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05-25-2012, 12:09 PM   #1
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having problems with M42 lens, advice much appreciated!

Hi guys,

I've been trying out an obscure m42 lens I got from my dad on my K-r: Federal Auto 28mm 2.8. It is a mighty huge 28mm lens (bigger than any I've seen on ebay) with a diameter of 62mm at the front for filters. I've been carrying it with me on a few trips to town (unfortunately once it was the only lens I brought and almost all my photos were blah to say the least) and I've been trying to learn how to use it and work around its limitations to get some nice shots. However, I just feel that I do not understand "where" this lens stands with respect to its other 28mm brethren. I love 28mm as a focal range though and would like to continue shooting at 28mm with manual primes, but could you guys help diagnose what exactly I'm doing wrong/is wrong with the lens?

Attached are links to the photos which had me really baffled.

Glowy Billboard 1 | Flickr - Photo Sharing!
Glowy Billboard 1: I tried taking this shot from the shade of the monorail station. I did not understand why the billboard (and the entire image) was so soft/glowy. IK was also starting to panic because I stupidly left my 50mm 1.7 prime at home. Realizing that I should try letting less light in, I stopped it down...

Glowy Billboard 2 | Flickr - Photo Sharing!
Glowy Billboard 2: ... and got this

Bright lights 1 | Flickr - Photo Sharing!
Bright lights 1: in other news, I was trying to take a shot of a friend in a food court. The lighting was pretty dim for the lens so I tried increasing the ISO and slowing down the shutter speed. I did a few other things actually, but the fact remained ...

Bright lights 2 | Flickr - Photo Sharing!
Bright lights 2: ... that the lights in the ceiling were too darn bright and they had this weird (not pretty) halo around them. When I used the DA-L the lights didn't have that weird glow :-S

So, while I do like this lens I do wonder whether I should be concerned about its image and optical quality. If I should just look at other 28mm lenses could you leave a recommendation please? Otherwise I look forward to hearing from you on what I can do to take better pics with this lens

05-25-2012, 12:28 PM   #2
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Check the elements for dust, haze and fungus. I have an old M 40mm f/2.8 with a weird ring of fungus/weird stuff in-between the two rear elements (they're cemented together so I can't clean them). They give it a glowy effect when shot wide open, like this:




Note the weird halos around bright highlights. It might be something similar in your case. The lens doesn't seem to be focused properly in the second picture, which might account for the lack of sharpness. There's a rail in the bottom right that looks sharp in the corner. Are you using an M42 adapter flush with the mount?

If it is fungus or whatever then grab a cheap jewellers screwdriver and crack the thing open and give it a clean out. If you keep on top of everything they're pretty easy to put back together again, and if it's an old, cheap lens it doesn't matter too much anyway!
05-25-2012, 12:29 PM   #3
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Hi. I see you have a problem with proper exposure and maybe focus. Try focusing the lens using live view, 10x magnification (INFO button).
I would have taken the first picture around f/8 - f/11 anyway. At that aperture, even your cheap, "obscure" lens as you call it, should be OK regarding sharpness and colour abberation. If not, consider another.
The second picture - I personally wouldn't have taken it at all, given the light conditions and the relatively small aperture of the lens. But if you do, be absolutely sure that you are in focus. Regarding the glow around the lights, I don't understand what bothers you. This is how cameras render them.
Your EXIF data says that you had the focal length set at 50mm. change it to the correct length so you won't have blur that you don't know where it comes from.
Secondly, change metering from spot to center weighted average, unless you really know what you're doing. In your second picture, you should have raised the ISO to at least 800.
05-25-2012, 12:31 PM   #4
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Pentax limited lenses are very high quality. You can get that kind of IQ only from some m42 lenses, but most probably not from an unknown, no-brand 28mm. Pentaxforum's lens database is a very good place to identify those jewels from the old times.

05-25-2012, 12:46 PM   #5
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I would be interested to know how you are using the lens, i.e. aperture and shutter speed etc.

Although not a pentax lens, most 28mm lenses, when stopped down 1-2 stops can deliver good results.

