Returned K5 - Where to now?


timbo

Link Posted 20/05/2011 - 08:07
With regards to IQ I have no problem whatsoever with Pentax cameras, and poor image quality is usually down to my technique

I have A2 images on the wall of my dining room taken on my Pentax K-7, and they are still amazingly sharp at that size. I imagine the quality will be even better from a K-5.

I think there are three main ways for anybody to improve their image quality. In rapidly increasing order of cost these are - improve their technique, get (and use!!) a tripod/monopod, buy better quality lenses.
Tim

http://www.timpile.co.uk

johnriley

Link Posted 20/05/2011 - 08:12
Smeggypants wrote:
I thought DOF was down to the focal length, not the size of the sensor ???

Only in a simplistic sense, in fact it's down to magnification. It relates to a lens focal length but also the format it is projecting its image onto.

This is why different formats have different "standard" lenses to give the normal field of view. A 35mm film body has a standard lens of 50mm (should be 43mm really), but a 50mm lens on a 110 film camera is a telephoto. Both lenses still have the same DOF though, both being 50mm. So the telephoto lens on a small format has the same DOF as a standard lens on the larger format.

The Minox "spy camera" has a standard lens of 15mm, which has immense DOF. My Pentax I-10 has a zoom from 5-25mm and also has immense DOF.

That's why compact digital cameras are superb for detailed macro shots.
Best regards, John

bretbysteve

Link Posted 20/05/2011 - 09:58
Sorry to say this, but judging by the photos posted (which are awful) I cannot help but feel this is yet another case of someone who knows very little about what they are doing and then critises the equipment. The interent is full of this.

thoughton

Link Posted 20/05/2011 - 10:10
bretbysteve wrote:
Sorry to say this, but judging by the photos posted (which are awful) I cannot help but feel this is yet another case of someone who knows very little about what they are doing and then critises the equipment. The interent is full of this.

A bit harsh perhaps, especially to a newcomer to our forum. Judging from his avatar NikontoPentax knows how to take a photograph. (I assume that is his own photo).
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27, Macbook Pro 17, iPad, iPhone 3G
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Last Edited by thoughton on 20/05/2011 - 10:11

fatspider

Link Posted 20/05/2011 - 10:23
thoughton wrote:
bretbysteve wrote:
Sorry to say this, but judging by the photos posted (which are awful) I cannot help but feel this is yet another case of someone who knows very little about what they are doing and then critises the equipment. The interent is full of this.

A bit harsh perhaps, especially to a newcomer to our forum. Judging from his avatar NikontoPentax knows how to take a photograph. (I assume that is his own photo).

Agreed,
Tact and diplomacy would be a good idea or we may find "Dave" leaves for another forum with the name NikontoPentaxtoCanon So it up to us as Pentax Users to save him from a fate worse than death

Dave: are you sure the noise you can hear is not the sensor moving about, that has a knocking sound and is quite normal. Some lenses do have more play than others against the body but I would have thought a DA70mm should be spot on.
My Names Alan, and I'm a lensaholic.
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DaveN

Link Posted 20/05/2011 - 12:11
bretbysteve wrote:
Sorry to say this, but judging by the photos posted (which are awful) I cannot help but feel this is yet another case of someone who knows very little about what they are doing and then critises the equipment. The interent is full of this.

I don't claim to be a pro or anywhere near that. Photography is a hobby and I enjoy it. I have owned and used at least 3 DSLR. (Started with a borrowed Sony A100, then was given a D60 and finally my own D5000).

The pictures I took with the K5 was purely for testing as it became obvious it had the stain issue and had to be returned. You may think whatever of the photos I posted, I don't have to justify them.
Discovering the joys of photography with Pentax

SteveEveritt

Link Posted 20/05/2011 - 18:37
NikontoPentax don't jump ship quite yet, get your K-5 replaced at SRS and you will be overjoyed. I have a K-7 and if the opportunity arose I would not hesitate to buy.
My Flickr link

"Life is what happens to you while you're busy making other plans" (John Lennon)

DaveN

Link Posted 25/05/2011 - 21:56
Just received my K5 number 2 and I am happy to report a quick test shows no stains (Serial No 400XXX, build date Feb 2011). Hope tomorrow's weather is nice for a walk around!

Thank you all esp to the 2 gentleman who PM me. I can wait to get snapping
Discovering the joys of photography with Pentax

Smeggypants

Link Posted 26/05/2011 - 00:19
NikonToPentax wrote:
Just received my K5 number 2 and I am happy to report a quick test shows no stains (Serial No 400XXX, build date Feb 2011). Hope tomorrow's weather is nice for a walk around!

My K-5s arebuilt around that time and work great.

