michel_wilson

Well, sad face.

I changed the capacitor, which went pretty smoothly. Then, bit of a scare, as my computer did not see the USB device anymore. After I fully pushed in the USB connector, the scanner was detected again and my heart restarted. But: no joy, still the same noise pattern.

Next, I noticed an odd solder blob next to the crystal under the (I think) CPU. You can actually spot it in the first photo! So, I set out to remove that blob, it seemed like it could cause such an issue. But, again no joy, same noise pattern.

So, I'm out of options for this scanner I think. I'll take my loss I guess, and start looking for other likely candidates. At least I can keep this one and use it for parts.

So, cable-fiddling did nothing. It does seem to have ferrite around all the ribbon cables, have never seen anything like this before. It's hotglued to the PCB connectors it seems:

http://merope.crondor.net/~michel/forum/20201113-minolta-overview.jpg

But, what do we see on the left? Indeed:

http://merope.crondor.net/~michel/forum/20201113-minolta-cap.jpg

That looks somewhat suspicious. Unfortunately it looks like a surface-mount capacitor, I've never soldered SMD stuff before. Still, might be worth a try!

So, got the adapter today. I have to say build-wise it actually looks quite decent, sturdy construction and okayish finish. Definitely made in China, not in Japan, but good enough. Also, there's a connector that sorta fits...not quite, but good enough to make it turn on. That's about the end of the good news though, still wavy interference-like noise...

Some tests I did:

- fiddling/fudging with the tray (softly pushing it, or softly pulling it) does nothing at all to the noise pattern. I think this would eliminate anything caused by mechanical play, because then you would be able to see it

- moving the scanner: no effect

- reversing the AC plug also doesn't do anything ... little chance that this had effect, but easy to try

- i've been scanning a bit of fully exposed trailer of positive film, and there's also a sticker on this part. There's also noise in the sticker, which is opaque, so it's not related to anything in the film itself, must be in the analog part of the circuit before the conversion to digital (or bits are being flipped, but that would look differently i think?)

I'll open the thing up and start fiddling with cables at random. Also cheap to try, can't hurt you'd think, right? ;)

I'm not so sure. There could be some play in the transport mechanism that allows the slide to skew back and forth as it's stepped.

Ah that's a good point. If there's play in the mechanism I'm not sure what I could do to fix that. Lubricating it will probably not help much, but can't hurt to try it ...

My first suspect would still be electrical interference or PSU ripple, but check electrical cable proximity first.

 

I had a similar effect suddenly appear on one of my scanners. It turned out to be a mains cable that had got routed underneath the scanner. I moved the cable away and the scans cleared to normal.

I've ordered a new power supply, some kind of generic supply that can do 24V, by Ansmann, which is a reputable German brand (at least, I think it is). Probably won't be made in Germany, but you'd hope they would do proper QA on something that carries their name. Let's hope that this will improve things.

FWIW, my source of small pieces of ND gel has been a book of Lee Filters sample swatches of lighting gels. These used to be given free on request, but in these more frugal times I think there's a small charge for them these days.

Ah, nice idea. I'm also still searching for the IT8 targets I'm supposed to have somewhere. I'm sure I used to have them. But no clue where they are hiding currently :D :D

It's a "Delta C7690-84202 24v 0.84a" power supply with UK plug, which seems to be originally used for some HP scanner/printer, oddly enough. It has to be switch mode, it's one of these plug-type supplies. I will measure it hopefully tonight to see the ripple output. If there's substantial ripple in the output, the question is then, what supply do I get to replace it? The connector seems to be an EIAJ-03 connector, 5.0mm OD, 1.7mm ID, which is some kind of not very standard Japanese connector ... but I can always do a bit of soldering of course.

Wrt your idea of mechanical "stutter": the crop was taken from a slide in portrait orientation, so the wavy lines are perpendicular to the transport direction of the film, so that does not really make sense, right? I also unfortonately do not own ND gel filters, and it doesn't really make sense to buy something like that specifically for testing this. I will test with another film type.

It could be grain, but I have a hard time believing that grain, which is essentially random noise, could generate such moire-like pattens. I think interference can only happen when two frequencies interact in some way, and the white noise of the grain should not give this pattern. I will try to scan and enhance a different kind of film sometime, to be very sure.

