Picture mystery fault:?:

[Peter Mugridge]

I have an interesting technical mystery here; wondering if anyone has any ideas:

Photographs perfectly exposed in the middle, but rather dark to one side and rather light at the other side. This is on the negatives as well, so it's not a D&P machine fault.

Now, as the camera is a 35mm SLR, my first thought was that the shutter and mirror might have gone out of synchronisation, but in that instance I would expect the fault to be horizontal rather than vertical.

Also, it is not on every picture; just some of them - and in some cases the dark bit is on the left and on the next frame it is on the right. So it's not consistent either. The film is in date - that was the first thing I checked. Neither is it a flare effect in the lens - the Sun was behind me at the time.

Scratching my head here as to a possible cause...



Unfortunately I cannot post up examples just yet - the pictures in question were taken under an Underground photo permit, one of the conditions of which is that the resulting pictures cannot be loaded up to the Internet. If this fault manifests itself on pictures taken elsewhere ( of which I did a few today ) then I will post an example or two up.

 

[Old Timer]

Peter,

It could be the shutter blind, if it is an old film camera.

I had a similar type of problem many, many years ago, but it sounds as if your shutter blind mechanism might be slightly distorted.

 

[K9-70]

Sounds like your shutter is out of sync with the speed range you were using.
You might need to leave your camera in for a full service.

Were you using a flash gun or on board flash at the time you were taking the photos ?
If so, did you have the correct speed set to operate with the flash, eg: 1/60th or 1/125th ?

K9-70

 

[DaveNewcastle]

I tend to agree with Old Timer that the shutter blind is very likely to be the element at fault, but I'm not so confident in assuming that its distored (because of the inconsistency of the error).
It may simply be a small particle of debris which sometimes obstructs (and consequently slows down) the timely closure of the aperture. Any delay will over expose the trailing side in the horizontal movement of the shutter. A deformation may be introduced if the occasional hesitation introduced by debris was persistent, so my analysis is not actually inconsistent with OT's - just slightly less confident!

 

[Peter Mugridge]

Ah.... so next time I change the film I should have a quick look to see if there is any visibly obvious debris in the blind? I assume this is the thing in the front that I see when I change the film; sort of like a metal curtain but with horizontal sections? Though surely if this is the cause it would result in the problem being top and bottom rather than side and side?

It's a Centon DF-300 which I have owned since new and it's double bagged to protect it from knocks; it lves in the original padded camera bag which in turn is carefully positioned within my shoulder bag.

K9-70, no - I wasn't using flash. This was on the railway, remember. Plus it was bright sunlight conditions; I was using ASA200 film ( Kodak ) with F8 at 1/500th shutter speed.

 

[Track Basher]

Peter,

I would go for faulty shutter as well.

A suggestion. When you change film with the camera empty take off the lens then set to B and see what is happening.

Just a thought. It is nothing to do with the processing as this is film not digital? I have had poorly processed film back in the past.

I can sympathise with you. I had a problem with my DSLR and it took me over a year to work out what was going on as the problem was intermittent. £100 later and fixed, back to normal.

 

[Peter Mugridge]

I had a look during a film change today - I think it may indeed be the blind out of synch; it is in fact a vertical one - I must have been thinking of my previous camera last night!

No obvious grit on the blind.

However it did occur to me that as the blind is somewhat bigger than the shutter it may be an early sign of the batteries getting low; I changed the batteries today and also used a slightly slower shutter speed with a smaller apperture ( figure that if the blind is out of synch it'll affect a faster speed more ); I'll see if that has made any difference - finished one film today with the new batteries in and I'll take it in tomorrow for collection on Wednesday and will report back.

Once my Underground permit expires and I can relax a bit I'll make sure to finish a film at the end of the day so I can look at it with the B stop open. What am I looking for? I'm guessing that when I press the button on B then I should not see any of the blind movement and that if I do then that's a definite diagnosis?

