[Isnwm]

First and foremost, I want to introduce myself. I am a beginner, living in Austin, Tx. I just bought my Pentax K-5 about 2 weeks ago. I have the kit lens 18-55, a tamron 28-300 3.5-5.6, Pentax A50mm/2.0, Zenitar 16mm. I'm just getting into photography as a hobby. I work out of town for two weeks at a time, then I'm off work for a week. So I'm picking this up to have something to do during my time away from work. If it turns into something I can do part time, and maybe shoot be wedding a month, then great. But that's not my intentions right now.

Ok, all that being said, now I have a question. I went to my cousins wedding and shot about 350 pictures just for the practice. It was ugly. Real ugly. Anything shot in the church was dark, and not good. I was advised to use my 50 because it has a fixed aperture and shouldve shot sharp enough pictures that I could crop to zoom and make them large enough. So, then we go to the reception and I get the chance to talk to their photographer and pick his brain and find out what he's shooting with. He had a Canon 5D with a 24-70 f/2.8. He called it a prime lens because the aperture stays at 2.8 no matter what his focal length is. What amazed me was how FAST his focus was. He just threw his arm out to the side,immediately clicked, and pulled his camera back towards me to show me the picture. It was RAZOR SHARP. No blur, perfect lighting, everything. It was jaw dropping. I know a lot of that has to do with the iso, and his flash, but the speed that his lens focused, was unreal. What lens do they make for us Pentax users that are capable of those results ? I'm kinda looking at the sigma 24-70 f/2.8, but wasn't sure if anyone could recommend for or against it ? Does it have that fixed aperture through the entire lens ? Is it a lightning quick focus lens in low light situations ? Any advice would be greatly appreciated. Thank you in advance for your help.

[veato]

A prime lens has a fixed focal length not fixed aperture. For example your A50 is a prime lens. His 24-70 is not.

Fixed aperture would infact be a pretty bad thing as it would severely limit the usefulness of the lens. What you want (I what I think you mean) is a constant aperture. The Sigma 17-70 f/2.8-4.5 changes its maximum aperture depending on focal length (e.g f/2.8 @ 17mm to f/4.5 @ 70mm) whereas a lens like the Tamron 17-50 f/2.8 has a constant usable f/2.8 throughout the focal range (e.g. f/2.8 @ 17mm to f/2.8 @ 50mm).

[northcoastgreg]

The Canon 5D is a full frame camera with professional class features. The Pentax has a small APS-C sensor; so a 24-70 lens would give a different field-of-view on the Pentax camera. Also, I would expect the Canon 5D to focus faster than the Pentax K-5, particularly in low light (although whether the differences in speed are all that critical might be debatable). Keep in mind, the Canon 5D, when it first came out, sold for over $3,000, which is twice the price of the K-5.

The equivalent lens for the Pentax would be something like the DA* 16-50. That lens has a reputation for focusing slowly. Not sure if it can keep up, AF wise, with a Canon 5D matched with a 24-70/2.8. But a good copy of the 16-50 will deliver sharp images with stunning color.

All zoom lenses described by a single aperture number are fixed aperture. If they are variable aperture, they will give two apertures, like the DA 18-55 f3.5-5.6. All the readily available fixed aperture f2.8 zoom lenses are pretty good, whether made my Pentax, Tamron, or Sigma.

I know a lot of that has to do with the iso

Well actually I don't think it had a lot to do with the iso, as the Pentax K-5 is very capable in that respect. It had to do with the fact that the professional photographer had an expensive camera, lens, and flash and that he had a lot of experience using this equipment. You can come close to matching what the Canon shooter had with a Pentax system, without quite equalling him. Pentax has no full-frame professional camera; inferior AF in low light; inferior flash system; top zoom glass tends to focus slower. But these differences may not amount to much; skill in using equipment is even more important. Pentax has advantages in smaller size cameras and lenses (which can be quite important if you have to handhold your gear for a long wedding shoot) and, IMO, lenses that render more beautifully.

[jatrax]

Pentax A50mm/2.0

This is an OK lens but for natural light in a church the f/1.4 would be better. The problem with these lenses is that wide open the depth of focus is extremely small, sometimes only an inch or so. An inexperienced photographer in low light with lens @ f/2 is not going to turn out well. Manual focus takes a lot of practice to get right especially at wide open apertures. The slightest bit off and you miss the shot.

Anything shot in the church was dark, and not good.

This is an exposure problem, not a lens problem. The f/2 is capable of taking pictures in almost complete darkness, (on a tripod), with the right settings. What mode did you have the camera set on? Post a couple of pictures with the EXIF intact and we can take a look.

What amazed me was how FAST his focus was.

Canon is generally respected as having a very fast auto-focus system at least in its upper end models. However, I have seen studies showing that Pentax (at least the k-5) is more consistently accurate, just not as fast.

I'm kinda looking at the sigma 24-70 f/2.8, but wasn't sure if anyone could recommend for or against it ?

