UV or not UV

Why is a fair question.

A hood will serve to physically protect the lens for a start. An impact will likely be caught first by the hood which will avoid most possible causes of damage to the front element. It will shield the front element to some extent from spray and debris as well.

Most importantly, the hood shields the lens from unwanted light and therefore increases contrast and apparent sharpness. It reduces flare.

An ideal lens hood will mask off all the unwanted field of view whilst avoiding vignetting. This is why it's a real advance that these days most Pentax lenses have a dedicated lens hood.

To understand how a lens hood improves the image, stand outside on a bright day and then see how putting our hand above our eyes makes it so much easier to see clearly. This is what a lens hood achieves.

OK - all this makes sense

BUT [ here I go again ]

Why the difference in types of hoods ?

my kit DA-L 18-55 doesn't have one

The Samsung 18-55 has a 'flower petal' one [ I'm sure there's an official description of that ]

The Samsung 50-200 has a sort of Flower Pot one - not quite a tube , but it's not far off

I think ideally the lenses would all have "Flower pots", but the trouble is it would intrude into the frame for shorter length lenses. Most longer zooms, or primes, come with a simple hood - that said, my DA* 60-250 has a petal hood - perhaps the diameter of the front element of the lens is also a factor?

If your DA-L had its hood it would be the same as the Samsung 18-55mm one. The petal shape allows light into the corners of the image where needed, to avoid vignetting, and the long and short petals correspond to the long and short sides of the image shape.

Long lenses have a smaller field of view and generally need longer, deeper hoods to be effective.

Wide lenses need shorter hoods so they don't obscure the image area. There is more of a compromise the wider the lens gets, as it becomes very difficult to make a hood that shields the lens fully.

A very good "lens hood" is to stand in the shadow of a tree or building.

Thanks John

Now I get it.

OK will probably get a hood for the DA-L next month along with a few other bits and bobs I want .

I'm not going to put a Samsung marked hood on my Pentax lens - would look daft and anyway I wish to be able to sell the Samsung 18-55 so it will need it's hood

"Petal" is indeed what that type of hood is usually known as! The shape maximises the shading without obscuring the corners of the rectangular image on the sensor.

Ideally, your 50-200mm would have a petal shape hood as well, but because of the longer focal length, the hood can be long enough to provide a good amount of shading without needing to have an ideal shape. It's cheaper to design and make a simple barrel shape.

EDIT: Also the petal shape for a telephoto would be so subtle that it wouldn't be worth bothering.

The shorter the focal length, the shorter the hood must be, so the more efficient the shape needs to be for it to be of any use.

The DA L doesn't come with any hood at all because Pentax save money that way. That's the main reason. Maybe they also think people who like a lightweight lens also like to save some further weight by not having a hood. I do recommend buying one anyway, though. See the eBay link I posted above.

Or maybe to reduce the cost of the lens as much as possible for a different market segment. Do Pentax save money by doing this? Or is their profit margin actually the same or even less because the unit cost is lower overall?

A scratched filter can be replaced easily!
My filters do not affect my shots,(they are also inexpensive).
A scratched lens on the other hand, is very expensive to replace, and remember that accidents can happen to the best of us.

Sorry iceblinker but I don't agree with you and my lenses are always protected with a filter!

Filters break more easily than lenses, and a broken filter can damage the lens underneath it. Also a UV/glass filter can noticeably affect the image in some circumstances.

I've never scratched a lens in 26 years, and I've mostly used them without filters.

I also don't wear a helmet when walking along the pavement. Although if I did, I might take less care and fall and bang my head!

You're right. I should say: the lens doesn't come with a hood to reduce costs and to lower the price. Although the consumer doesn't save quite as much as they might first think if they want to buy a hood separately.

The filter issue (to get back to the OP) is an old debate which is unlikely to meet with any agreement. I use them because I usually work in very dirty and dusty places. The argument that it just adds another two surfaces to clean is spurious as only the outside face of the filter gets dirty. I am also puzzled that people who complain they degrade image quality will happily put a polariser or ND grad in front of their lens. When I can I use Pentax SMC filters and I doubt you could tell the difference.

In reality it is courses for horses. If you rarely work in dusty environments and are the sort of careful tidy person who doesn't have accidents, I wouldn't bother. If you do work in dirty, dusty environments and are a cack-handed chaotic accident-prone klutz like myself, I would (and do).

Now back to my glass of Hobgoblin...

K.

Because a polariser or ND grad adds an effect where an UV filter does so good as nothing on digital for your image so all it does is be there for protection.
Since it's the first glass the light will go through it does need some coatings to prevent flaring and glares since that's the main problem for filters and then you end up with quite a pricey filter that only is there for protection and then of course you need to weight down the pros against the cons.
Most of the time you then come to the conclusion it's better not to use an filter, of course there are exceptions.
If you take your camera always with you for a walk on the beach each weekend then with the salty air and the blow up sand it does make sense to use an filter to protect your lens but for an walk in the woods or on the streets I think you're better off without and use an hood to keep branches and zippers away from the front element.

ps. why does zippers turn out to be a spellings mistake, do you Brits have a different word for it?

Only if you leave it on all the time. Despite trying to be careful, I've found they get dirty on both sides when removing and storing in wallets. Shine an LED torch on your filter to check.

A recent thread on the forum proves that they do degrade image quality in some circumstances:

https://www.pentaxuser.com/forum/topic/strong-flare--effects--in-polluted-enviro...

Well - right at the beginning I had said that there were to two views - the "yes you should " and the" no you should not "

I almost said to DarstardlyDarcey that it was a case of you pays your money and you takes your choice

Stefan

you saidDo you mean zips - the things with teeth that you have a slider to mesh them together as you close the opening ?