Also, do you have a filter on the front. I find that filters, especially older cheap store brand ones, introduce more problems than they solve.

also consider the use of a filter, it is (or was) there to reduce the UV content of light that could lead to some contrast and fogging issues with film, bit film is gone, and who cares about protection on a cheap lens any way.
05-25-2012, 12:46 PM   #6
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I'm not familiar with that lens, but you are aware, aren't you, that your camera has no mechanism to stop down an M42 lens?

To be useful, an M42 lens must have an auto/manual switch. In manual, the aperture stops down to the selected aperture immediately. In auto mode, it only stops down at the moment of exposure, when the (M42) camera pushes the pin on the rear of the lens.

If your lens has no auto/manual switch, it will only shoot wide open, which can be a problem, unless you're going for minimum depth of field. Such lenses can be modified to operate in manual mode only.
05-25-2012, 01:07 PM   #7
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Federal Manufacturing and Engineering Corp, Garden City N.Y. ?
The Federal logo in inside a style outline of a sheriff's badge ?
I have an old 1950's Federal enlarger and i replaced the lens because it was "hazy"
When looking through the lens into a bright window I get a kind of a whited out hazy image on the dark areas compared to the real image.
I know that is a bit subjective.
Something like your first and third images.
Maybe the coating just gave up with age.
Or maybe the lens here was uncoated, as the manual says, in relation to cleaning"..it may scratch the finely polished surface of the lens"

"The fact that there may be one or more tiny air bubbles in your lens need not disturb you"

Wow, Imagine the kerfuffle on this forum if we started getting lenses with air bubbles in the glass!

".. The presence of these bubbles is an inherent characteristic of the optical glass used in the manufacture of fine lenses and does not in any way affect either the quality, the correction, or the transmission of the lens"
05-25-2012, 01:08 PM   #8
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QuoteOriginally posted by Mareket Quote
There's a rail in the bottom right that looks sharp in the corner. Are you using an M42 adapter flush with the mount?

If it is fungus or whatever then grab a cheap jewellers screwdriver and crack the thing open and give it a clean out. If you keep on top of everything they're pretty easy to put back together again, and if it's an old, cheap lens it doesn't matter too much anyway!
OK thanks for your advice. Yes I am using an adapter with it.

QuoteOriginally posted by kcobain1992 Quote
Hi. I see you have a problem with proper exposure and maybe focus. Try focusing the lens using live view, 10x magnification (INFO button).
I would have taken the first picture around f/8 - f/11 anyway. At that aperture, even your cheap, "obscure" lens as you call it, should be OK regarding sharpness and colour abberation. If not, consider another.
The second picture - I personally wouldn't have taken it at all, given the light conditions and the relatively small aperture of the lens. But if you do, be absolutely sure that you are in focus. Regarding the glow around the lights, I don't understand what bothers you. This is how cameras render them.
Your EXIF data says that you had the focal length set at 50mm. change it to the correct length so you won't have blur that you don't know where it comes from.
Secondly, change metering from spot to center weighted average, unless you really know what you're doing. In your second picture, you should have raised the ISO to at least 800.
Yep I do have problems with exposure. These were pretty bad shots but they just demonstrated what I thought were troubling aspects of the lens :S I didn't realize it was on 50mm at the time, thank you for pointing that out! I'll try shooting with center weighted average in the day then And it's just I'm used to the lights being more "suppressed" and star-like. But now that you pointed out that the focal length was wrong I wll have to try this kind of shot again (with proper iso and the other things you mentioned) to see if this happens again.

QuoteOriginally posted by Lowell Goudge Quote

Also, do you have a filter on the front. I find that filters, especially older cheap store brand ones, introduce more problems than they solve.
.
Nope no filters, just the lens and adapter...

QuoteOriginally posted by noblepa Quote
I'm not familiar with that lens, but you are aware, aren't you, that your camera has no mechanism to stop down an M42 lens?

To be useful, an M42 lens must have an auto/manual switch. In manual, the aperture stops down to the selected aperture immediately. In auto mode, it only stops down at the moment of exposure, when the (M42) camera pushes the pin on the rear of the lens.

If your lens has no auto/manual switch, it will only shoot wide open, which can be a problem, unless you're going for minimum depth of field. Such lenses can be modified to operate in manual mode only.
Yep I'm aware of that. Sorry for the dumb question but when I screw on a M42 into my Pentax with the adapter I've basically sacrificed the A mode right?