I did notice slow scan speeds, the scanner was mechanically faster than the USB connection, which is a bit of a pity (it stopped and restarted several times during scanning). My system reported it as USB 2.0 high speed device, so it should be able to keep up, but apparently this is not the case.

My current plan of attack is to first double-check with another type of film, if I can repeat the wavy pattern, and then to check the noise levels in the power supply, using an old scope I still have.

I've recently acquired a Minolta Scan Dual III (yesss, finally a film scanner). However, the scanner exhibits an odd "wavy" noise pattern, mainly noticable in dark areas. The following sample show it clearly. This was taken from a color slide, scanned using VueScan. And yes, I did allow the scanner to warm up, and I did use the "Calibrate" function in VueScan prior to scanning (several times, even).

This is a 100% crop at full resolution with only basic sharpening applied:

http://merope.crondor.net/~michel/forum/20201107-noise-crop.png

Depending on screen brightness, the noise is actually pretty noticeable. To show it more clearly, I've extracted the green channel (in this channel, the noise is most noticeable) and increased the contrast a lot using levels:

http://merope.crondor.net/~michel/forum/20201107-noise-crop-green-leveled.png

Obviously, I would normally never do this, but it does serve to show that there appears to be some kind of issue. I've played around a bit with multi-sampling, which helps a bit, but the old adage of "garbage in, garbage out" applies here as well: if the individual scan is plagued by too much patterned noise, multi-sampling only does so much.

Does anybody have a clue as to what is happening here? My gut feeling says something related with interference due to maybe the non-original power supply, or possibly some kind of voltage stabilisation internally not working properly to maybe old capacitors? Is this a known issue perhaps?

Don't forget Bibble as an alternative. They recently released a

special x-mas version update with support for, among others, the

K10D. See <a

href=http://support.bibblelabs.com/webboard/viewtopic.php?t=6894>this</a>

topic. There also is a special unlock code available for testing

this version, see <a

href=http://support.bibblelabs.com/webboard/viewtopic.php?t=6914>here</a>.

Ahh ok. I wonder how I missed that! I thought it had a slight

yellowish tint (the often-described yellowing effect), when compared

with the Pentax-M 28mm I also bought that day, and thus concluded

that it probably contained the thorium element. Thanks for the

information.

I recently got my hands on a Pentax-K 50mm f/1.4 and I was wondering about any

radiation. The M42-variant of this lens is known to have a thorium element,

and I thought the Pentax-K version used the same lens design. Therefor I

suspected that the Pentax-K variant also had this element. I dropped the lens

off at my father's, to have him check it at work where he has access to a

Geiger counter, but the lens emitted no radiation at all. Can anyone confirm

that this lens indeed has a different design than the Takumar version? Not

that I'm really worried about the radiation, it just surprised me, and now I'm

curious about this lens.

Thank you for your responses. I contacted Mamiya by the way, but the

guy couldn't tell me much about the grease he used, he just ordered

it from Mamiya Japan ... I have obtained some moly grease, I don't

know if it's synthetic or not, I'll definitely check before applying

it.

I recently acquired a 150mm f/4 Mamiya-Sekor lens, but unfortunately

it included a free sample of tropical beach or somesuch--focusing

was 'gritty' and had an un-even un-smooth feel to it. I opened the

lens and removed lots of sand from it. I also removed the grease

from the helicoids. My question is: what kind of grease should I

replace it with? Specifically: what viscosity should be used, and

which properties should it have (acid-free, for example)? Somewhere

I remember reading that moly grease should be used, is this true?

<br>

<br>

Regards,<br>

<br>

Michel.

The Sigma 12-24 is available in Pentax mount, as far as I know, and

is definitely on my wishlist!

Derek: your teleconverter idea got me looking somewhat better. The

Russian lens is not bare metal, but it's barrel is wider, so that it

does make contact with the contacts of the mount. The Takumars are

less wide, and don't make contact. When shorting some of the

contacts to ground with some metal, focus indication works with the

Takumars as well. <br><br> Question is now, why did Pentax design

the MZ-5 this way? Obviously, the focus indicator works perfectly

with manual lenses! And, even more important, what is a good fix to

permanently make the indicator work? Shorting the contacts with some

conductive tape is not really an option, I use KAF-lenses as well,

and I want these to keep working...

