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01-08-2007, 08:41 PM   #1
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Help! My 1st Lens... 18-55mm or 16-45?

Hello all,

First post + First DSLR (almost) = First shout for lens advice.

This is my first post and it's a frantic one. Just today I made it to a camera shop and got my hands on the K100D for the first time - and it's the 'one'. :-)

So I am now rushing to order one before the rebate window ends tomorrow - and I would appreciate your thoughts on my idea of a first lens.

On my budget I can either get the K100d with the kit 18-55 *or* (with the $70 'saved' from a body only plus the $100 rebate,) I can get the "Pentax DA 16-45mm f/4.0 ED AL" lens *instead*.

I'm looking at the 16-45mm (instead of the 18-55mm) simply because I'm typically frustrated with the 'narrow' field of view my 28mm gives on my film-SLR which (at X1.5) should be roughly equivalent (ie. 18-55mm on DSLR * 1.5 ~= 28-80mm on SLR). What I don't know is how much of a difference in field of view that 2mm difference makes... but I'll take what I can get (and I can't find anything else in my budget that is wider than the 16mm).

So... are there any 'quality' issues I should know about between the 16-45mm and the 18-55mm? Can someone point me to a resource which would suggest why one might be better suited for purpose x/y/z than the other?

Also, is there an easy formula to determine what the viewing angle of x lens is on a DSLR? For example the angle of view for the 16-45mm is listed as 83-35 degrees. Is the angle of view now equal to it's equivalent (on film), a 24-68mm lens?

And in a more general (and less frenzied note), can someone point me to resources (in addition to the "Lens Review Database") that would (for example) help someone unfamiliar with the Pentax lineup compare lenses? For example the difference between the "J" and non-J versions of the "Pentax SMC FA 28-80mm f/3.5-5.6" and to tell me of it's general quality/distortions/etc.

Note: Found "Lens Review Database"

Or/And is it okay to start a thread (for example) simply stating that "I only have $60 to spend on a telephoto zoom... is the Pentax SMC FA J 28-80mm f/3.5-5.6 'worth' purchasing, or would you suggest something else?"

Please forgive any search failings / abruptness / poor grammar / etc - just last week I was about to order a Nikon (which I had researched for weeks)... and now having thrown that out the window (so to speak) after a single demo session at the camera shop, and with less than 18 hours to choose my kit and order, I'm a bit stressed... But at least I found this forum. :-)

Thank you for reading this... it's all quite a bit to push in to my head.

Thanks - Don


Last edited by Cedar; 02-01-2007 at 01:59 PM. Reason: fixed some (but not all) grammar problems. :-)
01-08-2007, 08:50 PM   #2
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If you want a wide angle lens you should not really rely on the kit 18-55. It's not a wide angle lens, it's a normal street zoom. The 16-45 is much better, but also bigger and has ED glass. If you KNOW that you want that kind of lens, then it's a very good choice. There's no such thing as a good $60 telephoto zoom unless you get it used. Check out e-bay, and don't be in such a hurry. I would stay away from any FA-J lenses if possible.
01-08-2007, 09:23 PM   #3
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QuoteOriginally posted by Lipo Quote
The 16-45 is much better, but also bigger and has ED glass. If you KNOW that you want that kind of lens, then it's a very good choice.
Thank you for your quick response.

I know I want wide... and the 16-45 both seems to have good reviews and is the widest lens I can afford. :-) Although the 10-17mm FishEye is also definitely in my future... Oh No! LBD already!


QuoteOriginally posted by Lipo Quote
There's no such thing as a good $60 telephoto zoom unless you get it used. Check out e-bay, and don't be in such a hurry. I would stay away from any FA-J lenses if possible.
Why how did you guess that the 28-80mm was on ebay. :-) I used the $60 as a for example. It could have been $100/$1000/$10,000... I was just asking if such a 'focused' inquiry was generally welcomed, and any suggestions on where to find reviews (and hopefully sample images) besides the local Lens Database :-)

If anyone is interested, a discussion of 'for example' 28-80mm is linked below... but my question is for good pleaces to find 'reviews'. :-)
Link: Pentax Forum: Pentax SMC FA J 28-80mm f/3.5-5.6 Autofocus Zoom Lens thanks google!

QuoteOriginally posted by Lipo Quote
I would stay away from any FA-J lenses if possible.
That's exactly the kind of 'background knowledge' I'm looking for - perhaps in a 'tutorial site'.

And are you suggesting that the FA is generally 'better' than the FA-J, or that both should be avoided?

Do you know where a description of not only what the (again, for example) "J" designates, but also 'means' to a photographer.

Thanks! - Don

Last edited by Cedar; 02-01-2007 at 01:59 PM. Reason: fixed some of my mix-mash. added link
01-08-2007, 10:22 PM   #4
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16-45 all the way. The difference of 2mm on the low end is much more noticeable than you would think. At the long end 2mm is negligible.

16 will get you into the reasonable wide range, though at the cost of size and weight.