 

[Track Basher]

I am not convinced it is out of sync. This would more than likely be the same across the whole picture. The batteries is possible but again this is likely to be the whole picture.

When you set to B and press the shutter release does everything clear as it should. Don't forget everything is taken upside down. Is anything in the way? I have had another thought. After taking a shot do you wind on or wind on before the taking the shot. If you do the former this can stretch the shutter release spring as it is under tension all the time and become less efficient.

 

[blackfive460]

You have a problem with the camera's focal plane shutter. I used to see this a lot.
What is happening is that the two blinds are running at different speeds so, either the trailing blind is catching the leading blind as it runs across the focal plane or vice-versa.
It's unlikely to be a battery problem and the solution is either to get the camera serviced or buy a new one.
You may be able to see the effect if you remove the lens, open the back then, with the shutter speed set to a speed higher than 1/50th, hold the camera up to a fluorescent strip light so that the light can be seen across the frame then fire the shutter. As the fluorescent flashes 50 times a second you may be able to see a variation in brightness across the frame.
On the subject of should the camera be left with the shutter cocked or not; it shouldn't matter. I'd leave it cocked. You can easily miss that master shot when you forget.
If I were you, I'd bite the bullet and go digital!

 

[Peter Mugridge]

I don't leave it wound on, no.

Hmmm... I do know a good independent camera repair man as it happens...

Well, I will report further after collecting my prints tomorrow....


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Edited 27th July to add:

Interesting... of the two films I collected today, far fewer pictures are affected and none of the ones after I changed the batteries. The next film to be developed will be a critical test; it is nearly finished ( same day as previous film and so fully after the battery change ) so this should only be a few days to wait....

 

[Peter Mugridge]

.
.
Latest update: two further films collected; the majority of the pictures are unaffected - and indeed crystal sharp and well balanced - but the problem is still present and unpredictably intermittent.

I am going to try to get the thing repaired, but as it's a Centon rather than one of the better known names I'm guessing spares are more of a problem.

On the assumption that I may have to do what I don't want to do - go digital - I had a look at a couple of more reasonably priced DSLRs today and would like an opinion on which is the better choice for railway photography. The ones I looked at were:

Canon EOS 1000 at £349

Nikon 3100 at £399

Both seemed fairly similar in control functions and had a normal range up to ISO 3,200, though the Nikon could be pushed to ISO 12,800 (!) - I am wondering if using that sort of setting results in any excess drain on the battery or reduced picture quality?

For railway purposes, both have a manual focus mode so I can avoid the AF light problem, though I did find changing the settings rather more fiddly than with the film SLR; at least they both have knob controls rather than having to use a screen menu for everything.

But which to go for in the event that my film SLR cannot be repaired? ( I have a couple of older SLRs - Praktika - somewhere which might be possible to overhaul as a back up, but obviusly I do need to keep all my options open ).

 

[Track Basher]

Peter,

I would say the same as you until I tried it. I was an SLR user for many years but did not want to convert because of quality problems. Film was better than digital. I don't think this the case any longer. Digital is now better. I made the change nearly 4 years ago and have used my DSLR ever since.
It took me about 6 months to get it set up how I wanted it. I would never go back.

Things to watch out for:

Manual setting so that you can set the exposure and appature you wish particularly important in low light settings. Digital is much less forgiving in low light conditions.

Focal lengths are 1.5 x 35mm. A 50 mm lens is 75mm lens in the digital world.

I have found that digital cameras suffer more with internal light relection / refraction within the lens. The sensor on mine detects this and records on the image. Multi lens zoom lenses are worse. Much more of a problem in low light and trains fitted with spotlights. If you are going to take low light conditions a 35mm (50 mm equivelent) is a must have. Less elements so less chance of reflection / refraction problems.

Read some on line camera reviews.

