how to avoid lens ghosts?

phritz phantom · Feb 11, 2007

aren't those round objects called "ghosts"? or "ghosting"?
i mainly do night photography, in the city with lots of street lights. and at least one or two shots per roll are ruined because of those round dots.
my camera is a mamiya 7 with 65mm lens. is using a rangefinder a disadvantage under those circumstances, would those "ghosts" be visible through a mirror reflex finder?
according to the ken rockwell site, the mamiya 7 lenses are very unlikely to produce "ghosts", so this is double annoying.
i have just developed a roll with two images, that were ruined by an exceptionally big "ghost" that has the pentagonal shape of the shutter. i can post a scan later, when the film is dried.

just one little dot can ruin a otherwise perfect picture. is there any way to avoid or predict those annoying ghosts?

David A. Goldfarb · Feb 11, 2007

Well, if you have a light source in the scene, it's hard to avoid, even with modern multicoated optics as fine as those available for the Mamiya 7. If the light sources are outside the scene, then using an adequate lens shade will reduce the problem.

You can often see this effect in the finder with an SLR when it happens and compose around it, but sometimes it's more obvious on film than it is in the finder.

Pinholemaster · Feb 11, 2007

Are you using a filter on the lens?

Many times it's not the lens, but the filter.

I usually take any skylight or UV filter off the lens in difficult lighting situations.

Yes an SLR makes it easier to see any "ghosts".

phritz phantom · Feb 11, 2007

thanks.
i don't use any filters and the lens hood's always on. plus the lens is a good one. and still...
so is there any kind of trick with rangefinder cameras? like, when using a tripod, taking a look, from the opposite side, at the lens and looking for reflections?

Roger Hicks · Feb 12, 2007

phritz phantom said:
Is there kind of trick with rangefinder cameras? like, when using a tripod, taking a look, from the opposite side, at the lens and looking for reflections?

Alas, no. Believe me -- I've beem shooting RFs for decades, from several manufacturers and in various formats.

Cheers,

R. (www.rogerandfrances.com -- where you'll also find details of our book Rangefinder)

Jim Jones · Feb 12, 2007

Like others have said, avoiding bright lights in the image area and using a very efficient lens hood can help. Lens hoods are often made more for convenience than effectiveness. Making a huge one that blocks everything outside the image area might help. Sometimes you can compose the shot so the brightest lights in the image area are blocked by the foreground. What you see in a viewfinder can be quite different than what you record on film.

dmr · Feb 12, 2007

Yes, these are annoying and can ruin an otherwise great shot.

I've found that very bright lights outside the field of view are the most troublesome.

If you look at the following shot, which is a good (bad?) example of pushing the capabilities of a lens:

http://www.letis.com/dmr/pics/oma/oma3/w400demo2.jpg

You'll see a bright distracting semicircular "swoosh" which almost appears to eminate from a light between two of the buildings. If you carefully examine things you can see that the center of this circle is the street light mounted on the pole that holds the "One Way" sign.

This is a test shot with the Canon QL17 GIII with W/A 400 film and the lens wide open at f1.7. I've seen similar patterns when using this wide open or close to wide open when there are bright lights outside the field.

This also shows the astigmatism of this lens, which I've been told is typical, when using it wide open. Notice that the lights toward the right are football shaped, tangential to the center of the frame.

PHOTOTONE · Feb 12, 2007

It is true now, as always, to avoid many issues, use a lens shade as deep as you possibly can get away with. Works just as well at night, as in daylight. Course, won't affect aritfacts from light sources within the frame.

phritz phantom · Feb 13, 2007

dmr said:
I've found that very bright lights outside the field of view are the most troublesome.

this is my experience too. this nice specimen was caused by a streetlight out of the picture, slightly to the left. the shadow in the picture is caused by the pole of the light. picture taken with mamiya 7, lens hood and at f8.

Roger Hicks · Feb 13, 2007

PHOTOTONE said:
It is true now, as always, to avoid many issues, use a lens shade as deep as you possibly can get away with. Works just as well at night, as in daylight. Course, won't affect aritfacts from light sources within the frame.

Two problems here with rangefinders:

1 You can't easily tell how deep your hood can safely be, without the back off and a piece of ground glass in the film gate

2 Hoods that are too big cut into the viewfinder area

Cheers,

R.

Helen B · Feb 13, 2007

Roger Hicks said:
Two problems here with rangefinders:

1 You can't easily tell how deep your hood can safely be, without the back off and a piece of ground glass in the film gate

2 Hoods that are too big cut into the viewfinder area

Cheers,

R.

Roger,

I'm not sure that you need a GG.

Though Point 2 pretty much prevents the use of a deep hood for wide angle lenses on rangefinders (there was a url link here which no longer exists), if anyone is interested, is a fairly long thread on designing lens hoods.

Best,
Helen

Jim Jones · Feb 13, 2007

Roger Hicks said:
. . . 2 Hoods that are too big cut into the viewfinder area

Cheers,

R.

Leica, Canon, and probably others made rectangular hoods with a cutout in the back that let one look through viewfinder and through the hood.

Roger Hicks · Feb 14, 2007

Helen B said:
I'm not sure that you need a GG.

Dear Helen,

True. I've never figured out which is easier: with or without. Well, no. Without is clearly easier, but I never quite trust it...

Cheers,

R.

Roger Hicks · Feb 14, 2007

Jim Jones said:
Leica, Canon, and probably others made rectangular hoods with a cutout in the back that let one look through viewfinder and through the hood.

Dear Jim,

Yes, I've owned some of them. That little bit of lens-hood is always EXACTLY where you don't want it.

Another thought which occurs to me is that part of the charm of an RF is that it's small, light and handy. A big rectangular hood may add very little weight, but boy, do they add bulk! Even the folding ones, which I've also owned.

Cheers,

R.

PHOTOTONE · Feb 15, 2007

Roger Hicks said:
Two problems here with rangefinders:

1 You can't easily tell how deep your hood can safely be, without the back off and a piece of ground glass in the film gate

2 Hoods that are too big cut into the viewfinder area

Cheers,

R.

Well, after using rangefinders for a few decades now, I can easily deal with a hood, or a big lens that cuts into the viewfinder area.

Usually, when I am shooting night photography, I use a tripod and cable release, because I like tack sharp photos. In this case, it is easy enough to see if any light outside the shot is hitting the lens, and then I generally hold my hand up in the air to block it. it is no 100% successful, but works pretty well.

In the daylight, if the sun is hitting the lens, you can see that thru the rangefinder (you can see the sun hitting the barrel of the lens), I then, and I even do this handheld, put my left hand up in the air and block the direct sun, I can tell because the lens barrel goes into shadow.

Roger Hicks · Feb 15, 2007

PHOTOTONE said:
Well, after using rangefinders for a few decades now, I can easily deal with a hood, or a big lens that cuts into the viewfinder area . . . I put my left hand up in the air and block the direct sun, I can tell because the lens barrel goes into shadow.

Sure, so do I. My point, really, was that once you've done the obvious (including big shades if you get on with 'em), no, there's no way of predicting/preventing diaphragm images with direct vision cameras. At least, I've not found out how in thirty-odd years.

Cheers,

R.

how to avoid lens ghosts?

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