Thanks a lot for the feedback! I really appreciate it

05-25-2012, 01:13 PM   #9
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Yes, you can only use M42 lenses on DSLR in M mode, stop down metering. Sorry if I was misunderstood, you should always use center-weight avg. metering, not just during the day
Now I understand what you mean with the lights. Things that are bright and out of focus (they are called specular highlights) take shape of the lens opening (aperture). If your lens was wide open, the highlights look like that. If you are stopped down, they look like a star with N corners, where N is the number of your aperture blades. You will sometimes see pictures with strange hexagons in the background, they are caused by this phenomenon.
05-25-2012, 01:17 PM   #10
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QuoteOriginally posted by wombat2go Quote
Federal Manufacturing and Engineering Corp, Garden City N.Y. ?
The Federal logo in inside a style outline of a sheriff's badge ?
I have an old 1950's Federal enlarger and i replaced the lens because it was "hazy"
When looking through the lens into a bright window I get a kind of a whited out hazy image on the dark areas compared to the real image.
I know that is a bit subjective.
Something like your first and third images.
Maybe the coating just gave up with age.
Or maybe the lens here was uncoated, as the manual says, in relation to cleaning"..it may scratch the finely polished surface of the lens"

"The fact that there may be one or more tiny air bubbles in your lens need not disturb you"

Wow, Imagine the kerfuffle on this forum if we started getting lenses with air bubbles in the glass!

".. The presence of these bubbles is an inherent characteristic of the optical glass used in the manufacture of fine lenses and does not in any way affect either the quality, the correction, or the transmission of the lens"
Emm there's nothing on the lens which betrays its identity except for the words "FEDERAL", "AUTO" and the typical lens specs. It was made in Japan too. Through the viewfinder I get a kinda dirty image of what I'm capturing in low light... Yeah it could be the coating (or lack of) ...
05-25-2012, 01:21 PM   #11
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QuoteOriginally posted by kcobain1992 Quote
Yes, you can only use M42 lenses on DSLR in M mode, stop down metering. Sorry if I was misunderstood, you should always use center-weight avg. metering, not just during the day
Now I understand what you mean with the lights. Things that are bright and out of focus (they are called specular highlights) take shape of the lens opening (aperture). If your lens was wide open, the highlights look like that. If you are stopped down, they look like a star with N corners, where N is the number of your aperture blades. You will sometimes see pictures with strange hexagons in the background, they are caused by this phenomenon.
OK thanks kcobain for the heads up I just set my KR to center weight avg. (in case I forget to later). I won't change this setting again

oh right! Yeah I've noticed the cool aperture shaped lights before. Now I know what they're called..
05-25-2012, 01:55 PM   #12
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QuoteOriginally posted by slappyfin3 Quote
OK thanks for your advice. Yes I am using an adapter with it.
Aaaah, but is the front of teh adapter perfectly in line with the front of the mount on the camera? I used to have an old m42 adapter that had a ring of metal that added a millimetre or so to the front of the mount, which as far as I'm aware meant that it couldn't focus to infinity anymore. Given that it's a 28mm lens you should have enough DoF anyway, but tis always something to consider.

I love cracking open old lenses to see how they tick. It's rather fun.
12-11-2016, 05:41 AM   #13
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QuoteOriginally posted by Mareket Quote
Check the elements for dust, haze and fungus. I have an old M 40mm f/2.8 with a weird ring of fungus/weird stuff in-between the two rear elements (they're cemented together so I can't clean them). They give it a glowy effect when shot wide open, like this:




Note the weird halos around bright highlights. It might be something similar in your case. The lens doesn't seem to be focused properly in the second picture, which might account for the lack of sharpness. There's a rail in the bottom right that looks sharp in the corner. Are you using an M42 adapter flush with the mount?

If it is fungus or whatever then grab a cheap jewellers screwdriver and crack the thing open and give it a clean out. If you keep on top of everything they're pretty easy to put back together again, and if it's an old, cheap lens it doesn't matter too much anyway!
I'm getting similar outlines around bright lights but in night shots esp around streetlights.
The lens used is a Pentax 24-70mm f2.8 hd fa!!!
No idea why I get those outlines
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