Perhaps not made from a tank, but as heavy as one.

[daveh]

We wandered in to a few charity shops yesterday (Monday) and I came out with this Vivitar 400mm f5.6 pre-set with T2 fitting for £20. I perhaps wouldn't have paid that for it from a "normal" shop, bu the money goes to good use.
The lens:

Heavy is not the word. It is from that era when a 400mm lens was 400mm long. The filter size is 82mm. It must be more than 2 kilos, 4¹/₂ pounds in weight.

One of the first photos. f8 at 1/80 ISO 3200 - the light was poor all day. I have just realised this is the photo that I sharpened a fair bit - I did do an untouched version, but I'll have to look for that later.


Full frame taken from about 60 feet away.

[col]

"wandered in to a few charity shops"

I never dont that

[truls]

Lucky you having charity shops around... The lens must be needing a trailer to carry. The bokeh looks smooth.

[lloydy]

That's a nice lens, not a lens that will be used every day, but still a nice lens to have.
I just love charity shop bargains. If they're happy, I'm happy.

[daveh]

I've just sent for a lens hood. It might help the sharpness a little.

[Stephen]

A hood will not increase sharpness as such, it will increase contrast a bit, and therefore the apparent sharpness, as will slightly limiting the exposure for colour slide, but it might throw negs a bit unless you print them yourself.
With B/W film, yellow or red filters increase contrast and apparent sharpness.

The best aperture for the Vivitar is about 6.3 to 8. Don't forget the temperature, dismissed with standard lenses, higher heat affects long lenses, it can cause focus shift.

A huge leap in sharpness would be to use as high a shutter speed as possible, and as rigid a tripod as practical. It is surprising how much vibration and movement is caused by the camera, most reflexes are awful!!

The rise of the mirror is often only stopped by a bumper, foam or rubber, there are few designs with proper dampers, and this, plus the first blind can move the body quite a bit, almost unnoticed with a standard lens.

Also the iris closing mechanism can add vibration, although the Vivitar is manual, but don't forget even on manual, mechanisms are still moving in the camera body.

To test the maximum sharpness possible, use two tripods, one for the camera and one for the lens, and hang weights on each. This should reveal what is possible, and allow a test against one tripod and hand held, the results will surprise you!!

Stephen.

[daveh]

Stephen, in the end most of what we see is apparent sharpness. It's only when all other factors have been ruled out that we see the underlying sharpness.

Basically all the points you have raised above affect apparent sharpness - not the actual sharpness. The real sharpness of a lens is inherent in the lens and that can not be changed no matter what the operator does (barring things like dropping the lens) other than changing the f-stop. It, the sharpness, is a factor of design, engineering tolerances and of the glass used.

The f-stop makes a difference to sharpness, but less so as the quality of manufacture of the lens gets better - but then the price paid for that better quality is, well, it's in the price paid.

All the shutter speeds, and clamping of the camera and lens you like will not affect the sharpness of the lens: they will only affect the apparent sharpness.

Mind you, there could be argument that a lens hood is actually part of the lens. Indeed, some lenses have such a deeply recessed front element that they in effect have a lens hood permanently attached. Certainly I would argue that a lens hood is nearer to affecting real sharpness in a lens than does any of the "camera shake" items which have no bearing at all on the matter (unless there is something like a loose element).

[Stephen]

It is the camera motion blur, vibration, that is minimised on testing, "locked down" is impractical in actual use with a long lens.

Even minute fractions of a second of arc vibration mean a blur on the image. We made telescopes for theodolites, even the air causes wobbles!! It is actual sharpness that increases as they are locked down, the image becomes clearer in definition.

A locked down test is worthwhile, it shows how much real sharpness is available, or whether your chasing something the lens just cannot deliver.

The Vivitar should give good results, most less expensive telephotos do, they are simple lens formulae types, there very little to go wrong with them!!

STEPHEN.

[lloydy]

I use a simple method to test camera / lens shake on a tripod.

I set it all up, get a small dish, a jar top or something, about 2 inches diameter and as deep as I can find. Put some water in the dish, just a bit - don't fill it. And place the dish of water on the top of the camera, balance it on the hotshoe. Then remotely fire the camera and watch the ripples in the water. I have given away tripods after this test. Few survive.