Comments made by johnriley - Page 129

Topics Created Topics Contributed Forum Comments Photo Comments

All Forum Comments

There is also the problem of focus shift. Lenses can change the point of focus when stopped down. They more often than not also change the point of focus (very dramatically) when zoomed.

Fortunately, the amount of precision we can achieve is sufficient to ensure top quality results.

Comment by johnriley posted on Focusing issues on Pentax cameras at 26/07/2017 - 15:11

There seems to be some confusion in this thread. The macro lens shown is an FA not a D-FA and is from a totally different era to the WR lens mentioned.

If the OP can confirm the model details I'll change the heading for you.

Comment by johnriley posted on Lenses for sale: D-FA 100 mm 2.8 Macro and DA 55-300 ED at 26/07/2017 - 09:07

Quote:
What's the vibe on distance to the subject? Do the results work better if it's up close than further away etc?

And What's the consensus around zoom lenses? If you have a 55-300, where does one look across the focal range to undertake this test?

You've revealed a central issue with the whole process of AF. If you were to routinely use say a 55-300mm lens at 200mm and distances of about 30 feet, then it would make great sense to carry out the calibration at those settings, but of course we use these lenses at all focal lengths and many different distances. We only have one AF setting, so I would test at various points in the range and then apply an average correction. It could take some time.....

Comment by johnriley posted on Focusing issues on Pentax cameras at 26/07/2017 - 09:02

Are these messages relevant to something you are in communication about? Or spurious spam messages?

Please make a report by using the report problem link at the bottom of this page. The more specific detail you give the easier looking into it will be.

Comment by johnriley posted on More messaging issue? at 24/07/2017 - 13:23

Please don't quote spam posts, it increases the exposure of the spammer. It also means it needs removing as well as the spam, thus doubling the amount of work.

Comment by johnriley posted on For sale: Pentax K-1 Body and Lenses. at 24/07/2017 - 09:26

It would be nice if they would come clean and just explain what their problem really is. It's hard to bluff these days because people don't stand for it like they might at one time.

One answer is the Pentax Q with the 15-45mm lens, equivalent to more than your 70-200mm lens and hardly anything that will cause alarm bells to ring. f/2.8 all the way as well!

Comment by johnriley posted on What is a Professional lens..? at 21/07/2017 - 18:15

No, you haven't. Let's have less of the insults please - send me a PM if anyone has doubts about a post.

Financial advisers are allowed to be photographers!

Comment by johnriley posted on Forum member "robbiec"? at 21/07/2017 - 11:29

The descriptions of excellence are against the potential of the camera used, not an absolute value. It's not connected to price point in terms of performance. Price only becomes part of the Value For Money equation, but that's not just about price.

So a lens tested on a 16MP camera will deliver different figures to one tested on a 36MP camera, and the difference is taken into account. Of course two 16MP cameras can be compared directly.

Comment by johnriley posted on Irix 11mm Firefly at 20/07/2017 - 23:03

We don't need to complicate things. Working in sRGB throughout gives excellent results without agonising over it. There are some more advanced techniques that involve using CMYK or Lab modes, but for most it won't be needed.

Comment by johnriley posted on Photoshop photography Plan £69.99 for 12mths! at 18/07/2017 - 21:51

One 2nd January, a few years back, we travelled from Manchester to Portmeirion through blizzards. Once there, it was clear skies and warm sunshine. The area is a small micro-climate all of its own as it is so sheltered.

So the chances of good weather are very high!

Comment by johnriley posted on Portmeirion at 18/07/2017 - 21:49

Proudly supporting Pentax User

johnriley

All Forum Comments

All Forum Comments

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

Proudly supporting Pentax User