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12-16-2007, 11:48 AM   #1
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18-250 and set mm lens is there a big differance.

Hi all Im new to taking picture ,I got my k10d to take pictures of teeth.Im a dental lab tech.But I have been taking a lot of picture out side the dental office .I don't know what the big deal is about the 14mm,20mm 50mm ect . that don't adjust. Is the pictures that much better than the 18-250 . I don't plan on selling anything I take a picture of .Im just finding out I like taking pictures. I love my k10d I got it last Christmas and I still don't know every thing about it . My wife is going to get me the af540 fgz flash this Christmas, thanks to people In this forum helping me deside on that one. I guess what I want to know will I be able to tell the differance in the pictures from the 18-250 and the single mm lens thanks for your help,Steve

12-16-2007, 12:11 PM   #2
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You're talking about the difference between a prime and an ultra zoom, so, yes you'd probably be able to tell. Usually primes are sharper, faster (better for low light/portraits) and smaller. As a trade off you lose the flexibility of a focal length range.
12-16-2007, 12:38 PM   #3
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thanks for that wengler ,does it make a differance in how the picture turns out if I get lens that are no a big range instead of 18-250 should I get something like 16-20 mm 21-40 mm lens like that . Can you or anyone out there take a picture with the lens of the 18-250mm set at say fiftymm and take the same picture with a fifty mm prime and point out the differances to me so I can see what the big deal is . Thanks again for your help, Steve

Last edited by pentaxk10duser; 12-16-2007 at 12:52 PM.
12-16-2007, 12:40 PM   #4
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Hi pentaxk10duser

Before doing anything else, I'd seriously suggest you check out the relevant information discussed in these previous posts:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/10438-tamron-1...amron+18-250mm

https://www.pentaxforums.com/forums/pentax-news-rumors/12646-pentax-18-250-he...amron+18-250mm

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/14513-anyone-h...amron+18-250mm

If the idea appeals of purchasing a general all-purpose 'walkaround' lens to start with, I can't recommend this lens highly enough. I bought Tamron's 18-250mm Di II superzoom earlier this year and certainly have no regrets about doing so. Like many other owners, I have been highly impressed by the optical sharpness of this lens. Many would argue that non-zoom (i.e. fixed 'prime' lenses) produce a better image, but if you're never going to produce prints bigger than say 10" x 8", I honestly don't think you're going to notice much if any difference. There are some obvious disadvantages in using prime lenses, not least the considerable cost involved, carting around the excess weight, missing shots whilst swapping lenses over and finally getting unwanted dust on the camera's digital sensor. It's truly a case of 'swings & roundabouts'.....the decision is yours !!

Best regards
Richard


Last edited by Confused; 12-16-2007 at 12:55 PM.
12-16-2007, 01:30 PM   #5
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QuoteOriginally posted by pentaxk10duser Quote
thanks for that wengler ,does it make a differance in how the picture turns out if I get lens that are no a big range instead of 18-250 should I get something like 16-20 mm 21-40 mm lens like that . Can you or anyone out there take a picture with the lens of the 18-250mm set at say fiftymm and take the same picture with a fifty mm prime and point out the differances to me so I can see what the big deal is . Thanks again for your help, Steve
There is no "big" deal. It is a "small" deal, but more important to some people than others, is all.
12-16-2007, 01:44 PM   #6
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QuoteOriginally posted by pentaxk10duser Quote
thanks for that wengler ,does it make a differance in how the picture turns out if I get lens that are no a big range instead of 18-250 should I get something like 16-20 mm 21-40 mm lens like that . Can you or anyone out there take a picture with the lens of the 18-250mm set at say fiftymm and take the same picture with a fifty mm prime and point out the differances to me so I can see what the big deal is . Thanks again for your help, Steve
Well say you had a 50mm f/1.4, then this lens is about 3 stops faster than the 18-250 which makes it better for low light situations. Assuming you use them at the same aperture (something like f/4) then sharpness would be the main difference. I don't think the 18-250 lens is of unacceptable quality but a prime will be sharper and better for low light. If you're getting a flash along with the 18-250 this will help a lot by making it usable indoors. What is your budget? What are all of the intended uses for your camera (i.e. type of photography)? Generally, smaller focal ranges tend to yield higher quality but sometimes convenience is more important.
12-16-2007, 02:10 PM   #7
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Ok I think im getting it now, but what I really want to know is how much better is the prime compared to 18-250 .Ill be using like a walkaround like cofused said above .I have looked at pics in the forum of the prime and 18-250 but I can't find one that someone has taken with both lens of the same picture say 40mm or 60mm or what ever setting so I can see for my self what the differance is .I only have one lens its the one that came with the camera 18-55. I will never print a picture bigger than 8x10.confused I looked at the pics you took with your 18-250 they look great to me .Can the pentax 18-250 do anything that the tanron 18-250 can do on a k10d or vice verca thanks again for your help Im learning a lot here this is a great forum. Steve
12-16-2007, 02:33 PM   #8
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First, on the prime vs zoom debate, google will help. Here are the first links I got on the topic Prime vs Zoom Lenses - Which are Best?, Timothy Edberg Photo Tip: Zoom vs. Prime Lenses, Lenses - Prime vs Zoom, which is better?