Here's a lens link:
Pentax lens overview for Digital Cameras - DCVIEWS

01-08-2007, 11:01 PM   #5
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QuoteOriginally posted by SpecialK Quote
16-45 all the way. The difference of 2mm on the low end is much more noticeable than you would think. At the long end 2mm is negligible.
...
Here's a lens link:
Thank you. The link will be very handy.

I have seen the difference in stated view angles(max 83' for the 16mm and 76' for the 18mm), (and have experienced the difference between 18mm and 28mm 'maximums' on my film SLR), but I didn't/don't know if the angles were for a film or digital SLR - which would be nice for comparing and shopping for the next lens.

It seemed like an obvious 'upgrade' for someone who wants to go wide... and I just can't justify the $ to have the both (with an almost total overlap)... unless the 18-55mm "has other abilities" than or has better image quality than the 16-45.

One newbie thing I wondered about was that while the 16-45mm is rated straight f4... the 18-55mm is f3.5-5.6. I assume this makes the 18-45mm 'faster' at 18mm than the 16-55mm at 18mm, but 'slower' (less light) at some number X (which I don't know how to find). How noticible is the image quality 'shift' due to the difference in f3.5 to f4, (or from f4 to 5.6) (due to the corresponding change in shutter speed and/or ISO sensitivity) in A size or smaller prints? See... I told you I was new. :-)

Thanks again. - Don

Last edited by Cedar; 02-01-2007 at 01:59 PM. Reason: clarification
01-09-2007, 12:13 AM   #6
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Area = pi R^2. The f-stop change doubles the amount of light for each stop.

...2, 2.8, 4, 5.6, 8, 11, 16, 22, 32...

So... 3.5 vs 4 is about 1/2 stop, and 4 to 5.6 is a full stop.
01-09-2007, 12:47 AM   #7
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In my case I went with the 18-55mm because I needed a little more length. In your case from reading your opening statement, I would recommend spending the extra cash and buying the 16-45.

My wife went the other way and definitely wanted the "fishbowl". https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/2138-i-caught-fish.html Be careful with this lens. It can be tricky.

I'm saving up for my telephoto. Think of spending a little over $100 USD for a used telephoto in semi decent shape and to me that price is questionable. $60 is too little for a telephoto - I won't buy it.
01-09-2007, 01:16 AM   #8
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QuoteOriginally posted by SpecialK Quote
Area = pi R^2.
Sure. The math I'm missing (and which I doubt is an even curve anyway), is how to determine at which focal range the f3.5-5.6 18-55mm becomes 'slower' than f4, and hence 'slower' than the 16-45mm. Not that once I have my camera I'll probably care much about the math, only the results. :-)

What I was wondering is, and what I have no idea how to quantify... is how much the loss in IQ (say to higher ISO sensitivity) that a .5 or 1 stop of aperture is going to "cost" at 8.5x11 size or smaller prints. I'm rather certain that the answer is, as it always is... it depends. But I'm wondering if *generally* this is it something most people c/would be able to see?

As to the angle of view for a lens, I assume (but may well be wrong) that a 18mm lens which has a maximum wideness of 100*, when used on a DSLR has a maximum view wideness of a 28mm lens on a film SLR, IE, ~75*.

- Don


Last edited by Cedar; 02-01-2007 at 02:00 PM.
01-09-2007, 01:46 AM   #9
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QuoteOriginally posted by Alvin Quote
In my case I went with the 18-55mm because I needed a little more length. In your case from reading your opening statement, I would recommend spending the extra cash and buying the 16-45. My wife went the other way and definitely wanted the "fishbowl"
Thanks. Ever since I did the math I've been heavily favoring the 16-45mm... even if it does put my next glass purchase back a bit. :-)

I think I'm just worried about pitfalls the 16-45mm might have, or any amazing qualities (digital glass???) which the 18-55mm might have, which my rushed research might have missed.

I don't think I'll miss the extra reach of the effective 68mm vs 82mm (must stop thinking in film), as I'm thinking more of landscapes, architecture, and groups in small spaces rather than needing much reach. That will be another lens. :-)

Besides, my lovely wife will keep using her film SLR, and I'll have the K100d all to myself for as long as I don't buy a more 'powerful' zoom. No kidding. So maybe my next lens won't be a mid-range zoom after all.... perhaps it will be time for the 10-17mm FE. :-) And not to be a 'spoil sport', but how well does PTLens do on the 10-17?

QuoteOriginally posted by Alvin Quote
$60 is too little for a telephoto - I won't buy it.
Scary huh? My question wasn't so much about those two lenses, but how to better research lenses. I just can't seem to get google to find reviews that would explain the relative merits of the (again, only for example) the "Pentax SMC FA J 28-80mm f/3.5-5.6" vs the non "J" version.

And after looking at KEH's site, I have to ask how to tell which lenses have camera controlled apertures. Auto focus vs manual focus is easy enough, but I do care about thru camera metering, and camera controlled apertures are indispensable for those snap shots. Bah. More newbie questions. :-)

Thanks for the responses. - Don

Last edited by Cedar; 02-01-2007 at 01:59 PM.
01-09-2007, 06:57 AM   #10
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There are other conciderations -

The 18-55 focuses to 10" for a magnification of 1:3, it weighs 7.9oz and is 2.7 x 2.7 in length x diameter
The 16-45 focuses to 10.8" for a magnification of 1:3.8, and weighs 13oz and is 3.6x2.8 lengthxdiameter

In other words, you'll get a bit closer with the kit lens, and save a bit of weight and size.