Here is the link to the review section on that lens. I do not have it, so I cannot speak to the quality. For weddings I would go with at least a two lens kit, one lens in the 17-50 range to cover the wide end and then something in the 50-135 or 200 range to get the long shots. In crowded receptions the 24mm is not going to be wide enough on aps-c.

I know a lot of that has to do with the iso, and his flash,

Correct, and also his experience. You could do the same with your k-5 and a good lens and flash. Don't be overawed by what you saw, he gets paid to do that so it had better work. Put a good flash and say the Pentax*16-50 on your k-5 and you could do the same or close enough that no one could tell.

It was ugly. Real ugly.

I suspect this has more to do with your experience level than the gear. You should be able to get very good quality images with the k-5 and the kit lens when using a flash if everything is set up properly. The key is practice and experimenting. I came away from some early shoots, a couple friends weddings like yourself, wondering why I had spent all this money on gear when my wife's P&S camera took better pictures. But you can improve, and you must remember it is not the gear, it is the photographer. People shot great images with fully manual cameras for many years because they studied, practiced and made the gear work.

[Tom S.]

I'm going to steer clear of the which lens is best argument, because it's like discussing politics - only worse.

However I will offer this: nothing will help unless you take your camera and use it in the conditions you speak off and then post an example of it here for folks to look at and give advice. Then take that advice and try it, and if you still aren't happy, post a picture again. Trying to help without having something to look at is (excuse the upcoming pun) a shot in the dark.

I'm not being negative, just trying to help! The only way to avoid a recurrence though it to get advice and then practice (repeat as needed). Like the man said when asked how to get to Carnegie Hall: "Practice.".

[SpecialK]

use my 50 because it has a fixed aperture...

Confusion of terms. The lens is neither fixed aperture nor fixed focus. It is a fixed focal length (does not zoom). A "fixed aperture" is one that can not be adjusted.

24-70 f/2.8. He called it a prime lens because the aperture stays at 2.8 no matter what his focal length is....

Well he's wrong :-) Again, confusion of terms. "Constant aperture" is the term for zoom lenses that do not change the minimum aperture when zoomed. A "prime" is a lens that only has one focal length and does not zoom, like the 50.

What lens do they make for us Pentax users that are capable of those results ?

Nothing focuses quickly in Pentaxland.

Many people like the Tamron 28-75, though the Sigma is slightly wider and that may be helpful.

[Isnwm]

I will post some pictures later. I haven't gotten them all uploaded on my computer yet. I'm making these posts from iPad/iPhone. The pictures I have are dark, blurry, grainy. Pretty much unusable. The only ones that turned out halfway decent were the ones with the 28-300 tamron. I was able to get the focus & flash okay. But I was frustrated by how slow my auto focus was. It was taking 2-3 seconds to AF. I can't shoot like that. I'd miss 90% of every candid shot I attempted. The only shots I made that were ok we're posed pictures. And even then, I didn't feel they were as sharp as they could've been. Or should've been. I did a boat load of research on the K-5 before getting it, and everyone said he was amazing. I know it's all my inexperience issues that's causing such poor results. But All I have are cheap lenses. I paid $180 for the 28-300 tamron. And $60 for the A50. I've been told to spend as much as I can afford on lenses. Everyone preaches about lens quality. It's all so confusing. I know the K5 isn't full frame, so do they make lenses specific to the K5 and it's sensor ? Or will all lenses be full frame and I just lose some width ? Sorry, I'm rambling. I'm just overwhelmed and looking for any advice possible.

[bassek]

Nothing focuses quickly in Pentaxland.

Some lenses focus faster than others. I assume this has something to do with the focus throw?
At least my F35-105 is really fast compared to the kit or the Sigma 180 macro which is really slow.
My other F's are also fast. EDIT: fast focus, not a fast lens!

Seb

[jatrax]

Newer lenses made for auto-focus tend (usually but not always) to focus faster than older ones because the focus throw is shorter. There are exceptions to this, as noted above many 'F' lenses are very quick. My F 70-210 is just "whir, bang, in focus", noisy but quick. Also, keep in mind the amount of light available makes a big difference, outside in sunlight things should be much faster, in low light all systems struggle though admittedly Pentax is a bit behind in this area.

The 'DA' line from Pentax is designed for aps-c sensors (which is what the k-5 has). Older lenses such as the 'FA' and 'F' lines were designed for full frame film cameras. There are two things to consider when using film era lens, first is that the image taken on aps-c will be a crop out of the center of the full image circle. In some cases this is a good thing because the center is usually the sharpest portion of the image circle. The second is that film deals with light differently, in particular the angle the light strikes film makes little difference, but it does make a difference on digital. So lenses designed for digital do a better job of correcting for this.