Hope this helps

 

[blackfive460]

It's true to say that film has the capability of providing far better resolution than digital even with large sensor cameras but, from the sound of things, you wouldn't notice the difference.
If you are happy with the D&P prints you are currently getting from film then a similar service for digital images should be just as satisfactory.
The two cameras you mentioned will be quite capable of, for the most part, matching film up to A4 size prints. If you are going above A3 things might be different!
As to which is best; as someone has suggested, read as many on-line reviews as you can find to see if there are any obvious problems that will affect you and, after that, it comes down to personal preference.
One thing I will say about high ISO settings; while they do enable hand held shots in very dark conditions, the results can be very, very noisy and at worst, unusable so don't worry too much about that particular feature. The on-line reviews will usually show sample images so you'll see how bad they can be.
I suspect that, if you do decided to go digital you'll be more than happy. After all, you can take a lot more pictures for a lot less money.
If, on the other hand, you want to stick with film and can't get your camera repaired, there are still plenty of film cameras going second hand for bargain prices but I'd try for a better known name rather than another Centon. If you have other lenses for your existing camera, it could be worth looking for a Minolta as I think they shared the same bayonet mount but you'd need to check that as it's been a long time since I had to know about such things.

 

[DaveNewcastle]

I do not comment on the move to a digital camera, but looking again at your evidence from these latest imagtes . . .

. . . . . . the majority of the pictures are unaffected - and indeed crystal sharp and well balanced - but the problem is still present and unpredictably intermittent.

I am going to try to get the thing repaired, but . . . .

this confirms that its highly unlikely that anything has actually broken or become deformed or worn to the point of uselessness. It suggests that all the moving parts are perfectly capable of operating correctly, so if the cause is not simply a transient particle of debris it is still likely to be a minor misalignment of the trailing shutter which can sometimes delay its movement slightly. I wouldn't expect it to be an expensive adjustment or service, and maybe won't require any parts at all!

 

[jrhilton]

One big issue with film SLRs is actually getting hold of a newly made one if you want one. What is still being manufactured today for 35mm still is mainly rangefinder focused as that is the only sizable market.

Talk to a Canon or Nikon rep and you can soon wean out of them how low sales are for their top line film SLRs (1V and F6), and good luck getting a 1V or F6 that were manufactured in this decade....

Cosina still make them, and they are often branded as other makes (e.g Nikon FM10, or Zeiss models). I actually don’t know of any Chinese or Russian SLR makers still in business, and as far as I am aware the Cosina factory in Nagano Japan is the only place in the world still making film 35mm SLRs that are exported and sold around the world in any number (excluding lomo style things being made elsewhere).

Unless you are willing to buy second hand, you may have to end up going digital or spending a lot.

 

[Peter Mugridge]

I've e-mailed the repair bloke - awaiting a response...

 

[Bevan Price]

In addition to shutter problems, I suggest you try to check the movement of the iris. On many SLR's, the iris is fully open when you look through the viewfinder, but closes partly to give your f-stop setting when you activate the shutter. I had a Practica camera in which (after several years use), the iris tended to "stick" on occasion, giving uneven exposures across the image (or sometimes failed to stop down at all, giving grossly over-exposed slides.) Behaviour was totally unpredictable, and probably due to "wear & tear" of the iris mechanism.

 

[Peter Mugridge]

I've heard back from the repair man; I'll take it in later this month when the current film is finished ( my permit expired on Friday so I'm not shooting off dozens of frames a day now ).

 

[Peter Mugridge]

Took the camera in for repair today; the problem was quickly diagnosed - it's a lubrication fault with the apperture blind ( the multi segmented round one ). Examination of the lens under a bright light revealed the tell tale reflection of oil not being where it is supposed to be, resulting in this blind sometimes working slower than it should.

This is easily sorted, fortunately. So the camera is now in the repair queue at that place and should not take too long to do, although because of my working patterns ( I'll be covering for people in the next few weeks ) it'll be four weeks before I can pick it up.

The shutter and shutter blind tested OK when put on the special testing device ( forgotten what it's called! ) and tested several times at all shutter speeds.