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Pentax Ashai Pentax Ghostless Filter (49 mm)

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4 11,118 Sun June 29, 2014
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Recommended By Average Price Average User Rating
75% of reviewers $15.75 6.67
Pentax Ashai Pentax Ghostless Filter (49 mm)
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Description:
Asahi Pentax Ghostless Filter (49 mm)

This filter was introduced at some point in the 1970s or possibly earlier as it is shown on a Spotmatic in the link below. It is beautifully made filter as were all Pentax products of this era. It was not SMC coated and is not related in any way to the current “ghostless” coatings Pentax is putting on its newest lenses. Instead of a flat surface, still found on most filters even today, the surface of this filter is curved. The curved surface of this U.V. filter is supposed to eliminate the ghost images which sometimes appear on film when pictures are taken against neon signs, street lights etc.
Check the link below for diagrams and technical details:

http://whitemetal.com/pentax/ap_filters/index.htm#Ghostless
Price History:



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Veteran Member

Registered: September, 2010
Location: Oregon
Posts: 495

1 user found this helpful
Review Date: June 29, 2014 I can recommend this item: No | Price: $1.00 | Rating: N/A 

 
Pros: Cool
Cons: Unnecessary in the modern age.

I bought it yesterday.

The box says Honeywell and the 'GHOSTLESS' on the end of the box is obviously a stamp rather than a sticker. UV is not mentioned.

The filter is embossed 49mm rather than 49Φ.

'ASAHI PENTAX 49mm UV GHOSTLESS JAPAN'

It masses 18.5 grams. I have no idea how jbondo arrived at 2 to 3 ounces.

It came with the airmail thin datasheet: 63007. If anyone asks I'll submit a copy.

The rest of the kit offered predated SMC Takumar.

Edit. My point is to add historical data.
   
Loyal Site Supportaxian

Registered: September, 2013
Location: Texas
Posts: 489
Review Date: December 7, 2013 I can recommend this item: Yes | Price: $22.00 | Rating: 7 

 
Pros: Serves intended purpose well. Still better than cheap modern filters.
Cons: Slight FL shift. Only in 49mm. Not suitable for use in rear filter lenses.

Information is scarce on these. I'll try to add to what the other reviewers have not covered.

These increase the apparent focal length of the lens by a tiny amount (~1-2mm) Not enough to notice unless you're looking for it. Not suitable for use in rear filter lenses.

When you can find these, it seems the "UV" type is the most often seen. The other types are more rarely seen.

The weight varies. On the low end, I have a "Daylight" weighing just 55g, and on the high end, a "UV" weighing 70g. The mounting cells appear to be identical, so as far as I can tell, the difference is due to the glass.

The coatings vary. I have one that appears to be completely uncoated (pure white reflection) and some have a whitish-purple that is a little better than the front elements of some older Super Takumars, and I have one that has a very effective coating that reflects a very muted blue-purple. I don't have any with coatings that resemble SMC, but the best one I have is actually quite good.

If you want to shoot vintage equipment and stay period correct, these are GREAT! If you are shooting digital, these are still as good or better than modern low-to-mid-end filters. They can't keep up with the best money can buy today, and you can only get them in 49mm, but overall pretty impressive for vintage filters. I wouldn't hesitate to use these in the field for protection purposes.
   
Senior Member

Registered: August, 2007
Location: Los Angeles
Posts: 233

2 users found this helpful
Review Date: October 17, 2012 I can recommend this item: Yes | Price: $30.00 | Rating: 8 

 
Pros: No reflections. Historical Value
Cons: Not multicoated or even coated

These ghostless filters are something of an obsession of mine ever since I initially heard about it. I went out of my way to get them and research them.

Pentax wanted to make a filter that minimized reflections (ghosts) due to the flat glass. This was before widespread use of multicoating. The way they work is that the glass is curved the same amount on both sides so the thickness of the glass is the same and no magnifcation is achieved. The benefit of doing this is that reflections (ghosts) project to a different location other than the focal plane. It works too, if you take some shots using a plain glass filter or even a modest quality coated filter on incoming headlights or lightbulbs at certain angles, you will see lots of reflections, with this filter you will see almost no reflections. But there are three main problems with this filter:

1. Making perfectly cut curved glass that was even throughout was expensive (more or less like making a lens element). That is why you don't see too many of them.

2. Multicoatings became more common (a good multicoated filter will also have almost no reflections despite the flat glass).

3. This filter being uncoated results in the loss of light transmittance.

Also if your lens wasn't really well multi-coated, you would still get reflections, which made it pointless. Finally, since Pentax had a patent to this and Nikon, et al didn't want to pay, they said it didn't work, and fanboys being what they are, took their word for it. (They said the same thing about multi-coating, until basically the patent expired and suddenly everyone had it.) The real killer of this idea was basically that flat multi-coated filters could be made a lot cheaper than a ghostless filter even without patent payments.

So lots of history with something apparently so simple.

PS - One company Hama (from Germany) did license the ghostless filters and they did multi-coat them, so if you really are interested, you can find some on sizes other than 49mm. Although as I mentioned, nowadays, a good multi-coated filter will work justs as well.
   
Pentaxian

Registered: February, 2008
Location: Waterloo, Ontario
Posts: 4,462
Review Date: March 16, 2011 I can recommend this item: Yes | Price: $10.00 | Rating: 5 

 
Pros: Well made
Cons: No SMC Coating

The Ghostless filter is one of those ideas that sound good in theory. I always wondered why the front element on all my lenses were curved yet all my filters were flat. I can’t honestly say I ever saw much of a difference with the "ghostless" filter on digital which is the only format in which I have ever used it. Perhaps it was more effective when used with film.

Lack of SMC coating has to be a bit of a drawback for this filter. Perhaps the curved surface was felt to allow greater light transmission.

In any case they are not made any more so one can only assume they either didn’t work well or didn’t sell well. Something of a novelty item and I recommend it with reservations for the Pentax collector only. Although it's beautifully made it is probably not much good for anything more than a simple protection filter.
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