LONG Hood on an A Series 50mm f/1.4

**UncleVanya** · 10-08-2015, 10:00 AM

For grins I decided to mount my SMC A series 50mm f/1.4 on the K3 and have a little fun. I wanted to see how long a hood was too long. I had a couple of hood lying around and thought I would try them out. I started with the longest 49mm native threaded hood I had - a genuine Pentax metal hood designed to fit the Takumar 135mm f/3.5 and the f/5.6 200mm lenses. The hood is at least as long as the lens which makes it look quite funny mounted there but what the heck.

Imagine my surprise when I put the camera to my face and found no viewfinder vignetting. I then took the camera outside and did a series of sky shots with and without the hood. Upon reviewing the images I can not find any evidence the hood caused any vignetting over and above the norm for the lens. All shots were made with the K3 in JPG mode some with and some without the filter. Attached are a couple I selected from the batch. I'll be curious what you guys see.

Attached Images

View Picture EXIF

View Picture EXIF

bertwert · 10-08-2015, 10:10 AM

I think I see some small vignetting is the second photo.
Might just be me though

pacu · 10-08-2015, 10:35 AM

I think the second picture has a notch more vigneting than the first. If you measured it, I think it would be about 20% to 30% more, just barelly perceptible. The uniformity of brightness is better in first picture, in the second you start to see corners differentiate from the center.

**UncleVanya** · 10-08-2015, 10:45 AM

You guys have better eyes and or monitors than I do. You nailed it. The 2nd picture is the one with the hood. In any case the hood is exceptionally long and the effect is modest even wide open. I am very surprised. I may try again with the F 50 f/1.7 and see if that has any issues.

bertwert · 10-08-2015, 11:10 AM

Originally posted by UncleVanya

You guys have better eyes and or monitors than I do. You nailed it. The 2nd picture is the one with the hood. In any case the hood is exceptionally long and the effect is modest even wide open. I am very surprised. I may try again with the F 50 f/1.7 and see if that has any issues.

I think it's my eyes not my monitor

---------- Post added 08-10-15 at 12:12 ----------

Originally posted by UncleVanya

The hood is at least as long as the lens which makes it look quite funny mounted there but what the heck.

Have you got a picture of the hood on the lens?

**UncleVanya** · 10-08-2015, 11:19 AM

Originally posted by bertwert

I think it's my eyes not my monitor

---------- Post added 08-10-15 at 12:12 ----------

Have you got a picture of the hood on the lens?

Here you go...

---------- Post added 10-08-15 at 02:20 PM ----------

That's a slip-on cap made from a Pentax Binocular Objective lens cover BTW...

**Lowell Goudge** · 10-08-2015, 12:28 PM

There is a file I uploaded many years ago now. Do a search for hoodcalc.zip

It gives the hood length, based upon hood diameter and format of sensor, for any focal length. One word of caution. In using it you need to subtract the front element recess distance from the total length it gives.

Also, don't trust your eyes.

Use your photo editor to measure the greyscale value in the centre and corner of the images you take, using normal contrast JPEG, and exposing for the sky, every 45 greyscale value in the middle of the range (from about 40-210 grey scale is 1 full stop

stevebrot · 10-08-2015, 01:58 PM

I have been using a round metal "tele" hood on my 50mm lenses on APS-C for some time. Performance is much better than with the collapsible rubber hoods intended for that focal length on FF.

Steve

**K-Three** · 10-08-2015, 07:07 PM

I frequently add a little corner vignetting in PP
Looks like you found a way to automate the process!

**Lowell Goudge** · 10-08-2015, 10:05 PM

Originally posted by K-Three

I frequently add a little corner vignetting in PP
Looks like you found a way to automate the process!

Actually no. The 50/1.4 design is known for vignetting wide open

Stop down to f2.8 and it all goes away

mtux · 10-08-2015, 11:27 PM

Originally posted by UncleVanya

For grins I decided to mount my SMC A series 50mm f/1.4 on the K3 and have a little fun. I wanted to see how long a hood was too long. I had a couple of hood lying around and thought I would try them out. I started with the longest 49mm native threaded hood I had - a genuine Pentax metal hood designed to fit the Takumar 135mm f/3.5 and the f/5.6 200mm lenses. The hood is at least as long as the lens which makes it look quite funny mounted there but what the heck.

I've been using a third party screw in long hood, almost as long as yours on both A50/1.4 and FA50/1.4 with no issues.

pathdoc · 10-09-2015, 04:23 AM

Originally posted by Lowell Goudge

The 50/1.4 design is known for vignetting wide open. Stop down to f2.8 and it all goes away

Of course if you're using it in low light or against a dark background, chances are the vignetting blends in and gets lost anyway.

wkraus · 10-09-2015, 10:03 AM

I suggest you redo the test at f/11. You might be in for a surprise.

**UncleVanya** · 10-09-2015, 11:14 AM

Originally posted by wkraus

I suggest you redo the test at f/11. You might be in for a surprise.

