JPGs with no post processing whatsoever.

Image A

Image B

The metadata is attached so it isn't blind; you can use DPP4 or another post processor to remove it?

Also, might be wise to use spot metering (and meter the same spot on both) as there is some exposure drift between the two even though your metadata does show you used the same exposure settings. Evaluative metering appears to be causing a cloud or otherwise to change the actual exposure (which you can tell with the 1/2000 vs 1/1000 exposure of the two).

Not blind as pointed out above.

I was a bit confused with your repeated typo - was it 18-55mm or 18-150mm (not 18-155mm). The exif data showed my that it was 18-150mm.

The fact that the images are shot at different exposures as well makes it hard to truly compare - the 32mm photo is brighter and had twice the exposure (1/1000th) of the 18-150mm (1/2000th). This makes the roof look brighter and show more detail.

Colin

...you've got to erase the EXIF data which clearly shows that the first photo is the 32 MM and the 2nd photo is the 18-150 - sigh.

But having said that, the 32 MM is clearly sharper, in particular in the corners.  Those all-in-one longer zooms have optical tradeoffs, that's for sure.  But for the genre, the 18-150 is mighty nice!

abruzzopat wrote:

Andy01 wrote:

Not blind as pointed out above.

I was a bit confused with your repeated typo - was it 18-55mm or 18-150mm (not 18-155mm). The exif data showed my that it was 18-150mm.

The fact that the images are shot at different exposures as well makes it hard to truly compare - the 32mm photo is brighter and had twice the exposure (1/1000th) of the 18-150mm (1/2000th). This makes the roof look brighter and show more detail.

Colin

Yeah, ok, not blind since you can cheat and look at the EXIF. And not sure why I typed 18-155 which of course should have been 18-150. Sorry for the confusion.

Anyway, point was mostly about comparing the sharpness of the two lenses, and I was not surprised at the gap between the two... I wish the zoom was sharper, but the new prime is MUCH better. Doesn't really need pixel peeping to see the difference. I've seen an obvious difference in the 11X14 prints I have done using both lenses.

BUT: about that difference with the shutter speed... I noticed and wondered why that happened. The camera was on a tripod on a full sunny day. These pics were 3 min apart because it took me some time to get the zoom lens to exactly 32mm. But I switched back and forth over 15 min with a couple different angles and every shot with the 32mm the camera chose 1/1000, and every shot with the 18-150 the camera chose 1/2000.

These are the two possibilities I think:

1) Some slight change in cloudiness happened just as I changed lenses (several times) which was enough to cause the camera to alter shutter speed

2) These lenses don't actually let in the same amount of light at their stated settings.

Actually, #2 probably has some truth to it, but if anything, it would actually cause the opposite choice of shutter speeds.  Primes usually have notably better light transmission (T-stop) than zoom lenses at the same f-number.  Therefore, the zoom lens would require a longer exposure (slower shutter speed) than the prime at the same f-number to achieve the same brightness in the image.  However, as noted, the opposite choices occurred (zoom had half of the exposure), which is why the second image is so much darker.  This must be an issue with the metering algorithm.

In the future, for a fairer test, use manual mode to control the aperture, shutter speed and ISO.  Again, you may notice a slightly brighter image with the prime, which you could manually adjust the shutter speed to compensate.

abruzzopat wrote:

BUT: about that difference with the shutter speed... I noticed and wondered why that happened. The camera was on a tripod on a full sunny day. These pics were 3 min apart because it took me some time to get the zoom lens to exactly 32mm. But I switched back and forth over 15 min with a couple different angles and every shot with the 32mm the camera chose 1/1000, and every shot with the 18-150 the camera chose 1/2000.

These are the two possibilities I think:

1) Some slight change in cloudiness happened just as I changed lenses (several times) which was enough to cause the camera to alter shutter speed

2) These lenses don't actually let in the same amount of light at their stated settings.

Hi,

have you checked wether the focus point is exactly on the same spot?

You should add or change the steps!

a) Use M-Mode in order to control the exposure!

b) Use Manual Focus to always focus on the same point!

(c) Always use the EF-M 18-150mm first for framing, focusing and taking the first shot. Than switch to the EF-M 32mm.)

Additionally, mark the spot where the EF-M18-150mm is zoomed in to 32mm.

I gonna try to do the same for the same lenses and maybe other lenses Cool Idea!