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Forum: Pentax SLR Lens Discussion 05-27-2018, 03:24 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
IF you

go up to Lenses above and look at the reviews of the lenses

YOU

may be able to find info about the lenses so you can learn many of the answers to your questions

SMC Pentax-DA 18-135mm F3.5-5.6 ED AL [IF] DC WR Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database

Max. Magnification
0.24x

Diam x Length 73 x 76 mm (2.9 x 3.0 in.)

Weight 405 g (14.3 oz.)


Read more at: https://www.pentaxforums.com/lensreviews/SMC-Pentax-DA-18-135mm-F3.5-5.6-ED-...#ixzz5GhFZyHR6
Forum: Pentax SLR Lens Discussion 05-26-2018, 11:05 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
Thanks for helping me understand your valid points
Forum: Pentax SLR Lens Discussion 05-26-2018, 04:24 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
I own the K 3 and K 3 II with their ASP-C " crop " sensors and the following lenses:

SMC Pentax-D FA 2.8 100 mm macro [ not WR ]

HD Pentax-D FA* 70-200mm F2.8 ED DC AW

HD Pentax-D FA 4.5 - 5.6 150-450mm ED DC AW

I have never thought of or worried that the light allowed to the sensor by the lens is larger than the sensor itself

I don't see the harm of it

I bought the lenses for their quality

but then I am a newbie eager to learn

having said all that on the crop sensor a 24mm gives a field of view which is not a wide angle field of view
Forum: Pentax SLR Lens Discussion 05-25-2018, 02:47 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
have you looked at the user reviews for the third party lens yet?

Pentax Lenses by Sigma, Tamron, Zeiss, and more - Reviews and Specification Database - Pentax Lens Review Database

here is the link for the reviews for the Pentax lenses

Pentax Lenses - Pentax Lens Reviews & Lens Database
Forum: Pentax SLR Lens Discussion 05-25-2018, 02:30 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
I hold the international copy rights to all stupid and/or silly questions but I allow others to use them without charge

it is possible that you had a badly made lens, it happens

as far as doing anything special with an HD lens, I use mine just like my other lenses.

I currently have:

HD Pentax DA 3.5-5.6 16 - 85 mm wr 72 f

HD Pentax-D FA* 70-200mm F2.8 ED DC AW 77 f

HD Pentax-D FA 4.5 - 5.6 150-450mm ED DC AW 86 f

HD Pentax -DA af rear converter 1.4 AW

____________________________________________


HD is just the coating placed onto the lens

" Lens Coating

The lens name prefix smc or HD indicates the type of coating. SMC stands for Super Multi Coating and was introduced back in the 1960'es. Naturally this coating has evolved and been improved over time. HD stands for High Definition and is a new coating introduced in 2012. The purpose of a lens coating is to reduce light loss as light rays travel through the lens elements and also to reduce stray light reflecting off the lens element surfaces. The net effect is less flare, less ghosting and better contrast.
Certain budget lenses from the film era lack SMC or HD coating and have no smc or HD prefix in their name. "

here are a couple of articles discussing the difference between lenses made with the SMC coating ( the older style ) and the new HD coating

Pentax Launches New HD Limited Lenses - Pentax Announcements | PentaxForums.com

Farewell to flare? Pentax’s HD Limited lens lineup gets a real-world test

______

" Lens Name Suffixes
The following abbreviations are used in lens names:

AL: Aspheric Lens. Special lens elements that improves the optical quality. Particularly valuable in wide angle lenses.
AW: All Weather. The highest degree of sealing against dust and rain.
DC, PLM or SDM: The lens has a built-in motor for autofocus (K10D, K100D and newer cameras can take advantage of this).
ED: Extra-low Dispersion. Special glass material which helps reduce chromatic aberration. Particularly valuable in tele photo lenses.
IF: Internal focusing. Focusing is achieved by moving lens elements within the lens. The lens barrel doesn't move. IF lenses generally focus faster than ordinary lenses.
RE: Retractable lens. The lens collapses in length when not in use.
XS: Lenses with an exterior design by Mark Newson matching the Pentax K-01. Works like an ordinary DA lens.
WR: Weather Resistant. The lens is sealed against dust and light rain.

http://www.mosphotos.com/PentaxLensesExplained.html

________________

pn most zooms, the aperture changes as you change focal length

a constant aperture zoom lens allows you to use the same aperture, should you choose to do so, at any focal length

the F2.8 70 - 200mm zoom allows me to use F2.8 at 70mm all the way to 200mm.

What is a Constant Aperture Lens

__________________________________________________

I will let the folks with better knowledge reply to your other questions
Forum: Pentax SLR Lens Discussion 05-24-2018, 04:51 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
another thought

if you are willing to go the route of " experienced " lenses I have had good luck buying from members via the forum's Market Place " buy/sell " above

you can even search the postings by country if you wish
Forum: Pentax SLR Lens Discussion 05-24-2018, 04:12 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
I have another suggestion as well

consider checking with the companies that rent photography equipment and the cost of doing your own " trials ' if any lenses they carry might be of interest

I have used LensRentals.com with success but their may be other companies as well
Forum: Pentax SLR Lens Discussion 05-24-2018, 03:59 AM  
Need Advice For Secondary Zoom Lens
Posted By aslyfox
Replies: 37
Views: 2,918
Welcome

you have come to the right place for advice ( especially on spending your $ )

are you aware you can go up to " Lenses " above and find reviews of all Pentax lenses ( both by users and " in depth " ) and of many third party lenses ( users )

sorry to hear of your experience with " H D " coatings , I was going to recommend one of my favorites

HD Pentax-DA 16-85mm F3.5-5.6 ED DC WR

HD Pentax-DA 16-85mm F3.5-5.6 Review - Introduction | PentaxForums.com Reviews

it seems to work for many of us

DA 16-85 WR,show us what it can do. - PentaxForums.com

since I have that one, I don't have experience with the ones you list

if you can be more specific with your problems with the H D coating, perhaps someone here might be able to help you out?
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