Manual focus "normal" zoom

**mgvh** · 08-01-2016, 05:31 PM

Originally posted by m42man

Definitely a big drawback. Be careful with your FL guess though, as if you enter a value much higher than the actual value you risk amplifying your shake.

Either enter the shortest focal length - which is totally safe, and SR will be at full strength when shooting at the wide end - or you can use a simple formula. I'll definitely be accused of boring everyone if I reiterate it, but, don't worry, the answer is the same for all your lenses: 100mm.

Agree about the 75-150 though - I've had one from new and it's certainly sharp enough.

(By the way, it's been a long time - hello again everyone!)

Welcome back!
Yes, you're right, and I do not simply average the short/long focal length. Someone once gave a very sophisticated formula for working out the best focal length, but roughly it came down to setting it about 1/3 of the way higher of the total focal range. So, for my 70-210, I'll usually set it at 100 or 120mm. For the 75-150, at 100mm. For the 80-200, at 120mm.

volosong · 08-01-2016, 09:34 PM

Originally posted by Swift1

The Pentax 24-50mm f/4 is a good lens.

And you're not getting mine! At least until I'm pushing up daisies. Got my copy off the bay in anticipation of the K-1. The more I use this lens, the more I fall in love with it. Small, lightweight, quality construction, handles well. Only complaint I can make about it is the lack of a hood.

m42man · 08-01-2016, 11:17 PM - **2 Likes**

Originally posted by mgvh

Welcome back!
Yes, you're right, and I do not simply average the short/long focal length. Someone once gave a very sophisticated formula for working out the best focal length, but roughly it came down to setting it about 1/3 of the way higher of the total focal range. So, for my 70-210, I'll usually set it at 100 or 120mm. For the 75-150, at 100mm. For the 80-200, at 120mm.

Ta!

I think that someone was me, and the formula was 2*min*max/(min+max). So you're just right with you're settings.

Just to repeat a warning for everyone: if you input more than 2x the actual focal length, you will magnify any effects of shake.

**goatsNdonkey** · 08-02-2016, 08:31 AM

I like seeing the zoom recommendations in this thread!

As for SR settings. If one has the time to enter the focal length you're using the zoom at, picture by picture, is that ever wrong?

I can see how if one wants to be constantly and rapidly zooming around for reframing or other reasons having just one setting for a zoom lens would be an advantage, but if you have time to reset the SR to the zoom focal length you're actually using, why not?

**mgvh** · 08-02-2016, 09:48 AM

Originally posted by goatsNdonkey

I like seeing the zoom recommendations in this thread!

As for SR settings. If one has the time to enter the focal length you're using the zoom at, picture by picture, is that ever wrong?

I can see how if one wants to be constantly and rapidly zooming around for reframing or other reasons having just one setting for a zoom lens would be an advantage, but if you have time to reset the SR to the zoom focal length you're actually using, why not?

Yes, if you have time, then it is best to set SR to the actual focal length you are using.
Set your camera to remember the last location when you invoked the menu. Inputting focal length is in the 3rd panel of setup menu (on my K-30), so I just push the Menu button, go to the bottom to input focal length (so I go up one to make it go around to the bottom), and sets focal length. Not so bad, but when I'm in a hurry, I just use that proximate setting.

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08-01-2016, 05:31 PM	#16
mgvh Site Supporter Join Date: Sep 2010 Location: MD Photos: Gallery \| Albums Posts: 1,030	Originally posted by m42man Definitely a big drawback. Be careful with your FL guess though, as if you enter a value much higher than the actual value you risk amplifying your shake. Either enter the shortest focal length - which is totally safe, and SR will be at full strength when shooting at the wide end - or you can use a simple formula. I'll definitely be accused of boring everyone if I reiterate it, but, don't worry, the answer is the same for all your lenses: 100mm. Agree about the 75-150 though - I've had one from new and it's certainly sharp enough. (By the way, it's been a long time - hello again everyone!) Welcome back! Yes, you're right, and I do not simply average the short/long focal length. Someone once gave a very sophisticated formula for working out the best focal length, but roughly it came down to setting it about 1/3 of the way higher of the total focal range. So, for my 70-210, I'll usually set it at 100 or 120mm. For the 75-150, at 100mm. For the 80-200, at 120mm.

08-01-2016, 09:34 PM	#17
volosong Veteran Member Join Date: Sep 2006 Location: North Idaho Photos: Gallery Posts: 696	Originally posted by Swift1 The Pentax 24-50mm f/4 is a good lens. And you're not getting mine! At least until I'm pushing up daisies. Got my copy off the bay in anticipation of the K-1. The more I use this lens, the more I fall in love with it. Small, lightweight, quality construction, handles well. Only complaint I can make about it is the lack of a hood.

08-01-2016, 11:17 PM - 2 Likes	#18
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623	Originally posted by mgvh Welcome back! Yes, you're right, and I do not simply average the short/long focal length. Someone once gave a very sophisticated formula for working out the best focal length, but roughly it came down to setting it about 1/3 of the way higher of the total focal range. So, for my 70-210, I'll usually set it at 100 or 120mm. For the 75-150, at 100mm. For the 80-200, at 120mm. Ta! I think that someone was me, and the formula was 2minmax/(min+max). So you're just right with you're settings. Just to repeat a warning for everyone: if you input more than 2x the actual focal length, you will magnify any effects of shake.

08-02-2016, 08:31 AM	#19
goatsNdonkey Site Supporter Join Date: Jan 2016 Location: Fulton County, Illinois Posts: 3,729	I like seeing the zoom recommendations in this thread! As for SR settings. If one has the time to enter the focal length you're using the zoom at, picture by picture, is that ever wrong? I can see how if one wants to be constantly and rapidly zooming around for reframing or other reasons having just one setting for a zoom lens would be an advantage, but if you have time to reset the SR to the zoom focal length you're actually using, why not?

08-02-2016, 09:48 AM	#20
mgvh Site Supporter Join Date: Sep 2010 Location: MD Photos: Gallery \| Albums Posts: 1,030	Originally posted by goatsNdonkey I like seeing the zoom recommendations in this thread! As for SR settings. If one has the time to enter the focal length you're using the zoom at, picture by picture, is that ever wrong? I can see how if one wants to be constantly and rapidly zooming around for reframing or other reasons having just one setting for a zoom lens would be an advantage, but if you have time to reset the SR to the zoom focal length you're actually using, why not? Yes, if you have time, then it is best to set SR to the actual focal length you are using. Set your camera to remember the last location when you invoked the menu. Inputting focal length is in the 3rd panel of setup menu (on my K-30), so I just push the Menu button, go to the bottom to input focal length (so I go up one to make it go around to the bottom), and sets focal length. Not so bad, but when I'm in a hurry, I just use that proximate setting.