How to select the appropriate lens hood?

z3r01 · 11-02-2009, 05:24 AM

Hi there everyone, I have a SMC Takumar 35mm f3.5 lens and a Super Tak 55mm f1.8 lens and I have read articles upon articles stating the usefulness of a lens hood. However, I am at a lost as to what kind of lens hood would be appropriate for my SMC Tak 35mm and the Super Tak 55m. I have searched around for info but still, am unable to find any info about it. Also, I understand that it has been advised by many, to use a lens hood for wide angle lenses, but in your own opinion, would it be good to get a hood for the Super Tak 55mm?

Sorry for asking so many questions. I am very new to all of these and am pretty excited to know more and I wish someone could enlighten me. Thank you.

*Wheatfield* · 11-02-2009, 06:51 AM

Presuming you are mounting these things to a DLSR, then you want a lens hood designed for a longer lens.

z3r01 · 11-02-2009, 07:07 AM

Hi wheatfield, I am using both these lenses with a Spotmatic SP.

*geauxpez* · 11-02-2009, 08:29 AM

If you want a decent hood to use for the field, I recommend the Hoya hood. Rubber with 3 positions to cover different focal lengths, thus it should work interchangably for both lenses. The downside (which is why I mention field use) is that you can't put a lens cap on your lens while using it. I tend to leave lens caps off while out shooting and put them on for storage, so it isn't a problem for me.

Lowell Goudge · 11-02-2009, 08:36 AM

you might want to try this link

Custom lens hoods

there was also a spreadsheet called Hoodcalc.xls but I can't find a link any longer.

note that when making the calculation, the lens diameter is the front element diameter not the filter diameter and the length will be from the plane of the front element not the filter ring. You will need to estimate somewhat the depth of recess of the front element.

z3r01 · 11-02-2009, 09:03 AM

Hi geauxpez, thanks for the information. I checked out the hoya rubber hood, seems pretty good but the only downside, as you have said, is that I cannot use it together with my filters. Seems like I got to think about whether or not I want to use both the hood and filter together or just either one. Thanks a lot for the info still.

Hi Lowell Goudge, wow, that sounds Greek to me, but it is great to learn more about this since I just got started with this hobby. I think I know what you are talking about. Will try and figure this out. Thanks you.

I truly appreciate the advice that you all have given me. Thank you.

Fixcinater · 11-02-2009, 09:56 AM

You can check on KEH.com to see if there are any original Pentax hoods floating around for those lenses.

Personally, on my S-M-C 35mm f/3.5, I haven't needed a hood (using my hand to block the sun has sufficed), but the 55mm f/1.8 would benefit greatly.

*reeftool* · 11-02-2009, 10:34 AM

I had a collapsable lens hood I bought at Ritz many years ago on my 55mm Tak for years. The slip on cap fit on nicely. It also was threaded for a filter so any clip fit lens cap should work. It finally came apart from age as the rubber became brittle and cracked. Ritz is gone now (at least around here) but maybe their online store still sells it.

*geauxpez* · 11-03-2009, 06:32 AM

Originally Posted by z3r01

Hi geauxpez, thanks for the information. I checked out the hoya rubber hood, seems pretty good but the only downside, as you have said, is that I cannot use it together with my filters. Seems like I got to think about whether or not I want to use both the hood and filter together or just either one. Thanks a lot for the info still.

The issue with this hood is really with lens caps and not filters. Since it is a screw-in hood, it will screw into the threads if filters. Lens caps on the other hand....

*reeftool* · 11-03-2009, 08:45 AM

The one I had has threads for a filter. Thats another problem of not having camera stores around, you never know exactly what you are going to get until it arrives and a cheap item like a collapsable rubber lens hood isn't worth the hassle of sending back and the shipping will cost more than the product. B&H has pages of lens hoods on their website as do other vendors from collapsable rubber to metal.

z3r01 · 11-04-2009, 02:01 AM

Hi geauxpez, oh I must have read it wrongly. My bad. I read it as filter instead of lens cap. My apologies. Hmm I can still live with the fact that I have to go without the lens cap. Anyways, I am not too sure about the exact size to get. For filters, my 55mm Super Tak uses a 49mm size filter, that I know. But as for lens hood, should it be 55mm instead? Please bear with me for asking so many questions. Thank you.

Hi reeftool, yeah it can be a little frustrating when all I can depend on is guess work. I am having problems determining the right size of the lens hood because I am using film, I really hope I don't get one that is oversized at the front, resulting in the lens hood being part of the picture. Don't know if I am making any sense here. hmmmm...

Lowell Goudge · 11-04-2009, 06:51 AM

I went back and looked again for the calculations for hood length.

I can no longer find the spreadsheet Hoodcalc.XLS on the web, or the download version Hoodcalc.zip.

It was developed by someone named J.C. Oconnell in 2000,

BUT in order to calculate hood length, you need to know the folllowing.

- the diameter of the front element (not the filter but the actual front element excluding the body of the lens)
- the hood diameter
- the field of view of the lens (for the format you intend to use)

If you know the field of view (FOV) for the lens, from the lens data sheet you can skip the next step, but if you don't know the field if view it can be calculated as follows

Field of view = 2 x arctan( dimension / 2 / focal length)

where dimension is the distance across the sensor (usually diagonal for round hoods), use mm as the units. Note you can use the formula to calculate tulip hoods also but you need to do a lot of geometry.

you can then calculate the length of the lens hood as follows

Hood length = ( hood diameter / 2 - front element diameter / 2) / tan(FOV)

Note that the hood length is from the center of the front element, and you need to consider that many lenses have the element recessed, therefore if you make the hood exactly the length predicted in the calculation, when you mount it on the lens it will be too long due to the recessed element.

*geauxpez* · 11-05-2009, 04:00 AM

If you know the angle of view of your lenes, you can use this guide. THere is also a chart on the back of the hood box.

Also from the back of the box: on 35mm cameras, the fully-extended position covers 70mm, Mid-way covers 55-70mm and the "wide angle" position covers 35-50mm.

BTW: I bought 2 for less than $20 on the auction site.

georgweb · 11-05-2009, 05:28 AM

Hello z3rxavida (i changed your name just for fun .-)

here's a ways to check your hood Ohne_mit_Sonnenblende on Flickr - Photo Sharing!

I for one only use metal srew-in hoods with a snap-cap. Filters go in between if necessary or on top if lazy. If you have a snap cap which can't scratch the lens when flying around loose you can be quite sure to just use the equipment and never worry about scratching the lens - don't need a filter for protection.

My most used hood is about 2cm long and screws in 55mm (I'm using steprings for 49mm and 52mm lenses) and has 58mm on the front.

Good luck,
G8akjxc8954739 :-)

z3r01 · 11-05-2009, 05:56 AM

Hi Lowell Goudge, yeah that is quite a bit of mathematics involved. Think I'll be able to get past that, provided I do not get the wrong measurement from the wrong part. lol Thanks a lot for helping me dig out that whole load of information.

Hi geauxpez, I see I see, will try and find out what are the angle of view of the 2 lenses. I checked out the rubber Hoya hoods, looks pretty good but somehow, something in me is itching to find the original Pentax hoods and it is driving me crazy! The bay is probably a good area to look for it, if not then I guess it would have to be the Hoya hood. Thanks for the advice.

Hi G8akjxc8954739 aka georgweb. = ) I got a lil lost when I read your guide on how to check the hood, but I think I get it, it is really informative. Thanks for your advice too. I really appreciate all the help that everyone has given me.

Thanks!