Quote:


Thank you all esp to the 2 gentleman who PM me. I can wait to get snapping

Enjoy. I'm loving the K-5 more than ever
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Smeggypants

Link Posted 26/05/2011 - 00:35
johnriley wrote:
Smeggypants wrote:
I thought DOF was down to the focal length, not the size of the sensor ???

Only in a simplistic sense, in fact it's down to magnification. It relates to a lens focal length but also the format it is projecting its image onto.

This is why different formats have different "standard" lenses to give the normal field of view. A 35mm film body has a standard lens of 50mm (should be 43mm really), but a 50mm lens on a 110 film camera is a telephoto. Both lenses still have the same DOF though, both being 50mm. So the telephoto lens on a small format has the same DOF as a standard lens on the larger format.

The Minox "spy camera" has a standard lens of 15mm, which has immense DOF. My Pentax I-10 has a zoom from 5-25mm and also has immense DOF.

That's why compact digital cameras are superb for detailed macro shots.

Still trying to get my head around this ...

I do understand the FOV differences on different formats. FF being 1.5 times APS-C, etc

However I was under the impression that, for example, if the subject is 10 feet away and the DOF is from 9 feet to 11 feet, then that would be the case, all settings and focal length being equal, on both the FF and APS-C camera. the onyl difference being that FOV is different.

Is that the case or am I missing something?

just looking through K10Ds link
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

rparmar

Link Posted 26/05/2011 - 03:45
Depth of field is dependent on exactly four parameters: the focal length, subject distance, aperture (F number) and the circle of confusion diameter. The first three are objective measures but the last is subjective, which makes sense when you consider how much something is out of focus is an individual determination. Only objects exactly at the focus distance are in focus; everything else is out of focus to some extent or another.

The circle of confusion is the smallest point that can be clearly discerned by the average person under normal conditions. The Zeiss formula relates this directly to the diagonal of the sensor.

So yes, DOF is certainly dependent on sensor size, as common sense observations show. The smaller the sensor the greater the depth of field, all other parameters being equal.
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Smeggypants

Link Posted 26/05/2011 - 04:33
rparmar wrote:
Depth of field is dependent on exactly four parameters: the focal length, subject distance, aperture (F number) and the circle of confusion diameter. The first three are objective measures but the last is subjective, which makes sense when you consider how much something is out of focus is an individual determination. Only objects exactly at the focus distance are in focus; everything else is out of focus to some extent or another.

The circle of confusion is the smallest point that can be clearly discerned by the average person under normal conditions. The Zeiss formula relates this directly to the diagonal of the sensor.

So yes, DOF is certainly dependent on sensor size, as common sense observations show. The smaller the sensor the greater the depth of field, all other parameters being equal.

Ahhh!! Thanks rparmar. I think you've provided the bit I'm missing. i.e the circle of confusion diameter is dependent on sensor size.

I had known the following ...

Quote:
Depth of field is dependent on exactly four parameters: the focal length, subject distance, aperture (F number) and the circle of confusion diameter.

but I didn't link the circle of confusion diameter being proportional to the sensor size.

Thanks for that. Cheers
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

johnriley

Link Posted 26/05/2011 - 08:00
The circle of confusion is a parameter that can be decided upon. Make your requirement for this smaller and you need a higher resolution lens.

In general, smaller formats have a smaller circle of confusion to make a standard print, say 12" x 16", of the the same quality. This means that lenses for smaller formats need to have higher resolution, and they do.

So 645 and 67 lenses do present lower figures regarding MTF as they are targeted at their respective formats. An APS-C lens will need more resolution.

Also, Depth of Focus becomes more critical as formats become smaller, because it reduces, whereas depth of field increases. Depth of Focus is the amount of leeway at the film/sensor plane and smaller formats need more precise location of the film or sensor. There is no free lunch when balancing design in cameras and lenses.

This is why the 110 (and 126) format failed as a precision format - there is no pressure plate in the platic film cartidge and therefore the film plane location was imprecise.

For those who are busy polishing mirrors and cutting down focusing screens, it's a point that should be borne in mind.
Best regards, John

Gwyn

Link Posted 26/05/2011 - 09:28
NikonToPentax wrote:
Just received my K5 number 2 and I am happy to report a quick test shows no stains (Serial No 400XXX, build date Feb 2011). Hope tomorrow's weather is nice for a walk around!

Thank you all esp to the 2 gentleman who PM me. I can wait to get snapping

Congratulations! I hope you now get some real enjoyment out of it .

i-Berg

Link Posted 26/05/2011 - 10:40
Well glad that's worked out then! Happy shooting.
http://www.pbase.com/iberg
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