Second; the Pentax vs Tamron 18-250 debate. The jury is still out on which one is better. Todate, I have not seen a side by side comparison of images from these two lenses. Regarding the build, some have reported feeling them and not noticing any difference, one person said the pentax felt better. There is also an ongoing discussion on the coating as in.. would the pentax coating make it better. But one wisely pointed out that Tamron has its own coating which may actually be as good.

My reading is many who have found themselves in your situation have found the 6 year US warranty of the tamron very attractive.

So, for a walkabout solution to weight, the 18-250 is perfect replacement to the 18-55 and 50-200 combo. It will suffice for most day to day shooting in good light conditions ("tourist shooting") and you will zoom your way into happiness [you will not miss another daylight shot because you had the wrong lens on]. However, I fear you may not be as happy in low light and night time conditions which is when a fast prime would be your best friend.

12-16-2007, 02:58 PM   #9
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If you bought the camera for dental work, I would imagine a macro lens and a ring flash are your top priorities if you don't already have those.

As for the primes versus zoom. At one time, zoom lenses were far inferior to what a prime can do. However, zoom lenses have gotten better; meanwhile prime lenses haven't really...since there was little room to improve those to begin with.

I just got the Pentax 18-250 lens as a gift and just came back after a quick outing with it. All I can say is wow. This lens is a sharp performer. I did notice a little corner vignetting wide at 18mm but nothing to really cry about. So far, I am very pleased with this lens.
12-16-2007, 03:15 PM   #10
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Thanks for the web sight that was great readings .I didnt know there was a debate about it.looks like the pictures differance is't that much differance if I use my new af 540 flash ,well I have It, but my wife has it hid somewhere in the house and she won't even let me look at it ,Its a christmas present She got it today its killing me lol. I told her i needed to read about it so I could take picture of the kids on christmas day shes not going for it . thanks for all the help ,Steve
12-16-2007, 03:38 PM   #11
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Hi pentaxk10duser

Here are some other shots I posted a while ago....see what you make of them ?

https://www.pentaxforums.com/forums/85055-post8.html

As for your comment that:

QuoteQuote:
my wife has it hid somewhere in the house
......you do realise that if you pay me ENOUGH, I'll reveal precisely which floorboard it's concealed under......
......doh, I nearly gave the game away........when will I ever learn to keep my 'big trap' door shut !
You've got a trap-door ? It might be worth a look under it, just in case ? Ah, a briefcase......have you checked it lately ?
I bet she's stuffed it inside the turkey, to be on the safe side ? Hey, this game is fun........don't worry, it'll be over in a "flash" !
Inci"dentally", I'm no expert but I can't help thinking that a 'ring-flash' of some description would give a more even light for close-up dental work ? Purely my 2-cents worth.....

QuoteQuote:
Can the pentax 18-250 do anything that the tamron 18-250 can do on a k10d or vice verca
To all intents and purposes, dimension-wise their pretty much identical as far as I can make out.
The Pentax has *SMC (Super Multi Coating) on some of it's elements, but the Tamron also has excellent coatings, so I wouldn't worry on that account !

* See:

About Super-Multi Coating (SMC)

In conclusion, I entirely agree with Chako when he said:
QuoteQuote:
I just got the Pentax 18-250 lens........All I can say is wow. This lens is a sharp performer.
Best regards
Richard

Last edited by Confused; 12-18-2007 at 12:32 PM.
12-16-2007, 04:04 PM   #12
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I have a ring light not a ring flash the flash makes the top part of the tooth turn blue I want it to look like it really is it helps me when I make the crown .my sister is a dentist ans shes got a cannon and a 100mm lens and a ring flash the set up cost her 4,000 lol she can't get no where close to what mine looks like lol and it is so heavy the girls in the office can't hold it up lol ,I send her pictures from time to time just to rub it in lol. here is a pic I took that helps me to make a crown. thanks again for the help ,Steve

Last edited by pentaxk10duser; 03-20-2014 at 12:24 PM.
12-16-2007, 05:35 PM   #13
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Hi pentaxk10duser

This is what Matix had to say on the subject of Macro photography:

QuoteQuote:
The Tamron 18-250 will focus down to about 8.5" from the subject, and using it at 18mm the object is still pretty small.

Luckily, the minimum focus distance of 8.5" is the same throughout the zoom range, so by zooming in you can in effect, shoot a Macro or an image that takes up most of the field of view.

This is what a Macro is, an in focus shot that fills the screen or field fo view, so you have a high res image that you do not have to enlarge to see, losing the resolution in the process.

Phil
Best regards
Richard
12-16-2007, 05:54 PM   #14
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Confused will you take a pic with your 18-250 and get as close as you can and still be in focus at the 250mm zoom and put it in this string ,thanks Steve
12-18-2007, 12:25 PM   #15
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Hi pentaxk10duser

Sorry it's taken a while to get back to you, but here's an indoor 'macro' shot (it was too cold outside !!) using the 250mm end of the Tamron Di II. The camera was firmly attached to a tripod and positioned approx 9" directly above & parallel to the subject matter, utilising the self-timer in order to prevent any vibration. The coins (R: 50p, L: 2.00) were lit by a single lightbulb and the photo has been corrected to 6500K so as to remove the unavoidable colour-cast. It has then been reduced to 800 x 536 pixels, to meet with forum requirements. You may notice a small amount of vignetting, but unfortunately my old Version 8 of Paint Shop Pro has no means of removing this ! Anyhow, I hope this is the kind of illustration you required ?

Best regards
Richard
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Last edited by Confused; 12-18-2007 at 12:36 PM.
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