Also, the 16-45 gets longer the wider you go, and will interfere with the built in flash at some point as you're zooming wide.

Those are the negatives. I have the 16-45, I'm using it on a film body, and I can report it's a wonderful lens: very sharp and concentrated, with great color rendition. A super lens, better optics than the kit.

So it's a trade-off, like anything else.

Re. the rebates, I bought mine when another rebate was about to expire. Pentax put out another, identical, rebate right when the other one expired. They are likely to do so again, or, if not, the I think the selling prices might come down to compensate.
01-09-2007, 12:28 PM   #11
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QuoteOriginally posted by Nesster Quote
There are other conciderations -
...
In other words, you'll get a bit closer with the kit lens, and save a bit of weight and size.

Also, the 16-45 gets longer the wider you go, and will interfere with the built in flash at some point as you're zooming wide.
Thanks for bringing up these points.

I don't recall ever shooting closer than 1ft so the focus isn't really a concern, but you mention the built in flash casting shadows with the 16-45 extended. Would this (due to the angle) be less likely with a hot shoe flash? On film I avoid direct flash by using a homemade bounce card or diffuser (and I always forget to use fill flash), so a Pentax compatible flash will actually precede any other lens purchases.

I'm somewhat sensitive to the size issue (but will put up with it for superior images), but is the weight concern generally about hand balancing the camera or lugging it around? If about balance, have you found the weight of the 16-45mm to be difficult to hand balance?

QuoteOriginally posted by Nesster Quote
Re. the rebates, I bought mine when another rebate was about to expire. Pentax put out another, identical, rebate right when the other one expired. They are likely to do so again, or, if not, the I think the selling prices might come down to compensate.
Nesster, from your keys to Pentax's ears. And I hope I haven't just offended anyone.

Thank you all for helping to reassure me that my idea to swap out the kit lens for the 16-45mm isn't a totally foolhardy move. Unless a wider zoom at a similar price comes out, I'm pretty sure I'd be getting it anyway, and I just can't justify also buying a (mostly overlapping) 18-55mm - at least not until after a flash, the fish, a mid-zoom, lowlight prime, etc. :-)

Hello... my name is Don... and I'm excited about photography again. That's step 1 right?

- Don

Last edited by Cedar; 02-01-2007 at 02:00 PM.
01-09-2007, 02:51 PM   #12
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LOL, Don, the rest of the steps go faster and faster till you've spent all of next year's income!

As the lens zooms 'out' when 'wider' (opposite of what's typical) the interference with built in flash is somewhat moot - the flash won't cover past a certain width in any case. But I've got some nifty shadows to show... There have been threads, either here or elsewhere, on this issue. A hot shoe flash won't have the problem as it's higher up.

I shoot a pz10 which I think is even lighter than the K100D, or in the same ballpark. I don't find the balance is bad at all, and figure I'd rather have the lugging weight in the good lens than in the bigger body. If anything, the camera with it's kit lens (from the 35mm era) is a bit too light.

I bought the lens so that the sticker shock when I buy the actual digital body will be that much less, and I'm already having a blast with it.

For low light situations, you'll end up with the lens-mania: a prime lens, and/or like me, I have an old Tamron SP 35-80 that's a decent macro AND has a max aperture of 2.5-3.8. I figure autofocus gets a bit balky in macro and low light anyhow...

I say: go for it! The K100D + 16-45 + flash is still cheaper (I think) than K10D + kit lens! IMHO you'll have the potential for technically better photos with the first kit than with the second.
01-09-2007, 03:09 PM   #13
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Go for DA 16-45mm/f4

I've tried DA 18-55/f3,5-5,6 shortly and it is definately not as good optically as DA 16-45mm/f4.

If you can get both lenses for the same prise, definately go for DA 16-45mm/f4.
01-10-2007, 01:17 PM   #14
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QuoteOriginally posted by Cedar Quote
Thank you all for helping to reassure me that my idea to swap out the kit lens for the 16-45mm isn't a totally foolhardy move.

...

Hello... my name is Don... and I'm excited about photography again. That's step 1 right?
Yeah, what he/I said.

At the last moment (for the rebates) I did indeed place an order for the K100D (body only) and the 16-45mm.

Now I just have to wait...... nope... nope... still not on my porch... where is that truck?

If it goes well I'll be posting in a few months (when I remember to start eating again), or possibly sooner if it's 'not so well'. :-)

Thanks again.

- Don "Patience is step 2??? How long will that take?" Cedar

Last edited by Cedar; 02-01-2007 at 01:58 PM.
01-10-2007, 06:23 PM   #15
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You made the right choice, Don. Have fun. I "almost" wish I got the 16-45 instead of my Sigma 18-50 , but f2.8 won out, at a cost of an extra $75 and 3 ounces...
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