Re: Takumar Pentax 6x7 tests RE: [ap-gto] [ap-ug] A colorful Southern Sky Beauty


Richard Crisp
 

No problem there Anthony except I did this about 15 years ago and I don’t see myself repeating the exercise. I’m just offering up what I have that I think is relevant.

 

 

 

From: main@ap-ug.groups.io <main@ap-ug.groups.io> On Behalf Of ROBERT WYNNE
Sent: Friday, April 30, 2021 3:47 PM
To: main@ap-ug.groups.io; ayiomamitis <anthony@...>
Subject: Re: Takumar Pentax 6x7 tests RE: [ap-gto] [ap-ug] A colorful Southern Sky Beauty

 

I was always taught the widest aperture was the worst aperture to capture a sharp image due a number of factors. The median apertures F5.6 - F8-11 were optimum unless you entered a F 64 club contest and then everything had to be in sharp focus plus a full range of black to white tones in the photograph. That did not include the selection of a subject of artistic merit. Then all criterion were met it was said you had a worthy photograph. All this technique has been lost over the years. -Best, Robert

On 04/30/2021 3:32 PM ayiomamitis <anthony@...> wrote:

 

 

Richard,

My RHA is at f3.8, my Tak FSQ is at f5 and my 130GT is at f6.3. I think a better (and fairer) comparison involving the Pentax 67 lenses would be at similar f/rations. Shooting wide open is effectively begging for a biased comparison. If we are happy shooting at f5 (ex FSQ), I am sure we can be equally happy shooting at f5 (or something close to it) with a Pentax 67 lens.

Anthony.

On 01-May-21 01:15, Richard Crisp wrote:

Note the lens tests I posted were shot at several different f/ratios 

“Corrected” by my iPhone



On Apr 30, 2021, at 3:05 PM, ayiomamitis <anthony@...> wrote:

Rolando,

Why shoot wide open (say f2.8) when our astrographs are f4 or slightly slower? I would rather see results at such f-ratios (ex f4 to f6.3) so that results can be that much more comparable.

Anthony.

On 01-May-21 00:48, Roland Christen via groups.io wrote:

Try shooting stars wide open with a color digital chip. You will see the limitations. I wish I had kept the result of my 90mm F2.8 Pentax lens - you would not believe how bad it is wide open.

 

Rolando

 

-----Original Message-----
From: Richard Crisp <rdcrisp@...>
To: main@ap-ug.groups.io; robert-wynne@...
Sent: Fri, Apr 30, 2021 3:28 pm
Subject: Takumar Pentax 6x7 tests RE: [ap-gto] [ap-ug] A colorful Southern Sky Beauty

Some years back I did some tests of a handful of Pentax6x7 lenses I had picked up on the cheap

 

Even though they aren’t very well corrected over an electronic imager’s broad spectral responsivity, it seemed if you stopped them down, used a single wavelength filter with a mono sensor, you could get pretty decent results

 

You might find the slide deck useful that I made

 

 

I was using an FLI ML4022 camera (KAI series sensor w/7.4 micron interline pixels).

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