Can't help you with the Cobra flash, but your assumption on zoom

heads seems correct. The viewing angle of the lens is the only thing

that should matter.

I have a Pentax MZ-5, a collection of old M42 lenses, and a K-mount

adapter for them. I observed that with one of the lenses (a Russian

20mm lens), the focus indicator of the MZ-5 works. With other

(Takumar) lenses, the focus indicator is not working! Both in MF and

AF mode, it will give no indication of focus. Releasing the shutter

in AF mode is possible, even when the indicator is not lit. With the

20mm lens, shutter release is blocked when the indicator is not lit!

What exactly is needed for the focus indicator to work? And why does

it work with the Russian lens, but not with my Pentax lenses....

I have the Pentax 80-320, but I can't say I'm really excited about

it, yet. It is f/5.6 at 320mm, but to be usable, you have to close

it down one stop at least, otherwise you will get a lot of light

falloff in the corners. At f/9.5 it performs well, although it is

not very sharp in the corners. But f/9.5 is painfully slow. And the

feel and construction of the lens is quite cheap ... too much

plastic. Then again, I'm used to solid all-metal Takumar M42 lenses,

so all the plastic was quite a shock to me.

The MZ-5n should have all of these, except MLU. Not sure about

DOF-preview though. Personally, I have a MZ-5, which lacks DOF

preview, MLU and exposure locking (which you probably would like to

have as well). For the rest, these cameras are a joy to work with,

the interface is brilliantly straightforward, manuals are definitely

not needed.

For wideangle, you could also consider the excellent Sigma 12-24mm

lens. As an added bonus, this is a fullframe lens (!) giving you an

awesome 12mm full frame rectilinear image. That's a 122 degree field

of view.

Shutter times can only be set in full stops. On all Mamiya lenses I

have, and have seen, the aperture ring only has clicks at full

stops, as Peter says. However, putting the ring in between clicks

works perfectly, even the metering prism will give proper indication

that way.

<br><br>

Regards,

<br><br>

Michel.

Thank you for your answers. I have examined the tubes a bit more,

with a lens mounted on them. When holding them at a certain angle,

pointed at a bright light source, I see a lot of reflections in the

tube, so it is probably indeed a case of internal reflections due to

bad coating.

<br>

Tonight I will be at my parents' house, I'll go through their stack

of old equipment, I sort-of remember them having another set of

tubes. Hopefully they will be better coated, and otherwise I'll

experiment somewhat with some black paint.

<br>

<br>

Michel.

The 105mm and 135mm lenses both work perfectly without the extension

tubes. I have put two sample pictures online.

<br>

<a href=http://oxygen.crondor.net/105mm-and-tube.jpg>Here</a> is a

(quite old

and bad) scan of a shot with the 105mm lens and the smallest

extension tube. The white 'spot' is not very noticable, but it is

definitely there. A loss of contrast is apparent in the middle of

the picture.

<br>

<a href=http://oxygen.crondor.net/135mm-and-tube.jpg>Here</a> is a

recent shot

of the 135mm with extension tube. The effect is much more severe

here, this is not a crop of the center, you see the entire slide

here. Maybe the effect is worse with the 135mm lens, or the slide

film might be showing the effect better. Anyway, it is definitely

not a usable combination.

<br>

As you say you have used the 105mm with tubes without problems

(beautiful flower shot, by the way!) it must be my extension tubes

then? Some sort of internal reflection problem which only happens

with the possibly larger image circle of these telelenses??

Hello,

Has anybody ever had success using extension tubes with the longer

(105mm and 135mm) Takumar telelenses (M42 mount version)? The few

times I used these lenses with my extension tubes I suffered from a

very ugly white 'spot' in the middle of the picture! Using them with

a 55mm lens doesn't give this spot ... what causes it, can it be

fixed, and how? I'd love to use a small extension tube with the

105mm, because the minimal focussing distance is quite large,

unfortunately...

Regards,

Michel.