QL17 GIII astigmatism and lens assembly questions ...

[dmr]

I'll ask the questions first and discuss after ...

1. Is this degree of astigmatism (see examples below) typical of the QL17 GIII lens when wide open or close to wide open?

2. Is there a "right way" and a "wrong way" to install the front lens element? Meaning, is it asymmetrical in that if it were installed wrong side out, could it introduce astigmatism?

I love shooting with this camera, but there is one thing that is starting to bother me, and that is if I'm shooting wide open and there are bright point light sources toward the edges of the frame, they tend to come out football shaped. The gang here identified this as astigmatism a couple month back, and I thank everybody again for this.

I got to thinking (yeah, dangerous) of anything I could have done to cause or worsen this, and I remembered that when I took this thing apart, I was careful to place everything the way it went, but I did clean off the front lens element with alcohol and lens tissue, and I could have re-assembled it opposite of the way it came out.

I guess I could take a test roll, reverse it, and take another test roll, but I thought I would ask the collective expertise here before doing something nasty like that. 🙂

Thanks in advance, gang. 🙂

 

[Gabriel M.A.]

Feels nice to be ignored, eh?

I'm not sure what it is that you're seeing that makes you say there is evidence of astigmatism here, but I do see some vignetting. I haven't seen any vignetting on the pictures taken with my QL17 when shot wide open.

The last picture shows some flare, which I haven't experienced with my Canonet. Maybe others have the same experience as you, but I haven't shot more than a few rolls yet with mine.

 

[kvanderlaag]

Gabriel: Do you see the point lights in the third picture? See how they appear elongated, taller than they are wide? They're circular lights, and the image is being stretched about the edges. I think that's what he means when he says astigmatism.

Cheers,
Keegan

 

[Sonnar Brian]

Annie,

1) There is no way you could miss installing that front element backwards. It would bang into the second element and not mount.

2) That level of astigmatism is not abnormal in a lens. Here is a shot with the Nikkor 5.8cm F1.4, wide-open and close-up. This is a 7 element lens, based on the Planar with the front element "split" into two elements of lesser strength. Your Canonet uses the classic 1-2-2-1 Planar formula.

 

[Gabriel M.A.]

Gabriel: Do you see the point lights in the third picture? See how they appear elongated, taller than they are wide? They're circular lights, and the image is being stretched about the edges. I think that's what he means when he says astigmatism.

:: in awe :: I see. I have noted this on shots wide open, but didn't pay attention to these shots on how exaggerated they were here. That is indeed pronounced. Hmm...another excuse to take the Canonet out for a shoot-out.

 

[dmr]

Feels nice to be ignored, eh?

Uh, I usually don't get ignored here. I was sure some people would jump in eventually. 🙂

I'm not sure what it is that you're seeing that makes you say there is evidence of astigmatism here,

The first probably isn't the best example, but it's one I took last weekend and the one I most noticed when I was going over them. If you look at the lights in the lower right, they are elongated. The second shot (lights on the lower left) and the third shot (street lights, upper right) show the effect better.

but I do see some vignetting. I haven't seen any vignetting on the pictures taken with my QL17 when shot wide open.

I see what you see in the first one, and somewhat in the second, but I'm not too concerned about it. The first one was shot looking southwest on an east-west street. The twilight sky looks much brighter (and bluer) in the photo than I remember it. The glow in the southwest sky did fall off in the direction of the upper right corner.

The last picture shows some flare, which I haven't experienced with my Canonet. Maybe others have the same experience as you, but I haven't shot more than a few rolls yet with mine.

I admit I push things with the GIII. I use it for low light stuff, often times close to wide open with bright lights in the frame or just out of it, and many times I've got the rainbow in the dark and the UFOs when shooting into bright light. See attached. 🙂

 

[dmr]

Annie,

1) There is no way you could miss installing that front element backwards. It would bang into the second element and not mount.

Thanks. 🙂 I was sure I put it back the way it came out, but I didn't want to take it apart again to see if there was a difference.

2) That level of astigmatism is not abnormal in a lens. Here is a shot with the Nikkor 5.8cm F1.4, wide-open and close-up. This is a 7 element lens, based on the Planar with the front element "split" into two elements of lesser strength. Your Canonet uses the classic 1-2-2-1 Planar formula.

Your example looks a bit more subtle, as part of the "bokeh", but I can see it. That's what I needed to hear. I'm cool with it if I know I'm pushing the limits of the lens, and that there's nothing really wrong, in particular something I did. Thanks, Brian. 🙂

 

[kvanderlaag]

She? My mistake! This is why I usually use gender-neutral pronouns on the internet!

I need to get one of these cameras, methinks!

Anyone interested in an Original Canonet + Canonet S for one? =D

 

[dmr]

Wow, I thought my ears were burning! 🙂

DMR has a digital self portrait currently running for her Avatar.

Actually, that isn't really a self-portrait. It's a scan of something that appeared on the bulletin board a few years back with the scrawled note "Who does this look like?" 🙂

You'll see variations of that one on various ASCII Art sites. One of our "resident artists" obviously added a bit more hair to the original. 🙂 (Some say my hair is still "big", but it's not as big as back in those days. It's also not as big as the one who posts on one of the other photo boards regularly. Pnet? Apug?) Attached is a real life photo from that era. 🙂

I still like the "Who I am, Things I say" ,

Ok, I'll go with that one when I rotate it again. I admit I stole that one from somebody on the Las Vegas Talk board.

My first "DIGITAL IMAGES" were done with printer overstrike using FORTRAN

In these days of the web and photo quality images, ASCII art has become kind of a lost art form. I can remember some very impressive, almost halftone quality, mural size ASCII print outs that were really nice.

 

[Gabriel M.A.]

In these days of the web and photo quality images, ASCII art has become kind of a lost art form. I can remember some very impressive, almost halftone quality, mural size ASCII print outs that were really nice.

Ok, thanks for making me feel older than I already feel. Back in 1984 (no relation to the book or movie) I was at a camp where they showed us an "old" BASIC program on an IBM System 36 (or was it 34?) that could use the halftone principle and print out in these super-advanced multi-daisy-wheel (note smirk) which, as Brian has pointed out, could do multiple strikes on a given spot. It used good old-fashioned ink ribbons.

My dad still has that picture. I'm missing a tooth in that one; I'd rather have it, um, taken care of, see? 😀