What do you predict?

wkraus · 10-09-2015, 11:45 AM

Originally posted by UncleVanya

What do you predict?

Dark corners--unless I'm in for a surprise!
Do you own a film body?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
For Sale - Sold: Pentax F series 50mm 1.4 prime lens Lowered Price	17dew	Sold Items	11	09-15-2015 06:39 PM
Using an F-series lens with an 'A' setting on a Pentax dSLR	Ex-Camera	Pentax SLR Lens Discussion	4	09-10-2015 05:58 PM
For Sale - Sold: Pentax FA Series Lens: 31mm f/1.8 Ltd & 50mm f/1.4 with hood	anirban	Sold Items	4	08-02-2014 02:13 PM
Series FA and A 50mm f/1.4	metalfab	Pentax SLR Lens Discussion	6	03-29-2008 05:53 PM

10-08-2015, 10:10 AM	#2
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,173	I think I see some small vignetting is the second photo. Might just be me though

10-08-2015, 10:35 AM	#3
pacu Forum Member Join Date: Dec 2014 Posts: 91	I think the second picture has a notch more vigneting than the first. If you measured it, I think it would be about 20% to 30% more, just barelly perceptible. The uniformity of brightness is better in first picture, in the second you start to see corners differentiate from the center.

10-08-2015, 10:45 AM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401 Original Poster	You guys have better eyes and or monitors than I do. You nailed it. The 2nd picture is the one with the hood. In any case the hood is exceptionally long and the effect is modest even wide open. I am very surprised. I may try again with the F 50 f/1.7 and see if that has any issues.

10-08-2015, 11:10 AM	#5
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,173	Originally posted by UncleVanya You guys have better eyes and or monitors than I do. You nailed it. The 2nd picture is the one with the hood. In any case the hood is exceptionally long and the effect is modest even wide open. I am very surprised. I may try again with the F 50 f/1.7 and see if that has any issues. I think it's my eyes not my monitor ---------- Post added 08-10-15 at 12:12 ---------- Originally posted by UncleVanya The hood is at least as long as the lens which makes it look quite funny mounted there but what the heck. Have you got a picture of the hood on the lens?

10-08-2015, 12:28 PM	#7
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	There is a file I uploaded many years ago now. Do a search for hoodcalc.zip It gives the hood length, based upon hood diameter and format of sensor, for any focal length. One word of caution. In using it you need to subtract the front element recess distance from the total length it gives. Also, don't trust your eyes. Use your photo editor to measure the greyscale value in the centre and corner of the images you take, using normal contrast JPEG, and exposing for the sky, every 45 greyscale value in the middle of the range (from about 40-210 grey scale is 1 full stop

10-08-2015, 01:58 PM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I have been using a round metal "tele" hood on my 50mm lenses on APS-C for some time. Performance is much better than with the collapsible rubber hoods intended for that focal length on FF. Steve

10-08-2015, 07:07 PM	#9
K-Three Loyal Site Supporter Join Date: May 2014 Location: Pugetopolis, WA Photos: Gallery Posts: 938	I frequently add a little corner vignetting in PP Looks like you found a way to automate the process!

10-08-2015, 10:05 PM	#10
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by K-Three I frequently add a little corner vignetting in PP Looks like you found a way to automate the process! Actually no. The 50/1.4 design is known for vignetting wide open Stop down to f2.8 and it all goes away

10-08-2015, 11:27 PM	#11
mtux Veteran Member Join Date: Apr 2013 Location: the Netherlands Photos: Gallery \| Albums Posts: 2,444	Originally posted by UncleVanya For grins I decided to mount my SMC A series 50mm f/1.4 on the K3 and have a little fun. I wanted to see how long a hood was too long. I had a couple of hood lying around and thought I would try them out. I started with the longest 49mm native threaded hood I had - a genuine Pentax metal hood designed to fit the Takumar 135mm f/3.5 and the f/5.6 200mm lenses. The hood is at least as long as the lens which makes it look quite funny mounted there but what the heck. I've been using a third party screw in long hood, almost as long as yours on both A50/1.4 and FA50/1.4 with no issues.

10-09-2015, 04:23 AM	#12
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by Lowell Goudge The 50/1.4 design is known for vignetting wide open. Stop down to f2.8 and it all goes away Of course if you're using it in low light or against a dark background, chances are the vignetting blends in and gets lost anyway.

10-09-2015, 10:03 AM	#13
wkraus Pentaxian Join Date: Jan 2013 Location: Near Vienna, Austria Photos: Gallery Posts: 2,059	I suggest you redo the test at f/11. You might be in for a surprise.

10-09-2015, 11:14 AM	#14
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401 Original Poster	Originally posted by wkraus I suggest you redo the test at f/11. You might be in for a surprise. What do you predict?

10-09-2015, 11:45 AM	#15
wkraus Pentaxian Join Date: Jan 2013 Location: Near Vienna, Austria Photos: Gallery Posts: 2,059	Originally posted by UncleVanya What do you predict? Dark corners--unless I'm in for a surprise! Do you own a film body?