Photography is an art / science thing and there is an enormous learning curve. If you try to learn all of it at once you will get frustrated. Pick one thing, and figure out how to do that well. Then something else. For example, put your 50mm on and set the camera to Av mode. Find a stationary target, maybe a brick wall in good light. Take pictures of that wall with various aperture settings until you understand what the aperture control is doing. You will also be practicing your manual focusing at the same time.

There are people on this forum with 40-50 years of photo experience and all of them will tell you they are still learning.

If you want a good basic book that explains some of the principals of photography try "Understanding Exposure" by Bryan Peterson. I think 4th edition is just out this past winter. Oh, and read the manual again. You did read the manual, right?

[wildweasel]

Can't really add much to the above, but I can say the Tamron 24-70 is a fantastic lens. I got one a few months back and use it the most out of my dozen or so lenses. It is very fast to focus in pretty much all lighting conditions, is sharp enough wide open and goes super-sharp when stopped down a little, and is a pleasure to use. It is a big, heavy lens though, which I don't mind at all, but that might put some off.

[lytrytyr]

nothing focuses quickly in pentaxland.

The DA 70?

[Marc Sabatella]

I will post some pictures later. I haven't gotten them all uploaded on my computer yet. I'm making these posts from iPad/iPhone. The pictures I have are dark, blurry, grainy. Pretty much unusable.

As others have suggested, this is something like 99% technique, 1% equipment. Not fun to hear, I realize, but take it as a challenge - to learn to use your equipment more effectively. Again as others have said, seeing sample images would help. Most likely, it will turn out you are getting blur from not fast enough shutter speeds, resulting from their just not being enough light for the aperture and ISO you are using. As for noise, get used to it in low light photography - it's a fact of life. But also, learn how to work to the NR controls in your camera and PP software to minimize it as much as possible.

But I was frustrated by how slow my auto focus was. It was taking 2-3 seconds to AF. I can't shoot like that. I'd miss 90% of every candid shot I attempted.

So, you either switch to MF, or get good at anticipating and pre-focusing. But FWIW, superzooms are notoriously slow at focusing. DId you not get the kit lens (DA18-55) - with your camera? That would generally be more appropriate.

I know the K5 isn't full frame, so do they make lenses specific to the K5 and it's sensor ? Or will all lenses be full frame and I just lose some width ?

Unless you are already experienced with full frame cameras (eg, film cameras) and therefore have intimate knowledge of how different focal lengths "feel", then forget you ever heard of this. All lenses for your camera work exactly the same whether they are FF or not. There is no point in worrying about how that lenses would work on some other camera you don't own.

[selar]

Nothing focuses quickly in Pentaxland.

Try Sigma HSM, lightning quick on K5 with Sigma 70-200/2.8 HSM II.

[alphanerd]

I will post some pictures later. I haven't gotten them all uploaded on my computer yet. I'm making these posts from iPad/iPhone. The pictures I have are dark, blurry, grainy. Pretty much unusable. The only ones that turned out halfway decent were the ones with the 28-300 tamron. I was able to get the focus & flash okay. But I was frustrated by how slow my auto focus was. It was taking 2-3 seconds to AF. I can't shoot like that. I'd miss 90% of every candid shot I attempted. The only shots I made that were ok we're posed pictures. And even then, I didn't feel they were as sharp as they could've been. Or should've been. I did a boat load of research on the K-5 before getting it, and everyone said he was amazing. I know it's all my inexperience issues that's causing such poor results. But All I have are cheap lenses. I paid $180 for the 28-300 tamron. And $60 for the A50. I've been told to spend as much as I can afford on lenses. Everyone preaches about lens quality. It's all so confusing. I know the K5 isn't full frame, so do they make lenses specific to the K5 and it's sensor ? Or will all lenses be full frame and I just lose some width ? Sorry, I'm rambling. I'm just overwhelmed and looking for any advice possible.

It would still be very useful to see some examples, with EXIF intact. That will tell us what settings you were using.

Autofocus performance varies based on camera and lens. The K5 is Pentax's best autofocusing dSLR, but I'm not familiar with the tamron lens you mention. There are adjustments that you can make to help prevent back/front-focusing, which for my Tamron 18-200 greatly increased AF performance as well (but still not great). Obviously, the A50 f2 is manual focus, and there are various manual focus techniques that can be used to improve accuracy (plus practice!).

I tend to MF my AF lenses in various situations: Macrophotography and low light (especially staged work). Then again, I'm using a k10d

[TER-OR]

I rented the Sigma 28mm f1.8 and did the same thing indoors with no flash all weekend at a convention - hotel etc. Great lens for the spaces. It's a big mutha, but it's built for FF, so if Pentax ever goes that way it will work. It looks pretty on the K-5, too. It's not HSM, but the focus throw isn't huge, so it was a quick shot.


If not mentioned yet, the 18-135 is a very quick focus, too. Quite accurate and quiet to boot.


I am kind of dismayed he would call a constant-aperture zoom a prime lens, though. Those are fixed definitions.